JPH11337869A - Focus adjustment method for crt projection display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make focus adjustment easily performable in the production process of a CRT projection TV in a short time with a high precision with a simple equipment. SOLUTION: CCD line sensors S1a to S13a directed in the lateral direction and CCD line sensors S1b to S13b directed in the longitudinal direction are arranged on focus adjustment object areas e1 to e13 on a projection screen 2 of the CRT projection TV, and a bright line (b) is projected from a projector 1 of this CRT projection TV to arrangement positions of sensors S1a to S13a and sensors S1b to S13b of areas e1 to e13 in the lateral direction and the longitudinal direction, and widths in the lateral direction and the longitudinal direction of the bright line (b) are obtained from illuminance distributions in the lateral direction and the longitudinal direction of the bright line (b) detected by sensors S1a to S13a and S1b to S13b, and focus adjustment of the projector l is performed based on these obtained widths.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting the focus of a CRT projection display device, and more particularly to a method for adjusting the focus of a CRT projection display device.
The present invention relates to an apparatus for improving adjustment accuracy, simplifying equipment for adjustment, and facilitating adjustment work.

[0002]

2. Description of the Related Art In a manufacturing process of a CRT projection television of a separate system in which a projector including a projection tube and an optical system and a projection screen are separated, a projector 1 and a projection screen 2 (for example, a diagonal of 120 inches) are connected. ,
As illustrated in FIG. 10A, in a state where the user is installed at a standard distance assumed when performing the installation on the user side, as illustrated in FIG. For the areas e1 to e13 at a total of 13 places (a total of a peripheral part and a central part in the figure), a monochromatic projection tube of each primary color of R (red), G (green) and B (blue) in the projector 1 is used. Focus adjustment is performed by adjusting the focus circuits. (At the time of installation on the user side, after the projector and the projection screen have been installed, the final focus adjustment is performed by adjusting the lens position of the optical system according to the actual distance between them.)

Conventionally, focus adjustment in the manufacturing process of such a CRT projection television is performed by areas e1 to e in FIG. 10B.
The size or shape of the spot of the light beam projected on each focus adjustment area such as 13 is obtained by one of the following methods (a) and (b), and the size of the spot is minimized and the shape is It was going to be a perfect circle.

(A) An image is projected from a projector onto a projection screen, each focus adjustment area on the projection screen is photographed by one video camera, and a dot of the image in each area detected by these video cameras is used. Then, the size and shape of the spot in each area are obtained by image processing.

(B) An image is projected from a projector onto a projection screen, and the size and shape of a spot in each area are measured by observing each area on the projection screen with human eyes.

[0006]

However, the method (a) has the following disadvantages. (A1) In recent years, in a CRT projection television, the scanning speed of an electron beam is increased in order to enable connection to a computer. However, as the scanning speed increases, the illuminance of light projected on a projection screen decreases. The contrast of the reflected light from the projection screen on which such low illuminance light is projected is considerably reduced.Therefore, it is not possible to accurately determine the size and shape of the spot from the detection output of a video camera that has entered the reflected light. Have difficulty. (Especially, since a video camera has lower sensitivity to red and blue than green, sensitivity of a three-tube CRT projection television provided with R, G, and B single-color projection tubes causes red or blue light to be emitted. The accuracy of the beam spot is reduced.) As a result, the focus adjustment accuracy is reduced. (A2) Since one video camera is required for each focus adjustment area, the equipment becomes large.

The method (b) has the following disadvantages. (B1) In recent years, the projection screen has been described in the example of FIG.
Although such a large projection screen is used as a 20-inch projection screen, it is difficult to approach the large projection screen in order to observe the upper focus adjustment area (areas e1 to e5 in FIG. 10). In order to solve this difficulty, the focus adjustment area on the upper part of the projection screen is set as shown in FIG.
There is also a method of enlarging and displaying an image photographed on the monitor television 4 and measuring while watching the monitor television 4.
However, in this method, a video camera and a monitor television are required, so that the equipment is also large. (B2) Since the measurement is performed based on sensory properties, skill is required and time is required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and enables a focus adjustment in a manufacturing process of a CRT projection type display device such as a CRT projection type television to be performed accurately and easily with a simple facility in a short time. The purpose of this is to provide a method that can be performed on a computer.

[0009]

According to a first aspect of the present invention, there is provided a focus adjusting method for a CRT projection display device, wherein an image sensor is arranged in a focus adjustment target area on a projection screen of the CRT projection display device. An image is projected onto the area from the projector of the CRT projection display device, and the focus of the projector is adjusted based on the illuminance distribution of the image detected by the image sensor.

