JP3863206B2 - Display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a display device, and is particularly useful when applied to a liquid crystal display device provided in an imaging device such as a video camera or a TV camera.
[0002]
[Prior art]
Currently, many video cameras are provided with a liquid crystal display device, and it is possible to take a picture while confirming an image of a subject by using the liquid crystal display device, or to reproduce a video tape after taking a picture and view it with the liquid crystal display device.
[0003]
FIG. 4 is a rear perspective view showing an example of a video camera provided with such a liquid crystal display device. As shown in the figure, the video camera 21 is provided with a display unit 17 of a liquid crystal display device at the top of the main body. The display unit 17 is configured to be openable and closable, and is in a state as shown in FIG. 4 when opened. The display unit 17 is provided with a liquid crystal display (LCD) 14 and a backlight 13.
[0004]
In the figure, 16 is a lens, 22 is a battery, and 23 is an optical viewfinder.
[0005]
[Problems to be solved by the invention]
However, in the liquid crystal display device according to the above prior art, since the brightness of the backlight 13 is constant, the brightness of the LCD 14 is constant. In a dark place indoors, the LCD 14 may be too bright and difficult to see.
[0006]
In addition, various functions are being provided in the video camera 21 at present. However, as the number of functions increases, the amount of power consumption increases accordingly, which affects the life of the battery 22. For this reason, efforts have been made to reduce the power consumption of each part as much as possible, but at that time, it has become clear that the power consumption of the backlight 13 is relatively large. Therefore, it has been desired to reduce the power consumption of the backlight 13.
[0007]
On the other hand, Japanese Patent Laid-Open No. 4-167679 discloses a technique of detecting ambient light intensity using a dedicated optical sensor and adjusting the brightness of the display according to this detection signal. . However, with this method, a dedicated optical sensor must be newly provided, which may increase the cost and increase the size of the video camera.
[0008]
Some video cameras have a volume for adjusting the brightness, but it is extremely cumbersome for a person to adjust the brightness by operating the volume each time according to the brightness of the surroundings. .
[0009]
Therefore, in view of the above prior art, the present invention has an object to provide a display device capable of automatically adjusting the brightness of a display unit according to the ambient brightness without newly providing a dedicated optical sensor. To do.
[0010]
[Means for Solving the Problems]
A first invention that solves the above problem is a display device that is provided in an imaging device that captures an image of a subject using an imaging device, and that displays the image of the subject on a display unit that is visually recognized with both eyes .
Integrating means for integrating the luminance signal component of the output signal of the image sensor;
The integrated value of the luminance signal output from this integrating means, and the iris opening value obtained from the table data of the iris meter rotation angle-iris opening characteristic measured in advance by detecting the rotation angle of the iris meter by the Hall element. A calculation means for obtaining the absolute brightness of the subject based on,
And adjusting means for adjusting the brightness of the display unit in accordance with the absolute brightness of the subject obtained by the calculating means.
[0012]
According to a second aspect , in the first aspect , the display unit includes a display using liquid crystal and a backlight, and the adjusting means adjusts the brightness of the backlight to adjust the brightness of the backlight. The brightness of the display is adjusted.
[0013]
Therefore, according to the above-described invention, the brightness of the subject is obtained based on the integrated value of the luminance signal and the iris opening value, and the brightness of the display unit is adjusted according to the brightness of the subject (for example, the backlight The brightness of the liquid crystal display can be adjusted by adjusting the brightness).
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0015]
FIG. 1 is a block diagram of an image pickup apparatus provided with a liquid crystal display device according to an embodiment of the present invention, FIG. 2 is a flowchart of automatic exposure control (AE control) and backlight control, and FIG. 3 is a graph showing iris opening characteristics. is there.
[0016]
As shown in FIG. 1, the imaging apparatus includes a lens 16, an iris 1, a CCD 2 that is an imaging device, a preamplifier 3 having an AGC circuit 3a, an A / D conversion circuit 4, a signal processing circuit 5, an integrating circuit 6, and a microcomputer 7. , A D / A converter circuit 8, an iris driver 9 for driving the iris 1, a decorator 10, an LCD controller 11, a timing generator 12, a DC / AC inverter 15, and a display unit 17 provided with a backlight 13 and an LCD 14. ing.
