JPH0744655B2 - Video tape recorder with integrated camera and LCD display - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera-integrated video tape recorder with a liquid crystal display, and more particularly to a camera with a liquid crystal display having a function of controlling the brightness of an image displayed on the liquid crystal display. The present invention relates to an integrated video tape recorder.

[Prior Art] Liquid crystals have been put into practical use as displays for wristwatches, electronic desk calculators (calculators), character / graphics displays, televisions, etc., and have become widespread. This is a liquid crystal display CR
Compared to the T-display (abbreviation of Cathode Ray Tube Display), it is easy to make thin and consumes less power. Initially, it was used for the purpose of simple display of numbers and characters such as clock display and calculator display. These LCD displays allow you to freely adjust the brightness (brightness), color tone, color depth, etc. according to the user's preference and usage environment, and because it is not an image that requires delicate adjustment technology, it is easy for beginners to adjust. Can be done. The camera-integrated videotape recorder that uses this liquid crystal display as a viewfinder has the advantage that you can shoot while checking the subject to be captured by the viewfinder, and even if you are a beginner, you can shoot relatively easily. That is.

[Problems to be Solved by the Invention] However, in the conventional camera-integrated video tape recorder with a liquid crystal display, the brightness of the screen of the liquid crystal display, which is a viewfinder, is lower than the ambient brightness in the case of outdoor shooting. Therefore, there is a problem that the liquid crystal display is difficult to see especially in a bright place. This is because the liquid crystal display used in televisions and the like uses a method in which light is made incident from the back surface by a dedicated light source (backlight).
The light transmittance of iquid Crystal Display is about 2-3.
%, So most of the light energy from the backlight on the back of the LCD is not transmitted and the LCD screen brightness is not sufficient.

In order to solve this problem, the brightness of the backlight or the voltage applied to the LCD was conventionally adjusted with a bright volume control to fine-tune the brightness to match the surrounding brightness. It is troublesome, and for beginners, there is a problem in that the fine adjustment is confused, and adverse effects such as interruption of the original purpose of shooting with the camera are caused.

Therefore, an object of the present invention is to automatically control an optimum image of a liquid crystal display which is a viewfinder, thereby eliminating manual adjustment in adjusting the brightness of the liquid crystal display according to various conditions including a use environment. It is an object of the present invention to provide a camera-integrated video tape recorder with a liquid crystal display, which has improved operability and is capable of multi-stage automatic adjustment of its brightness, and at the same time being capable of greatly increasing its brightness.

[Means for Solving the Problem] A camera-integrated video tape recorder with a liquid crystal display according to the present invention is a camera-integrated video tape recorder equipped with a liquid crystal display for displaying captured images. Means, backlight means, and backlight driving means, and the backlight driving means includes a power supply voltage switching means and an applied voltage switching means.

The image pickup means picks up an image of a subject and extracts a video signal. The light amount detecting means is provided in association with the image pickup means and detects the light amount incident on the camera. The backlight unit is provided on the back surface of the liquid crystal display, and receives the voltage application to illuminate the liquid crystal display from the back surface.

The backlight drive means is supplied with a power supply voltage, operates to supply an applied voltage to the backlight means based on the power supply voltage, and controls the applied voltage in response to the light quantity detection output from the light quantity detection means. The irradiation light amount of the backlight unit is controlled.

The power supply voltage switching means receives a plurality of power supply voltages having different levels, and switches the power supply voltage used to supply the applied voltage among the power supply voltages in response to the light amount detection output in order to control the applied voltage.

The applied voltage switching means switches the applied voltage supplied to the backlight means in a plurality of stages in response to the light amount detection output.

[Operation] The camera-integrated video tape recorder with a liquid crystal display according to the present invention obtains a video signal by the image pickup means, detects the light quantity from the video signal by the light quantity detection means, and further emits light from the back surface of the liquid crystal display. The backlight means for irradiating operates so as to adjust the irradiation light amount according to the light amount detection output. Therefore, it is possible to automatically obtain the brightness of the liquid crystal display according to the brightness according to the use condition, and thus it is possible to improve the visibility of the liquid crystal display due to the brightness change depending on the use condition.

