JPH02308679A - Camera integrated video tape recorder with liquid crystal display device - Google Patents

Abstract

PURPOSE:To eliminate the need for manual adjustment of the lightness of an LCD and to improve the operability by adjusting the radiation luminous quantity of a back light radiating a rear of the LCD in response to the detection output of the luminous quantity of a video signal. CONSTITUTION:A standard color video signal Y/C obtained from a video camera section 40 is inputted to a Y/C separator circuit 20 and a synchronizing separator circuit 24 of an LCD section 50. The circuit 24 extracts a synchronizing signal and separates the signal into a horizontal synchronizing signal H and a vertical synchronizing signal V and outputs them to a CB and CP generating circuit 25 and an LCD drive circuit 26. The circuit 26 outputs a drive signal to the panel 30 via a Y driver 27. On the other hand, the color burst signal CB from the circuit 25 is outputted to a color detection circuit 21 and a clamp pulse CP is outputted to a clamp circuit 23. The primary color R, G, B signals synthesized at the matrix circuit 22 are inputted to a clamp circuit 23, in which the DC component of the video signal is reproduced, inputted to the panel 30 via a line sequential circuit 29 and an X driver 28 and the contrast is expressed in response to the DC component.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a camera-integrated videotape recorder with a liquid crystal display, and 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. Relating to an integrated videotape recorder.

[Prior Art] Liquid crystals have been put into practical use as displays for wristwatches, electronic desktop calculators, character and graphic displays, televisions, and are now widely used. This means that the LCD display is
RT Display (Cathode Ray Tu
(abbreviation for be Display), it has the advantage of being easier to make thinner and having lower power consumption. Initially, it was used for simple displays of numbers and letters, such as for clock displays and calculator displays. With these LCD displays, the brightness (brightness), hue, and color density can be freely adjusted according to the user's preference and usage environment, and since the images do not require delicate adjustment techniques, even beginners can easily adjust them. I can do it. Camera-integrated videotape recorders that use this liquid crystal display as a viewfinder have the advantage of being able to take pictures while checking the subject captured in the viewfinder, making it relatively easy for even beginners to take pictures. That is what it is.

[Problems to be Solved by the Invention] However, in conventional video tape recorders with an integrated camera and an LCD display, when shooting outdoors, the brightness of the LCD screen that is the viewfinder is low compared to the surrounding brightness. Therefore, there was a problem that the LCD display was difficult to see, especially in bright places.

This is because liquid crystal displays used in televisions and other devices use a method in which light enters from the back of the display using a dedicated light source (backlight), but LCDs (
Liquid Crystal Display (abbreviation for Liquid Crystal Display) has a light transmittance of about 2 to 3%, so most of the light energy from the backlight on the back of the LCD does not pass through.
This is due to the fact that the CD screen brightness is not sufficient.

In order to solve this problem, conventional methods used a brightness volume to adjust the brightness of the backlight or the voltage applied to the LCD to finely adjust the brightness to match the brightness of the surroundings. It is troublesome, and it is confusing for beginners to make the fine adjustments, which has the problem of having negative effects such as interrupting the original purpose of photographing with the camera.

Therefore, an object of the present invention is to eliminate manual adjustment of the brightness of the liquid crystal display depending on various conditions including the usage environment by automatically controlling the optimum image of the liquid crystal display that is the viewfinder, and An object of the present invention is to provide a camera-integrated video tape recorder with a liquid crystal display that improves performance.

[Means for Solving the Problems] A camera-integrated videotape recorder with a liquid crystal display according to the present invention is a camera-integrated videotape recorder equipped with a liquid crystal display for displaying captured images, and for capturing an image of a subject. an imaging means for extracting a video signal; a light amount detection means provided in association with the imaging means to detect the amount of light incident on the camera; and a light amount detection means provided on the back of the liquid crystal display to illuminate the liquid crystal display from the back. and means for controlling the amount of light irradiated by the backlight means in response to a light amount detection output from the light amount detection means.

[Function] The camera-integrated videotape recorder with a liquid crystal display according to the present invention obtains a video signal by the imaging means, detects the amount of light from the video signal by the light amount detection means, and further outputs light from the back side of the liquid crystal display. The irradiating backlight means is operated to adjust the amount of irradiated light 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 depending on the usage conditions, so that it is possible to improve the difficulty in viewing the liquid crystal display when the brightness changes depending on the usage conditions.