According to this focus adjusting method, the projection light to the focus adjustment target area on the projection screen is
Directly enter the image sensor located in this area,
Focus adjustment is performed based on the detection result of the image sensor.

As described above, the reflected light from the focus adjustment target area is not made to enter the video camera as in the above-mentioned conventional method (a), but the projection light itself to this area is made to directly enter the image sensor. Therefore, even if the illuminance of the projection light is low, the illuminance distribution of the image is detected with a good S / N ratio. Therefore, the size and shape of the spot of the light beam can be accurately obtained from the illuminance distribution, so that the above-mentioned inconvenience (a1) is solved and the focus adjustment accuracy is improved. Further, since the image sensor is very small and inexpensive as compared with the video camera, the above-mentioned disadvantage (a2) is eliminated, and the equipment for focus adjustment is simplified.

Further, since the observation by the human eyes as in the above-mentioned conventional method (b) is not performed, even if the projection screen becomes large, it becomes difficult to measure the focus adjustment area above the projection screen. In addition, there is no need for skill or time. Therefore, the inconveniences (b1) and (b2) described above are eliminated, and the focus adjustment work is facilitated and the work time is shortened.

Next, the CR according to claim 2 of the present invention.
The focus adjustment method in the T-projection display device is the focus adjustment method according to claim 1, wherein a linear image sensor oriented in a horizontal direction and a linear image sensor oriented in a vertical direction are arranged in a focus adjustment target area. In the area, the bright line is projected vertically at the position of the linear image sensor oriented in the horizontal direction, and in this area, the bright line is projected horizontally at the position of the linear image sensor oriented in the vertical direction. The focus adjustment of the projector is performed based on the illuminance distribution of the bright line detected by the linear image sensor toward the vertical direction and the illuminance distribution of the bright line detected by the linear image sensor toward the vertical direction.

This focus adjustment method is a preferred method in the case where a linear image sensor (an image sensor in which photosensitive elements are arranged one-dimensionally) is used as the image sensor in the focus adjustment method according to the first aspect. This is an example. According to this focus adjustment method,
By projecting the bright lines in the vertical and horizontal directions on the linear image sensor arranged in the horizontal and vertical directions, respectively, the illuminance distributions in the horizontal and vertical directions of the bright lines projected in the vertical and horizontal directions are respectively determined. Are detected with a good S / N ratio.
Therefore, the size and shape of the spot can be accurately determined based on the illuminance distribution in the horizontal and vertical directions of the bright line.

In the focus adjusting method according to the second aspect, in order to determine the size and shape of the spot,
As an example, as described in claim 3, the horizontal width of the bright line is obtained based on the illuminance distribution of the bright line detected by the horizontal linear image sensor (that is, the horizontal illuminance distribution of the bright line). In addition, it is preferable to determine the vertical width of the bright line based on the illuminance distribution of the bright line detected by the linear image sensor oriented in the vertical direction (that is, the illuminance distribution of the bright line in the vertical direction). By doing so, the size and shape of the spot can be obtained from the vertical and horizontal widths of the bright line.

By the way, in a CRT projection type display device which performs projection by a raster scan method like a CRT projection type television, one bright line projected in one horizontal scanning period in one horizontal scanning period is exemplified as shown in FIG. 6A. 7A, the bright line projected in the vertical direction is a set of discontinuous dots (bright points) b2 over a plurality of adjacent horizontal scanning periods, as illustrated in FIG. 7A. .

Therefore, the illuminance distribution in the vertical direction of the bright line projected in the horizontal direction is constant regardless of the position in the horizontal direction on the projection screen as illustrated in FIG. The illuminance distribution in the horizontal direction of the projected bright line is
As illustrated in FIG. 7B, the difference differs depending on the position in the vertical direction on the projection screen (the position py2 of the gap between the adjacent dots b2 is smaller than the position py1 just above the dot b2).

As a result, when a linear image sensor is adopted as the image sensor as described in claim 2, for example, when a pixel having a small size (usually 14 μm × 14 μm) such as a CCD line sensor is used. Since the width of the linear image sensor is narrow, it is necessary to precisely align the vertical position of the linear image sensor directly above these dots. Will decrease.

Therefore, in the focus adjusting method according to the second aspect, as described in the fourth aspect, a diffusing means for diffusing a bright line projected from the projector is disposed in front of the horizontal linear image sensor. It is more preferable to do so.

By doing so, the bright lines projected in the vertical direction on the linear image sensor oriented in the horizontal direction are diffused by the diffusion means to eliminate the gap between the dots. It becomes one similar continuous emission line. Therefore, it is not necessary to perform high-precision positioning of the linear image sensor in the vertical direction, so that the focus adjustment operation is further facilitated.

