JPH0362793A - Color balance adjusting device for color monitor - Google Patents

Abstract

PURPOSE:To improve the adjustment accuracy with simple constitution by providing 3 sensors detecting the lightness of each color, a comparator detecting a difference of lightness among colors and an adjustment signal generating circuit so as to adjust the level of each color signal based on the difference of the measurements of the brightness for each color. CONSTITUTION:Three optical sensors 16 are fitted on the surface of a cathode ray tube 10 under a frame 12 while its photodetecting face is directed toward the cathode ray tube 10. When an adjustment switch 60 is turned on, a sensor 16 measures the brightness of the surface of the cathode ray tube 10 lighted based on the black level signal for each of 3 G, B, R components. Comparators 56a, 56b detect a difference B-G between G and B brightness and detect a difference R-G between G and R and input the result of detection to a control signal generating circuit 58. The control signal generating circuit 58 adjusts the black level in response to the difference. Then the white level is adjusted the same as the case with the black level adjustment.

Description

[Detailed description of the invention] [Industrial use! II)'-] The present invention relates to a color balance adjustment device for a color monitor that visually adjusts the color balance of the color monitor.

[Conventional technology]

In recent years, color monitors have been used to simulate images in various fields. For example, in the fields of printing and plate making, the actual working conditions are simulated in advance using a color monitor. In such cases, color monitors are required to have very strict color accuracy.

In particular, white is easy for humans to distinguish, and an imbalance in white is easily noticeable. Plate-making simulations are mainly used to see colors, and an imbalance in color on a color monitor can be fatal.

Here, the difference in color balance is the G of the color monitor.

Detection can be performed by inputting a test waveform having a gradation that changes stepwise from white to black to each of the B and H color component signal input terminals. That is, originally, a gray scale having gradations from white to black is reproduced on the screen, but if the color balance is off, this gray scale is reproduced with a tint.

The color balance of a color monitor becomes blurred due to thermal factors such as the heat generated by the color monitor itself and changes in ambient temperature, or due to factors over time.B.

There may be a difference in amplification between the G and R color signal system amplifier circuits, or the operating point of the cathode ray tube may change.

- Numerically, the color balance of a color monitor deteriorates over time.

None of the conventional color monitors is equipped with a device that automatically corrects color balance, so if the color balance deteriorates, the only option is to manually adjust it using the color adjustment function included in the color monitor.

For this reason, the human visual system notices the color balance after it has deteriorated to a certain extent, and then makes adjustments, so the response is slow, and as a result, the printer is used for a long time with the color balance deteriorated, resulting in the quality of plate making. had a great influence on.

Recently, there have been some models that fix an optical sensor on the surface of the color monitor during adjustment, detect the color balance according to the output of this sensor, and automatically adjust the color balance if it is out of alignment. Although it has been developed, it is troublesome to have to remove the sensor every time the adjustment is made.

[Problem to be solved by the invention]

This invention was made to deal with the above-mentioned circumstances,
To provide a color balance adjustment device for a color monitor that can easily adjust color balance at any time without requiring attachment and detachment of a sensor each time adjustment is made.

[Means to solve the problem]

The color balance adjustment device for a color monitor according to the present invention includes three sensors that are attached to a location other than the image display area on the screen of the color monitor and detect the brightness of each color through a color filter, respectively. , change the scanning range of the color monitor so that the sensor installation location is within the image display area, and detect the difference in brightness between each color from the sensor output with the same signal input to each color signal circuit of the color monitor. and an adjustment signal generation circuit that adjusts the color balance of the color monitor based on the output of the comparator.

[Effect]

According to the color balance adjustment device according to the present invention, although the sensor is fixed to the screen, the sensor does not interfere with the displayed image during normal image display, and the color balance adjustment device has the sensor fixed to the screen. Light emission can be made by human power. Therefore, each time you make an adjustment, please
There is no need to remove the sensor, and since measurements are taken at the same location on the screen, there is no variation in measurement values and highly accurate measurements are possible. Roughly speaking, by adjusting the level of each color signal circuit system based on the difference in the measured luminance values for each color, color balance can be adjusted with high precision with a simple configuration.

