JPH04125585A - Color crt display device - Google Patents

Abstract

PURPOSE:To improve chromaticity uneveness by dividing an image display area into plural areas, performing correction with correction data found at every area, and using selectively appropriate correction data fitted in the direction of earth magnetism at an installing place. CONSTITUTION:The display area of a CRT is divided into plural sections, and light from divided areas fetched in a photoelectric converter 600 are converted to digital signals, and are sent to an adjusting part 300. At this time, chromaticity uneveness correction data at every area are generated by a CPU, and stored in correction data memories 231, 232, and 233 in a correction circuit 200 with address information. Thence, a beam scanning position at present is found, and the address of each correction data memory is retrieved, and prepared correction data is taken out to the area, and the gain correction of a video amplifier 6 is performed, thereby, the chromaticity uneveness can be improved. Also, color uneveness due to the earth magnetism is detected by a magnetic sensor, and corrected by found data.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color CRT display device, and more particularly to a color CRT display device with improved chromaticity unevenness.

[Conventional technology]

2. Description of the Related Art Color CRT display devices used for color television, graphic display, etc. undergo white balance adjustment before being shipped.

For example, as described in Japanese Patent Application Laid-Open No. 60-257483, a video signal that displays white is applied from a video signal generator to a color CRT, and a color CRT
The light receiving unit installed opposite the tube surface measures the amount of red, green, and blue light emitted from a portion of the tube surface, and the intensity of each color is adjusted using a white balance adjuster to adjust the screen. The entire display is white or achromatic.

[Problem to be solved by the invention]

The above white balance adjustment operation uniformly displays the entire screen in white. In other words, this is done to make the chromaticity of the screen uniform, but in reality it is quite difficult to make the chromaticity of the screen uniform. There is a problem that the color appears pale.

One of the causes of this is a problem in manufacturing the color CRT, which is thought to be caused by local uneven coating of the red, green, and blue phosphors, or by variations in dot diameter. Another possible cause is that since the front surface of the CRT is not provided with a magnetic shield, the trajectory of the electron beam passing through the hole in the shadow mask is bent and deviates from the phosphor that it would normally hit.

There has been a need to improve this chromaticity unevenness, especially in recent high-definition color CRT display devices. In other words, high-definition color CRT display devices are often used in workstation display devices that display graphics, etc. on a solid or white background color, but in this case, the above-mentioned chromaticity unevenness is very unsightly and easily noticeable.

In view of the above, an object of the present invention is to provide a color CRT display device that can improve chromaticity unevenness caused by various causes.

[Means to solve the problem]

In the present invention, the image display area of a color CRT is divided into multiple areas, the chromaticity of each divided area is measured while white is displayed in the image display area, and the chromaticity of each area is corrected to uniformly display white. Red, green data.

Create and memorize the data in the blue line, and when actually using it, retrieve each correction data in synchronization with the scanning beam and set the corresponding red,
Adjust the gain of the green and blue video signals.

In addition, regarding the influence of geomagnetism, we prepare correction data similar to the above for several orientations of the color CRT display device, and when installing the color CRT display device, we prepare correction data for the geomagnetism measured at that point. Select and use appropriate correction data according to the direction.

[Effect]

According to the present invention, the gains of the red, green, and blue video signals are adjusted for each region, so that the entire image display region can have uniform chromaticity.

Moreover, since appropriate correction data is selected and used in accordance with the direction of the earth's magnetism measured at that point when installing the color CRT display device, unevenness in chromaticity due to the earth's magnetism is also improved.

〔Example〕

The present invention will be described in detail below, but before that, it will be clarified what chromaticity is.

First, the properties of color will be explained with reference to NHK Color Television Textbook (Part 1) edited by Japan Broadcasting Corporation, p. 13-p. 17.

To express color qualitatively, consider the following three properties called the three attributes of color.

10 Hue (color tone) As the wavelength of light goes from longer to shorter, the color changes in order as shown in Figure 2. This red → orange → yellow → green → cyan →
It exhibits a color tone such as blue → purple.