Next, the CR according to claim 5 of the present invention.
The focus adjustment method in the T-projection display device is CR
The focus adjustment area on the projection screen of the T-projection display device is divided into a first area and a second area that are arranged in either the vertical or horizontal direction, and the first area is oriented in the horizontal direction. A linear image sensor is arranged, and a linear image sensor oriented in the vertical direction is arranged in the second area, and the CRT is arranged in the first area.
A plurality of bright lines are vertically projected from the projector of the projection display apparatus at intervals shorter than the length of the horizontal linear image sensor. A plurality of bright lines are projected in the horizontal direction at intervals shorter than the length of the linear image sensor, and the illuminance distribution of the bright lines detected by the horizontal linear image sensor and detected by the vertical linear image sensor The focus of the projector is adjusted based on the illuminance distribution of the bright line.

The reason for proposing this focus adjustment method is as described below. On a three-tube television,
As is well known, R, R due to various causes such as distortion of the deflection waveform,
The mismatch between the projection positions of the G and B light beams is eliminated by registration adjustment.

The registration adjustment and the focus adjustment have the following relationship. In the registration adjustment, the projection position of the center of gravity g of the spot as illustrated in FIG. 8 is matched with R, G, and B. The center of gravity g is adjusted before the focus adjustment is performed as shown in FIG. And Figure 8
As shown in FIG. 8B, the spot exists at various positions in accordance with the spot shape, and after the spot shape becomes a perfect circle by performing focus adjustment, the spot moves to the center position of the spot as shown in FIG. 8B. become.

Therefore, if the focus adjustment is performed after the registration adjustment is performed first, the center of gravity moves to a position different from the position of the center of gravity when the registration adjustment was performed. The projection positions of the centers of gravity of R, G, and B do not match (that is, accurate registration adjustment is not performed). Therefore, in the manufacturing process of the television, the registration adjustment is performed after the focus adjustment is performed first.

In a three-tube CRT projection display device, R, G, and B are projected on a projection screen for focus adjustment before performing registration adjustment.
When the images of the respective primary colors are projected, their projection positions on the projection screen often shift in units of centimeters. Therefore, when a linear image sensor is used as the image sensor as described in claim 2, if a short length (usually about 3 to 8 cm) such as a CCD line sensor is used, R, G, When the displacement of the projection position of the B bright line exceeds the length of the linear image sensor, it may not be possible to project all the R, G, and B bright lines on one linear image sensor.

In order to avoid such a situation, for example, as shown in FIG. 9A, a plurality of bright lines b are vertically arranged at intervals shorter than the length of the linear image sensor Sa oriented in the horizontal direction over the entire surface of the projection screen. The period for projecting and the period for projecting a plurality of bright lines b in the horizontal direction at intervals shorter than the length of the linear image sensor Sb in the vertical direction over the entire surface of the projection screen as shown in FIG. Switching at time intervals (for example, during one frame period) may be considered. According to this method, even if there is a shift in the projection position of the R, G, and B bright lines, any one of the plurality of bright lines b projected in the vertical direction of R, G, and B is a linear image sensor. Since any one of the plurality of bright lines b projected in the horizontal direction of R, G, and B is projected on the linear image sensor Sb while being projected on the Sa, even before registration adjustment is performed. R, on one short linear image sensor
It becomes possible to project all the bright lines of G and B.

However, in this method, the period in which the bright line is projected in the vertical direction and the period in which the bright line is projected are different, so that it takes some time until both the horizontal width and the vertical width of the bright line are obtained. There is an inconvenience that it becomes longer. In addition, when the adjustment person performs the adjustment while looking at the projection screen, there is a disadvantage that eyes are tired due to flicker at the time of switching.

According to a fifth aspect of the present invention, there is provided a focus adjusting method comprising:
Even before the registration adjustment is performed, it is possible to project all the R, G, and B bright lines on one short linear image sensor, and it is suitable for preventing the inconvenience of the method shown in FIG. This is an example of a method, in which a focus adjustment area is divided into first and second areas, and a linear image sensor oriented in the horizontal direction is arranged in the first area, and bright lines are vertically arranged at intervals shorter than the length of the linear image sensor. In addition to projecting a plurality of bright lines in the second direction, a linear image sensor oriented in the vertical direction is arranged in the second area, and a plurality of bright lines are projected in the horizontal direction at intervals shorter than the length of the linear image sensor.

