JP4876680B2 - Driving method of liquid crystal display device assembly - Google Patents

Description

  The present invention relates to a method for driving a liquid crystal display device assembly.

  In the liquid crystal display device, the liquid crystal material itself does not emit light. Therefore, for example, a direct type planar light source device (backlight) that irradiates the display area of the liquid crystal display device is disposed on the back surface of the display area. In the color liquid crystal display device, one pixel is composed of, for example, three subpixels of a red light emitting subpixel, a green light emitting subpixel, and a blue light emitting subpixel. Then, the liquid crystal cell constituting each pixel or each sub-pixel is operated as a kind of light shutter (light valve), that is, by controlling the light transmittance of each pixel or each sub-pixel. An image is displayed by controlling the light transmittance of illumination light (for example, white light) emitted from the light source device.

  Conventionally, a planar light source device in a liquid crystal display device assembly illuminates the entire display area with uniform and constant brightness. However, the planar light source device has a configuration different from such a planar light source device, that is, a plurality of planar light source devices. For example, Japanese Unexamined Patent Application Publication No. 2005-17324 discloses a planar light source device having a configuration in which the distribution of illuminance in a plurality of display area units constituting a liquid crystal display device is changed. The planar light source unit disclosed in Japanese Patent Application Laid-Open No. 2005-17324 includes a red light emitting diode, a green light emitting diode, and a blue light emitting diode. Then, illumination light is emitted from white light with high color purity obtained by mixing red light emitted from the red light emitting diode, green light emitted from the green light emitting diode, and blue light emitted from the blue light emitting diode. It is said.

  By the way, the light emitting diode generates heat during driving. Even when driving under the same conditions, as a result of heat generation, the Vf characteristic fluctuates and the light output from the light emitting diode decreases, but the rate of decrease is as follows: red light emitting diode, green light emitting diode, Different for blue light emitting diodes. Therefore, white light as illumination light is obtained by mixing the light of each color emitted from the red light emitting diode, green light emitting diode, and blue light emitting diode. The chromaticity and white balance of this white light (color Variations in temperature).

  Therefore, in the technique disclosed in Japanese Patent Application Laid-Open No. 2005-17324, the amount of drive current detected by the drive current detection unit is fed back to the drive control unit, and the result of comparison between the amount of drive current fed back and a predetermined amount of current. Based on the above, the white balance of the display image is controlled by changing the drive control signal to control the light emission amounts of the three color light emitting devices.

On the other hand, controlling the surface light source device based on the method described below is disclosed, for example, in JP-A-11-109317. That is, the maximum luminance of the light source constituting the planar light source device is set to Y _max, and the maximum value (specifically, for example, 100%) of the light transmittance (aperture ratio) of the pixel in the display area is set to Lt _max . Further, when the light source constituting the planar light source device has the maximum luminance Y _max , the light transmittance (aperture ratio) of the pixel for obtaining the display luminance y ₀ in the display area is Lt ₀ . Then, in this case, the light source luminance Y ₀ of the light source constituting the planar light source device is
Y ₀ · Lt _max = Y _max · Lt ₀
It may be controlled so as to satisfy A conceptual diagram of such control is shown in FIGS. 7A and 7B. Here, the light source luminance Y ₀ is changed for each frame in the image display of the liquid crystal display device.

JP-A-2005-17324 JP-A-11-109317

  As described above, in a planar light source unit that uses a light emitting diode as a light source, characteristics such as luminance of the light source change with time, and each planar light source unit corresponds to such a characteristic change of the light source. The method of appropriately measuring the light emission state, brightness, chromaticity, and other characteristics of the light source constituting the light source and optimally adjusting the light emission state, brightness, chromaticity, etc. of the light source constituting each planar light source unit As far as the inventor investigated, it is not known.

  Accordingly, an object of the present invention is to provide a liquid crystal display device assembly including a transmissive liquid crystal display device and a planar light source device including a planar light source unit, and the characteristics such as luminance of the light source of each planar light source unit over time. Measure the characteristics of the light source, brightness, chromaticity, etc. of the light sources that make up each planar light source unit appropriately, and optimize the characteristics of the light source, such as the light emission state, brightness, chromaticity, etc. It is an object of the present invention to provide a method of driving a liquid crystal display device assembly that can be adjusted to the above.

A method for driving the liquid crystal display device assembly according to the first aspect of the present invention to achieve the above object is as follows:
(A) a transmissive liquid crystal display device having a display area composed of pixels arranged in a two-dimensional matrix,
(B) From the P × Q planar light source units corresponding to the P × Q display area units when it is assumed that the display area of the liquid crystal display device is divided into P × Q virtual display area units. Each planar light source unit comprises a light source and illuminates a display area unit corresponding to the planar light source unit from the back, and
(C) a driving circuit for driving the planar light source device and the liquid crystal display device;
A method of driving a liquid crystal display device assembly comprising:
A light source constituting a planar light source unit corresponding to the display area unit in a state where the light transmittance of all pixels constituting the display area unit is minimized in the operation period of the liquid crystal display device corresponding to the vertical blanking period The light emission state is measured by an optical sensor, and the measurement result is compared with the reference value in the drive circuit, and the light emission of the light source constituting the planar light source unit is made equal to (approaching) the reference value. It is characterized by controlling the state.

  In the driving method of the liquid crystal display device assembly according to the first aspect of the present invention, all the P × Q planar light source units are arranged in the operation period of the liquid crystal display device corresponding to one vertical blanking period. The light source constituting the light source may be configured to emit light, or the light source constituting one planar light source unit may be configured to emit light, or more than one, P The light source that constitutes less than Q planar light source units can be configured to emit light.

In the driving method of the liquid crystal display device assembly according to the first aspect of the present invention including the above preferable configuration,
The light source constituting the planar light source unit consists of a light emitting diode driven based on a pulse width modulation control system,
The driving of the light source constituting the planar light source unit during the operation period of the liquid crystal display device corresponding to the image display period is performed based on a K-bit pulse width modulation control method,
The light source constituting the planar light source unit during the operation period of the liquid crystal display device corresponding to the vertical blanking period is driven based on a pulse width modulation control method of K ′ bits (where K ′ <K). be able to. And by adopting such a form, even in a short time, the light source constituting the planar light source unit corresponding to the display area unit is set to the light emission state, and this light emission state is reliably measured by the optical sensor. Is possible.

Furthermore, in the driving method of the liquid crystal display device assembly according to the first aspect of the present invention including the various preferable configurations and forms described above,
A control signal for controlling the light transmittance of each pixel is supplied from the drive circuit to each pixel.
In the operation period of the liquid crystal display device corresponding to the image display period, in each of the planar light source units, the value of the drive signal input to the drive circuit to drive all the pixels constituting each display area unit _So that the luminance of the pixel can be obtained when it is assumed that a control signal corresponding to the drive signal having a value equal to the drive signal maximum value x _U-max in the display area unit which is the maximum value of the pixel is supplied to the pixel. The luminance of the light source constituting the planar light source unit corresponding to the display area unit can be controlled by the drive circuit. For convenience, such a method for controlling the luminance of the light source constituting the planar light source unit may be referred to as “divided driving of the planar light source unit”. In this case, each pixel is configured as a set of a plurality of sub-pixels each emitting a different color, and each sub-pixel constituting each pixel is controlled to control the light transmittance of each sub-pixel. The signal may be supplied from the driver circuit. That is, the liquid crystal display device in this case is a color liquid crystal display device. In this case, more specifically, each pixel is configured as a set of three sub-pixels of a red light-emitting subpixel, a green light-emitting subpixel, and a blue light-emitting subpixel, or alternatively, these three subpixels. One set of one or more subpixels added to the pixel (for example, one set of subpixels that emit white light to improve luminance, and a subpixel that emits complementary colors to expand the color reproduction range) 1 set including one sub-pixel that emits yellow to expand the color reproduction range, and one set including sub-pixels that emit yellow and cyan to expand the color reproduction range. . The same applies to the driving method of the liquid crystal display device assembly according to the second to third aspects of the present invention described below.

A method for driving a liquid crystal display device assembly according to the second aspect of the present invention for achieving the above object is as follows:
(A) a transmissive liquid crystal display device having a display area composed of pixels arranged in a two-dimensional matrix,
(B) From the P × Q planar light source units corresponding to the P × Q display area units when it is assumed that the display area of the liquid crystal display device is divided into P × Q virtual display area units. Each planar light source unit comprises a light source and illuminates a display area unit corresponding to the planar light source unit from the back, and
(C) a driving circuit for driving the planar light source device and the liquid crystal display device;
A method of driving a liquid crystal display device assembly comprising:
A control signal for controlling the light transmittance of each pixel is supplied from the drive circuit to each pixel.
In the operation period of the liquid crystal display device corresponding to the image display period in (F-1) frames among the continuous F frames, all the display area units in each of the planar light source units are included. A control signal corresponding to a drive signal having a value equal to the drive area maximum value x _U-max in the display area unit, which is the maximum value of drive signal values input to the drive circuit for driving the pixels of The luminance of the light source constituting the planar light source unit corresponding to the display area unit is controlled by the drive circuit so that the luminance of the pixel when it is assumed that the pixel is supplied to the pixel is obtained,
In the operation period of the liquid crystal display device corresponding to the image display period in the remaining one frame among the consecutive F frames, the drive signal input to the drive circuit to drive each pixel is displayed. when the maximum value was x _max, as the luminance of the pixel when the control signal corresponding to a drive signal having a value equal to the maximum value x _max is assumed to have been supplied to the pixel is obtained, corresponding to the display area unit The luminance of the light source constituting the planar light source unit is controlled by the drive circuit, and the light emission state of the light source constituting the planar light source unit is measured by the optical sensor, and the measurement result is compared with the reference value in the drive circuit. Thus, the light emission state of the light source constituting the planar light source unit is controlled to be equal to (approaching) the reference value.