■Saturation (color depth, saturation) Indicates the vividness of a color. Conversely, it represents the rate at which a color is diluted by white, or the intensity of the color. White is the least intense color.

■、Brightness The degree of light intensity is called brightness, and quantitatively it is called brightness.

FIG. 3 conceptually shows the relationship among hue, saturation, and brightness. In this figure, the disk is placed at the white position,
The circumference of the circle ranges from red to violet in the order of wavelengths shown in Figure 2. According to this, the hue is represented by concentric circles with white as the center, and the degree of saturation is determined by the distance from white. expressed.

In other words, the further away from white the color becomes darker and more vivid.

For example, the colors on the line connecting yellow and white are yellows with different degrees of saturation, such as white, yellowish white, whitish yellow, and bright yellow. As can be inferred from this cone, even if the brightness of a color changes, if the hue and saturation are the same, it will only become brighter or darker, and the image of the color will not change. (If it is white, it is imagined as white or gray.) Therefore, hue excluding brightness and saturation are collectively called chromaticity.

This chromaticity is represented by a plane on a disk in FIG. That is, with the center point (white) of the disk as the origin, the direction of a certain color can represent the hue, and the distance of a certain color from the center point can represent the degree of saturation. FIG. 4 shows a chromaticity diagram of the Commission Internationale de l'Eclairage (CIE), which is expressed in another way.

Next, color mixing and white balance will be explained.

Red, green, and blue are called the three primary colors of light and are the primary colors of all colors, and various colors can be created by additively mixing these three primary colors.

In other words, it is possible to create colors of any chromaticity (hue and saturation) and brightness. An example of additive coloring will be explained using the chromaticity diagram shown in FIG. By shining R (red) and G (green) at appropriate brightness and adding the two colors, YR (orange) or Y (yellow) can be created. Furthermore, if Y (yellow) and B (blue) are added with appropriate brightness, the color becomes whiter yellow and finally becomes white. Furthermore, it becomes whitish blue. YR (orange) and B
By adding (blue) with an appropriate brightness, pink can be created.

Any color can be created in this way. In this way, chromaticity is a term that includes hue and saturation, and chromaticity unevenness refers to the fact that although objects with the same chromaticity are displayed on a CRT, some of them have different chromaticities. To tell. It should be noted that the above-mentioned manufacturing problems and earth's magnetism are considered to be the causes of the unevenness of chromaticity.

FIG. 1 shows a schematic configuration of the present invention for creating correction data for correcting uneven chromaticity and performing correction.

In this figure, the CRT is a normal color CRT, with red, green,
The blue video signal 9 is amplified by the video amplifier 6 for each color, the potential between the cathode of each electron gun and the grid G1 is adjusted, and the CR
Display any figure on the T-tube surface. In the present invention, a gain control circuit 100 (101, 102, 103) adjusts the gain of each of the video signals 9 of this ordinary color CRT.
For example, the chromaticity unevenness correction circuit 200 (201, 202
, 203), a correction gain is established for each color to improve chromaticity unevenness. This correction gain is determined by determining the current display area according to the horizontal/vertical synchronization signal 7.

It is variable depending on this area. The adjustment unit 9 drives the driver 700 to position the photoelectric converter 600 at a predetermined position facing the CRT tube surface, and inputs detection signals for each color of red, green, and blue from the photoelectric converter 600. Then, chromaticity unevenness correction data used in the chromaticity unevenness correction circuit 200 is created. Positioning work and input of detection signals in adjustment section 3o○.

The CRT is divided into a plurality of areas, and the process is performed for each divided area.

The present invention is generally configured as described above, and among these, the specific configuration of the chromaticity unevenness correction circuit 200 and the adjustment section 300 is shown in FIG. 6, and the specific configuration of the photoelectric converter 600 is shown in FIG. A detailed explanation will be given later.

As inferred from the above description, the photoelectric converter 600 and the adjustment section 300 are used when adjusting the color CRT display device before shipping. A chromaticity unevenness correction circuit 200 is incorporated into a part of a color CRT display device and used when actually displaying graphics.

The details of each part of the present invention will be described below.
I will explain in this order.

