JP2003337319A - Illumination light controller for display part using optical sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively and accurately control illumination light illuminating a display surface by improving the sensitivity and accuracy of detection of external light. <P>SOLUTION: The optical sensor 3 and a light emission part such as an LED light 4 arranged alongside a light transmission plate 5, the display surface 1 is used even as the photodetection surface of the optical sensor 3, and light received by the display surface 1 is guided by the light transmission plate 5 to the optical sensor 3 to detect the quantity of the external light. The external light is detected on a time-division basis and a display period is switched to a light quantity detection period in specified timing; and the output of the optical sensor 3 is received in the detection period to fine the quantity of the external light and the light emission part is controlled according to the quantity of the external light to control the illumination light to the display surface. Thus, the optical sensor 3 is arranged together with the light emission part alongside the light transmission plate 5, so that characteristics of the light transmission plate are reversely used to measure the quantity of light over the entire display surface to be measured with good efficiency. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination light control device for illuminating a display section of a portable device, and more particularly, the present invention detects the amount of external light by an optical sensor and controls illumination light accurately and effectively. The present invention relates to an illuminating light control device for a display unit that can perform.

[0002]

2. Description of the Related Art In recent years, in order to reduce the power consumption of portable devices such as mobile phones, the amount of outside light is measured using an optical sensor, and a backlight (or front light) from a light emitting portion such as a light emitting diode is used. , When the outside light is bright, OF
F, ON / OF so that it is turned on when outside light is dark
F control is performed. FIG. 12 shows an example of the mounting position of the optical sensor in the mobile phone. Conventionally,
As shown in the figure, an optical sensor light receiving hole 2 is provided above the LCD display surface 1, and external light is received through the light receiving hole 2 by an optical sensor 3 provided therein. The external light amount detected by the optical sensor 3 is sent to a control unit (not shown), and the control unit controls lighting of a light emitting unit such as an LED light 4 provided below the LCD display unit 1 according to the external light amount. To do. The light of the LED light 4 is guided to the LCD display surface 1 via the light guide plate 5 and illuminates the display surface.

[0003]

Conventionally, as described above, external light is received through the photosensor light receiving hole 102 provided on the upper side of the LCD display surface 1, and the illumination light from the LED light is turned ON / OFF. It controlled OFF. The illumination light is for illuminating the display surface 1, and is originally ON / OF of the LED light depending on the amount of external light on the LCD display surface 1.
It is desirable to control F. However, conventionally, since the outside light is received through the optical sensor light receiving hole 2 as described above, the amount of outside light on the LCD display surface cannot be correctly detected, and the LED light can be appropriately controlled. There wasn't. Further, in the related art, external light is received through the light receiving hole of the optical sensor, and the light receiving sensitivity is low because the amount of light incident on the optical sensor is small, and the amount of external light cannot be accurately detected. The present invention has been made in view of the above circumstances, and the present invention improves the detection sensitivity / accuracy of external light by guiding light received on the entire display surface to an optical sensor and illuminates the display surface. The purpose is to control light effectively and accurately.

[0004]

