JP2000020045A - Image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely and easily adjust contrast by detecting a maximum level of an input video signal in a prescribed period and adjusting an amplification degree of an amplifier part so that the maximum level is displayed to maximum luminance. SOLUTION: A CPU 42 detects the maximum level of a video signal of a test pattern image when it receives automatic command adjustment through a communication adaptor 43. The detection of this maximum level is performed by comparing digital values of respective colors in order of pixel one by one synchronized with an SCLK signal generated from a PLL circuit 15. The maximum levels of respective colors obtained by comparing them are compared finally, and the maximum level Dmax in a test pattern is detected. Then, a ratio (a=X/Dmax) between a signal level X outputted to the maximum luminance on a display panel and the detected Dmax value is calculated. Then, respective amplification degrees of the amplifier parts 13a-13c are updated from the values set at present based on this value (a).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display apparatus such as a liquid crystal panel, a plasma display panel, and a CRT for performing a multi-tone display, and more particularly to a technique for adjusting a contrast in the tone display.

[0002]

2. Description of the Related Art Conventionally, adjustment of contrast in an image display device such as a CRT or an LCD (liquid crystal display) is performed by operating a button or the like provided on a front panel or the like. FIG. 6 is a block diagram showing a configuration of a conventional LCD monitor 10 used by being connected to a personal computer (personal computer system) main body.

[0003] The LCD monitor 10 uses analog signals (analog RGB signals, HSYNC, etc.) from a personal computer.
This is a color TFT LCD device that displays an image by receiving a (horizontal synchronization) signal and a VSYNC (vertical synchronization) signal, and includes a signal conversion unit 11, an LCD unit 12, an adjustment panel 17, an adjustment value memory 18, a CPU 19, and an internal bus. 16
It is composed of

The LCD unit 12 is a color TFT panel having a resolution of 640 × 480 dots. The signal converter 11 converts an analog video signal output from the personal computer under the control of the CPU 19 into the LCD unit 12.
Digital video signal (digital RGB signal) suitable for
CLK (sampling clock) signal and DE (data enable) signal.
An amplification unit 13 for amplifying the B signal, an AD conversion unit 14 such as a parallel type for converting the amplified analog RGB signal into, for example, an 8-bit digital signal, and an SCL signal from the HSYNC signal
PLL (Phase Locked loop) unit 15 for generating K signal
It is composed of Although not shown, the signal conversion unit 11 includes a data enable signal generation unit that generates a data enable signal. This data enable signal is output during a period during which the digital RGB signal is outputting valid data (data indicating the color of the pixel) (that is, during a period in which the digital RGB signal is output).
(A time excluding the horizontal and vertical synchronization periods). Although not shown, the gradation display control driver controls the LCD monitor 10 to display, for example, 6-bit 64 gradations by the FRC method, the dither method, or the like.

[0005] The SCLK signal is a pixel clock signal synchronized with the timing indicating each pixel in the digital RGB signal. The adjustment panel 17 includes a button assembly for adjusting the contrast, the horizontal / vertical display position, and the like on the LCD monitor 10, and an interface circuit for connecting the buttons to the internal bus 16.

The adjustment value memory 18 is a non-volatile memory, and stores in advance all types of screen adjustment values including the amplification degrees of the amplifiers 13a to 13c as initial values. CP
U19 includes a program ROM 19a and a RAM 1 in which a control program for adjusting contrast is stored in advance.
This is a 1-chip microcomputer having 9b therein, and controls 11, 17 to 19 for contrast adjustment.

The operation of the conventional LCD monitor 10 configured as described above when adjusting the contrast is as follows. The CPU 19 updates the amplification degrees stored in the adjustment value memory 18 based on the operation of the adjustment panel 17 by the operator, and sends them to the amplification unit 13. The amplification unit 13
The analog RGB signal is amplified based on the updated amplification degree sent from the CPU 19 and output to the LCD unit 12.

As a result, the maximum signal level of the digital RGB signals sent from the signal conversion unit 11 to the LCD unit 12 changes in accordance with the operation of the adjustment panel 17 by the operator, and the contrast of the LCD monitor 10 can be adjusted. .

[0009]

However, in the above-mentioned conventional method, the operator manually adjusts the contrast, and thus lacks accuracy and simplicity. Therefore, an object of the present invention is to provide an image display device capable of adjusting the contrast accurately and easily.

[0010]

In order to achieve the above object, in an image display device which performs multi-tone display based on a video signal amplified by an amplifier, a maximum level of an input video signal in a predetermined period is detected. The amplification degree of the amplification unit is adjusted based on the detection result so that the maximum level is displayed with the maximum luminance.