Further, in the backlight driving means for controlling the irradiation light amount of the backlight means, the power supply voltage switching means and the applied voltage switching means operate independently or simultaneously.

The power supply voltage switching means controls the irradiation light quantity of the backlight means by switching the power supply voltage used for supplying the applied voltage in a plurality of stages in response to the light quantity detection output. The applied voltage switching unit controls the irradiation light amount of the backlight unit by switching the applied voltage supplied to the backlight unit in response to the light amount detection output.

Therefore, by independently operating the power supply voltage switching means and the applied voltage switching means, the irradiation light amount of the backlight means can be controlled in multiple stages. Further, by simultaneously operating the power supply voltage switching means and the applied voltage switching means, it is possible to significantly increase the irradiation light amount of the backlight means.

[Embodiment] An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic block diagram showing the configuration of the brightness control function of a liquid crystal display according to an embodiment of the present invention.

In FIG. 1, the brightness control function of the liquid crystal display includes a video camera unit 40 that controls the operation of the video camera and a liquid crystal display unit 50 that controls the operation of the liquid crystal display. Further, the video camera unit 40 includes a plurality of optical lenses 10i (i = 1, 2, 3, ..., N) having different characteristics.
A lens system 10 that guides light to the inside while adjusting the zooming of the light entering the camera, and an aperture 11 that adjusts the light guided from the lens system 10 to an appropriate amount of incident light according to its opening and closing degree. The light entering through 11 is imaged on the element surface, and the formed optical image is converted into an electric signal.
CCD (abbreviation of Charge Coupled Device) image sensor 12, which outputs an image signal according to the brightness by so-called photoelectric conversion,
CCD drive signal generation circuit 13 that gives the operation signal to the CCD image pickup device 12, preamplifier 14 that amplifies the video signal output from the image pickup device 12 and performs processing such as low frequency noise suppression, video signal from the preamplifier 14 From the Y / C processing system 15, which outputs the standard color video signal Y / C by superimposing the luminance signal and the color difference signal that have undergone gamma correction, clipping processing, white balance processing, etc. A light amount detection circuit that detects the brightness of the video signal, compares the detected value with a standard level of predetermined brightness, and outputs a light amount detection signal LW that instructs the opening / closing control of the diaphragm 11 based on the comparison result. 16 and a lens aperture driver 17 which receives the light amount detection signal LW from the light amount detection circuit 16 and drives so as to control opening and closing of the aperture 11 in accordance with the signal LW.

By the way, most of the image pickup apparatuses such as color video cameras and video movies that are currently widespread have an iris function. With the O-Iris function, this function allows the aperture of the lens to be automatically set according to the brightness of the subject. Therefore, the image pickup device can pick up an image of the subject with an optimum light amount according to the brightness of the subject. The auto iris function of the video camera unit 40 is configured as follows. CCD image sensor 1
The peak value or average value of the standard color video signal Y / C obtained through the 2 to Y / C processing system 15 is compared by the light amount detection circuit 16 with a predetermined standard level. Based on the comparison result, the light amount detection signal LW is fed back to the lens aperture driver 17, and accordingly, the lens aperture driver 17 is configured to adjust the opening / closing of the aperture 11 to obtain the optimum amount of light on the CCD image pickup device 12. ing. In this case, the light amount detection circuit 16 compares the detection signal at the average value level of the standard color video signal Y / C with a predetermined reference level of the light amount, and the detection signal falls below the reference level (current incidence). The light amount detection signal LW that increases the current flowing through the lens aperture driver 17 is output to the driver 17, and the driver 17 responds accordingly.
Opens the diaphragm 11 of the lens until the amount of light becomes appropriate. On the contrary, if the current amount of incident light is too large, the driver 17 operates so as to close the diaphragm 11 of the lens.

Therefore, the video camera unit 40 has the auto iris function and can obtain the image signal of the subject with the optimal light amount adjustment.