〔Example〕

An embodiment of the color balance adjustment device for a color monitor based on this invention will be described below with reference to the drawings.

FIG. 1 is a front view of a color monitor according to this embodiment. An escutcheon (frame) 12 is attached to the surface of the cathode ray tube 10, and an edge 14 inside the escutcheon (frame) defines a screen. In addition, for plate making simulation,
The aspect ratio of the screen is often 1]. On the surface of the cathode ray tube 10 and below the escutcheon 12, three optical sensors ]-6 are attached with their light receiving surfaces facing the cathode ray tube 10 side. It is preferable that the three sensors 6 be located in positions hidden by the escutcheon 12 and as close as possible to the medium heat on the screen. Although not shown, the light receiving surfaces of the three sensors 6 are colored green (G) and blue (B), respectively.
, a color filter that passes red (R) color component light is attached.

As a result, the three sensors 6 are set to G and BR, respectively.
It is possible to detect the color component light of , and measure the color balance based on the difference between the detected values.

Here, normally, the cathode ray underscans so that its scanning range matches the screen range defined by the inner edge 14 of the escutcheon 12, so when detecting the color balance, the deflection angle is slightly increased and - As shown by a dashed dotted line 18, overscanning is performed so that the scanning range includes the mounting location of the sensor 6.

In this case, since the brightness on the screen decreases as the amplitude of deflection increases, it is necessary to make adjustments in consideration of the decrease.

Changing the scanning range is not limited to overscanning, but can also be done by varying the deflection centering current and shifting the normal rask position 22 to a position 24 that includes the mounting location of the sensor 16, as shown by the dashed line in FIG. Good too.

Furthermore, as shown in Figure 3, the signal of one scanning line is divided into an image display area and a color balance adjustment area except for the retrace period, and normally the signal is placed on the image display area and no signal is placed on the adjustment area. Conversely, when adjusting the color balance, a test signal indicating the black level and white level may be placed in the adjustment area, and the image display area may be left with no signal. Note that the sensor 16 is attached at a position corresponding to this color balance adjustment area. here,
Although it is not necessary to make the adjustment area non-signal during normal times, it is necessary to make the image display area non-signal during color balance adjustment. This is because when a signal waveform is placed on the image display area, when adjusting the level, especially when adjusting the black level, the light emitted by this signal waveform is repeatedly reflected on the glass surface of the cathode ray tube 10, reaches the sensor 16, and is detected. This is because

In this way, when displaying a normal image, the sensor 16
does not interfere with the displayed image. Therefore, the sensor 16 can be fixed on the screen at all times, and there is no need to attach or remove it each time an adjustment is made.The color balance is measured at the same location on the screen, so there is no variation in measurement values and highly accurate measurement is possible. is possible.

FIG. 4 is a circuit diagram of this embodiment. G.B.

The three R color signal input terminals 40g, 40b and 40r are three-man powered selectors 42g and 42b.

42r. selector 42g,
A black level signal and a white level signal for color balance detection are supplied from a control signal generating circuit 58 to the second and third input terminals of 42b and 42r.

Selectors 42g, 42b, and 42r are control signal generation circuit 5
It is switched by the black level signal from 8.

The outputs of the selectors 42g, 42b, 42r are outputted to amplifiers 44g, 44b as white level adjusters.

6+ is given to 44r. The gain of the white level adjuster 44g of the G signal circuit system is set by a resistor 46.

The gains of the white level adjuster 44b of the B signal circuit system and the white level adjuster 44r of the R signal circuit system are controlled by the white (B) level adjustment signal and the white (R) level adjustment signal from the control signal generation circuit 58. . White level adjuster 44g, 44b, 4
The outputs of 4r are respectively supplied to the input terminals of adders 48g, 48b, and 48r as black level (pedestal level) adjusters. G signal circuit system black level adjuster 48g
A resistor 50 is connected to the second input terminal of the G signal, and the pedestal level of the G signal is set by the resistor 50.