As a result, any one of the plurality of bright lines projected in the vertical direction of R, G, and B is projected on the linear image sensor in the first area, and at the same time, the R, G, B Since any one of the plurality of bright lines projected in the horizontal direction is projected on the linear image sensor in the second area, R, R, and R are placed on one short linear image sensor even before registration adjustment is performed. It becomes possible to project all the bright lines of G and B.

Since the bright lines are simultaneously projected in the vertical direction and the horizontal direction, the time until both the horizontal width and the vertical width of the bright lines are obtained as in the method of FIG. 9 may be long. Absent. Further, since flicker does not occur, eyes are not tired as in the method shown in FIG. 9 even if the adjustment is performed while looking at the projection screen.

[0031]

FIG. 1 shows an example in which a focus adjusting method according to the present invention is applied to a CRT projection television of a separate system. In FIG. 1, parts corresponding to those in FIG. And a duplicate description is omitted.

In this example, as shown in FIG. 1B, each focus adjustment area e1 to e13 on the projection screen 2
The CCD line sensors S1a each oriented in the horizontal direction
To S13a and the CCD line sensor S1 oriented vertically
b to S13b are arranged. Each CCD line sensor S
Each of 1a to S13a and S1b to S13b has a pixel size and the number of pixels of 14 μm × 14 μm and 2000, respectively. Therefore, the length is 14 μm × 2000 =
2.8 cm. (In the figure, each CCD line sensor is drawn larger than the actual size with respect to the projection screen 2.)

Then, as shown in FIG. 2B, the bright lines b are projected in a grid pattern from the R, G, and B monochromatic projection tubes in the projector 1 onto the projection screen 2, respectively.
Among the areas e1 to e13, the CCD line sensor S1
The bright line b is projected in the horizontal direction at each of the arrangement positions of a to S13a, and the bright line b is projected in the vertical direction at the arrangement position of the CCD line sensors S1b to S13b.

In this example, although not shown in FIG. 1, a foggy filter 5 for diffusing the projection light from the projector 1 is disposed in front of the projection screen 2 as shown in FIG. 2A. ing. Each C turned sideways
Since the bright line b projected on the CD line sensors S1a to S13a in the vertical direction is diffused by the foggy filter 5 and the gap between dots disappears, as shown representatively for the CCD line sensor S1a in FIG. One continuous bright line b1 having a constant width H in the horizontal direction.

Thus, each CCD line sensor S1a
The illuminance of the bright line b projected in the vertical direction on each of the CCD line sensors S1a to S13a is constant without performing the high-precision positioning in the vertical direction from S13a to S13a. (still,
FIG. 2C shows a bright line b projected vertically on the CCD line sensors S1a to S13a when the foggy filter 5 is not arranged in comparison with FIG. In this case, as described with reference to FIG. 7, the bright line b projected in the vertical direction is a set of discontinuous dot-shaped bright lines b2, so that the vertical direction of the CCD line sensors S1a to S13a is obtained. It is necessary to precisely adjust the position right above this dot. )

In this example, the illuminance distribution in the horizontal direction of the bright line b projected in each of the areas e1 to e13 in the vertical direction is C.
Since it is detected by the CD line sensors S1a to S13a, the horizontal width H of the bright line b of R, G, B in each of the areas e1 to e13 is obtained by image processing from the detection results of the CCD line sensors S1a to S13a. .

Further, since the illuminance distribution in the vertical direction of the bright line b projected on each of the areas e1 to e13 in the horizontal direction is detected by the CCD line sensors S1b to S13b, respectively,
From the detection results of the CD line sensors S1b to S13b, R, G,
The vertical width V of the bright line b of B is determined.

Then, from the widths H and V in the horizontal and vertical directions, the spot diameter r of the R, G, and B light beams in each of the areas e1 to e13 is calculated by the following equation (1).

(Equation 1)

Then, for each of the areas e1 to e13,
Each of the R, G, and R in the projector 1 is set such that the spot diameter r becomes minimum and the horizontal width H and the vertical width V of the bright line b become equal (that is, the spot shape becomes a perfect circle).
Adjust the focus circuit of each B monochromatic projection tube.

According to the focus adjustment method of the example of FIG. 1, the bright lines b projected on the respective focus adjustment areas e1 to e13 are directly transferred to the CCD line sensors S1a to S13.
a, S1b to S13b make the emission line b
Is low, the illuminance distribution is detected with a good S / N ratio. Accordingly, the horizontal and vertical widths H and V of the bright line b and the spot diameter r can be accurately obtained from the illuminance distribution (for example, the original image spot is clearly distinguished from the surrounding halo (ring). Can be performed), so that focus adjustment can be performed with high accuracy.