FIG. 5 shows the relationship between the photoelectric converter 600 and the CRT. First, the display area of the CRT is virtually divided into four sections in the horizontal direction (H direction) and three sections in the vertical direction (■ direction). and is divided into 12 regions (Rg 1 to Rgiz). The driver 700 in FIG. 1 has a horizontal driver and a vertical driver, and the CRT tube surface area monitored by the camera unit 601 of the photoelectric converter 600 is the divided area Rg.
t” Rt 12.
Perform positioning of 01. Adjustment section 3 performs this positioning operation.
00 to positioning signal 310. Light from the divided areas taken into the photoelectric converter 600 via the camera unit 601 is separated into red, green, and blue light by the dichroic mirror 620, and is transmitted through reflecting mirrors 621 and 622 as appropriate. photoelectric converter circuit (601, 602, 6
03), and the brightness of each part of red, green, and blue is converted into a voltage signal.

These voltage signals are each input to an analog/digital converter 604.
．． 605 and 606 generate digital signals 610 (611,
612, 613) and sent to the adjustment unit 300.

Next, the adjustment section 300 will be explained. This configuration is the sixth
As shown, a programmable read-only memory FROM, a FROM writer 340, and a main bus 3
12. Address bus 218° Data bus 311. It is composed of a calculation control unit CPtJ. Among these, FROM is
This is for storing the luminance data taken in by the photoelectric converter 600 and the correction data created by the CPU. F.R.O.
The M writer 340 writes data to FR according to instructions from the CPU.
This is to be stored in the OM.

In this adjustment section 300, the CPU executes various functions, one of which is positioning the camera section 601 and inputting detection data for each divided area, but a more detailed explanation of this processing will be omitted. The most important process of the CPU is the process of creating chromaticity unevenness correction data for each area, and an example of this procedure will be described below.

To carry out this process, first, a white image is displayed over the entire image display area, and brightness data of red, green, and blue is captured for each zone and stored in the FROM. Further, the brightness ratio (r, g, b) of red, green, and blue corresponding to the chromaticity of white color that is ultimately desired to be displayed is prepared.

Assuming that the red, green, and blue brightness data of any zone on the CRT tube surface obtained through a photoelectric converter are R, G, and B, here, first, the combined brightness Y is calculated by taking the sum of them, (1
) is calculated using the formula.

Y=R+G+B...(1) Here, as a correction method, for example, red and green after correction.

Chromaticity is corrected so that the composite luminance of blue is equal to the composite luminance Y before correction, and the luminance of each color after correction is R', G''
, B'' are calculated using equations (2'), (3), and (4), respectively.

R=XY...
・(2) r+g+b G = XY ・
...(3) r+g+b B mock yo XY...
(4) r+g+b The correction data in this zone will ultimately be red, green,
It is necessary to use this as correction data for the gain control circuit 100 of the blue video amplifier (FIG. 1, 6). Therefore, first (2),
From equations (3) and (4), find the brightness gains to be corrected for red, green, and blue, and then calculate back from the output amplitude versus brightness characteristics of the video amplifier to find the correction gains for the red, green, and blue video amplifiers. seek. Actually each is ART Aa + As
If we put (5) and (6).

(7) Execute equation.

Note that γ is an index representing the brightness characteristic with respect to the output amplitude of the video amplifier. Here's the brightness ratio! ``+g+b'' may be determined in advance, or may be the average ratio of red, green, and blue over the entire image display area.

Also, when adjusting the white balance, the red in the center of the CRT tube surface,
When adjusting while measuring the brightness of green and blue, check the brightness ratio r, g at the center of the CRT screen after white balance adjustment is complete.
, b is more practical.

The gain correction data for each color for each divided area obtained in this way is stored in the FROM shown in FIG. 6 as shown in FIG. 7 corresponding to the horizontal and vertical positions of the CRT tube surface shown in FIG. be done. Although FIG. 7 shows only red, it goes without saying that green and blue are also stored in the same way. The correction data obtained in the above manner is then stored in each correction data memory 231, 232 in the chromaticity unevenness correction circuit 200.
233 along with address information (horizontal and vertical position). In this case, the address is address bus 218.
Address selector 220. The address portions of the memories 231, 232, and 233 are specified and applied via the address bus 219, and the correction data is stored at the specified address of the memory via the data bus 311.