In order to solve the above problems, according to the present invention, as shown in FIG.
And the light emitting parts such as the LED light 4 are arranged beside the light guide plate 5,
The display surface 1 is also used as a light receiving surface of the optical sensor 3, and the light received by the display surface 1 is guided to the optical sensor 3 by the light guide plate 5 to detect the amount of outside light. The detection of the outside light is performed in a time division manner,
The display period is switched to the light amount detection period at a predetermined timing, the output of the optical sensor 3 is captured during the detection period, the amount of outside light is obtained, and the light emitting unit is controlled according to the amount of outside light to control the illumination light on the display surface To do. As described above, since the optical sensor 3 is arranged beside the light guide plate 5 side by side with the light emitting portion, the characteristics of the light guide plate can be used to the contrary, and the amount of light on the entire display surface to be measured can be efficiently measured. Can be measured. Also,
Since the light incident on the entire surface of the display surface can be captured by the optical sensor, the light receiving sensitivity can be made higher than in the conventional case, and the illumination light can be controlled with high accuracy. Further, if the display of the display unit is switched to all white during the above detection period, the illumination light can be controlled as it is without the correction processing of the output of the optical sensor. In addition, the amount of light detected by the optical sensor during the detection period is set to the RG during the display period.
By correcting the lighting information of each color B and the spectral sensitivity characteristic of the photosensor to obtain the amount of outside light, the display can be continued during the detection period without affecting the display quality. Furthermore, by switching the display of the display unit from white to gray or from gray to white during the detection period, the dynamic range can be switched so that the output of the optical sensor falls within a predetermined range, and a wide input range can be obtained. It is possible to measure light with high accuracy.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention applied to a mobile phone will be described below. The present invention can be applied not only to mobile phones but also to various devices such as PDAs and notebook computers that need to illuminate the display surface. 1 is a conceptual diagram showing an arrangement of an LCD, a light guide plate, a backlight light source, and an optical sensor according to an embodiment of the present invention, FIG. 2 is a diagram showing a configuration example of a mobile phone according to the embodiment of the present invention, and FIG. L
The state where the cover of the CD display section is removed is shown. In addition,
Here, the case of using the backlight light source will be described, but in the case of using the front light source, the LCD and the light guide plate are arranged upside down in FIG. 1 and 2
In the present embodiment, as shown in FIG.
A light 4 (hereinafter also referred to as a backlight light source 4) is arranged beside the light guide plate 5, and the LCD display surface 1 is also used as a light receiving surface of the optical sensor 3. That is, the LCD display surface 1
When illuminating, the light from the backlight light source 4 is guided to the LCD display surface 1 through the light guide plate 5 to illuminate the display surface 1, and when the amount of external light is detected, the LCD display surface 1 receives the light. The emitted light is guided to the optical sensor 3 through the light guide plate 5 to detect the amount of outside light. The measurement of the amount of outside light is performed by the time division processing unit, and for example, the timing for turning off the backlight is temporarily made, and the amount of outside light is detected by the optical sensor 3 during that time.

FIG. 3 shows an example of the configuration of the control unit of this embodiment.
As shown in the figure, the external light amount detected by the optical sensor 3 is output as a current signal, converted into a voltage signal by the detection resistor 11, and the analog / digital converter 12 time-division controlled by the time-division processing control unit 14. Sent to. The analog / digital converter 12 converts the above voltage signal into a digital signal in the detection period of the amount of outside light and sends it to the processing device 13 including the CPU 13a, the memory 13b and the like. The processing device 13 recognizes the external light amount from the output of the optical sensor 3 converted into a digital signal, and according to the detected external light amount,
The backlight source 4 is turned on / off. Further, as described in the first and second embodiments described later, the LCD display unit 16 is controlled by the LCD controller 15 which is time-division controlled by the time-division processing control unit 14 during the detection period of the external light amount. Switch the LCD display.

Next, a first embodiment of the present invention will be described.
In the present embodiment, the display of the LCD display unit 16 is switched to the all white display during the period of detecting the amount of external light, and the optical sensor 3 is activated during that period.
An example in which the amount of outside light is detected is shown. FIG. 4 is a flow chart for explaining the processing by the processing device 13 in this embodiment, and this embodiment will be described below with reference to the figure. In step S1 of FIG.
It is checked whether it is the display period, and if it is the display period, the display by the LCD display unit 16 is set to the normal display in step S2. When it is not the display period, the external light amount is detected as the light amount detection period. That is, in step S3, the display data displayed on the LCD display unit 16 is saved, and in step S4, the LCD display is switched to the all white display. If the backlight light is ON at this time, the backlight light is turned OFF. In step S5, the amount of external light received by the LCD display surface 1 and detected by the optical sensor 3 via the light guide plate 5 is taken into the CPU 13a via the analog / digital converter 12 to recognize the amount of external light. Then, in step S6, the display data is restored, and in step S7, until the display period comes,
Return to step S1. The processing device 13 controls ON / OFF of the backlight light, as described above, according to the amount of outside light detected during the detection period. FIG. 5 shows an example of switching timing between the display period and the detection period. As shown in the figure, the time division control unit 14 controls the digital / analog converter 12 and the LCD controller 16 to switch the display period to the detection period at a cycle of 1/60 s, for example. Then, the amount of outside light detected by the optical sensor 3 during the detection period is transferred to C through the analog / digital converter 12.
Takes in the PU 13a and turns on the illumination light according to the amount of external light
/ OFF is controlled. In the present embodiment, as described above, the light received by the LCD display surface 1 is guided to the optical sensor 3 through the light guide plate 5 to detect the amount of external light, so that the detection sensitivity and detection accuracy of external light can be improved. It is possible to improve and control the illumination light that illuminates the display surface effectively and accurately.