The liquid crystal display unit 50 receives the standard color video signal Y / C from the video camera unit 40 and separates it into a luminance signal Y and a color signal C from a Y / C separation circuit 20 and a Y / C separation circuit 20. The color signal C is input and the color difference signal RY and the color difference signal BY are input.
The color detection circuit 21, the color difference signal RY from the color detection circuit 21, the color difference signal BY from the color detection circuit 21, and the luminance signal Y from the Y / C separation circuit 20 are input to the color primary color signals R and G, A matrix circuit 22 for converting and outputting to B, a clamp circuit 23 for fixing the operating point potential of the liquid crystal, and color primary color signals R, G, B whose operating point potential of the liquid crystal is fixed by the circuit 23 are input,
A line sequential circuit 29, which outputs this as an RGB line sequential signal by a synchronization signal, outputs color primary color signals from the line sequential circuit 29, determines a liquid crystal to be driven, and applies a voltage for driving the liquid crystal. X driver 28, LC that arranges a plurality of liquid crystals in a matrix to form a display screen composed of liquid crystal elements
Includes D panel 30.

Further, the liquid crystal display unit 50 receives the standard color video signal Y / C from the Y / C processing system 15, separates the horizontal synchronizing signal H and the vertical synchronizing signal V from the signal Y / C, and outputs them. Input the horizontal sync signal H from the sync separation circuit 24,
The LCD panel 3 receives the horizontal sync signal H and the vertical sync signal V from the CB and CP generation circuit 25, which generates and outputs the color burst signal CB and the clamp pulse CP, and the sync separation circuit 24.
LCD drive circuit 26 for generating a drive signal of 0, LCD drive circuit 26
It includes a Y driver 27 for inputting a drive signal from the LCD panel 30 to determine a liquid crystal column to be driven in the LCD panel 30 and applying a voltage for driving to the corresponding column. In addition, L from the back of the LCD panel 30
It includes a backlight 32 for irradiating the CD panel 30 with light, and a backlight driving DC-AC converter 31 as a backlight driving means for driving the backlight 32.

The processing operation of the liquid crystal display unit 50 configured as above will be described.

First, the standard color video signal Y / C obtained by the imaging process of the video camera unit 40 is input to the Y / C separation circuit 20 and the sync separation circuit 24 of the liquid crystal display unit 50.

In the sync separation circuit 24, the input standard color video signal Y /
Only the sync signal is taken out of C, separated into a horizontal sync signal H and a vertical sync signal V, and both signals are output to the CB and CP generation circuit 25 and the LCD drive circuit 26 in the next stage. The synchronization signal extracted from the signal Y / C functions to assemble the image on the LCD panel 30 side, that is, the same image as that captured by the video camera unit 40. The LCD drive circuit 26, which receives the horizontal sync signal H and the vertical sync signal V from the sync separation circuit 24, generates a drive signal for the LCD panel 30 based on the both sync signals and outputs it to the Y driver 27. In response, the Y driver 27 applies a drive signal for applying a voltage to the corresponding liquid crystal column based on the drive signal from the LCD drive circuit 26 to the LCD panel 3.
Output to 0. Therefore, the LCD panel 30 is displayed on the liquid crystal by the same synchronizing signal as the image picked up by the video camera unit 40, so that the image display can be performed in synchronism with the image pickup side.

On the other hand, the CB and CP generation circuit 25 receives the horizontal synchronizing signal H from the cycle separation circuit 24, generates the color burst signal CB and outputs it to the color detection circuit 21, and also generates the clamp pulse CP and outputs it to the clamp circuit 23. ing.

A Y / C separation circuit 20 is a circuit for inputting the standard color video signal Y / C from the video camera unit 40. Y / C separation circuit 20
Then, in order to faithfully reproduce the color, the signal Y / C is changed to the color signal C.
And the luminance signal Y separately. Color detection circuit 21
Inputs the color signal C from the Y / C separation circuit 20, and outputs CB and CP.
The color burst signal CB input from the generation circuit 25 is input as a phase reference to form a color image signal for transmission,
The color difference signal RY and the signal BY are output to the matrix circuit 22. In response, the matrix circuit 22 receives the color difference signal RY and the color difference signal B- input from the color detection circuit 21.
Luminance signal Y input from Y / C separation circuit 20 is added to Y and 3
The primary color signals R, G, B are generated and output to the clamp circuit 23 at the next stage.