Further, in an image display device which converts a video signal amplified by an amplifier into a digital signal by an AD converter and performs multi-tone display by binary light emission, a maximum level of an input video signal in a predetermined period is determined. Detection is performed, and the amplification degree of the amplification unit or the reference voltage of the AD conversion unit is adjusted based on the detection result so that the maximum level is displayed with the maximum luminance.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an LCD monitor according to an embodiment of the present invention will be described with reference to the drawings. FIGS. 1A to 1C are views showing the appearance of an image display system for displaying a multi-tone image according to the present invention. This image display system is a system having an automatic adjustment function of the LCD monitor 50, and includes a personal computer main body 30 and an LCD monitor 50 with a touch panel to be adjusted.

FIG. 1A is a view showing the appearance of an LCD monitor 50 with a touch panel. The LCD monitor 50 with a touch panel is a unit in which a touch panel is bonded on a color TFT-LCD and integrated, and is an adjustment target and also serves as a display device and a pointing input device as a man-machine interface.

FIG. 1B is a view of a state in which the LCD monitor 50 with a touch panel and the personal computer main body 30 are connected to each other as viewed from the back. The video signal cable 32 is used to input a video signal output from the personal computer 30 to the LCD monitor 50 with a touch panel. R
The S232C cable 33 is used for transmitting two types of information. One is for transmitting data indicating a touch position detected on the touch panel of the LCD monitor with a touch panel 50 to the personal computer main body 30, and the other is for transmitting a command related to screen adjustment output from the personal computer main body 30 to the LCD with the touch panel. This is for transmission to the monitor 50. The commands include an automatic adjustment command for starting the automatic adjustment of the contrast in the LCD monitor 50 with a touch panel.

FIG. 1C is an enlarged external view of the lower right portion of the back of the LCD monitor 50 with a touch panel. On the lower right of the back of the LCD monitor 50 with a touch panel, RS232C
An adjustment panel 17 is provided in addition to the connector for connecting the cable 33 and the video signal cable 32. The adjustment panel 17 includes a brightness adjustment volume (VIDEO LEVE
L), horizontal display position adjustment button (H-POSITION), vertical display position adjustment button (V-POSITION), screen flicker adjustment button (PHASE-LOCK), color shading adjustment volume (BRIGHT
NESS) and a reset button (RESET).

FIG. 2 is a block diagram showing the configuration of the personal computer 30. As shown in FIG. The personal computer body 30 has a hardware configuration of a general computer system, that is, the CPU 30.
a, a memory unit 30b, a keyboard 30c, a hard disk device 30d, a video controller 30e for outputting a video signal, a communication adapter 30f which is a communication interface based on the RS232C standard, and the like. An adjustment program is stored and the program is stored in the CPU 30a.
Is different from a general computer system in that it executes.

FIG. 3 shows an LCD monitor 50 with a touch panel.
FIG. 3 is a block diagram showing the configuration of FIG. L with touch panel
The CD monitor 50 is the same as the conventional LC shown in FIG.
The components 11 to 18 and 42 (C
PU), a touch panel 41 and a communication adapter 43 are further provided. The conventional LCD shown in FIG.
The components having the same reference numerals as those of the monitor 10 indicate that they have the same function.

The AD converters 14a to 14c perform sampling and digitizing on each of the analog RGB signals input through the video signal cable 32 in synchronization with the SCLK signal input from the PLL unit 15, thereby performing digital conversion. An RGB signal is generated and output to the LCD unit 12. Under the control of the CPU 42, the PLL unit 15 receives the HSYN input via the video signal cable 32.
An SCLK signal synchronized with the C signal is generated.

Although not shown in detail, the PLL unit 15 includes a general PLL circuit configuration, that is, a phase comparator, a low-pass filter, a voltage-controlled oscillator, and a 1 / N frequency divider. (1 / N) is, for example, eight kinds of horizontal resolutions (400, 480,
600, 640, 768, 1024, 1280, etc.).

The touch panel 41 is connected to the LCD unit 12
And a position detection module that detects a position pressed by a pen with a position resolution of, for example, 4096 × 4096 based on an analog resistive film system and outputs a digital value indicating the position. Communication adapter 43 is RS2
This is a communication interface based on the 32C standard. CPU
Reference numeral 42 denotes a program ROM 42a and a RAM 42b which store a control program unique to the present invention.
This is a -chip microcomputer, which controls the components 14, 15, 17, 41, 43 connected to the internal bus 16 to automatically adjust the contrast of the LCD monitor 50 with a touch panel. Specifically, the CPU 42 obtains and decodes the automatic adjustment command sent from the personal computer 30 via the communication adapter 43 based on the control program stored in the program ROM 42a, and reads the automatic adjustment command.
, A characteristic value (video signal level) related to the video signal actually input, and a preset value of a frequency division ratio, a horizontal synchronization counter and a direct synchronization counter are set.