In the first embodiment, the LCD display is switched to the white display during the detection period of time division processing, but the white display may adversely affect the display quality of the LCD. In the second embodiment described below, the display during the detection period is not the white display but is kept as the normal display, the lighting information of each RGB color of the display data at that time is obtained, and the sensitivity of each RGB color of the optical sensor is obtained. The amount of outside light that is not affected by the display content is detected from the characteristics and the like, and the illumination light of the display unit is controlled. That is, the spectral sensitivity characteristic is calculated from the sensitivity characteristic of each color of RGB of the optical sensor, the lighting information of each color of RGB is multiplied by the spectral sensitivity characteristic to obtain the luminance correction coefficient, and the luminance correction coefficient and the optical sensor 3 detect the luminance correction coefficient. The amount of external light is multiplied by the amount of external light to calculate the true amount of external light, which controls the illumination light.

The amount of outside light is calculated, for example, as follows. FIG. 6 shows an example of sensitivity characteristics of each color of RGB of the optical sensor, and FIG. 7 shows an example of input luminance-sensor sensitivity characteristics of each color of RGB of the optical sensor obtained from FIG. The horizontal axis of FIG. 6 represents the wavelength, the vertical axis represents the output characteristics (relative value) of the optical sensor,
In FIG. 7, the horizontal axis represents the amount of light incident on the optical sensor, and the vertical axes represent R, G, B.
The sensor sensitivity characteristic (relative value) of each color is shown. In FIG. 7, for example, the sensor sensitivities when the amount of incident light of the photosensor is 100 are R = 10, G = 80, and B = 50. Therefore, the sensitivity of the optical sensor for each of the RGB colors is as follows. [R sensitivity]: [G sensitivity]: [B sensitivity] = 0.1:
0.8: 0.5 Here, the lighting states of R, G, and B colors on the display screen are LR, LG, and LB, respectively, and when all white is displayed, LR is displayed.
= 1, LG = 1 and LB = 1. From the above, the output of the optical sensor at the time of displaying all white is calculated as follows. LR × 0.1 + LG × 0.5 + LB × 0.8 = 0.1 + 0.5 + 0.8 = 1.4 That is, the output of the optical sensor in the case of all white is 1.4.

Further, it is assumed that the lighting information of each color of RGB of the display data displayed on the LCD display screen is as follows. LR = 0.5, LG = 0.5, LB = 1 In the above lighting state, if the same amount of light as in the case of the all white display is incident on the LCD display surface, external light is transmitted through the LCD display surface. The output of the optical sensor that receives the light is calculated from the sensitivity information of the optical sensor for each of the RGB colors of the optical sensor as follows. LR x 0.1 + LG x 0.5 + LB x 0.8 = 0.5 x 0.1 + 0.5 x 0.5 + 1 x 0.8 = 1.1 From the above, the lighting information on the LCD display surface is LR = 0.5,
The luminance correction coefficient K when LG = 0.5 and LB = 1 is as follows. Luminance correction coefficient K = 1.4 / 1.1 Therefore, the LCD display surface is in the lighting state (LR =
0.5, LG = 0.5, LB = 1), and the light quantity detected by the photosensor through the LCD display surface is Ls, the outside light quantity L0 is calculated from the brightness correction coefficient K as follows. Calculated. External light amount L0 = K × Ls As described above, from the sensitivity characteristics of the RGB colors of the optical sensor,
By calculating the spectral sensitivity characteristic, multiplying the lighting information of each color of RGB by the spectral sensitivity characteristic to obtain a luminance correction coefficient, and obtaining the external light amount from the luminance correction coefficient and the external light amount detected by the optical sensor, the LCD display surface is obtained. It is possible to detect the amount of outside light that is not affected by the display content without displaying the white color.