A method for driving a liquid crystal display device assembly according to the third aspect of the present invention to achieve the above object is as follows:
(A) a transmissive liquid crystal display device having a display area composed of pixels arranged in a two-dimensional matrix,
(B) From the P × Q planar light source units corresponding to the P × Q display area units when it is assumed that the display area of the liquid crystal display device is divided into P × Q virtual display area units. Each planar light source unit comprises a light source and illuminates a display area unit corresponding to the planar light source unit from the back, and
(C) a driving circuit for driving the planar light source device and the liquid crystal display device;
A method of driving a liquid crystal display device assembly comprising:
A control signal for controlling the light transmittance of each pixel is supplied from the drive circuit to each pixel.
In the operation period of the liquid crystal display device corresponding to the image display period in (F′−1) frames in the continuous F ′ frames, each display area unit is configured in each of the planar light source units. A control corresponding to a drive signal having a value equal to the drive area maximum value x _U-max in the display area unit, which is the maximum value of drive signal values input to the drive circuit for driving all pixels The luminance of the light source constituting the planar light source unit corresponding to the display area unit is controlled by the drive circuit so that the luminance of the pixel when it is assumed that the signal is supplied to the pixel is obtained,
In the operation period of the liquid crystal display device corresponding to the image display period in the remaining one frame among the consecutive F ′ frames, the light transmittance of all the pixels constituting the display area unit is minimized. In the state, the light source constituting the planar light source unit corresponding to the display area unit is set to the light emission state, the light emission state is measured by the optical sensor, and the measurement result is compared with the reference value in the drive circuit, and becomes equal to the reference value. As described above, the light emission state of the light source constituting the planar light source unit is controlled.

  As described above, in the liquid crystal display device assembly driving methods according to the second to third aspects of the present invention, the split driving of the planar light source unit is employed.

  In the driving method of the liquid crystal display device assembly according to the third aspect of the present invention, the liquid crystal display device has an operation period corresponding to an image display period in the remaining one frame among the consecutive F ′ frames. In other words, the light sources constituting all the P × Q planar light source units can be in a light emission state, or the light sources constituting one planar light source unit can be in a light emission state. Alternatively, the light source constituting the planar light source unit exceeding one and less than P × Q may be set to the light emitting state.

  In the liquid crystal display device assembly driving method according to the second to third aspects of the present invention including the various preferable configurations described above, each pixel includes a plurality of sub-pixels that emit different colors. It is configured as one set, and a control signal for controlling the light transmittance of each sub-pixel can be supplied from the drive circuit to each sub-pixel constituting each pixel.

  Furthermore, in the driving method of the liquid crystal display device assembly according to the first to third aspects of the present invention including the various preferable configurations described above, the light source is measured as the light emission state measured by the optical sensor. Brightness and / or chromaticity (specifically, the luminance of the light source, or the chromaticity of the light source, or the luminance and chromaticity of the light source). The number of photosensors may be at least one, but a configuration in which one set of photosensors is arranged in one planar light source unit can change the light emission state of each planar light source unit. This is desirable from the viewpoint of reliable measurement. As the optical sensor, a known photodiode or CCD device can be cited. When the light source is configured, for example, as a set of a red light emitting diode, a green light emitting diode, and a blue light emitting diode, the light emission state of the light source measured by the optical sensor is the luminance and chromaticity of the light source. Also, in this case, a pair of photosensors is connected to a photodiode with a red filter attached to measure the light intensity of red light, a photodiode attached with a green filter to measure the light intensity of green light, And, it can be composed of a photodiode with a blue filter attached to measure the light intensity of blue light.

  In the following description, the operation period of the liquid crystal display device corresponding to the vertical blanking period is abbreviated as “vertical blanking operation period”, and the operation period of the liquid crystal display device corresponding to the image display period is referred to as “image display operation period”. May be abbreviated as "."

  Here, the light transmittance (also referred to as aperture ratio) Lt of the pixel or sub-pixel, the luminance (display luminance) y of the display area corresponding to the pixel or sub-pixel, and the luminance of the light source constituting the planar light source unit (Light source luminance) Y is defined as follows.

Y ₁ ... Is the maximum luminance of the light source luminance, for example, and may be hereinafter referred to as the light source luminance and the first specified value.
Lt ₁ ... Is the maximum value of the light transmittance (aperture ratio) of the pixels or sub-pixels in the display area unit, for example, and may be hereinafter referred to as light transmittance / first specified value.
Lt ₂ ... When the light source brightness is the light source brightness / first specified value Y ₁ , the control signal corresponding to the drive signal having a value equal to the display area unit / drive signal maximum value x _U-max is the pixel or This is the light transmittance (aperture ratio) of the pixel or the sub-pixel when it is assumed that the pixel is supplied to the sub-pixel, and may be hereinafter referred to as light transmittance / second specified value. In addition, 0 ≦ Lt ₂ ≦ Lt ₁
y ₂ ... When the light source luminance is the light source luminance and the first specified value Y ₁ and the light transmittance (aperture ratio) of the pixel or sub-pixel is assumed to be the light transmittance and the second specified value Lt ₂ The display brightness obtained in the following is sometimes referred to as “display brightness / second prescribed value”.
Y ₂ ... · In the display area unit • Assuming that a control signal corresponding to a drive signal having a value equal to the drive signal maximum value x _U-max is supplied to the pixel or sub-pixel, light transmission of the pixel or sub-pixel When the rate (aperture ratio) is assumed to be the light transmittance / first prescribed value Lt ₁ , a planar light source unit for setting the luminance of the pixel or sub-pixel to the display luminance / second prescribed value (y ₂ ) The light source brightness of the light source to be configured.

In the driving method of the liquid crystal display device assembly according to the first aspect or the third aspect of the present invention, the remaining one of the remaining F ′ frames in the vertical blanking operation period or in the continuous F ′ frames. In the image display operation period in the frame, with the light transmittance of all the pixels constituting the display area unit minimized, the light source constituting the planar light source unit corresponding to this display area unit is set to the light emitting state. The light emission state of the light source at this time may be, for example, light source luminance / first specified value Y ₁ , or light source luminance / light source luminance lower than the first specified value Y ₁ (for example, light source luminance / first The light source intensity may be set to 1/16 times the specified value Y ₁ ), or may be set to a plurality of levels of light source luminance in one vertical blanking period or an image display operation period in the remaining one frame. Alternatively, the light emission state of the light source in a certain vertical blanking period or the image display operation period in the remaining one frame is set to the “bright” state, and image display in the next vertical blanking period or the remaining one frame is performed. A method may be employed in which the light emission state of the light source during the operation period is set to the “dark” state. Note that the driving conditions of the light sources constituting all the planar light source units are the same in the vertical blanking operation period or in the image display operation period in the remaining one of the consecutive F ′ frames. It is preferable from the viewpoint of simplification of driving of the light source and ease of measurement of the light emission state.

Further, in a preferred configuration in the driving method of the liquid crystal display device assembly according to the first aspect of the present invention, or in the driving method of the liquid crystal display device assembly according to the second to third aspects of the present invention, In the display area unit, the luminance of the pixel when the control signal corresponding to the drive signal having a value equal to the drive signal maximum value x _U-max is supplied to the pixel (the light transmittance at the first specified value Lt ₁ ) The luminance of the light source constituting the planar light source unit corresponding to the display area unit is controlled by the drive circuit so that the display luminance / second predetermined value y ₂ ) is obtained. The light source luminance Y ₂ may be controlled (for example, decreased) so that the display luminance y ₂ can be obtained when the light transmittance (aperture ratio) of the pixel is, for example, the light transmittance · the first specified value Lt _1. Just do). That is, for example, the light source luminance Y ₂ of the planar light source unit may be controlled every image display operation period in the frame (every frame) so as to satisfy the following expression (1). Note that Y ₂ ≦ Y ₁ .

Y ₂ · Lt ₁ = Y ₁ · Lt ₂ (1)

Furthermore, in the driving method of the liquid crystal display device assembly according to the second aspect of the present invention, the pixel when it is assumed that a control signal corresponding to a driving signal having a value equal to the maximum value x _max is supplied to the pixel. like the luminance can be obtained, but is controlled by the drive circuit to the luminance of the light source forming the planar light source unit corresponding to the display area unit, in this case, for example, the light source luminance is the light source luminance · first specified value Y ₁ Thus, the luminance of the light source may be controlled by the drive circuit. At this time, it is preferable that the driving conditions of the light sources constituting all the planar light source units are the same from the viewpoints of simplification of driving of the light sources and ease of measurement of the light emission state.

  In the driving method of the liquid crystal display device assembly according to the first to third aspects of the present invention including the preferred embodiments described above, the measurement result of the light emission state measured by the optical sensor is displayed in the driving circuit. Compared with the reference value, the reference value may be stored in the drive circuit, and the reference value can be obtained by examining in advance the relationship between the light source luminance serving as the reference and the light emission state measured by the optical sensor. it can. Here, the reference value may be, for example, a value measured when the liquid crystal display device assembly is assembled.

  In the driving method of the liquid crystal display device assembly according to the second aspect of the present invention, the value of “F” in consecutive F frames may be a constant value, for example, F = 10 and F = 20. A mode in which the value of F is reduced during a period in which the amount of fluctuation at the beginning of energization of the liquid crystal display assembly is expected to be large, and the value of F is increased as the energization time is increased. 10, F = 50 after 5 minutes from the start of energization, and F = 200 after 30 minutes from the start of energization may be employed. On the other hand, in the method for driving the liquid crystal display device assembly according to the third aspect of the present invention, F ′ = 3 can be exemplified as the value of “F ′” in consecutive F ′ frames.

  In the liquid crystal display device assembly driving method according to the first to third aspects of the present invention including the preferred embodiments described above (hereinafter, these may be collectively referred to simply as the present invention). In the case where the light source is configured as a set of a red light emitting diode, a green light emitting diode, and a blue light emitting diode to obtain white light, the red light emitting diode emits red light having a wavelength of 640 nm, for example. For example, green light having a wavelength of 530 nm is emitted, and the blue light emitting diode emits blue light having a wavelength of 450 nm, for example. In addition, you may further provide the light emitting diode which light-emits 4th color other than red, green, blue, 5th color .... However, the light source is not limited to the light emitting diode, and other examples include a white light emitting diode, a cold cathode fluorescent lamp, and a light source using electroluminescence (EL).

