JPH05292364A - Display device - Google Patents

Abstract

PURPOSE:To set automatically a liquid crystal display panel in the optimum state at all times by calculating blightness information based on an output signal of a CCD image pickup element so as to control the blightness of the liquid crystal display panel via a brightness control circuit. CONSTITUTION:Upon the receipt of an output of a CCD image pickup element 3 via a sample-and-hold circuit 5, an A/D converter 6 and an automatic exposure(AE) detection circuit 8, a controller 13 calculates the blightness information. A brightness control circuit 17 is controlled in response to the information and a back light 18 is controlled via the circuit 17 and the blightness of the liquid crystal display panel 12 is automatically adjusted. Thus, the liquid crystal display panel is set automatically in the optimum state at all times without adjustment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a display device, for example,
The present invention relates to a color liquid crystal display device used in a video camera.

[0002]

2. Description of the Related Art A video camera is provided with a viewfinder for viewing an image being recorded or reproduced. The viewfinder is made of liquid crystal and is supplied with only the luminance signal in the video signal. Therefore, a black and white image is displayed on the viewfinder, and the user can monitor the state of the recording signal or the reproduction signal by viewing the image.

For a viewfinder with a black and white display,
Recently, a video camera having a color liquid crystal capable of color display may be used. In such a video camera, an LCD controller for varying the transmittance of liquid crystal and a bright controller for controlling the brightness of the color liquid crystal backlight are additionally provided. By the way, in such a color display viewfinder, the appearance is greatly different depending on the external light. That is,
When the surroundings of the subject are dark, by making the brightness of the backlight darker, the color liquid crystal can be effectively used and a clear image can be obtained on the liquid crystal panel. Further, when viewing an image of a subject in a bright place such as outdoors, external light may be reflected on the liquid crystal surface. In this case, the backlight must be brightened by the bright controller. By adjusting the backlight in this way, the user can obtain a clear video signal in the viewfinder.

[0004]

However, in order to adjust the color liquid crystal to the optimum state, the user has to operate the LCD controller and the bright controller each time. The same applies to a liquid crystal color television, and the LCD adjustment knob and the brightness adjustment knob must be controlled. As described above, in order to obtain the optimum color image, the user has to adjust the brightness of the liquid crystal panel to the optimum state according to the change of the ambient brightness.

Therefore, an object of the present invention is to provide a display device which can always set the liquid crystal panel in an optimum state even if the brightness of the liquid crystal panel is not adjusted by the user.

[0006]

According to the present invention, the brightness of a display means is controlled using a calculation means for calculating brightness information by using the output of a solid-state image pickup device and the brightness information calculated by the calculation means. And a control means for controlling the display device.

Further, the present invention is a display device characterized in that the calculating means calculates the brightness information F = V / G when the optical gain = G and the image pickup signal level = V. is there.

Further, according to the present invention, when the iris gain = G _iris , the AGC amplifier gain = G _AGC and the image pickup signal level = V, the arithmetic means is brightness information F = V / (G
_iris × G _AGC ).

[0009]

The amount of incident light is calculated from the output of the image pickup signal, the iris gain and the AGC gain. The bright control circuit is controlled in accordance with this calculation result.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a video camera to which the present invention is applied will be described below with reference to the drawings. FIG. 1 is a circuit block diagram of a video camera to which the present invention is applied. Figure 1
At, the amount of light incident from the lens 1 is equal to the iris 2
It is supplied to the CCD image pickup device 3 via. Photoelectric conversion is performed in the CCD image pickup device 3, and the output signal thereof is converted into a digital signal by the A / D converter 6 via the sample hold circuit 4 and the AGC amplifier 5. The digital signal from the A / D converter 6 is supplied to a signal processing circuit 7 and an automatic exposure (hereinafter referred to as AE) detection circuit 8. The digital signal, which has been subjected to predetermined signal processing in the signal processing circuit 7, is converted into an analog signal in the D / A converter 9 and then output as a luminance signal Y and a chroma signal C, and also supplied to the adder 10. ..

The luminance signal Y and the chroma signal C added by the adder 10 are supplied to the liquid crystal panel 12 via the LCD control circuit 11. As a result, the liquid crystal panel 1
The brightness of 2 is controlled. Instead of the luminance signal Y, an output signal of a bright control circuit described later may be supplied to the adder 10.

On the other hand, the digital signal supplied to the AE detection circuit 8 is supplied to the controller 13. Further, the output from the Hall element 14 for detecting the opening of the iris 2 is amplified by the Hall amplifier 15 and converted into a digital signal by the A / D converter 19, and then the controller 1
3 is supplied. The controller 13 is the D / A converter 1
The AGC amplifier 5 is controlled via 6 and the brightness of the backlight 18 is controlled via the bright control circuit 17. Further, a control signal is supplied from the controller 13 to the iris driver 20 for controlling the opening and closing of the iris, whereby the opening degree of the iris 2 is controlled.