Next, the operation of the present system configured as described above will be described. FIG. 4 is a flowchart showing the operation procedure of the present system. According to this system, the operator simply activates the automatic adjustment program stored in the hard disk device 30d in the personal computer body 30, and the processing in the personal computer body 30 (step S1).
Then, the subsequent processing (steps S2 to S6) on the LCD monitor 50 with a touch panel is sequentially executed, so that the contrast adjustment can be completed.

More specifically, when the operator starts the above program, the CPU 30a of the personal computer 30 generates an analog video signal for displaying a test pattern image for only one second from the video controller 30e, and indicates this. Automatic adjustment command to communication adapter 30
It transmits to LCD monitor 50 with a touch panel via f (step S1).

In the LCD monitor with a touch panel 50 that has received the automatic adjustment command, the CPU 42 performs the following processing (steps S2 to S6) during the one second according to the control program stored in the program ROM 42a. Upon receiving the automatic adjustment command via the communication adapter 43, the CPU 42 detects the maximum level of the video signal of the test pattern image (Step S).
2). The detection of the maximum level is performed by comparing the digital values of each color pixel by pixel in the pixel order in synchronization with the SCLK signal generated from the PLL circuit 15. As a result of the comparison, the higher level video signal is stored in the RAM 42b for each color (step S3). Such processing is executed for all pixels of one frame of the test pattern image (determined in step S4). In addition, 1
The determination as to whether or not the frame has been executed is made by detecting the VSYNC signal. Then, the maximum level of each color obtained by comparing the digital values for each color is finally compared to detect the maximum signal level (Dmax) in the test pattern. Here, the AD converter is designed so that the peak value of the input voltage of the video signal falls within the input voltage range of the AD converters 14a to 14c.

Then, the CPU 42 calculates a ratio (a = X / Dmax) between the detected Dmax value and the signal level (X, usually about 0.7 V) output to the maximum luminance on the display panel (step S5). . Next, the CPU 42 updates the amplification degree of each of the amplifiers 13a to 13c from the currently set value based on the value a (step S).
6). Specifically, the amplification degree of each amplification unit is set to a times. As a result, the maximum signal level Dmax is displayed as the maximum luminance on the LCD unit.

FIG. 5 shows the signal level obtained by AD conversion and the LCD.
It is a figure showing correspondence of a signal level expressed as maximum luminance on a unit. In this figure, the horizontal axis represents the time axis, and the vertical axis represents the signal level. The amplification units 13a to 13c and the AD conversion units 14a to 14c
An analog video signal for each color is amplified and converted to a digital signal for each color. Specifically, the signal represented by the curve k1 in the drawing is converted into a digital signal so that the level H1 is displayed at the maximum luminance on the LCD unit. In this state, when the video signal k2 whose maximum signal level is higher than H1 is input, the dots corresponding to the level H2 exceeding the signal level H1 exceed the level that can be expressed by the LCD unit 12, so that the dots are expressed with the original luminance. Not, signal level H
As a result, the image is expressed with the same luminance as 1, and the gradation of a high-luminance image cannot be expressed, and the image is crushed.

Here, the signal level H2 can be expressed by setting the amplification degree to a times obtained as described above, so that the contrast is improved and the image becomes clear. By setting the amplification level of each color analog video signal to a times, the maximum level of the currently input video signal is made to match the maximum signal level that can be displayed on the LCD unit, and the image in the bright area as described above is displayed. Eliminate the collapse.

As described above, according to the present embodiment, the operator only activates a certain program (automatic adjustment program) in the personal computer body 30, and after a certain time,
Adjustment of the optimum contrast for the video signal unique to the personal computer body 30 ends. Therefore, in particular, many LC
When adjusting the contrast of the D monitor, or when adjusting the contrast suitable for different manufacturers or different models of personal computers, the individual LC
Compared with the case where the D monitor is manually adjusted, the work amount and the work time required for the contrast adjustment are remarkably reduced, and the adjustment difference by the operator is extremely small and accurate.

In this embodiment, the case where the amplification degree of the amplification unit is updated has been described.
The reference voltages of 4a to 14c can be multiplied by (1 / a). By doing so, the maximum signal level that can be converted by the A / D conversion unit becomes (1 / a) times while the number of bits is the same. Is made to be equal to the maximum signal level that can be displayed, thereby eliminating the collapse of the image in the bright area as described above.

In the above description, the automatic contrast adjustment has been described by taking as an example the case where the level of the video signal exceeds the maximum value (X) of the LCD unit. However, the level of the video signal is adjusted to the maximum value (X) of the LCD unit. If lower, it is of course possible to display it to match the maximum value (X). In the present embodiment,
The automatic adjustment program executed in the personal computer body 30 only adjusts the contrast.
The content may include adjustment by an on-screen device that performs manual adjustment by the adjustment panel 17 remotely.