[Embodiment] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic block diagram showing the configuration of a 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 section 40 that controls the operation of a video camera and a liquid crystal display section 50 that controls the operation of the liquid crystal display. Further, the video camera unit 40 includes a plurality of optical lenses 10i (iml, 2.3,
. . . n), a lens system 10 that guides light into the camera while adjusting zooming of the light incident on the camera;
A diaphragm 11 adjusts the light guided by the lens system 10 to an appropriate amount of incident light depending on the opening/closing degree of the lens system. COD (Charge) outputs an image signal according to the brightness by converting it into a signal, so-called
Coupled Device) image sensor 12,
A CCD that provides its operating signal to the CCD image sensor 12
A drive signal generation circuit 13, a preamplifier 14 that amplifies the video signal output from the image sensor 12 and performs processing such as suppressing low frequency noise, inputs the video signal from the preamplifier 14, and performs gamma correction, clip processing, white balance, etc. A Y/C processing system 15 that superimposes the processed luminance signal and color difference signal and outputs a standard color video signal Y/C, detects the luminance of the video signal from the signal Y/C, and compares the detected value with the A light amount detection circuit 16 outputs a light amount detection signal LW that instructs opening/closing control of the diaphragm 11 based on the comparison result, and a light amount detection signal LW from the light amount detection circuit 16 is compared with a predetermined standard level of brightness. Input,
It includes a lens aperture driver 17 that is driven to control opening and closing of the aperture 11 in accordance with the signal LW.

By the way, most of the currently popular imaging devices such as color video cameras and video movies are equipped with an O-iris function. What is the auto iris function?
This function allows you to automatically set the lens aperture depending on the brightness of the subject. Therefore, the image sensor can image the subject with an optimal amount of light depending on the brightness of the subject. The auto iris function included in the video camera unit 4o is configured as follows. The peak value or average value of the standard color video signal Y/C obtained through the CCD image sensor 12 or the Y/C processing system 15 is compared with a predetermined standard level by a light amount detection circuit 16. Based on the comparison result, the light amount detection signal LW is fed back to the lens aperture driver 17, and the lens aperture driver 17 adjusts the opening/closing of the aperture 11 accordingly to obtain the optimum amount of light on the CCD image sensor 12. ing. in this case,
The light amount detection circuit 16 compares the detected signal at the average level of the standard color video signal Y/C with a predetermined light amount reference level, and the detected signal fJ falls below the reference level (the current incident light amount is (less) and lens aperture driver 1
A light amount detection signal LW that increases the current flowing through the lens 7 is output to the driver 17, and in response, the driver 17 opens the aperture 11 of the lens until an appropriate amount of light is reached. Conversely, if the current amount of incident light is too large, the driver 17 operates to close the aperture 11 of the lens.

Therefore, the video camera section 40 has an auto-iris function and can obtain a video signal of a subject whose light amount has been adjusted to be optimal.

One liquid crystal display section 50 is connected to the video camera section 40.
A Y/C separation circuit 20 which inputs the standard color video signal Y/C from Y/C and separates it into a luminance signal Y and a color signal C;
A color detection circuit 21 receives the color signal C from the separation circuit 20, demodulates it into a color difference signal R-Y and a color difference signal -FjB-Y, and outputs the demodulated color signal C.
, color difference signal R-Y from color detection circuit 21, color difference signal B-
A matrix circuit 22 inputs the luminance signal Y from the Y and Y/C separation circuit 20, converts it into primary color signals R, , G, and B, and outputs the same, a clamp circuit 23 that fixes the operating point potential of the liquid crystal, and a circuit 23. A line sequential circuit 2 which inputs the color primary color signals RSG and B in which the operating point potential of the liquid crystal is fixed and outputs them as RGB line sequential signals using a synchronization signal.
9. An X driver 28 which receives primary color signals from the line sequential circuit 29, determines the liquid crystal to be driven, and applies a voltage to drive the liquid crystal; It includes an LCD panel 30 forming a display screen.

Further, the liquid crystal display section 50 includes a Y/C processing system 15.
input the standard color video signal Y/C, and input the signal Y/C.
A sync separation circuit 24 separates and outputs a horizontal sync signal H and a vertical sync signal V, and a CB and CP generator receives the horizontal sync signal H from the sync separation circuit 24 and generates and outputs a color burst signal CB and a clamp pulse CP. A circuit 25 inputs the horizontal synchronization signal H and vertical synchronization signal V from the synchronization separation circuit 24 to generate a drive signal for the LCD panel 30.An LCD drive circuit 26 inputs the drive signal from the LCD drive circuit 26 to drive the LCD panel 30. Decide which liquid crystal column to use and apply the voltage to drive the corresponding column.
A driver 27 is included.