As described above, the uneven chromaticity correction data is stored in the memory 231.
232 and 233, the chromaticity unevenness correction circuit 2
Color CRT display devices equipped with 00 are shipped.

Chromaticity unevenness correction circuit 20 during actual operation after installation at the customer.
0 works as follows. 1 Chromaticity unevenness correction circuit 20
The portions of the color CRT display device other than 0 operate in the same manner as those known in the art and remain unchanged, and therefore will not be described.

This chromaticity unevenness correction circuit 200 includes a zone address generator 210, an address selector 220, and correction data memories 231, 232, and 233 for red, green, and blue.
Digital/analog converters 241, 2 for red, green, and blue
42,243. Zone address generator 210 generates synchronization signal 7 (horizontal and vertical synchronization signals)
is input, and an address for reading out the chromaticity correction data for each zone on the screen stored in the red, green, and blue correction data memories 231, 232, and 233 is generated according to the scanning of the electron beam. . The address selector 220 is
This is for switching between giving the memory (231, 232, 233) an address generated by the zone address generator or an address generated by the adjustment section 300. The red, green, and blue correction data memories 231, 232, and 233 store chromaticity correction data necessary for correcting chromaticity unevenness of a color CRT.

D/A converters 241, 242, 243 are red and green.

The red, green, and blue chromaticity correction data read from the blue correction data memory are converted into analog signals, and the red, green,
Gain control circuits 101 and 1 for each blue video amplifier 6
A control voltage or control current is applied to 02 and 103.

FIG. 6 shows a specific embodiment of the zone address generator 210. In this figure, the zone address generator 210 includes a phase-locked oscillator PLL, a horizontal address counter 213 . Sample synchronization circuit 214. It consists of a vertical zone segment counter 2154 and a vertical address counter 216. The phase-locked oscillator PLL outputs, from the horizontal synchronization signal 7H, a quadruple oscillation frequency necessary to make the horizontal address counter 213 go around once during the synchronization period, and the frequency is further synchronized with the horizontal synchronization signal every round. The horizontal address counter 213 is.

This is used to set the number of zone segments in the horizontal direction to four zones and to specify this horizontal zone address. The vertical zone segment counter 215 counts 200 vertical zone segments (6 vertical zone segments).
The vertical address counter 216 generates a segment address in the vertical direction, and the vertical zone counter 215 and the vertical address counter 216 sample the leading edge of the vertical synchronization signal 7V. 214 and is reset, and a vertical zone address is generated cyclically in synchronization with the vertical synchronization signal. Since the zone address generator 210 is configured as described above, 1 of the horizontal synchronizing signal 7H
Outputs 4 times within a period, 3 times within one period of vertical synchronization signal 7V
Output times.

Since the starting point position of the scanning beam (starting point of the vertical synchronizing signal) can be specified from 7H and 7■, the output of the horizontal address counter 213 is the horizontal position Hv, Hzy in FIG.
Ha+Ha (Ha), and the output of the vertical address counter 216 is the vertical position Vz, Vzt V in FIG.
s (Vo).

Therefore, by the combination of signals 213 and 216, the current beam scanning position is divided into the divided display area (Fig. 5, Rgz-Rgx
It is possible to know in which of the correction data memories 231 and 23
2,233 addresses can be built horizontally, and the correction data prepared in that area can be taken out to make it possible to correct the gain of Image Enhancement II@16. In addition, although the above idea is to use horizontal or vertical synchronization signals to identify the divided areas, in reality, the retrace part of the scanning beam or the display on the screen It goes without saying that since there are vacant time portions that are not used, it is necessary to take these wasted times into account when determining an area using a synchronization signal, and to determine an area based only on the effective display time. These ideas can be implemented as appropriate.

In FIG. 8, the address selector 220 is connected to the address bus 217 from the zone address generator 210.
The above address signal is selected during actual operation, and the address signal on the address bus 218 from the adjustment section 300 is sent to the correction data created in step 300 to a predetermined position in the correction data memory 231, 232, 233 via the data bus 311. When used selectively.