In such a circuit, the AGC amplifier 5
The controller 13 controls the iris 2 and the AGC amplifier 5 so that the output of is constant regardless of the increase or decrease of the incident light amount (brightness of the subject). by the way,
The brightness of the subject (the amount of incident light) can be obtained by detecting the gain of the AGC amplifier 5 and the opening of the iris 2. Here, when the output signal (imaging signal level) of the AGC amplifier 5 is V _A , V _A = G _iris × G _AGC × F (1) (where F is the incident light amount and G is the optical gain (G _iris Is an iris gain, and G _AGC is an AGC gain) Further, from the formula (1), F = V _A / (G _iris × G _AGC ) ... (2) holds, whereby the incident light amount F Is large, the iris 2 is controlled in the closing direction, so that the gain of the AGC amplifier 5 is reduced, and when the incident light amount F is small, the iris 2 is controlled in the opening direction. The gain of the amplifier 5 is increased, and the output of the AGC amplifier 5 is kept constant in this way.

The AGC amplifier 5 is connected to the controller 13 via a D / A converter 16. Therefore, A
The gain of the GC amplifier 5 is controlled by the controller 13. Further, the opening degree of the iris 2 is controlled by the controller 13 via the iris driver 20. Further, the output signal V _A of the A / D converter 6 is the AE detection circuit 8
Is supplied to the controller 13 via. As is apparent from these, the controller 13 can measure the gain of the AGC amplifier 5 (G _AGC ), the gain of the _iris (G _iris ) and the image pickup signal level V _A.
Thereby, the incident light amount F can be calculated.

When the controller 13 determines that the incident light amount F is large, the bright control circuit 17 controls the backlight 18 to make it bright. On the contrary, when it is determined that the value of the incident light amount F is small, the bright control circuit 17 controls the backlight 18 to be dark. Also,
The LCD control circuit 11 is similarly controlled. Thus, the liquid crystal panel 12 and the backlight 18
By controlling the brightness of both, the liquid crystal panel 12 can always be kept in the optimum state.

FIG. 2 shows a circuit block diagram of a liquid crystal television to which the present invention is applied. In FIG.
The incident light amount F is a silicon photodiode (hereinafter, SP
It is incident on a photoelectric conversion element such as (D) 21 and is photoelectrically converted. The output signal of the SPD 21 is the A / D converter 2
It is converted into a digital signal by 2 and supplied to the controller 23. The controller 23 calculates the value of the incident light amount F based on the signal supplied from the A / D converter 22.

When it is determined that the value of the incident light amount F is large, the bright control circuit 24 is controlled so as to make the backlight 25 brighter, and conversely, when it is determined that it is small, the backlight 25 is turned on. The bright control circuit 24 is controlled to darken. The brightness of the liquid crystal panel 26 is controlled by the tuner 28 via the LCD control circuit 27. In this way, by controlling the brightness of both the backlight 25 and the liquid crystal panel 26, it becomes possible to keep the liquid crystal panel 26 in an optimum state at all times.

[0018]

According to the present invention, the magnitude of the amount of incident light is calculated, and the brightness control circuit and the LCD control circuit are automatically controlled by the calculated value. Therefore, the user can save the trouble of adjusting the brightness of the backlight. Further, since the brightness of the viewfinder can be automatically and continuously controlled to the optimum state, it is possible to prevent power consumption due to excessively brightening the liquid crystal panel.

[Brief description of drawings]

FIG. 1 is a circuit block diagram of a video camera to which the present invention is applied.

FIG. 2 is a circuit block diagram relating to screen brightness of a television to which the present invention is applied.

[Explanation of symbols]

 2 Iris 5 AGC amplifier 8 Automatic exposure detection circuit 12, 26 Liquid crystal panel 13, 23 Controller 17, 24 Bright control circuit 18, 25 Backlight

Claims (3)

[Claims] 1. A calculation means for calculating brightness information using an output of a solid-state image sensor, and a control means for controlling brightness of a display means using the brightness information calculated by the calculation means. Display device. 2. The calculating means sets an optical gain = G,
When the image pickup signal level = V, the brightness information F = V / G
The display device according to claim 1, characterized in that 3. The iris gain = G
_{When iris} , AGC amplifier gain = G _AGC and image pickup signal level = V, brightness information F = V / (G _iris ×
The display device according to claim 1, wherein the display device is _operated as G _AGC ).