  When split driving of the planar light source unit is adopted, in the method of measuring the light emission state of the light source constituting the planar light source unit by the optical sensor during the image display operation period, an image displayed in a certain display area unit is displayed. Therefore, since the light emission state of the light source constituting the planar light source unit corresponding to the display area unit changes every frame, the light emission state of the light source constituting the planar light source unit can be stably measured. It becomes difficult. However, in the driving method of the liquid crystal display device assembly according to the first aspect of the present invention, the light transmittance of all the pixels constituting the display area unit is minimized in the vertical blanking operation period. That is, when the liquid crystal display device is in the “black display” state, the light source constituting the planar light source unit corresponding to the display area unit is set as the light emission state, and this light emission state is measured by the optical sensor. The light emission state of the light source can be measured by an optical sensor. Therefore, it is possible to control the luminance and chromaticity of the light source for each frame with high accuracy.

In a preferred configuration of the method for driving the liquid crystal display device assembly according to the second or third aspect of the present invention and the method for driving the liquid crystal display device assembly according to the first aspect of the present invention, Pixel brightness (light transmittance, display brightness at the first specified value Lt ₁ ) when it is assumed that a control signal corresponding to a drive signal having a value equal to the intra-unit maximum drive signal value x _U-max is supplied to the pixel Since the luminance of the light source constituting the planar light source unit corresponding to the display area unit is controlled by the drive circuit so that the second specified value y ₂ ) is obtained, the power consumption of the planar light source device can be reduced. In addition, it is possible to obtain a high contrast ratio.

In addition, in the method for driving the liquid crystal display device assembly according to the second aspect of the present invention, the maximum value x _max is set during the image display operation period in the remaining one of the consecutive F frames. The luminance of the light source constituting the planar light source unit corresponding to the display area unit is obtained so as to obtain the luminance of the pixel when it is assumed that the control signal corresponding to the driving signal having a value equal to is supplied to the pixel. Therefore, the light emission state of the light source can be measured by the optical sensor under a desired stable condition. Therefore, it is possible to control the luminance and chromaticity of the light source for each frame with high accuracy.

  On the other hand, in the driving method of the liquid crystal display device assembly according to the third aspect of the present invention, in the image display operation period in the remaining one frame among the consecutive F ′ frames, the liquid crystal is displayed in the entire frame. When the display device is in the “black display” state (that is, in the “black insertion drive” state), the light source constituting the planar light source unit corresponding to the display area unit is set as the light emission state, and this light emission state is measured by the optical sensor. Therefore, the light emission state of the light source can be measured by the optical sensor under a desired stable condition. Therefore, it is possible to control the luminance and chromaticity of the light source for each frame with high accuracy. In addition, black insertion driving can solve problems such as afterimages and blurring of moving images.

  Hereinafter, the present invention will be described based on examples with reference to the drawings.

  Example 1 relates to a method of driving a liquid crystal display device assembly according to the first aspect of the present invention. In Example 1 or Examples 2 to 3 described later, the transmissive liquid crystal display device is a transmissive color liquid crystal display device.

As shown in the conceptual diagram of FIG. 3, the transmissive color liquid crystal display device 10 in Example 1 has a total of M ₀ , which is M ₀ along the first direction and N ₀ along the second direction. A display area 11 in which × N ₀ pixels are arranged in a two-dimensional matrix is provided. Here, it is assumed that the display area 11 is divided into P × Q virtual display area units 12. Each display area unit 12 is composed of a plurality of pixels. Specifically, for example, the image display resolution satisfies the HD-TV standard, and the number M ₀ × N ₀ of pixels (pixels) arranged in a two-dimensional matrix is expressed as (M ₀ , N ₀ ). For example, (1920, 1080). In addition, a display area 11 (indicated by a one-dot chain line in FIG. 3) composed of pixels arranged in a two-dimensional matrix is divided into P × Q virtual display area units 12 (the boundary is indicated by a dotted line). ing. Here, the value of (P, Q) is, for example, (19, 12). However, in order to simplify the drawing, the number of display area units 12 (and planar light source units 42 described later) in FIG. 3 is different from this value. Each display area unit 12 is composed of a plurality of (M × N) pixels, and the number of pixels constituting one display area unit 12 is, for example, about 10,000. Each pixel is configured as a set of a plurality of sub-pixels that emit different colors. More specifically, each pixel has three light emitting subpixels (subpixel [R]), a green light emitting subpixel (subpixel [G]), and a blue light emitting subpixel (subpixel [B]). It consists of sub-pixels (sub-pixels). The transmissive color liquid crystal display device 10 is line-sequentially driven. More specifically, the color liquid crystal display device 10 includes scan electrodes (extending along the first direction) and data electrodes (extending along the second direction) that intersect in a matrix. Then, a scanning signal is input to the scanning electrode to select and scan the scanning electrode, and an image is displayed based on the data signal (a signal based on the control signal) input to the data electrode to constitute one screen. Note that a transmissive color liquid crystal display device 10 in Examples 2 to 3 described later also has the same configuration and structure.

  The direct-type planar light source device (backlight) 40 includes P × Q planar light source units 42 corresponding to the P × Q virtual display area units 12. The display area unit 12 corresponding to the light source unit 42 is illuminated from the back. Although the planar light source device 40 is positioned below the color liquid crystal display device 10, the color liquid crystal display device 10 and the planar light source device 40 are separately displayed in FIG. A schematic partial sectional view of the planar light source device 40 and the color liquid crystal display device 10 is shown in FIG. Each of the planar light source units 42 includes a light source. Here, the light source includes a light emitting diode 41 driven based on a pulse width modulation (PWM) control method.

  The planar light source device 40 includes a housing 51 having an outer frame 53 and an inner frame 54. The end of the transmissive color liquid crystal display device 10 is held by the outer frame 53 and the inner frame 54 so as to be sandwiched between the spacers 55A and 55B. A guide member 56 is disposed between the outer frame 53 and the inner frame 54 so that the color liquid crystal display device 10 sandwiched between the outer frame 53 and the inner frame 54 does not shift. A diffusion plate 61 is attached to the inner frame 54 via a spacer 55 </ b> C and a bracket member 57 in the upper portion of the housing 51. On the diffusion plate 61, an optical function sheet group such as a diffusion sheet 62, a prism sheet 63, and a polarization conversion sheet 64 is laminated.

  A reflection sheet 65 is provided inside and below the housing 51. Here, the reflection sheet 65 is disposed so that the reflection surface thereof faces the diffusion plate 61, and is attached to the bottom surface 52 </ b> A of the housing 51 via an attachment member (not shown). The reflection sheet 65 can be composed of, for example, a silver-enhanced reflection film having a structure in which a silver reflection film, a low refractive index film, and a high refractive index film are sequentially laminated on a sheet base material. The reflection sheet 65 reflects light emitted from the plurality of light emitting diodes 41 (light sources 41) and light reflected by the side surface 52B of the housing 51. Thus, the light is emitted from a plurality of red light emitting diodes 41R (light source 41R) that emits red light, a plurality of green light emitting diodes 41G (light source 41G) that emits green light, and a plurality of blue light emitting diodes 41B (light source 41B) that emit blue light. The red light, green light, and blue light thus mixed are mixed, and white light with high color purity can be obtained as illumination light. The illumination light passes through the optical function sheet group such as the diffusion plate 61, the diffusion sheet 62, the prism sheet 63, and the polarization conversion sheet 64, and irradiates the color liquid crystal display device 10 from the back side. In the vicinity of the bottom surface 52A of the housing 51, photodiodes 44R, 44G, and 44B, which are optical sensors, are arranged. The photodiode 44R is a photodiode to which a red filter is attached in order to measure the light intensity of red light, and the photodiode 44G is a photo diode to which a green filter is attached in order to measure the light intensity of green light. The photodiode 44B is a photodiode to which a blue filter is attached in order to measure the light intensity of blue light. Here, one set of photosensors (photodiodes 44R, 44G, 44B) is arranged in one planar light source unit 42. The light emission states of the light sources 41R, 41G, and 41B measured by the photodiodes 44R, 44G, and 44B that are optical sensors are the luminance and chromaticity of the light emitting diodes 41R, 41G, and 41B.

  The arrangement state of the light emitting diodes 41R, 41G, and 41B includes, for example, a red light emitting diode 41R that emits red light (for example, a wavelength of 640 nm), a green light emitting diode 41G that emits green light (for example, a wavelength of 530 nm), and a blue light (for example, A plurality of light emitting diode units each including a blue light emitting diode 41B that emits light having a wavelength of 450 nm may be arranged in a horizontal direction and a vertical direction.

  The planar light source unit 42 constituting the planar light source device 40 divides the plurality of light emitting diodes 41 into opaque partitions with respect to illumination light of the planar light source unit 42 (more specifically, emitted light of the light emitting diodes 41). It can be obtained by sorting with a plate (not shown). In such a configuration, the luminance of the planar light source unit 42 is not affected by the adjacent planar light source unit 42.