Further, an LCD monitor 50 with a touch panel
It is also easy to notify the PC main body 30 of the detection value obtained as a result of the detection from the LCD monitor with a touch panel 50 via the RS232C cable 33. As a result, the personal computer body 30 stores the notified detection value, updates the content of the adjustment value memory using the detected value after reconnecting to another LCD monitor with a touch panel to be adjusted. Thus, the contrast adjustment suitable for the video signal from the personal computer is completed for other types of LCD monitors that do not have the function of detecting the maximum level.

Further, in the present embodiment, the LCD monitor for performing the automatic contrast adjustment after receiving the test pattern from the personal computer has been described.
The monitor itself stores the test pattern image in the memory in advance, and in response to an instruction to enter a contrast adjustment mode by an operator's button operation or the like, reads the test pattern from the memory and performs the above-described automatic contrast adjustment. Of course, it is possible.

Further, in the above embodiment, the color LCD
Although the unit has been described as an example, the present invention is also applicable to a monochrome LCD unit. Further, in the present embodiment, it is not excluded that the operator operates the adjustment panel 17 to manually adjust the contrast to his or her own preference. Lastly, the above-described technology of automatic contrast adjustment is not limited to LCDs, but is not limited to LCDs. Other image display devices that perform grayscale display by making light-emitting elements emit light in a binary manner, such as plasma display panels, and CRTs that do not convert to digital signals. The present invention can be applied to an image display device such as the one described above.

[0033]

As described above, according to the image display apparatus of the present invention, the maximum level of an input video signal in a predetermined period is detected, and the maximum level is displayed with the maximum luminance based on the detection result. The amplification degree of the amplification unit or the reference voltage of the AD conversion unit is adjusted so that, for example, each L
Compared with the case of manual adjustment of the CD monitor, there is an effect that the amount of work and the operation time required for the contrast adjustment are remarkably reduced, and the adjustment difference by the operator is extremely reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing an appearance of a display position adjusting system according to the present invention. FIG. 1A is a diagram showing the appearance of an LCD monitor 50 with a touch panel. FIG. 1B is a view of a state where the LCD monitor with a touch panel 50 and the personal computer body 30 are connected as viewed from the back. FIG. 1 (c)
FIG. 2 is an enlarged external view of a lower right portion of a rear surface of the LCD monitor 50 with a touch panel.

FIG. 2 is a block diagram showing a configuration of a personal computer main body 30 in the same system.

FIG. 3 is a block diagram showing a configuration of an LCD monitor with a touch panel 50 in the same system.

FIG. 4 is a flowchart showing an operation procedure of the system.

FIG. 5 is a diagram showing a correspondence between a signal level subjected to AD conversion and a signal level expressed as a maximum luminance on a display.

FIG. 6 is a block diagram showing a configuration of a conventional LCD monitor 10.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Signal conversion part 12 LCD unit 13a-3c Amplification part 14a-14c AD conversion part 15 PLL part 16 Internal bus 17 Adjustment panel 18 Adjustment value memory 18a Amplification degree 30 Personal computer body 30a CPU 30b Memory part 30c Keyboard 30d Hard disk device 30e Video controller 30f Communication adapter 32 Video signal cable 33 RS232C cable 41 Touch panel 42 CPU 42a Program ROM 42b RAM 43 Communication adapter 50 LCD monitor with touch panel

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09G 5/00 G09G 5/00 X 5C080 H04N 5/14 H04N 5/14 5C082 5/57 5/57 17 / 04 17/04 CF term (reference) 2H091 GA11 LA17 5C006 AA22 AF52 AF54 AF81 BB11 BB16 BF25 EA03 5C021 PA58 RA08 RB03 XA13 5C026 CA01 CA02 5C061 BB15 CC05 EE05 EE07 5C080 AA05 AA10 BB05 EJ03 EJ03 EJ05 BB05 5C082 BA34 BA35 BD02 CA81 CB01 CB06 DA51 MM09 MM10

Claims (3)

[Claims] 1. An image display device for performing multi-tone display based on a video signal amplified by an amplifier, detecting a maximum level of an input video signal in a predetermined period,
An image display device, wherein the amplification degree of the amplifier is adjusted based on the detection result so that the maximum level is displayed with the maximum luminance. 2. The video signal amplified by the amplifying unit is subjected to AD
In an image display device that converts a digital signal into a digital signal by a conversion unit and performs multi-tone display by binary light emission, a maximum level of an input video signal in a predetermined period is detected
An image display device comprising: adjusting an amplification degree of an amplifier or a reference voltage of an AD converter so that the maximum level is displayed with the maximum luminance based on a result of the detection. 3. The image display device according to claim 1, wherein the image display device is communicably connected to a computer, and performs the adjustment in response to transmission of a test pattern image from the computer. An image display device according to claim 1.