FIG. 8 is a flow chart for explaining the processing of the second embodiment of the present invention, and this embodiment will be described with reference to the same figure. In step S1 of FIG. 8, it is checked whether or not it is the display period. If it is the display period, the display by the LCD display unit 16 is set to the normal display in step S2. When it is not the display period, the external light amount is detected as the light amount detection period. That is, in step S3, L
The RGB lighting information of the display data displayed on the CD display unit 16 is calculated, and in step S4, the amount of outside light detected by the optical sensor 3 is used as the analog / digital converter 1
It is taken into the CPU 13a via the CPU 2. If the backlight light is ON at this time, the backlight light is turned OFF. Then, in step S5, the brightness correction coefficient is calculated as described above on the basis of the RGB lighting information and the spectral sensitivity characteristic of the photosensor, and in step S6, the light amount detected by the photosensor is multiplied by the brightness correction coefficient. Then, the amount of outside light is calculated. The process waits until the display period is reached in step S7, and the process returns to step S1. The processing device 13 controls ON / OFF of the backlight light, as described above, according to the amount of outside light detected during the detection period. In the present embodiment, as described above, the display during the detection period is not the white display but is kept as the normal display, the lighting information of each color of RGB of the display data at that time is obtained, and the sensitivity of each color of RGB of the optical sensor is obtained. Since the amount of external light that is not affected by the display content is detected from the characteristics and the illumination light of the display unit is controlled, the amount of external light can be detected without adversely affecting the display quality of the LCD.

By the way, the sensitivity of the optical sensor can be adjusted by setting the value of the detection resistor 11 shown in FIG. 3. For example, when the input / output characteristic of the optical sensor is the characteristic shown in FIG. By adjusting the value of the detection resistor 11, the detection sensitivity can be increased as shown in FIG. That is, the range of the detection circuit setting A surrounded by a square in FIG. 9 can be measured by full-thru as shown in FIG. However, if the detection resistance is adjusted as described above and the sensitivity of the optical sensor is increased as shown in FIG. 10, the sensor output when the light larger than the light whose optical sensor output is 4.5 or more is incident on the optical sensor. Becomes saturated and measurement becomes impossible. On the contrary, as shown in FIG. 9, when the measurement range is widened, the sensitivity of the optical sensor decreases. That is, there is a trade-off relationship between the sensitivity of the optical sensor and the dynamic range of the light amount measurement, and in an environment where the amount of light incident on the optical sensor changes significantly, the sensitivity / dynamic range of the optical sensor can be adjusted according to the environment, It is desirable to be able to measure a wide range of light quantities with high sensitivity.

As described above, it is possible to adjust the sensitivity and the dynamic range of the optical sensor by adjusting the value of the detection resistor 11, etc., but the value of the detection resistor, the set value of the measuring circuit, etc. are simple. Cannot be changed to. Therefore,
In the third embodiment described below, the display color of the LCD during the light amount detection period is changed to white → gray or gray → white and the brightness of the LCD display is adjusted to set the measurement circuit. It is possible to measure a wide range of input light with high accuracy without changing. In the present invention, as described above, since the external light incident on the LCD display surface is made incident on the photosensor via the light guide plate, the amount of light incident on the photosensor is changed by changing the brightness of the LCD display section. This can be changed, and in the present embodiment, this is used to adjust the sensitivity and dynamic range of the optical sensor. FIG. 9 shows the input / output characteristics of the optical sensor when the display brightness of the LCD display section is set to 30% (gray display) which is about 1/3, and FIG. 10 shows the display brightness of the LCD display section at 100%. It shows the input / output characteristics of the optical sensor when it is set to (all white display).
By changing the brightness of the LCD display, the sensitivity and dynamic range of the photosensor can be adjusted.