The driving circuit for driving the planar light source device 40 and the color liquid crystal display device 10 is based on the pulse width modulation control method, and the red light emitting diode 41R, the green light emitting diode 41G and the blue light emitting diode 41B constituting the planar light source device 40. The backlight control unit 70, the planar light source unit driving circuit 80, and the liquid crystal display device driving circuit 90 that perform on / off control of the liquid crystal display device are configured. The backlight control unit 70 includes an arithmetic circuit 71 and a storage device (memory) 72. On the other hand, the planar light source unit driving circuit 80 includes an arithmetic circuit 81, a storage device (memory) 82, an LED driving circuit 83, a photodiode control circuit 84, switching elements 85R, 85G, and 85B composed of FETs, and a light emitting diode driving power source (constant). Current source) 86. These circuits and the like constituting the backlight control unit 70 and the planar light source unit driving circuit 80 can be known circuits. On the other hand, a liquid crystal display device driving circuit 90 for driving the color liquid crystal display device 10 includes a known circuit such as a timing controller 91. The color liquid crystal display device 10 is provided with a gate driver, a source driver, and the like (not shown) for driving a switching element (not shown) made of a TFT constituting the liquid crystal cell. The light emitting states of the light emitting diodes 41R, 41G, and 41B in a certain frame are measured by the photodiodes 44R, 44G, and 44B, and the outputs from the photodiodes 44R, 44G, and 44B are input to the photodiode control circuit 84 to control the photodiodes. In the circuit 84 and the arithmetic circuit 81, for example, data (signals) as the luminance and chromaticity of the light emitting diodes 41R, 41G, and 41B are transmitted to the LED driving circuit 83, and the light emitting diodes 41R, 41G in the next frame are transmitted. , 41B is controlled so that the light emission state is controlled. Details will be described later. Further, resistors r _R , r _G , r _B for current detection are inserted in series with the light emitting diodes 41R, 41G, 41B downstream of the light emitting diodes 41R, 41G, 41B, and the resistors r _R , r The operation of the light-emitting diode drive power supply 86 is controlled under the control of the LED drive circuit 83 so that the currents flowing through _{G 1} and r _B are converted into voltages, and the voltage drops in the resistors r _R , r _G and r _B have predetermined values. Is controlled. Here, FIG. 4 shows one light emitting diode driving power source (constant current source) 86, but actually, the light emitting diode driving power source for driving each of the light emitting diodes 41R, 41G, and 41B. 86 is arranged.

A display area composed of pixels arranged in a two-dimensional matrix is divided into P × Q display area units. When this state is expressed by “row” and “column”, Q rows × P It can be said that the display area unit is divided into columns. The display area unit 12 is composed of a plurality of (M × N) pixels. When this state is expressed by “row” and “column”, it is composed of pixels of N rows × M columns. I can say. It is arranged in a two-dimensional matrix and is located at the qth row and the pth column [where q = 1, 2,..., Q and p = 1, 2,. The display area unit and the planar light source unit to be displayed are represented as a display area unit 12 _{(q, p)} and a planar light source unit 42 _{(q, p)} , respectively, and the display area unit 12 _{(q, p)} or the planar light source. The subscript “(q, p)” or “-(q, p)” may be added to the elements and items related to the unit 42 _{(q, p)} . Note that the red light emitting subpixel (subpixel [R]), the green light emitting subpixel (subpixel [G]), and the blue light emitting subpixel (subpixel [B]) are collectively displayed as “subpixel [R]. , G, B] ”or the red light emission control signal, the green light emission control signal, and the blue light emission control signal may be collectively referred to as“ control signal [R, G, B] ”. In some cases, the red light emission subpixel drive signal, the green light emission subpixel drive signal, and the blue light emission subpixel drive signal are collectively referred to as “drive signals [R, G, B]”.

Each pixel has three subpixels (subpixels): a subpixel [R] (red light emitting subpixel), a subpixel [G] (green light emitting subpixel), and a subpixel [B] (blue light emitting subpixel). However, in the description of the following embodiments, the luminance control (gradation control) of each of the sub-pixels [R, G, B] is 8-bit control, and 2 from 0 to 255. ^{This is} done in ⁸ stages. Therefore, the value of the drive signal [R, G, B] input to the liquid crystal display device drive circuit 90 to drive each of the sub-pixels [R, G, B] in each pixel constituting each display area unit 12. x _R, x _G, each x _B, takes a value of 2 ⁸ steps. Also, pulse width modulation output signal values S _R , S _G , and S _B for controlling the respective light emission times of the red light emitting diode 41R, the green light emitting diode 41G, and the blue light emitting diode 41B constituting each planar light source unit are also provided. , Takes a value of 2 ⁸ steps from 0 to 255. However, the present invention is not limited to this. For example, 10-bit control can be performed in 2 ¹⁰ stages from 0 to 1023. In this case, if an 8-bit numerical expression is multiplied by, for example, 4 times Good.

A control signal for controlling the light transmittance Lt of each pixel is supplied from the drive circuit to each pixel. Specifically, a control signal [R, G, B] for controlling the light transmittance Lt of each of the sub-pixels [R, G, B] is transmitted to each of the sub-pixels [R, G, B]. Supplied from the drive circuit 90. That is, in the liquid crystal display device driving circuit 90, the control signal [R, G, B] is generated from the input drive signal [R, G, B], and the control signal [R, G, B] is subpixel. [R, G, B] are supplied (output). Since the light source luminance Y ₂ in the light source 41 constituting the planar light source unit 42 is changed for each frame, the control signal [R, G, B] is basically the drive signal [R, G, B]. Is a value obtained by performing correction (compensation) based on a change in the light source luminance Y ₂ . Then, a control signal [R, G, B] is sent from the timing controller 91 constituting the liquid crystal display device driving circuit 90 to the gate driver and source driver of the color liquid crystal display device 10 by a known method. Based on [R, G, B], a switching element (not shown) constituting each subpixel is driven, and a transparent first electrode and a transparent second electrode (these are not shown) constituting the liquid crystal cell are desired. By applying the voltage, the light transmittance (aperture ratio) Lt of each sub-pixel is controlled. Here, the larger the value of the control signal [R, G, B], the higher the light transmittance (subpixel aperture ratio) Lt of the subpixel [R, G, B], and the subpixel [R, G, B]. B] brightness (display brightness y) increases. That is, an image composed of light passing through the sub-pixels [R, G, B] (usually a kind of dot) is bright.

The display luminance y and the light source luminance Y ₂ are controlled for each frame, for each display area unit, and for each planar light source unit in the image display of the color liquid crystal display device 10. Further, the operation of the color liquid crystal display device 10 and the operation of the planar light source device 40 within one frame are synchronized.

  In addition, the matter demonstrated above is a matter applied similarly also in Example 2-Example 3 mentioned later.

In the first embodiment, in the vertical blanking operation period, the display region unit 12 _{(q, p,)} with the light transmittance Lt of all the pixels constituting the display region unit 12 _{(q, p)} minimized _{. The} light sources 41R _{(q, p)} , 41G _{(q, p)} , 41B _{(q, p)} constituting the planar light source unit 42 _{(q, p)} corresponding to _p) (hereinafter collectively referred to as the light source 41 _{(q , p))} may be expressed as a light emitting state, and photodiodes 44R _{(q, p)} , 44G _{(q, p)} , 44B _{(q, p)} (hereinafter referred to as optical sensors). 44 _{(q, p)} ), the light emission state is measured. Then, the measurement result is compared with the reference value in the drive circuit 80 _{(q, p)} , and the planar light source unit 42 ₍ so as to be equal to (or as close as possible) to the reference value). _q, controls the light emission state of the light source 41 constituting the _{p) (q, p).} In the first embodiment, in one vertical blanking operation period, the light sources 41 constituting all the P × Q planar light source units 42 are in a light emitting state, but the present invention is not limited to this. For example, the light source 41 constituting one planar light source unit 42 may be in a light emitting state during one vertical blanking operation period.

  In the first embodiment, the driving of the light source 41 constituting the planar light source unit 42 during the image display operation period is a pulse width of K bits (specifically, 8 bits in the first embodiment). The light source 41 constituting the planar light source unit 42 in the vertical blanking operation period is driven based on the modulation control method, and the driving of the light source 41 is K ′ bit (provided that K ′ <K. (4 bits) is actually based on a pulse width modulation control system.

Here, as described above, in the first embodiment, a control signal for controlling the light transmittance Lt of each pixel is supplied from the drive circuit to each pixel. More specifically, a control signal [R, G, B] that controls the light transmittance Lt of each of the sub-pixels [R, G, B] is supplied to each of the sub-pixels [R, G, B] constituting each pixel. B] is supplied from the drive circuit 90. During the image display operation period, in each of the planar light source units 42 _{(q, p)} , all the pixels (sub-pixels [R, G, B ₎ constituting each display area unit 12 _{(q, p)} are included. ] _{(Q, p)} ) to drive the driving signals [R, G, B] _{(q, p)} input to the driving circuits 70, 80 _{(q, p)} , 90 to drive the value x _{R- (q, p)} , x _{G- (q, p)} , x _{B- (q, p)} , the maximum value within the display area unit / drive signal maximum value x _{U-max (q, p)} The luminance (light transmittance, display luminance at the first specified value Lt ₁ ) of the pixel (sub-pixel [R, G, B] _{(q, p)} ) when it is assumed that a control signal corresponding to the drive signal is supplied to the pixel The light source 41 _(q, which constitutes the planar light source unit 42 _{(q, p)} corresponding to the display area unit 12 _{(q, p)} so that the second specified value y _{2- (q, p)} ) is obtained. _{, p)} is controlled by the drive circuit 80 _{(q, p)} .

  Hereinafter, a driving method of the liquid crystal display device assembly according to the first embodiment will be described with reference to FIGS. 1, 2A and 2B, FIG. 3, and FIG. 1A schematically shows a vertical blanking period and an image display period in one frame, and FIG. 1B shows PWM control in the vertical blanking period and the image display period. It is a figure which represents typically the state of brightness | luminance light control, etc. FIG.

[Step-100]
A drive signal [R, G, B] and a clock signal CLK for one frame sent from a known display circuit such as a scan converter are input to the backlight control unit 70 and the liquid crystal display device drive circuit 90 (FIG. 3). reference). The drive signals [R, G, B] are output signals from the image pickup tube, for example, when y ′ is the input light quantity to the image pickup tube. Is a drive signal that is also input to the liquid crystal display device drive circuit 90 to control the above, and can be expressed as a function of the input light amount y ′ to the power of 0.45. The values x _R , x _G , and x _B of the drive signals [R, G, B] for one frame input to the backlight control unit 70 are stored in a storage device (memory) 72 that constitutes the backlight control unit 70. First, it is memorized. In addition, the values x _R , x _G , and x _B of the drive signals [R, G, B] for one frame input to the liquid crystal display device driving circuit 90 are also stored in the storage device (FIG. (Not shown) once stored.