By the way, the video signal including the color primary color signal is finally displayed on the LCD display 30. At this time, a portion where the video signal level is higher than a certain reference level is displayed brightly, and a portion where the video signal level is low is displayed darkly. That is,
Brightness is represented by the DC component of the video signal. However, since this DC component is not transmitted or fluctuates due to the amplification processing up to the preceding stage, the clamp circuit 23 is provided to reproduce the DC component in consideration of this. Therefore, the DC components (average brightness of the video signal) of the color primary color signals R, G, B output from the clamp circuit 23 are reproduced and input to the line sequential circuit 29 in the next stage. The line-sequential circuit 29 inputs the color primary color signals R, G, and B having the brightness according to the imaging condition, and generates the line-sequential signal for each 1H by the horizontal synchronizing signal H obtained from the sync separating circuit 24. Output to the X driver 28. The X driver 28 applies a voltage to the LCD panel 30 according to the levels of the line sequential signals of the color primary color signals R, G and B. This signal voltage will be applied to the liquid crystal of the LCD panel 30. Further, at this time, since the voltage applied to the Y driver 27 synchronizes with the imaging side, it is possible to always see a proper LCD image in synchronization with the imaging side.

By the way, the LCD panel 30 applies the color primary color signals R, G, B from the X driver 28 to each RGB pixel including liquid crystal arranged in a matrix in the X direction and the Y direction.
Sampling is performed by the switching signal applied from the Y driver 27, and the light transmittance of the LCD is controlled according to the applied signal voltage values of the color primary color signals R, G, and B. Therefore, the transmitted light amount of the backlight light that illuminates the LCD from the back surface of the LCD panel 30 changes according to the transmittance of this light, and a dark and light image is displayed on the liquid crystal. Therefore, even if the voltage applied to the LCD is the same and the light transmittance is the same, the display screen of the LCD panel 30 can be made brighter by increasing the brightness of the backlight 32. That is, the DC-AC converter for driving the backlight is controlled by the light amount detection signal LW.
The voltage applied to the backlight 32 of 31 is changed, and the brightness of the backlight 32 is increased. The brightness control of the backlight 32 will be further described with reference to FIG.

FIG. 2 is a diagram showing an example of a circuit configuration of the backlight driving DC-AC converter shown in FIG.

Backlight driving DC-AC converter 31 shown in FIG.
Is an analog switch 33 which is a power supply voltage switching means, a switch 34 which is an applied voltage switching means, a coil L1, resistors R1 and R2, capacitors C1 and C3, and transistors Tr1 and T.
r2, coupling capacitor C2, transformer T1, light intensity detection signal LW input terminal A1, DC voltage V _DC input terminal A2, DC voltage V
Includes _DC1 input terminal A3. In addition, backlight drive DC-A
The power supply voltage of the C converter 31 is supplied to the circuit from the input terminals A2 and A3, and for the DC voltages V _DC and V _DC1 , (V
It is assumed that the relationship of _DC1 > V _DC ) is established.

Next, the circuit operation of the backlight driving DC-AC converter 31 shown in FIG. 2 will be described.

Now, the light amount detection signal LW is input from the input terminal A1. Accordingly, analog switch 33 is switched to the input terminal A2 side and takes in DC voltage V _DC as the power supply voltage. At this time, the transistors Tr1 and Tr2 oscillate at a frequency determined by the time constant of the coil L1 and the capacitor C1. Oscillations of the transistors Tr1 and Tr2 are boosted by the transformer T1 and an AC voltage is applied to the backlight 32 via the coupling capacitor C2 to cause it to emit light. At this time, the brightness of the backlight 32 is determined by the effective voltage value of the applied voltage. Therefore, if the power supply voltage that is selected by switching by the analog switch 33 is increased, the applied voltage to the backlight 32 also increases and becomes brighter. Therefore, when the subject becomes bright under the shooting conditions, the brightness of the backlight 32 is controlled to be bright. That is, by controlling the analog switch 33 to switch the connection from the input terminal A2 to the input terminal A3 by the light amount detection signal LW, the power supply voltage is changed from V _DC to V _DC1 (V _DC1 > V _DC1
When switched to _DC ), the applied voltage to the backlight 32 is also increased, and bright illumination of the backlight 32 can be obtained in parallel with the shooting conditions.