The amount of outside light when the brightness of the LCD display unit is adjusted as described above can be calculated in the same manner as in the second embodiment, and the RGB lighting information of the LCD display unit during the detection period can be calculated. It is possible to calculate the correction coefficient from the above, and multiply the amount of light detected by the optical sensor by the above correction factor to obtain the amount of outside light. Hereinafter, the calculation of the amount of outside light in the above-described embodiment will be described. Similar to the second embodiment, RG
The sensitivities of the photosensors for the respective colors B are as follows. [R sensitivity]: [G sensitivity]: [B sensitivity] = 0.1:
0.8: 0.5 Further, the lighting states of R, G, and B colors on the display screen are LR, LG, and LB, respectively, and when all white is displayed, LR =
1, LG = 1 and LB = 1. From the above, the output of the optical sensor when displaying all white is as described above. LR × 0.1 + LG × 0.5 + LB × 0.8 = 1.4 That is, the output of the optical sensor in the case of all white is 1.4.

In addition, R displayed on the LCD display screen
It is assumed that the lighting information of each color of GB is as follows. In addition,
In this case, since the display color is gray, LR, LG, and LB have the same value. LR = LG = LB = 0.6 In the above lighting state, if the same amount of light as in the case of the all white display is incident on the LCD display surface, the light sensor of the optical sensor that receives external light through the LCD display surface is displayed. The output is calculated as follows from the sensitivity information of the photosensor for each RGB color of the photosensor. LR x 0.1 + LG x 0.5 + LB x 0.8 = 0.6 x 0.1 + 0.6 x 0.5 + 0.6 x 0.8 = 0.6 x 1.4 From the above, the lighting information on the LCD display surface is LR = LG = L
The brightness correction coefficient K when B = 0.6 is as follows. Brightness correction coefficient K = 1 / 0.6 That is, the brightness correction coefficient in the case of gray display matches the lighting information of each of the R, G, and B colors. Therefore, the LCD display surface is in the lighting state (LR = LG = LB =
In the case of 0.6), if the light amount detected by the photosensor through the LCD display surface is Ls, the external light amount L0 is calculated from the brightness correction coefficient K as in the second embodiment as follows. To be done. External light quantity L0 = K x Ls

FIG. 11 is a flow chart showing the processing of the third embodiment of the present invention. This embodiment will be described with reference to FIG. In the following processing example, the case where the white display is switched to the gray display is shown, but the gray display may be performed and the white display may be switched when the sensitivity is too low. In step S1 of FIG. 11, it is checked whether it is the display period. If it is the display period, the display by the LCD display unit 16 is set to the normal display in step S2. When it is not the display period, the external light amount is detected as the light amount detection period. That is, in step S3, the display data displayed on the LCD display unit 16 is saved, and in step S4, the LCD display is switched to the all white display. If the backlight light is ON at this time, the backlight light is turned OFF. In step S5, the amount of external light received by the LCD display surface 1 and detected by the optical sensor 3 via the light guide plate 5 is taken into the CPU 13a via the analog / digital converter 12 to recognize the amount of external light.

Then, in step S6, it is checked whether or not the detection result by the optical sensor is equal to or more than the threshold value. If it is less than the threshold value, the process goes to step S9. The output result of the optical sensor is not less than the threshold value (for example, in FIG.
4.5 or more), go to step S7, LCD
The display brightness of is adjusted to gray display, the correction coefficient is calculated as described above, and the process returns to step S5. The above steps S5 to S7 are repeated while gradually lowering the brightness, and when the detection result becomes less than or equal to the threshold value, step S
Go to 8. In step S8, the amount of light detected by the optical sensor is multiplied by a correction coefficient to obtain the amount of outside light. The correction coefficient in the case of all white display is 1 as described above.
The display data is restored in step S9, and step S10
Wait until the display period comes, and then return to step S1. The processing device 13 controls ON / OFF of the backlight light, as described above, according to the amount of outside light detected during the detection period. As described above, in the present embodiment, the display color of the LCD during the light amount detection period is changed from white to gray or gray to white according to the light amount detection result to adjust the brightness of the LCD display. As a result, it is possible to measure a wide range of input light with high accuracy without changing the settings of the measuring circuit.