[Step-110]
Next, in the arithmetic circuit 71 constituting the backlight control unit 70, the value of the drive signal [R, G, B] stored in the storage device 72 is read and the (p, q) th [however, first, p = 1, q = 1] in the display area unit 12 _{(q, p)} , the sub-pixels [R, G in all the pixels constituting the (p, q) -th display area unit 12 _{(q, p)} , B] _{(q, p)} for driving the signals [R, G, B] _{(q, p)} x _{R- (q, p)} , x _{G- (q, p)} , x _{B- In} the display area unit / drive signal maximum value x _{U-max (q, p)} , which is the maximum value of _{(q, p)} , is obtained by the arithmetic circuit 71. The in-display area unit / drive signal maximum value x _{U-max (q, p)} is stored in the storage device 72. This step is executed for all of m = 1, 2,..., M, n = 1, 2,..., N, that is, for M × N pixels.

For example, x _{R- (q, p)} is a value corresponding to “110”, x _{G- (q, p)} is a value corresponding to “150”, and x _{B- (q, p)} is “ In the case of a value corresponding to “50”, x _{U−max (q, p)} is a value corresponding to “150”.

This operation is repeated from (p, q) = (1, 1) to (P, Q), and the display area unit internal drive signal maximum value x _{U-max (in} all display area units 12 _{(q, p)} . _{q, p)} is stored in the storage device 72.

Then, the control signal [R, G, B corresponding to the drive signal [R, G, B] _{(q, p)} having a value equal to the in-display area unit / maximum drive signal value x _{U-max (q, p).} ] _{(Q, p)} is assumed to be supplied to the sub-pixel [R, G, B] _{(q, p)} (light transmittance, display brightness at the first specified value Lt ₁ , second specified value y) _{2- (q, p))} as obtained by the surface light source unit 42 _{(q, p),} forming the planar light source unit 42 corresponding to the display area unit _{12 (q, p) (q} , p) The brightness of the light source 41 _{(q, p)} (light source brightness Y _{2− (q, p)} ) is increased or decreased under the control of the planar light source unit drive circuit 80 _{(q, p)} . Specifically, the light source luminance Y ₂ may be controlled for each frame and for each planar light source unit so as to satisfy the following expression (1). More specifically, the light source luminance Y ₂ may be controlled based on the equation (2) which is the light source luminance control function g (x _nol-max ) so as to satisfy the equation (1). A conceptual diagram of such control is shown in FIGS. 2 (A) and 2 (B). It should be noted that these relations regarding the control of the light source luminance Y ₂ , that is, the value of the control signal corresponding to the drive signal having a value equal to the maximum value x _U-max in the display area unit and the drive signal maximum value x _U-max . , The display luminance when assuming that such a control signal is supplied to the pixel (sub-pixel), the second specified value y ₂ , the light transmittance (aperture ratio) of each sub-pixel at this time [light transmittance / first 2 specified value Lt ₂ ], and a planar light source that provides display luminance and second specified value y ₂ when the light transmittance (aperture ratio) of each sub-pixel is set to light transmittance and first specified value Lt _1. The relationship between the brightness control parameters in the unit may be obtained in advance.

However, drive signals (drive signals [R, G, B]) input to the liquid crystal display device drive circuit 90 to drive the pixels (or the sub-pixels [R, G, B] constituting the pixels). _Where x _max is the maximum value of
x _nol-max ≡ x _F-max / x _max
And a ₁ and a ₀ are constants,
a ₁ + a ₀ = 1
0 <a ₀ <1, 0 <a ₁ <1
Can be expressed as For example,
a ₁ = 0.99
a ₀ = 0.01
And it is sufficient. The value x _R of the drive signals [R, G, B], x G, each x _B, and takes a value of 2 ⁸ steps, the value of x _max is "255".

Y ₂ · Lt ₁ = Y ₁ · Lt ₂ (1)
g (x _nol-max ) = a ₁ · (x _nol-max ) ^2.2 + a ₀ (2)

Then, the value of g (x _{nol-max (q, p)} ) obtained in the arithmetic circuit 71 constituting the backlight control unit 70 is in the range of 0 to 255 based on the conversion table stored in the storage device 72. Convert to the corresponding integer in. Thus, the value of the pulse width modulation output signal for controlling the light emission time of the red light emitting diode 41R _{(q, p) in} the planar light source unit 42 _{(q, p)} in the arithmetic circuit 71 constituting the backlight control unit 70. S _{R- (q, p),} a green light emitting diode 41G _{(q, p)} of the pulse width modulation output signal for controlling the light emission time of the value S _{G- (q, p),} the blue light emitting diode 41B _{(q, p )} , The value S _{B− (q, p)} of the pulse width modulation output signal for controlling the light emission time can be obtained.

[Step-120]
Next, the values S _{R- (q, p)} , S _{G- (q, p)} , S _{B- (q, p ) of} the pulse width modulation output signal obtained in the arithmetic circuit 71 constituting the backlight control unit 70. ₎ Is sent to the storage device 82 of the planar light source unit drive circuit 80 _{(q, p)} provided corresponding to the planar light source unit 42 _{(q, p)} and stored in the storage device 82. The clock signal CLK is also sent to the planar light source unit drive circuit 80 _{(q, p)} (see FIG. 4).

[Step-130]
Then, the planar light source unit 42 _{(q, p)} is configured based on the values S _{R- (q, p)} , S _{G- (q, p)} , S _{B- (q, p)} of the pulse width modulation output signal. ON time t _R-ON and OFF time t _{R-OFF of} the red light emitting diode 41R _{(q, p )} , ON time t _G-ON and OFF time t _{G-OFF of} the green light emitting diode 41G _{(q, p)} , blue The arithmetic circuit 81 determines the on time t _B-ON and the off time t _B-OFF of the light emitting diode 41B _{(q, p)} . still,
t _R-ON + t _R-OFF = t _G-ON + t _G-OFF = t _B-ON + t _B-OFF = constant value t _Const
It is. The duty ratio in driving based on pulse width modulation of the light emitting diode is
t _ON / (t _ON + t _OFF ) = t _ON / t _Const
Can be expressed as

The on-time t _{R− of} the red light emitting diode 41R _{(q, p)} , the green light emitting diode 41G _{(q, p)} , and the blue light emitting diode 41B _{(q, p)} constituting the planar light source unit 42 _{(q, p).} Signals corresponding to _{ON- (q, p)} , t _{G-ON- (q, p)} , t _{B-ON- (q, p)} are sent to the LED drive circuit 83, and from this LED drive circuit 83, Based on the value of the signal corresponding to the on-time tR _{-ON- (q, p)} , _{tG-ON- (q, p)} , _{tB-ON- (q, p)} , the switching element 85R _{(q, p )} , 85G _{(q, p)} , 85B _{(q, p)} are turned on times t _{R-ON- (q, p)} , t _{G-ON- (q, p)} , t _{B-ON- (q, p )} , The LED driving current from the light emitting diode driving power supply 86 is caused to flow to each of the light emitting diodes 41R _{(q, p)} , 41G _{(q, p)} , 41B _{(q, p)} . As a result, each of the light emitting diodes 41R _{(q, p)} , 41G _{(q, p)} , 41B _{(q, p)} has an on-time t _{R-ON- (q, p)} , Only t _{G-ON- (q, p)} and t _{B-ON- (q, p)} emit light. Thus, the (p, q) -th display area unit 12 _{(q, p)} is illuminated at a predetermined illuminance.

The states thus obtained are indicated by solid lines in FIGS. 6A and 6B. FIG. 6A shows a drive signal input to the liquid crystal display device drive circuit 90 to drive the sub-pixels. 6 is a diagram schematically showing a relationship between a value obtained by raising the value of x to the power of 2 (x′≡x ^2.2 ) and a duty ratio (= t _ON / t _Const ). FIG. It is a figure which shows typically the relationship between the value X of the control signal for controlling the light transmittance Lt, and the display brightness | luminance y.

On the other hand, the values x _{R- (q, p)} , x _{G- (q, p)} , x _{B- ( ) of} the drive signals [R, G, B] _{(q, p)} input to the liquid crystal display device driving circuit 90. _{q, p)} is sent to the timing controller 91. In the timing controller 91, a control signal [R, G, B] _{( q, p)} corresponding to the input drive signal [R, G, B] _{(q, p) ( q (p)} is supplied (output) to the sub-pixel [R, G, B] _{(q, p)} . Control signals [R, G, B] _(q generated by the timing controller 91 of the liquid crystal display device driving circuit 90 and supplied from the liquid crystal display device driving circuit 90 to the sub-pixels [R, G, B] _{(q, p) , p)} values X _{R- (q, p)} , X _{G- (q, p)} , X _{B- (q, p)} and the value x of the drive signal [R, G, B] _{(q, p) R- (q, p)} , _{xG- (q, p)} , _{xB- (q, p)} are the following formulas (3-1), (3-2), and (3-3) Are in a relationship. However, _{b1_R} , _{b0_R} , _{b1_G} , _{b0_G} , _{b1_B} , _{b0_B} are constants. Further, since the light source luminance Y _{2- (q, p)} in the light source 41 constituting the planar light source unit 42 _{(q, p)} is changed for each frame, the control signal [R, G, B] _{(q, p)} Is basically a correction (compensation ₎ based on a change in the light source luminance Y _{2− (q, p)} with respect to a value obtained by raising the value of the drive signal [R, G, B] _{(q, p) to} the power of 2.2. ). That is, in the prior art, the control signal [R, G, B] _{(1 )} is obtained so that the display brightness / second specified value y _{2- (q, p)} is obtained at the light source brightness / first specified value Y ₁ . The value of _{q, p)} is determined, and the light transmittance (aperture ratio) Lt of the pixel or sub-pixel is controlled. On the other hand, in the first embodiment, since the light source luminance Y _{2− (q, p)} changes for each frame, the display luminance / second luminance at the light source luminance Y _{2− (q, p)} (≦ Y ₁ ). The values X _{R- (q, p)} , X _{G- (q, p)} , X of the control signal [R, G, B] _{(q, p)} so that the specified value y _{2− (q, p)} is obtained. _{B- (q, p)} is determined and corrected (compensated) to control the light transmittance (aperture ratio) Lt of the pixel or sub-pixel. Here, the functions f _R , f _G , and f _B in the expressions (3-1), (3-2), and (3-3) are functions obtained in advance for performing such correction (compensation). is there.