The above explanation was about color unevenness correction when the orientation of the CRT is fixed in one direction, but in reality, the orientation of the CRT is often changed at the shipping destination, and in this case, due to the influence of the earth's magnetic field, , the pattern of uneven color changes.

Since the amount of correction required to correct this will naturally vary, further correction is performed using the following method.

FIG. 9 shows the overall configuration of the present invention when geomagnetic correction is also taken into consideration. This figure differs from FIG. This is what happened. Of these, 15
and 500 have been conventionally installed in color CRT display devices, and 90.400 is newly installed and shipped as part of the device.

Specifically, before shipping, the circuit shown in FIG. 9 first changes the direction of the CRT and causes the degaussing circuit 500 to generate an alternating demagnetizing magnetic field in the degaussing coil 15, and after sufficiently demagnetizing the CRT's demagnetization, Similarly, from the photoelectric converter 600, red,
The CPU in the adjustment unit 300 takes in the brightness data of green and blue.
Create chromaticity correction data for each zone using 300
Stored in PROM inside. The chromaticity correction data stored in the FROM in the geomagnetism correction unit 90 is sequentially transferred to and stored in the memory of the geomagnetic correction unit 90. At the second time, the direction and intensity of the earth's magnetism relative to the tube axis of the CRT are detected by the magnetic sensor 400 and stored in the memory of the earth's magnetic field correction section 90 together with the chromaticity correction data. This geomagnetic data will be used as search data when reading uneven color correction data for any orientation of the CRT during later installation. This series of operations (change of CRT direction, creation of demagnetization 9 chromaticity unevenness correction data and storage in geomagnetic correction section 90, detection of geomagnetism and storage in 90) is performed multiple times while changing the direction of CRT.

FIG. 10 is a diagram showing the main parts of the circuit of FIG. 9 in detail. In this diagram, the adjustment section 300 is basically the same as that of FIG. 6, but the chromaticity unevenness correction data for each color stored in FROM is This differs from FIG. 6 in that it is paired with geomagnetic data from the geomagnetic sensor 400 and stored in the geomagnetism-specific correction data memory 901 of the geomagnetism correction unit 90 as shown in FIG.

Note that 321 is an address bus for specifying a storage address of the memory 901, and 322 is a data bus for transferring correction data and the like to the area specified by the specified address. Transfer to the memory 901 is performed each time the adjustment unit 300 creates correction data and obtains geomagnetic data. The geomagnetism correction unit 90 has a configuration not shown in FIG.
It consists of As shown in FIG. 11, in the memory 901, correction data for each color and geomagnetic data at that time are stored in pairs for a plurality of trials before shipment.

During installation, the adjustment section 300 is separated and the start switch SW
When I is turned on, the arithmetic unit CPU-A operates. During this on-site installation (including subsequent changes in the CRT installation direction), in order to demagnetize the magnetism that had accumulated in the CRT (shadow mask), it is necessary to , demagnetize each time. As a result, CPU-A, which has already started up, receives a signal of 8 due to this demagnetization.
is applied. In the present invention, after this degaussing, the magnetic sensor 400 detects the direction of earth's magnetism relative to the current orientation of the device, and the magnetic signal 923 is input to the CPU-A. C
Since the correction data corresponding to several geomagnetic directions for RT has been prepared in advance, the CPU-A uses the magnetic signal 9231 to search for the geomagnetism that is most similar to the magnetic signal 9231.
21 to the geomagnetism-specific correction data memory 901, and
The memory 901 stores red, green, and blue chromaticity correction data corresponding to the geomagnetic direction closest to the current geomagnetic direction.
The correction data memory 231, 232, and 233 for red, green, and blue are moved to the corresponding addresses. This operation is performed using address bus 911 and data bus 912.

The subsequent operations in the chromaticity unevenness correction circuit 200 have already been explained and will be omitted here. According to the present invention, the influence of geomagnetism can be reduced as described above. Furthermore, from the chromaticity correction data corresponding to the nearest geomagnetic direction and the chromaticity correction data corresponding to the second nearest geomagnetic direction,
By creating supplementary data, more accurate chromaticity unevenness correction can be performed.