[0018]

As described above, the following effects can be obtained in the present invention. (1) Since the light received on the display surface is guided to the optical sensor via the light guide plate to detect the amount of outside light, the characteristics of the light guide plate are used in reverse, so that the light quantity on the entire display surface that is originally desired to be measured is used efficiently. Can be measured. Further, since the light incident on the entire surface of the display surface can be captured by the optical sensor, the light receiving sensitivity can be made higher than in the conventional case, and the illumination light can be controlled with high accuracy. (2) The display period is switched to the external light detection period at a predetermined cycle, and the display of the display unit is switched to all white during the detection period,
By guiding the external light to the optical sensor, the illumination light can be controlled as it is without correcting the output of the optical sensor. (3) The amount of light detected by the optical sensor in the detection period is corrected based on the lighting information of each color of RGB in the display period and the spectral sensitivity characteristic of the optical sensor to obtain the amount of outside light. Also, the display can be continued without affecting the display quality. (4) By switching the display of the display unit from white to gray or from gray to white during the detection period,
The dynamic range can be switched so that the output of the optical sensor falls within a predetermined range, and it is possible to accurately measure a wide range of input light.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an arrangement of a display unit, a light guide plate, a backlight light source, and an optical sensor according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration example of a mobile phone according to an embodiment of the present invention.

FIG. 3 is a diagram showing a configuration example of a control unit of the present embodiment.

FIG. 4 is a flowchart illustrating a process in the first embodiment of the present invention.

FIG. 5 is a diagram showing an example of switching timing between a display period and a detection period.

FIG. 6 is a diagram showing an example of sensitivity characteristics of RGB colors of an optical sensor.

7 is a diagram showing an example of input luminance-sensor sensitivity characteristics of RGB colors of the optical sensor obtained from FIG.

FIG. 8 is a flowchart illustrating a process of the second embodiment of the present invention.

FIG. 9 is a diagram showing the input / output characteristics of the optical sensor when the display brightness of the LCD display unit is set to 30% (gray display).

FIG. 10 is a diagram showing the input / output characteristics of the optical sensor when the display brightness of the LCD display unit is 100% (all white display).

FIG. 11 is a flowchart showing the processing of the third embodiment of the present invention.

FIG. 12 is a diagram showing an example of an attachment position of an optical sensor in a mobile phone.

[Explanation of symbols]

1 Display surface 3 optical sensor 4 LED light (backlight light source) 5 Light guide plate 1 LCD display surface 11 Detection resistance 12 Analog / digital converter 13 Processor 13a CPU 13b memory 14 Time division processing control unit 15 LCD controller 16 LCD display

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Claims (5)

[Claims] 1. A display unit, a light emitting unit that emits light for illuminating the display unit, a light guide plate that guides the light of the light emitting unit to the display unit, and external light through the light guide plate. Switch the display period to the external light detection period at a predetermined cycle with the light sensor that receives light,
An illumination light control device using an optical sensor, comprising: a control device that controls light emission of the light emitting unit in the display period based on the amount of light detected by the optical sensor in the detection period. 2. The illumination light control device using an optical sensor according to claim 1, wherein the control device switches the display on the display unit to all white during the detection period. 3. The controller controls the amount of light detected by an optical sensor during the detection period to be RG during the display period.
The illumination light control device according to claim 1, wherein the amount of outside light is obtained by performing correction based on the lighting information of each color B and the spectral sensitivity characteristic of the optical sensor. 4. The illumination light control device according to claim 1, wherein the control device switches the display of the display unit so that the output of the optical sensor falls within a predetermined range. 5. A display unit, a light emitting unit that emits light for illuminating the display unit, and a light guide plate that guides the light of the light emitting unit to the display unit. An illumination light control program for receiving light by an optical sensor and controlling light emission of a light emitting unit based on the amount of light received by the optical sensor, wherein the program switches a display period to an external light detection period at a predetermined cycle. hand,
A light for causing a computer to execute a process of reading a light amount detected by the optical sensor in the detection period and a process of controlling light emission of the light emitting unit in the display period based on the detected light amount. Illumination control program using sensors.