_{X R- (q, p) =} f R (b 1_R · x R- (q, p) 2.2 + b 0_R) (3-1)
_{X G- (q, p) =} f G (b 1_G · x G- (q, p) 2.2 + b 0_G) (3-2)
_{X B- (q, p) =} f B (b 1_B · x B- (q, p) 2.2 + b 0_B) (3-3)

  Thus, the image display operation period in one frame is completed.

[Step-140]
Next, the operation period of the color liquid crystal display device 10 is a vertical blanking operation period. In this vertical blanking operation period, the light transmittance Lt of all the pixels constituting the display area unit 12 is minimized, that is, the color liquid crystal display device 10 is in the “black display” state. The light source 41 constituting the planar light source unit 42 corresponding to the display area unit 12 is set to the light emission state, and the light emission state is measured by the optical sensor 44. Specifically, in this vertical blanking operation period, for example, the light source 41 constituting the planar light source unit 42 is driven by K ′ bits (where K ′ <K, and in the first embodiment, Specifically, it is performed based on a 4-bit) pulse width modulation control system. More specifically, the values s _{R- (q, p)} and s _{G- (q, p) of} the pulse width modulation output signal corresponding to the light source luminance and the light source intensity 1/16 times the first specified value Y _1. , S _{B- (q, p)} , the light emitting diodes 41R _{(q, p)} , 41G _{(q, p)} , 41B _{(q, p)} are driven. In addition, in all the planar light source units 42, the drive of the planar light source unit 42 can be simplified by making the value of the pulse width modulation output signal the same. The light emitting states of the light emitting diodes 41R _{(q, p)} , 41G _{(q, p)} , 41B _{(q, p)} (more specifically, the luminance of these light emitting diodes) are the photodiodes 44R _{(q, p)} , 44G _{(q, p)} and 44B _{(q, p)} .

The outputs from the photodiodes 44R _{(q, p)} , 44G _{(q, p)} , 44B _{(q, p)} are input to the photodiode control circuit 84, and are converted from analog to digital by the photodiode control circuit 84. The luminance data (digital signal) of the light emitting diodes 41R _{(q, p)} , 41G _{(q, p)} , 41B _{(q, p)} is used. Then, the luminance data (digital signal) is sent to the arithmetic circuit 81, and the luminance reference value stored in the storage device 82 is compared with the arithmetic circuit 81. Thus, the amount of deviation from the reference value of the brightness of the light emitting diodes 41R _{(q, p)} , 41G _{(q, p)} , 41B _{(q, p)} , the light emitting diodes 41R _{(q, p)} , 41G _{(q, p)} , A deviation amount from the reference value of chromaticity based on the luminance of 41B _{(q, p)} can be obtained. Here, these deviation amounts and the correction amount ΔS _R− of the value of the pulse width modulation output signal for controlling the light emission time of the red light emitting diode 41R _{(q, p) in} the planar light source unit 42 _{(q, p)} . _{(q, p),} a green light emitting diode 41G _{(q, p)} of the value of the pulse width modulation output signal for controlling the light emission time of the correction amount ΔS _{G- (q, p),} the blue light emitting diode 41B _{(q, p )} , A correction amount ΔS _{B− (q, p)} of the value of the pulse width modulation output signal for controlling the light emission time is determined in advance and stored in the storage device 82. Based on these correction amounts ΔS _{R- (q, p)} , ΔS _{G- (q, p)} , ΔS _{B- (q, p)} , the pulse width modulation output is output in [Step-130] in the next frame. The signal values S _{R- (q, p)} , S _{G- (q, p)} , S _{B- (q, p)} are corrected.

In the driving method of the liquid crystal display device assembly of the first embodiment, each frame in the image display of the liquid crystal display device has a value equal to the display area unit / drive signal maximum value x _{U-max (q, p).} The brightness of the pixel (light transmittance, display brightness at the first specified value Lt ₁ , second specified value y _{2− (q, p)} ) when it is assumed that a control signal corresponding to the drive signal is supplied to the pixel is obtained. As shown, the luminance (light source luminance Y _{2− (q, p)} ) of the light source 41 _{(q, p)} constituting the planar light source unit 42 _{(q, p} ) is driven by the drive circuits 70 and 80 _{(q, p)} . since the control, i.e., the planar light source unit 42 _{(q, p)} for each frame light source 41 constituting the _{(q, p)} the luminance of which is controlled by a drive circuit 70, 80 (q, _p), Not only can the power consumption of the planar light source device 40 be reduced, but also a high contrast ratio can be obtained. In addition, in the vertical blanking operation period, the display region unit 12 is in a state where the light transmittance of all the pixels constituting the display region unit 12 is minimized, that is, in the state where the color liquid crystal display device 10 is in the “black display” state. Since the light source 41 constituting the planar light source unit 42 corresponding to the light source 41 is set to the light emission state and the light emission state is measured by the optical sensor 44, the light emission state of the light source 41 is measured by the optical sensor 44 under a desired stable condition. Can do. Therefore, it is possible to control the luminance and chromaticity of the light source 41 for each frame with high accuracy.

  Example 2 relates to a driving method of a liquid crystal display device assembly according to a second aspect of the present invention. Hereinafter, a method of driving the liquid crystal display device assembly according to the second embodiment will be described.

[Step-200]
In the image display operation period in (F-1) frames among F consecutive frames (for example, F = 10 in the second embodiment), the planar light source unit 42 _{(q, p)} in each, all of the pixels constituting each display area unit 12 _{(q, p)} (subpixels [R, G, B] ( q, p)) drive circuit to drive the 70, 80 (q, _p) , 90 of the drive signals [R, G, B] _{(q, p)} values x _{R- (q, p)} , x _{G- (q, p)} , x _{B- (q, p)} The pixel when the control signal corresponding to the drive signal having a value equal to the drive signal maximum value x _{U-max (q, p)} is supplied to the pixel (subpixel [ R, G, B] _{(q, p)} ) brightness (light transmittance, display brightness at the first specified value Lt ₁ , second specified value y _{2− (q, p)} ) surface light source Yoo corresponding to area unit 12 _{(q, p)} Tsu DOO 42 _{(q, p)} the light source 41 _{(q, p)} composing the luminance driving circuit 80 _{(q, p)} of the control by.

  Specifically, [Step-100] to [Step-130] of the first embodiment are executed in the image display operation period in (F-1) frames among the consecutive F frames. In the second embodiment, after the image display operation period in one frame is completed, the operation period of the color liquid crystal display device 10 is a vertical blanking operation period. [Step-140] is not executed, and after the vertical blanking operation period is completed, the image display operation period in the next frame is executed. Then, after (F-1) frames in the consecutive F frames are completed, [Step-210] described below is executed.

[Step-210]
In other words, in the image display operation period in the remaining one frame among the F consecutive frames, the drive circuit 70, in order to drive each pixel (subpixel [R, G, B]), drive signal input to the 80, 90 when the [R, G, B] a maximum value of the x _max, the drive signal having a value equal to the maximum value x _max control signal corresponding to the [R, G, B] [ The luminance of the light source 41 constituting the planar light source unit 42 corresponding to the display area unit 12 is set to drive circuits 70 and 80 so that the luminance of the pixel when it is assumed that [R, G, B] is supplied to the pixel is obtained. Control by. As described above, the value x _R of the drive signals [R, G, B], x G, each x _B), and takes a value of 2 ⁸ steps, the value of x _max is "255". More specifically, for example, the luminance of the light sources 41 constituting all the planar light source units 42 is controlled by the drive circuits 70 and 80 so that the light source luminance becomes the light source luminance / the first specified value Y _1. That's fine. For example, the luminance of all the planar light source units 42 is substantially the same in one frame out of 10 frames, but the viewer of the color liquid crystal display device 10 does not feel any discomfort.

Then, in the state where the light source luminance becomes the light source luminance / first specified value Y ₁ , the planar light source unit 42 _{( )} is detected by the optical sensors 44R _{(q, p)} , 44R _{(q, p)} , 44B _{(q, p)} . _q, and measuring the emission state of the light source 41 constituting the _{p) (q, p),} the driving circuit 80 _(q, as compared to the baseline measurement results in _p), to be equal to the reference value (or, The light emission state of the light source 41 _{(q, p)} constituting the planar light source unit 42 _{(q, p)} is controlled so as to be as equal or as close as possible.