[0017]
Accordingly, light from a subject (not shown) is input to the CCD 2 through the lens 16 and the iris 1 and is converted into an electrical signal by the CCD 2. This electrical signal is sampled and gain controlled by the preamplifier 3 and then converted to a digital signal a by the A / D conversion circuit 4. The digital signal a is input to the signal processing circuit 5 and the integrating circuit 6, respectively.
[0018]
The signal processing circuit 5 processes the digital signal a and outputs a YC signal (video signal) obtained by mixing the luminance signal and the color signal.
[0019]
The YC signal output from the signal processing circuit 5 is also input to the decoder 10, decoded by the decoder 10 into R, G, and B signals and input to the LCD controller 11. The decoder 10 extracts a synchronization signal from the YC signal, creates a CSYNC (composite sync signal), and outputs it to the timing generator 12 and the DC / AC inverter 15. The timing generator 12 generates a clock signal based on the CSYNC signal and outputs it to the LCD controller 11. The LCD controller 11 generates a video signal and a clock signal for operating the LCD 14 from the R, G, B signals and the clock signal. The DC / AC inverter 15 converts a DC voltage from the battery 22 (see FIG. 4) into an AC pulse signal for the backlight 13. The CSYNC signal input to the DC / AC inverter 15 prevents the screen scanning on the LCD 14 and the AC pulse signal from being output simultaneously.
[0020]
On the other hand, the integrating circuit 6 integrates the luminance signal components for one screen from the digital signal a and outputs the integrated value (Y) of the luminance signal to the microcomputer 7.
[0021]
In the microcomputer 7, the AE control for automatically controlling the exposure by controlling the iris 1 and the AGC circuit 3a by the iris control signal b and the AGC control signal c, and the brightness of the backlight 13 by the backlight control signal d. Control the backlight to be controlled.
[0022]
That is, as shown in the flowchart of FIG. 2, the iris position information is first input from the iris 1 (S1), and the integrated value (Y) of the luminance signal is input from the integrating circuit 6 (S2). Subsequently, the brightness (Ev value) of the subject is obtained from the input position information of the iris and the integrated value (Y) of the luminance signal, the control value of the AGC circuit 3a held in the microcomputer 7, the sensitivity value of the CCD 2, and the like. . Details of how to obtain this Ev value are as follows.
[0023]
In the AE control of a general video camera as in the present imaging apparatus, the brightness of the image is controlled by feedback control, and therefore it is impossible to know the absolute brightness of the subject only from the output signal of the CCD. Therefore, in order to know the absolute brightness of the subject, the iris meter rotation angle is detected by a Hall element, and the iris meter rotation angle (= hall amplifier output) -iris aperture characteristics measured in advance (see FIG. 5). The aperture value (Av value) of the iris is obtained from the table data, and the brightness of the subject (Ev value) is calculated based on the following equation. Since this Ev value varies depending on the sensitivity of the camera, it is converted to a value at the time of sensitivity ISO 100 in order to eliminate variations among models.
[0024]
_{Ev = Av + Tv + Sv 100} + Eev-Agcv-Ccdv
Ev: Exposure value (subject brightness)
Av: Iris opening value Tv: Time value (calculated from shutter speed)
Sv _100: sensitivity value of ISO100 Eev: Exposure excess or deficiency values (A deficiency value of the exposure in control transition, the difference between the integrated value of the luminance signal (Y) and the set value SV ₁₎
Agcv: Sensitivity UP value by AGC (calculated from AGC control value)
Ccdv: CCD sensitivity value
After calculating the Ev value based on the above equation, EV control and backlight control are performed.
[0026]
EV control is performed as follows. That is, by comparing the integrated value of the luminance signal (Y) and the set value SV ₁ (S7), if the integrated value of the luminance signal (Y) is smaller than the set value SV _1, the iris control signal b or AGC control signal c adjust to control the iris 1 or AGC circuit 3a in a direction to increase the luminance signal (S8), if the integrated value of the luminance signal in the opposite (Y) is greater than the set value SV _1, the iris control signal b or AGC The control signal c is adjusted to control the iris 1 or the AGC circuit 3a so as to decrease the luminance signal (S9). The iris control signal b and the AGC control signal c are converted into analog signals by the D / A conversion circuit 8, and then input to the iris driver 9 and the AGC circuit 3a, respectively. In this AE control, the iris 1 is mainly controlled in a bright place such as outdoors, and the AGC circuit 3a is controlled in a dark place where the iris 1 is fully opened.