Also, a backlight 32 for irradiating light to the LCD panel 30 from the back side of the LCD panel 30;
2, including a backlight driving DC-ACC set 31 for driving the backlight.

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

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

The synchronization separation circuit 24 extracts only the synchronization signal from the input standard color video signal Y/C, separates it into a horizontal synchronization signal H and a vertical synchronization signal V, and sends both signals to the next stage CB and CP generation circuit. 25 and LCD drive circuit 26
It is output to. The synchronization signal extracted from signal Y/C is
It functions to assemble the same image as that captured by the image sending side, that is, the video camera section 40, on the surface of the LCD panel 30.

The LCD drive circuit 26 which receives the horizontal synchronization signal H and the vertical synchronization signal V from the synchronization separation circuit 24 generates a drive signal for the LCD panel 30 based on both periodic signals and outputs it to the Y driver 27. In response, the Y driver 27 outputs a drive signal to the LCD panel 3o to apply a voltage to the corresponding liquid crystal column based on the drive signal from the LCD drive circuit 26. Therefore, since the LCD panel 30 displays the liquid crystal using the same synchronization signal as the image captured by the video camera unit 40, it is possible to display the image in synchronization with the image capture side.

On the other hand, the CB and CP generation circuit 25 is connected to the period separation circuit 24.
input the horizontal synchronization signal H, and input the color burst signal CB.
is generated and output to the color detection circuit 21, and a clamp pulse CP is generated and output to the clamp circuit 23.

A Y/C separation circuit 20 is provided as a circuit for manually inputting the standard color video signal Y/C from the video camera section 40. Y
The /C separation circuit 2o separates the signal Y/C into a color signal C and a luminance signal Y and outputs the signal Y/C in order to faithfully reproduce colors. The color detection circuit 21 receives the color signal C from the Y/C separation circuit 20, receives the color burst signal CB input from the CB ti and CP generation circuit 25 as a phase reference, and forms a color video signal for transmission. and the color difference signal R-Y
and is output to the matrix circuit 22 as a signal B-Y. Accordingly, the matrix circuit 22 receives the color difference signal R-Y and the color difference signal B-Yi:Y input from the color detection circuit 21.
In addition to the luminance signal Y input manually from the /C separation circuit 20, three primary color signals RSG are generated.

B is generated and output to the clamp circuit 23 at the next stage.

Incidentally, the video signal including the primary color signal is ultimately displayed on the LCD display 30.

At this time, areas where the video signal level is high relative to the reference level are displayed brightly, and areas where the video signal level is low are displayed darkly. In other words, brightness and darkness are expressed 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 previous stage, the clamp circuit 23 is provided to take this into account and regenerate the DC component. Therefore, the DC components (average brightness of the video signal) of the primary color signals R, G, and B output from the clamp circuit 23 are reproduced and input to the two line sequential circuits at the next stage.

The line sequential circuit 29 inputs the primary color signals RSG and B having brightness according to the imaging conditions, generates them into line sequential signals for each IH using the horizontal synchronization signal H obtained from the synchronization separation circuit 24, and sends them to the X driver. Output to 28. The X driver 28 applies a voltage to the LCD panel 30 according to the level of the line sequential signal of the primary color signals R, G, and B. This signal voltage will be applied to the liquid crystal of the LCD panel 3o. Further, at this time, the voltage applied to the Y driver 27 allows synchronization with the imaging side, so that a proper LCD image that is synchronized with the imaging side can always be viewed.

By the way, the LCD panel 30 has an X
Applying the color primary color signal R%G%B from the driver 28,
This is sampled and held by a 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 primary color signals R and GSB. Therefore, the amount of transmitted light of the backlight that illuminates the LCD from the back surface of the LCD panel 30 changes depending on the transmittance of this light, so that images with shading are displayed on the liquid crystal. Therefore, even if the applied voltage to the LCD is the same and the light transmittance thereof 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 applied voltage value to the backlight 32 of the backlight driving ifl DC-AC converter 31 is changed by the light amount detection signal LW, and the backlight 32 is
control to increase the brightness. This backlight 32
The brightness control will be further explained with reference to FIG.

Figure 2 shows the backlight driving DC-AC shown in Figure 1.
FIG. 3 is a diagram showing an example of a circuit configuration of a converter.