Specifically, the output from the photodiodes 44R _{(q, p)} , 44G _{(q, p)} , 44B _{(q, p)} is substantially the same as [Step-140] in the first embodiment. Is converted into analog data by the photodiode control circuit 84, and the luminance data (digital signal) of the light emitting diodes 41R _{(q, p)} , 41G _{(q, p)} , 41B _{(q, p)} is obtained. Then, the luminance data (digital signal) is sent to the arithmetic circuit 81, and the luminance reference value stored in the storage device 82 is compared with the arithmetic circuit 81. Thus, the amount of deviation from the reference value of the brightness of the light emitting diodes 41R _{(q, p)} , 41G _{(q, p)} , 41B _{(q, p)} , the light emitting diodes 41R _{(q, p)} , 41G _{(q, p)} , A deviation amount from the reference value of chromaticity based on the luminance of 41B _{(q, p)} can be obtained. Here, these deviation amounts and the correction amount ΔS _R− of the value of the pulse width modulation output signal for controlling the light emission time of the red light emitting diode 41R _{(q, p) in} the planar light source unit 42 _{(q, p)} . _{(q, p),} a green light emitting diode 41G _{(q, p)} of the value of the pulse width modulation output signal for controlling the light emission time of the correction amount ΔS _{G- (q, p),} the blue light emitting diode 41B _{(q, p )} , A correction amount ΔS _{B− (q, p)} of the value of the pulse width modulation output signal for controlling the light emission time is determined in advance and stored in the storage device 82. Then, based on these correction amounts ΔS _{R− (q, p)} , ΔS _{G− (q, p)} , ΔS _{B− (q, p)} , (F−1) in subsequent F frames. In the same process as [Step-130] in each frame, the values S _{R- (q, p)} , S _{G- (q, p)} , S _{B- (q, p)} of the pulse width modulation output signal are corrected. To do.

Note that also in [Step-210], the values x _{R- (q, p)} , x _{G- (of} the drive signals [R, G, B] _{(q, p)} input to the liquid crystal display device driving circuit 90. _{q, p)} and x _{B- (q, p)} are sent to the timing controller 91, where the control corresponding to the input drive signal [R, G, B] _{(q, p)} is sent. The signal [R, G, B] _{(q, p)} is supplied (output) to the sub-pixel [R, G, B] _{(q, p)} . Control signals [R, G, B] _(q generated by the timing controller 91 of the liquid crystal display device driving circuit 90 and supplied from the liquid crystal display device driving circuit 90 to the sub-pixels [R, G, B] _{(q, p) , p)} values X _{R- (q, p)} , X _{G- (q, p)} , X _{B- (q, p)} and the value x of the drive signal [R, G, B] _{(q, p) R- (q, p)} , _{xG- (q, p)} , _{xB- (q, p)} are the following expressions (4-1), (4-2), and (4-3): Are in a relationship. However, b _{1_R} , b _{0_R} , b _{1_G} , b _{0_G} , b _{1_B} , and b _{0_B} are the same constants as the formula (3-1), the formula (3-2), and the formula (3-3). Incidentally, in this Step 210], because it is a planar light source unit 42 _{(q, p)} the light source luminance is the light source luminance · first specified value Y ₁ of the light source 41 constituting the control signals [R , G, B] _{(q, p)} is basically a value obtained by multiplying the value of the drive signal [R, G, B] _{(q, p) by} the power of 2.2. Correction (compensation) based on the change of Y _{2- (q, p)} is not performed. That is, as in the prior art, the control signal [R, G, B] _(q is obtained so that the display brightness and the second specified value y _{2− (q, p)} are obtained at the light source brightness and the first specified value Y ₁ . _{, p)} is determined, and the light transmittance (aperture ratio) Lt of the pixel or sub-pixel is controlled.

_{XR- (q, p)} = _{b1_R.xR- (q, p)} ^2.2 + _{b0_R} (4-1)
_{XG- (q, p)} = _{b1_G.xG- (q, p)} ^2.2 + _{b0_G} (4-2)
_{XB- (q, p)} = _{b1_B.xB- (q, p)} ^2.2 + _{b0_B} (4-3)

Also in the driving method of the liquid crystal display device assembly of the second embodiment, in the (F-1) frames in the image display of the liquid crystal display device, the display area unit internal drive signal maximum value x _{U-max (q , p)} , it is assumed that the control signal corresponding to the drive signal having a value equal to ( _p) is supplied to the pixel (light transmittance, display brightness at the first specified value Lt ₁ , second specified value y _{2− (q, p)} ) is obtained _, the luminance of the light source 41 _{(q, p)} constituting the planar light source unit 42 _{(q, p)} (the light source luminance Y _{2- (q, p)} ) is determined by the drive circuit 70. , 80 _{(q, p)} , that is, the luminance of the light source 41 _{(q, p)} constituting the planar light source unit 42 _{(q, p)} for each frame is determined by the drive circuits 70, 80 _{(q, p) . p)} , the power consumption of the planar light source device 40 can be reduced, and a high contrast ratio can be obtained. . In addition, in the remaining one frame, the light source 41 constituting the planar light source unit 42 corresponding to the display area unit 12 is set in the light emitting state with the luminance of the planar light source unit 42 set to the maximum luminance. Since the state is measured, the light emission state of the light source 41 can be measured by the optical sensor 44 under a desired and stable condition. Therefore, it is possible to control the luminance and chromaticity of the light source 41 for each frame with high accuracy.

  Example 3 relates to a driving method of a liquid crystal display device assembly according to a third aspect of the present invention. Hereinafter, a driving method of the liquid crystal display device assembly according to the third embodiment will be described.

[Step-300]
In the image display operation period in (F′−1) frames among consecutive F ′ frames (F ′ = 3 in the third embodiment), the planar light source unit 42 _{(q, p)} , Driving circuits 70 and 80 _{(q, p} ) for driving all the pixels (subpixels [R, G, B] _{(q, p)} ) constituting each display area unit 12 _{(q, p). )} , 90 of drive signals [R, G, B] _{(q, p)} of values x _{R- (q, p)} , x _{G- (q, p)} , x _{B- (q, p)} A pixel (sub-pixel) when it is assumed that a control signal corresponding to a drive signal having a value equal to the display area unit maximum value x _{U-max (q, p)} is supplied to the pixel. [R, G, B] _{(q, p)} ) brightness (light transmittance, display brightness at the first specified value Lt ₁ , second specified value y _{2− (q, p)} ) display area unit 12 _{(q, p)} planar light source unit 4 corresponding to the _{(q, p)} is controlled by the driving circuit 80 _{(q, p)} the brightness of the light source 41 constituting the _{(q, p).}

  Specifically, during the image display operation period in 2 (= F′−1) frames in 3 (= F ′) consecutive frames, [Step −100] to [Step 100] in the first embodiment. Step-130] is executed. In the third embodiment, after the image display operation period in one frame is completed, the operation period of the color liquid crystal display device 10 is a vertical blanking operation period. [Step-140] is not executed, and after the vertical blanking operation period is completed, the image display operation period in the next frame is executed. Then, after (F′−1) frames in the consecutive F ′ frames are completed, [Step-310] described below is executed.

[Step-310]
That is, in the image display operation period in the remaining one frame in the continuous F ′ frames, the light transmittance of all the pixels constituting the display area unit 12 is set in all the display area units 12. In the minimum state (that is, in the “black insertion driving” state), the light source 41 constituting the planar light source unit 42 corresponding to the display area unit 12 is set in the light emission state, and this light emission state is obtained by the optical sensors 44R, 44G, 44B. Measure. Specifically, the light emission state of the light source 41 at this time may be, for example, the light source luminance / the first specified value Y ₁ . In addition, in all the planar light source units 42, the drive of the planar light source unit 42 can be simplified by making the value of the pulse width modulation output signal the same. The light emitting states of the light emitting diodes 41R _{(q, p)} , 41G _{(q, p)} , 41B _{(q, p)} (more specifically, the luminance of these light emitting diodes) are the photodiodes 44R _{(q, p)} , 44G _{(q, p)} and 44B _{(q, p)} .

Then, the measurement result is compared with the reference value in the drive circuit 80 _{(q, p)} , and the planar light source unit 42 ₍ so as to be equal to (or as close as possible) to the reference value). _q, controls the light emission state of the light source 41 constituting the _{p) (q, p).}

Specifically, the output from the photodiodes 44R _{(q, p)} , 44G _{(q, p)} , 44B _{(q, p)} is substantially the same as [Step-140] in the first embodiment. Is converted into analog data by the photodiode control circuit 84, and the luminance data (digital signal) of the light emitting diodes 41R _{(q, p)} , 41G _{(q, p)} , 41B _{(q, p)} is obtained. Then, the luminance data (digital signal) is sent to the arithmetic circuit 81, and the luminance reference value stored in the storage device 82 is compared with the arithmetic circuit 81. Thus, the amount of deviation from the reference value of the brightness of the light emitting diodes 41R _{(q, p)} , 41G _{(q, p)} , 41B _{(q, p)} , the light emitting diodes 41R _{(q, p)} , 41G _{(q, p)} , A deviation amount from the reference value of chromaticity based on the luminance of 41B _{(q, p)} can be obtained. Here, these deviation amounts and the correction amount ΔS _R− of the value of the pulse width modulation output signal for controlling the light emission time of the red light emitting diode 41R _{(q, p) in} the planar light source unit 42 _{(q, p)} . _{(q, p),} a green light emitting diode 41G _{(q, p)} of the value of the pulse width modulation output signal for controlling the light emission time of the correction amount ΔS _{G- (q, p),} the blue light emitting diode 41B _{(q, p )} , A correction amount ΔS _{B− (q, p)} of the value of the pulse width modulation output signal for controlling the light emission time is determined in advance and stored in the storage device 82. Then, based on these correction amounts ΔS _{R− (q, p)} , ΔS _{G− (q, p)} , ΔS _{B− (q, p)} , (F′− 1) In the same process as [Step-130] in one frame, the values S _{R- (q, p)} , S _{G- (q, p)} , S _{B- (q, p)} of the pulse width modulation output signal Correct.