[0027]
On the other hand, backlight control is performed as follows. That is, the calculated Ev value is compared with the set value SV ₂ (S4), and if the Ev value is smaller than the set value SV ₂ (that is, if the subject is dark), the backlight control signal d is adjusted and the back value is adjusted. The DC / AC inverter 15 is controlled so that the light 13 is darkened. As a result, the width of the pulse signal output from the DC / AC inverter 15 becomes small, the backlight 13 becomes dark, and the LCD 14 becomes dark. Conversely, if the Ev value is larger than the set value SV ₂ (that is, if the subject is bright), the backlight control signal d is adjusted to control the DC / AC inverter 15 so that the backlight 13 is brightened. As a result, the width of the pulse signal output from the DC / AC inverter 15 is increased, the backlight 14 is brightened, and the LCD 14 is brightened. The backlight signal d is converted into an analog signal by the D / A conversion circuit 8 and then input to the DC / AC inverter 15.
[0028]
As described above, according to the liquid crystal display device according to the present embodiment, the visibility of the LCD 14 can be improved by brightening the backlight 13 and brightening the LCD 14 in a bright outdoor place. Further, in an indoor dark place, the backlight 13 is darkened and the LCD 14 is darkened, so that the visibility can be improved and the power consumption of the backlight 13 can be reduced. In addition, the brightness of the subject can be obtained without providing a dedicated optical sensor.
[0029]
Note that the backlight control signal d (that is, the brightness of the LCD 14) output from the microcomputer 7 may be linearly changed according to the brightness of the subject, or may be changed stepwise.
[0030]
Further, the integration circuit 6 may be a method of integrating one screen as described above, or may be a method of dividing the screen into a plurality of regions and integrating each region.
[0031]
In the above embodiment, the case of a liquid crystal display device has been described. However, the present invention is not necessarily limited to this, and the present invention can also be applied to a display device using a CRT.
[0032]
Further, Av the Ev value in the above embodiment, Tv, Sv _100, Eev, but accurately determined by a variety of information about the exposure such Agcv and cCDV, practically not necessarily be determined such accurate value For example, the Ev value may be obtained from Av (iris opening value) and Eev (overexposure / underexposure value).
[0033]
【The invention's effect】
As specifically described above with the embodiment of the present invention, according to the present invention, the brightness of the subject can be obtained without newly providing a dedicated optical sensor, and based on the brightness of the subject, The brightness of the display unit can be set to an optimum brightness according to the ambient brightness. That is, in a bright outdoor place, the display portion can be brightened to improve visibility, and in a dark indoor location, the display portion can be darkened to improve visibility and reduce power consumption.
[Brief description of the drawings]
FIG. 1 is a block diagram of an image pickup apparatus provided with a liquid crystal display device according to an embodiment of the present invention.
FIG. 2 is a flowchart of AE control and backlight control.
FIG. 3 is a graph showing the opening characteristics of an iris.
FIG. 4 is a rear perspective view showing an example of a video camera provided with a liquid crystal display device according to the prior art.
[Explanation of symbols]
1 Iris 2 CCD
3 Preamplifier 3a AGC circuit 4 A / D conversion circuit 5 Signal processing circuit 6 Integration circuit 7 Microcomputer 8 D / A conversion circuit 9 Iris driver 10 Decorator 11 LCD controller 12 Timing generator 13 Backlight 14 LCD
15 DC / AC converter 16 Lens 17 Display unit

Claims (2)

A display device that is provided in an imaging device that captures an image of a subject with an imaging element, and that displays an image of the subject on a display unit that is viewed with both eyes ,
Integrating means for integrating the luminance signal component of the output signal of the image sensor;
The integrated value of the luminance signal output from the integrating means and the iris opening value obtained from the table data of the iris meter rotation angle-iris opening characteristic measured in advance by detecting the rotation angle of the iris meter by the Hall element. A calculation means for obtaining the absolute brightness of the subject based on,
A display device comprising: adjusting means for adjusting the brightness of the display unit in accordance with the absolute brightness of the subject obtained by the calculating means. The display device according to claim 1,
The display unit includes a display using a liquid crystal and a backlight, and the adjusting means adjusts the brightness of the backlight to adjust the brightness of the display. apparatus.

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