A black (B) level adjustment signal and a black (R) level adjustment signal from the control signal generation circuit 58 are supplied to the 2 input terminals of the black level adjuster 48b of the B signal circuit system and the black level adjuster 48r of the R signal circuit system. The pedestal levels of the B and R signals are controlled by a control signal generation circuit 58.

The outputs of the black level adjusters 48g, 48b, 48r are connected to DC regeneration circuits 52g, 52b, 52r, and inverting phase width amplifiers 54g, 5.
4b and 54r to the cathode ray tube 10. The brightness signals B and G measured by the sensor 16 attached to the surface of the cathode ray tube 10 are supplied to a comparator 56a, and a brightness signal G is output.

R is provided to comparator 56b. Comparator 56a.

56b compares the power of both people to find a difference, and the difference signal is supplied to the control signal generation circuit 58. A color balance adjustment switch 60 is also connected to the control signal generation circuit 58 .

Next, the operation of this embodiment will be explained. To adjust the color balance, use the same test signal (
It can be detected by the difference in brightness detected by the optical power sensor 16 for each color component when a black level signal and a white level signal are input, and the gain of the white level adjuster and the black level are adjusted so that the difference in brightness of each color is equal to each other. This can be done by feedback controlling the pedestal level of the device.

Here, when combining the three luminances, one color line (
G) as a reference, the brightness of other colors, blue (B) and red (R), is adjusted to the brightness of G.

0 When the adjustment switch 60 is turned on, the black level is first adjusted, and then the white level is adjusted. This is because the black level is adjusted by varying the pedestal level, so even if the white level is adjusted first, if the black level is adjusted afterwards, the own level will also be off by the increase or decrease in the pedestal level.

When adjusting the black level, the control signal generation circuit 58 switches the black/white switching signal to the black side, connects the selectors 42g42b, 42r to the second input terminal side, and generates a black level signal in synchronization with the blanking period. do. As a result, G, B,
A common black level signal is input to the R signal circuit system. Here, if the value of the black level signal is the black level itself, the cathode ray tube 10 will not emit any light and the output of the optical sensor 16 will be 0, meaning that only feedback control is possible.
The signal has a value such that the black level provides a luminance of several percent of the white level, for example, about 5%.

When the adjustment switch 60 is turned on, the output circuit 58 sends the control signal 1 to the cathode ray tube code 0.
The scanning range of the cathode ray is changed by +/-J by one of the methods shown in Figs. The brightness of the cathode ray tube IO that emits light is determined by the sensor 16 based on the following. The sensor] 6 determines n++ the luminance of the surface of the cathode ray tube 10 emitting light based on the black level signal for each of the three color components of G, B, and H. Comparator 55a
, 56b is the difference BG between G luminance and B luminance, G luminance and R
The difference RG from the luminance is detected, and the detection result is input to the control signal generation circuit 58.

The control signal generation circuit 58 generates a black (B) level adjustment signal and a black (R) level adjustment signal proportional to the difference signals BG and RG, and controls the black level adjuster 48b.

At step 48r, 3□ is added to the black level signals of the B and R signal circuit systems to adjust the black level of the B and R signal circuit systems. For example, when the B luminance is higher than the G luminance as a reference, a positive black (B) level adjustment signal corresponding to the difference signal is generated, and the pedestal level of the B signal circuit system is adjusted to j; 11. Add 0-ru. in this way,
N11: By increasing the signal level in the line period, the signal level in both image display areas has decreased relatively.
The brightness of the image becomes correspondingly darker. On the other hand, in the case of BAG, a black (B) level adjustment signal of negative polarity is generated. FIG. 5 shows each signal waveform during black level adjustment.

The control signal generation circuit 58 repeats this operation every retrace period, and when the difference signal becomes sufficiently small, it latches this data and thereafter adjusts the levels of the black (B) level adjustment signal and the black (R) level adjustment signal. to be fixed.