Also in the driving method of the liquid crystal display device assembly according to the third embodiment, in the (F′−1) frames in the image display of the liquid crystal display device, the display area unit internal drive signal maximum value x _{U−max (} The brightness of the pixel (light transmittance, display brightness at the first specified value Lt ₁ , second specified value y ₂ ) when it is assumed that a control signal corresponding to a drive signal having a value equal to _{q, p)} is supplied to the pixel. _{-(q, p)} ) _, the luminance of the light source 41 _{(q, p)} constituting the planar light source unit 42 _{(q, p)} (the light source luminance Y _{2- (q, p)} ) is a drive circuit. 70, 80 _{(q, p)} , that is, the luminance of the light source 41 _{(q, p)} constituting the planar light source unit 42 _{(q, p)} for each frame is determined by the drive circuits 70, 80 _{(q ,} since it is controlled by _p), not only it is possible to reduce the power consumption of the planar light source device 40, it is possible to obtain a high contrast ratio . In addition, in the remaining one frame, in the black insertion driving state, the light emission state of the light source 41 constituting the planar light source unit 42 is set to, for example, the maximum luminance, and this light emission state is measured by the optical sensor 44. Under such conditions, the light emission state of the light source 41 can be measured by the optical sensor 44. Therefore, it is possible to control the luminance and chromaticity of the light source 41 for each frame with high accuracy. In addition, black insertion driving can solve problems such as afterimages and blurring of moving images.

In the third embodiment, the light sources 41 constituting all the P × Q planar light source units 42 in the image display operation period in the remaining one frame among the consecutive F ′ frames. The light source 41 _{(q, p)} constituting one planar light source unit 42 _{(q, p)} may be in a light emitting state.

  As mentioned above, although this invention was demonstrated based on the preferable Example, this invention is not limited to these Examples. The configurations and structures of the transmissive color liquid crystal display device, the planar light source device, the planar light source unit, and the liquid crystal display device assembly described in the embodiments are examples, and members, materials, and the like constituting these are also examples. It can be changed as appropriate. Luminance compensation (correction) and temperature control of the planar light source unit 42 may be performed by monitoring the temperature of the light emitting diode with a temperature sensor and feeding back the result to the planar light source unit drive circuit 80. Further, for example, it is possible to change the color temperature to an arbitrary color temperature by changing the color temperature setting information held when the liquid crystal display device assembly is assembled. In the embodiments, the description has been made on the assumption that the display area of the liquid crystal display device is divided into P × Q virtual display area units. However, in some cases, the transmissive liquid crystal display device has P × Q. You may have the structure divided | segmented into the actual display area unit.

In a planar light source device having a structure in which no partition plate is provided, for example, when brightness control of the planar light source unit 42 _(1,1) of (p, q) = (1,1) is assumed, P It is necessary to consider the influence from all of the Q planar light source units 42. This is because the light sensor 44 _(1,1) in the planar light source unit 42 _(1,1) detects the total sum of the light emitted from the light sources 41 constituting each planar light source unit 42 _{(q, p).} Because. Since the influence of the planar light source units 42 from all the planar light source units 42 is known in advance by the light emission profile for each planar light source unit 42, the difference can be calculated by back calculation, and as a result, the correction Is possible. The basic form of calculation will be described below.

The luminance of the planar light source unit at the time of assembling the liquid crystal display device assembly is represented by a matrix [L _PxQ ]. In actual operation, the measured luminance of the planar light source unit is represented by a matrix [L ′ _PxQ ]. Further, the correction value is represented by a matrix [α _PxQ ]. Then, the relationship between these matrices can be expressed by the following equation (5-1).
[L _PxQ ] = [L ′ _PxQ ] · [α _PxQ ] (5-1)
Therefore, it can be understood that correction is possible by obtaining the matrix [α _PxQ ] from the equation (5-1). The matrix [α _PxQ ] can be obtained from the inverse matrix operation. That is,
[Α _PxQ ] = [L _PxQ ] · [L ′ _PxQ ] ⁻¹ (5-2)
Should be calculated. The light source 41 _{(q, p)} may be controlled based on the correction amount represented by the matrix [α _PxQ ]. Specifically, information (data table) stored in the storage device (memory) 82 is used. Just do it. By performing this operation every frame (with an interval), constant luminance and chromaticity can always be maintained. In the control of the light source 41 _{(q, p)} , since the value of the matrix [α _PxQ ] cannot take a negative value, it goes without saying that the calculation result needs to be kept in a positive region. Therefore, the solution of equation (5-2) may not be an exact solution but an approximate solution. The same calculation may be performed when one set (one) of optical sensors 44 is provided for several planar light source units. In this case, P × Q planar light source units are used. May be appropriately grouped and corrected and adjusted in units of groups. Therefore, the matrix operation is reduced in terms of group and row / column terms, which is advantageous in terms of the amount of calculation, but the accuracy is lowered.

1A schematically shows a vertical blanking period and an image display period in one frame, and FIG. 1B shows PWM control and luminance in the vertical blanking period and the image display period. It is a figure which represents the state of light control etc. typically. (A) and (B) in FIG. 2 show the display luminance when assuming that a control signal corresponding to a drive signal having a value equal to the drive signal maximum value x _U-max is supplied to the pixel. A state in which the luminance (light source luminance Y ₂ ) of the light source constituting the planar light source unit is increased or decreased under the control of the planar light source unit driving circuit so that the second specified value y ₂ is obtained by the planar light source unit. It is a conceptual diagram for doing. FIG. 3 is a conceptual diagram of a liquid crystal display device assembly including a color liquid crystal display device, a planar light source device, and a drive circuit suitable for use in the first embodiment. FIG. 4 is a conceptual diagram of a part of a drive circuit suitable for use in the first embodiment. FIG. 5 is a schematic partial cross-sectional view of the planar light source device and the color liquid crystal display device according to the first to third embodiments. FIG. 6A shows a value (x′≡x ^2.2 ) obtained by multiplying the value of the drive signal input to the liquid crystal display device drive circuit to drive the subpixel by the power of ^2.2 and the duty ratio (= t _ON / t _Const) is a diagram schematically showing the relationship between, (B) in FIG. 6, the relationship between the value X of a control signal for controlling the light transmittance of the subpixel and the display luminance y schematically FIG. 7A and 7B are diagrams for explaining the relationship among the light source luminance of the planar light source device, the light transmittance (aperture ratio) of the pixel, and the display luminance in the display area in the prior art. It is a conceptual diagram.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Color liquid crystal display device, 11 ... Display area, 12 ... Display area unit, 40 ... Planar light source device, 41, 41R, 41G, 41B ... Light emitting diode (light source), 42 ... planar light source unit, 44, 44R, 44G, 44B ... photodiode (light sensor), 51 ... housing, 52A ... bottom of housing, 52B ... side of housing, 53 ... Outer frame, 54 ... Inner frame, 55A, 55B ... Spacer, 56 ... Guide member, 57 ... Bracket member, 61 ... Diffusion plate, 62 ... Diffusion sheet, 63 ... Prism sheet, 64 ... Polarization conversion sheet, 65 ... Reflection sheet, 70 ... Backlight control unit, 71 ... Arithmetic circuit, 72 ... Storage device (memory), 80. ..Surface light source unit Drive circuit, 81... Arithmetic circuit, 82... Storage device (memory), 83... LED drive circuit, 84... Photodiode control circuit, 85 R, 85 G, 85 B. ... Light-emitting diode drive power supply, 90 ... Liquid crystal display drive circuit, 91 ... Timing controller

Claims (8)

(A) a transmissive liquid crystal display device having a display area composed of pixels arranged in a two-dimensional matrix,
(B) From the P × Q planar light source units corresponding to the P × Q display area units when it is assumed that the display area of the liquid crystal display device is divided into P × Q virtual display area units. Each planar light source unit comprises a light source and illuminates a display area unit corresponding to the planar light source unit from the back, and
(C) a driving circuit for driving the planar light source device and the liquid crystal display device;
A method of driving a liquid crystal display device assembly comprising:
A light source constituting a planar light source unit corresponding to the display area unit in a state where the light transmittance of all pixels constituting the display area unit is minimized in the operation period of the liquid crystal display device corresponding to the vertical blanking period The light emission state is measured by an optical sensor, the measurement result is compared with a reference value in a drive circuit, and the light emission state of the light source constituting the planar light source unit is controlled to be equal to the reference value. A method for driving a liquid crystal display device assembly.   2. The liquid crystal display device according to claim 1, wherein light sources constituting all of the P × Q planar light source units are set in a light emitting state during an operation period of the liquid crystal display device corresponding to one vertical blanking period. Driving method of assembly.   2. The driving of a liquid crystal display device assembly according to claim 1, wherein a light source constituting one planar light source unit is set in a light emitting state during an operation period of the liquid crystal display device corresponding to one vertical blanking period. Method. The light source constituting the planar light source unit consists of a light emitting diode driven based on a pulse width modulation control system,
The driving of the light source constituting the planar light source unit during the operation period of the liquid crystal display device corresponding to the image display period is performed based on a K-bit pulse width modulation control method,
The driving of the light source constituting the planar light source unit during the operation period of the liquid crystal display device corresponding to the vertical blanking period is performed based on a pulse width modulation control system of K ′ bits (where K ′ <K). The method of driving a liquid crystal display device assembly according to claim 1. A control signal for controlling the light transmittance of each pixel is supplied from the drive circuit to each pixel.
In the operation period of the liquid crystal display device corresponding to the image display period, in each of the planar light source units, the value of the drive signal input to the drive circuit to drive all the pixels constituting each display area unit _So that the luminance of the pixel can be obtained when it is assumed that a control signal corresponding to the drive signal having a value equal to the drive signal maximum value x _U-max in the display area unit which is the maximum value of the pixel is supplied to the pixel. 2. The method of driving a liquid crystal display device assembly according to claim 1, wherein the luminance of the light source constituting the planar light source unit corresponding to the display area unit is controlled by a drive circuit. Each pixel is configured as a set of a plurality of sub-pixels each emitting a different color,
6. The method of driving a liquid crystal display device assembly according to claim 5, wherein a control signal for controlling the light transmittance of each sub-pixel is supplied from a drive circuit to each sub-pixel constituting each pixel. .   2. The driving method of the liquid crystal display device assembly according to claim 1, wherein the light emission state of the light source measured by the optical sensor is luminance and / or chromaticity of the light source.   2. The method of driving a liquid crystal display device assembly according to claim 1, wherein one set of photosensors is arranged in one planar light source unit.

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