In the present invention, the gain of the video amplifier is adjusted using the correction data, but this is because the CRT cathode and the first
The voltage between the grids may be adjusted, in short R-G-
The brightness of the light emitting surface may be adjusted using the correction data B.

〔Effect of the invention〕

According to the present invention, it is possible to provide a uniform image with improved chromaticity unevenness, regardless of manufacturing variations in CRTs or the influence of earth's magnetism.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of the present invention for creating correction data for correcting uneven chromaticity and performing correction, Fig. 2 is a diagram for explaining the hue of light, and Fig. 3 is a diagram for explaining the hue of light. A diagram conceptually showing the relationship between saturation and brightness, Figure 4 is a chromaticity diagram by the International Commission on Illumination, Figure 5 is a diagram showing the relationship between a photoelectric converter and a CRT, and Figure 6 is an adjustment unit. FIG. 7 is a diagram showing the storage status of correction data, FIG. 8 is a diagram showing the concrete configuration of the zone address generator 210, and FIG. 9 is a diagram showing the specific configuration of the chromaticity unevenness correction circuit. FIG. 10 is a detailed view of the main part of FIG. 9, and FIG. 11 is a diagram showing the storage contents of the correction data memory for each geomagnetic field. 1... Braun tube, 15... Degaussing coil, 100...
...Gain control circuit for video signal device, 200...Chromaticity unevenness correction circuit, 300...Adjustment unit, 400...Geomagnetic sensor, 210...Zone address generator,
231.232,233...Correction data memory, 33
0-PROM, 380-= CPU, 500...
Figure 11

Claims (1)

[Claims] 1. Color C that amplifies a video signal and performs scanning according to horizontal and vertical synchronizing signals to display images in color on a CRT screen.
In an RT display device, a memory stores correction data for each divided area of the CRT display area to make the chromaticity of the CRT display area uniform; A color CRT display device comprising a divided area specifying means for specifying a region, and a control means for extracting correction data of the divided area specified by the means from the memory and controlling the brightness of a CRT light emitting surface in accordance with the correction data. 2. In a color CRT display device that amplifies the video signal and displays the image in color on the CRT tube surface, correction data is used to make the chromaticity of the CRT display area uniform.
a first memory storing a plurality of sets for each CRT installation condition;
a geomagnetism detector that detects the direction of geomagnetism at a CRT installation location; and a second memory that stores any one of the plurality of sets of correction data in the first memory according to the output of the geomagnetism detector. A color CRT display device comprising a control means for controlling the brightness of a CRT light emitting surface according to the second memory correction data. 3. In a color CRT display device that amplifies the video signal and displays the image in color on the CRT tube surface, correction data is used to make the chromaticity of the CRT display area uniform.
a first memory storing a plurality of sets for each CRT installation condition;
a geomagnetism detector that detects the direction of geomagnetism at a CRT installation location; a second memory that stores correction data obtained from the plurality of sets of correction data in the first memory according to the output of the geomagnetism detector
memory, and the CRT according to the correction data of the second memory.
Color CRT equipped with a control means for controlling the brightness of the light emitting surface
display device. 4. In a color CRT display device that amplifies the video signal and displays the image in color on the CRT tube surface, correction data is used to make the chromaticity of the CRT display area uniform.
Memory that stores multiple sets for each CRT installation condition, CRT
A color CRT display device comprising a selection means for selecting one of the plurality of sets of correction data stored in the memory according to the direction of geomagnetism at an installation location, and a control means for controlling the brightness of a CRT light emitting surface according to the selected correction data. . 5. In a color CRT display device that amplifies the video signal and displays the image in color on the CRT tube surface, correction data is used to make the chromaticity of the CRT display area uniform.
Memory that stores multiple sets for each CRT installation condition, CRT
A color CRT comprising a calculation means for determining new correction data from a plurality of sets of correction data in the memory according to the direction of geomagnetism at an installation location, and a control means for controlling the brightness of a CRT light emitting surface according to the correction data of the calculation means. display device.