The backlight driving DC-AC converter 31 shown in FIG. 2 includes an analog switch 33, a switch 34, a coil L1, resistors R1 and R2, and capacitors C1 and C3.
, transistors Tri and Tr2, coupling capacitor C2, transformer T1, light amount detection signal LW input terminal A
1. DC voltage Voc input terminal A2, DC voltage Voc +
Including 3 to the input terminal. In addition, the backlight driving DC-
The power supply voltage of the AC converter 31 is connected to input terminals A2 and A.
3 to the circuit, DC voltages VDC and VDe+
It is assumed that the relationship (Voc+>Voc) holds true.

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

Now, the light amount detection signal LW is inputted from the input terminal A1. In response, it is assumed that the analog switch 33 is switched to the input terminal A2 side and takes in the DC voltage VDC as the power supply voltage. At this time, transistors Trl and Tr2 oscillate at a frequency determined by the time constants of coil L1 and capacitor C1. The oscillations of the transistors Trl 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, so if the analog switch 33 selects switching and increases the input power supply voltage, the voltage applied to the backlight 32 will also increase, making it brighter. Therefore, when the subject becomes brighter due to photographing conditions, the brightness of the backlight 32 is controlled to be brighter.

In other words, the analog switch 33
is controlled to switch the connection from input terminal A2 to input terminal A3, and the power supply voltage is changed from VDC to Voc + (V
oc + > Voc), the backlight 32
The applied voltage also increases, and bright backlight 32 irradiation can be obtained in parallel with the photographing conditions.

One way to increase the brightness of the backlight 32 is to turn on the switch 34 only when increasing the brightness. 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 connected to the backlight 32.

Accordingly, the secondary impedance of transformer T1 decreases,
Since the voltage applied to the backlight 32 increases, the brightness of the backlight 32 can be further increased. Therefore, since the voltage applied to the backlight 32 is controlled by switching the switch 34 in accordance with the light amount detection signal LW, the bright backlight 32 is controlled in parallel with the photographing conditions.
irradiation will be obtained.

The relationship between the luminance of the backlight 32 and the amount of light transmitted through the LCD will be described with reference to the drawings.

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

In FIG. 3, the characteristic curve VT indicates that as the input signal voltage V from the X driver 28 to the LCD panel 30 increases, the amount of light transmitted (brightness) T of the LCD panel 3o increases. and the input signal voltage is VII+
, this indicates that the amount of light transmission (brightness) T of the LCD is within the variation range vL. Now, the input signal voltage V,
When the brightness of the backlight 32 is increased without changing o,
The characteristic curve VT rises to the level of the characteristic curve VTI, and accordingly, the change range of the LCD brightness also changes to the change range V,
It shows that the light increases from VL+ to the change range VL+ and becomes brighter.

Note that the switching operations of the analog switch 33 and the switch 34 in the backlight driving DC-AC converter 31 may be operated independently, or may be operated simultaneously to control the brightness of the backlight 32. It may be increased further.

[Effects of the Invention] The camera-integrated videotape recorder with a liquid crystal display according to the present invention obtains a video signal by the imaging means, and detects the amount of light from the video signal by the light amount detection means.

Furthermore, it has a backlight means for emitting light from the back side of the liquid crystal display, and the brightness of the backlight of the liquid crystal display section is controlled by applying the light quantity detection output to the backlight means. therefore,
Even under bright usage conditions, the brightness of the backlight can be automatically increased according to the brightness, so the brightness of the LCD screen can be adjusted automatically, and the LCD display always has the appropriate brightness. This has the effect of being able to obtain a screen.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing the configuration of a 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 the circuit configuration of the backlight driving DC-AC converter shown in FIG. 1. FIG. 3 is a characteristic diagram showing the relationship between the amount of light transmitted through the LCD panel shown in FIG. 1 and the input signal voltage. In the figure, 40 is a video camera section, 50 is a liquid crystal display section, 30 is an LCD panel, 31 is a backlight driving DC-AC converter, 32 is a buffer light, and LW is a light amount detection signal. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] A camera-integrated videotape recorder equipped with a liquid crystal display for displaying captured images, comprising: an imaging means for imaging a subject and extracting a video signal; and a video tape recorder provided in association with the imaging means. , a light amount detection means for detecting the amount of light incident on the camera; a backlight means provided on the back surface of the liquid crystal display to illuminate the liquid crystal display from the back surface; and a light amount detection means responsive to the light amount detection output from the light amount detection means. and means for controlling the amount of light irradiated by the backlight means,
Video tape recorder with integrated camera and LCD display.