Next, self-level adjustment is performed, but as in the case of black level adjustment, the control signal generation circuit 58 generates a white level signal in synchronization with the retrace period, and sets the black/white switching signal inside. Selectors 42g42b and 42r are connected to the third input terminal side, and G.

A common white level signal is manually input to the B and R signal circuit systems, and the sensor 6 measures the brightness of each color.

123 The control signal generation circuit 58 generates a white (B) level adjustment signal and a white (R) level adjustment signal that are inversely proportional to the difference signals BG and RG, and outputs a white level signal W44b.

44r profit? ', adjust j. For example, when B>G, the white (B) 1 novel adjustment signal decreases, the gain of the B signal circuit system decreases, and the brightness becomes darker. On the other hand, when B<G, the white (B) level adjustment signal is increased, the gain is increased, and the brightness is brightened.

This is repeated every retrace period, and when the difference signal becomes small enough, this data is latched, and from then on, the white (B)
The levels of the level adjustment signal and white (R) level adjustment signal are fixed.

Note that the black level was adjusted to a brightness level of about 5%, so if you change the gain to adjust the white level, the black level will also shift, so you will need to adjust the black level and self level as described above 3 to 4 times. Repeat to complete color balance adjustment.

Second explanation: According to this embodiment, the black level and white level of each color signal concave path system are adjusted so that the luminances of the three primary colors are equal to each other, so that the colors 4 and 4 are balanced. Further, the sensor 16 is fixed on the surface of the cathode ray tube 10 at a position where it does not interfere with normal image display, and the sensor 16 is fixed to the surface of the cathode ray tube 10 at a position that does not interfere with normal image display.
Since the scanning range is varied so that the location is included in the scanning range, the brightness of the three primary colors can always be measured at the same location.
(I11 constant accuracy is high. Also, by suppressing the switch 60, the color balance can be adjusted in a short time, so if the switch 60 is linked to the aIλ switch, the adjustment can be made every time the power is turned on.) If you are concerned about deterioration, you can prevent it from being used.

Note that this invention is not limited to the above-mentioned practical example, and can be modified in various ways. For example, the brightness of each color component was determined separately by three sensors, but each time the brightness of each color is measured using one optical sensor,
You may replace the filter. Also, color balance or 3
Instead of comparing the brightness of each color relatively, by memorizing the brightness of the three colors at the initial stage of the monitor and comparing it with the initial value, it is possible to check the color balance. You may also adjust the settings. Furthermore, the number of color components may be three or more, and G may not be used as a reference for relative comparison.

〔Effect of the invention〕

As explained above, according to the French balance adjustment device according to the present invention, the sensor is fixed on the screen, the sensor does not interfere with the displayed image during normal image display, and the sensor is fixed on the screen during color balance adjustment. It is also possible to input the light emitted from the screen. Therefore, each time you make an adjustment,
There is no need to use a sensor (-1), and since measurements are taken at the same location on the screen, there is no variation in measurement values and highly accurate measurements are possible. By adjusting the white level and black level of each color signal circuit system according to the disturbance, color balance can be adjusted with high precision with a simple configuration.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the arrangement of optical sensors in embodiments of the color balance adjustment device according to the present invention, FIG.
FIG. 3 is a diagram showing a modification example of sensor arrangement, FIG. 4 is a circuit diagram of this embodiment, and FIG. 5 is a diagram showing signal waveforms during black level adjustment. ]6...Optical sensor, 44g, 44b. 44r...White level adjuster, 48g, 48b48r.
Black level adjustment device: (, 'E6a, 56b comparison 1☆ device, 58, control signal generation 4-way.

Claims (1)

[Claims] Three sensors are attached to a location other than the image display area on the screen of a color monitor and each detects the brightness of each color through a filter of a different color, and the mounting location of the sensor is within the image display area. color balance detection means for detecting the difference in brightness between each color from the output of the sensor while changing the scanning range of the color monitor and inputting the same signal to each color signal circuit of the color monitor; and means for adjusting the color balance of the color monitor based on the output of the means.