As a method of increasing the brightness of the backlight 32, there is a method of turning on the switch 34 only when the brightness is increased.
That is, the switch 34 is switched by the light amount detection signal LW input from the input terminal A1. When the switch 34 is turned on based on the light amount detection signal LW, the capacitor C3 becomes conductive and is connected in parallel with the coupling capacitor C2 with the backlight 32. Accordingly, the secondary impedance of the transformer T1 decreases and the voltage applied to the backlight 32 increases, so that the brightness of the backlight 32 can be further increased. Therefore, since the switch 34 is switched by the light amount detection signal LW to control the voltage applied to the backlight 32, the bright backlight 32 can be illuminated in parallel with the shooting conditions.

The relationship between the brightness of the backlight 32 and the LCD light transmission amount will be described with reference to the drawings.

FIG. 3 is a characteristic diagram showing the relationship between the light transmission amount of the LCD panel 30 shown in FIG. 1 and the input signal voltage.

In FIG. 3, the characteristic curve VT is the LCD as the input signal voltage V from the X driver 28 to the normal LCD panel 30 increases.
This shows that the light transmission amount (brightness) T of the panel 30 is increasing, and when the input signal voltage is V _in , the light transmission amount (brightness) T of the LCD is in the change range V _L. It indicates that there is. Now, the input signal voltage V _in does not change, the backlight 3
When the brightness of 2 is raised, the characteristic curve VT rises to the level of the characteristic curve VT1, and accordingly, the change range of the brightness of the LCD also rises from the change range _VL to the change range _VL1 and becomes bright. Shows.

Note that the switching operation of the analog switch 33 and the switch 34 in the backlight driving DC-AC converter 31 may be performed independently of each other, and the brightness of the backlight 32 is controlled by operating them simultaneously. You may raise it further.

[Effect of the Invention] The camera-integrated video tape recorder with a liquid crystal display according to the present invention obtains a video signal by the image pickup means and detects the light quantity from the video signal by the light quantity detection means.
Further, the liquid crystal display has a backlight unit for irradiating light from the back side thereof, and the light amount detection output is applied to the backlight unit to control the brightness of the backlight of the liquid crystal display unit. Therefore,
Even under bright usage conditions, the brightness of the backlight can be automatically increased according to the brightness, so that the brightness of the liquid crystal display screen can be adjusted automatically and the liquid crystal display always has proper brightness. The effect is that you can get a screen.

Further, both the power supply voltage switching means and the applied voltage switching means switch the irradiation light quantity of the backlight means in response to the light quantity detection output. Therefore, by independently operating the power supply voltage switching means and the applied voltage switching means, it is possible to automatically adjust the irradiation light amount of the backlight means in multiple stages. Further, by operating these means at the same time, the irradiation light quantity of the backlight means can be greatly increased.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing the configuration of the brightness control function of a liquid crystal display according to an embodiment of the present invention. FIG. 2 is a diagram showing an example of a circuit configuration of the backlight driving DC-AC converter shown in FIG. FIG. 3 is a characteristic diagram showing the relationship between the light transmission amount of the LCD panel shown in FIG. 1 and the input signal voltage. In the figure, 40 is a video camera unit, 50 is a liquid crystal display unit, 30 is an LCD panel, 31 is a backlight driving DC-AC.
A converter, 32 is a backlight, and LW is a light amount detection signal. In each drawing, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A camera-integrated video tape recorder having a liquid crystal display for displaying a picked-up image, the pick-up unit picking up an image of a subject and picking up a video signal; A light amount detecting means for detecting the amount of light incident on the camera, a backlight means provided on the back surface of the liquid crystal display for irradiating the liquid crystal display from the back surface with application of a voltage, and a power supply voltage A backlight for controlling an irradiation light amount of the backlight unit by operating to supply an applied voltage to the backlight unit based on a voltage and controlling the applied voltage in response to a light amount detection output from the light amount detection unit. A backlight driving means, the backlight driving means receives a plurality of types of power supply voltages having different levels, and applies the applied voltage to the backlight driving means. Power source voltage switching means for switching the power source voltage used to supply the applied voltage among the power source voltages in response to the light amount detection output, and the backlight means in response to the light amount detection output. A camera-integrated video tape recorder with a liquid crystal display, comprising: an applied voltage switching means for switching the applied voltage supplied to the device in a plurality of steps.