Since the CCD line sensor is very small and inexpensive, focus adjustment can be performed with simple equipment. In addition, since observation by human eyes is not performed, even when the projection screen 2 is enlarged, it is not difficult to measure the focus adjustment areas e1 to e5 above the projection screen 2, and it requires skill and time. It doesn't even cost. Therefore, the focus adjustment operation can be easily performed, and the operation time can be reduced. In addition, since it is not necessary to precisely position the CCD line sensors S1a to S13a in the horizontal direction in the vertical direction, the focus adjustment operation can be more easily performed from this point.

Next, FIG. 3 shows another example in which the focus adjusting method according to the present invention is applied to a CRT projection television of a separate system. In FIG. 3, parts corresponding to those in FIG. And duplicate explanations are omitted.

In this example, the entire surface of the projection screen 2 having a diagonal length of 120 inches (that is, the length of the side is 96 inches as shown in FIG. 4) is covered by a length of 6 inches (about 15 inches). .
As shown in FIG. 5, each of the focus adjustment areas e1 to e13 is represented as a first area e1a and a second area e1b in FIG. Are divided into a first area on the left side and a second area on the right side, which are arranged side by side. (However, areas e2 and e10, e4
And e12, the dividing planes m5 and m6, respectively.
The position in the horizontal direction is changed so as to be divided into such first and second areas by m11 and m12. )

The first area on the left side of each area e1 to e13
(Except for the areas e3, e7 and e11, the second area on the right side), the CCDs directed in the horizontal direction, respectively.
In addition to arranging the line sensors S1a to S13a, a second area on the right side of each of the areas e1 to e13 (however, the area e
In the first area on the left for 3, e7 and e11),
CCD line sensors S1b to S each oriented in the vertical direction
13b is arranged.

Then, from each of the R, G, and B monochromatic projection tubes of the projector 1, the entire division plane m (2i-1) (i = 1, 2,... 8) including the first area on the projection screen 2 is obtained. ,
By projecting a plurality of bright lines b in the vertical direction at intervals shorter than the length of 2.8 cm of the CCD line sensors S1a to S13a, the first areas e1 to e13 (however, for the areas e3, e7, e11). Are projected on the second area).

Further, from each of the monochromatic projection tubes of R, G, and B of the projector 1, the entire divided plane m 2 i (i = 1, 2,..., 8) including the second area on the projection screen 2 is converted to C
By projecting a plurality of bright lines b in the horizontal direction at intervals shorter than the length of 2.8 cm of the CD line sensors S1b to S13b, the second areas of the areas e1 to e13 (however, for the areas e3, e7, e11, Such a bright line b is projected on the first area). (In FIG. 3B, for convenience, the illustration of the bright lines b in places other than the areas e1 to e13 is partially omitted. Also, here, the individual CCD line sensors are drawn larger than the actual size of the projection screen 2. Accordingly, the interval between the bright lines b is drawn wider than it actually is.)

Although not shown in FIG. 3, a foggy filter for diffusing the projection light from the projector 1 is disposed in front of the projection screen 2 in this example as in the example of FIG. doing.

In this example, the illuminance distribution in the horizontal direction of the bright line b projected in each of the first areas in the vertical direction is detected by the CCD line sensors S1a to S13a.
From the detection results of the CD line sensors S1a to S13a, R,
The widths H of the G and B emission lines b in the horizontal direction are obtained.

Further, the illuminance distribution in the vertical direction of the bright line b projected in the second area in the horizontal direction is detected by the CCD line sensors S1b to S13b, respectively. The width V in the vertical direction of the bright line b of R, G, B in each of the areas e1 to e13 is obtained by image processing.

Then, from the horizontal and vertical widths H and V, the spot diameters r of R, G and B in the respective areas e1 to e13 are calculated by the above-described equation (1). The focus of each of the monochromatic projection tubes of R, G, and B in the projector 1 such that the horizontal width H and the vertical width V of the bright line b become equal to each other (that is, the spot shape becomes a perfect circle). Adjust the circuit.

According to the focus adjusting method of the example of FIG. 3, in addition to the effects already described for the focus adjusting method of the example of FIG. 1, the following effects can be obtained. That is, any one of the plurality of R, G, and B bright lines b projected in the vertical direction is a CCD in the first area.
Any one of a plurality of R, G, and B bright lines b projected on the line sensors S1a to S13a and projected in the horizontal direction is one of C lines in the second area.
CD line sensors S1a to S13a, S1b to S13b
Since each of the R, G, and B bright lines can be projected onto one short CCD line sensor even before registration adjustment is performed.

The focus adjustment areas e1 to e13
Since the bright line b is projected in the vertical and horizontal directions over the entire surface of the projection screen 2 other than the areas e1 to e13, if it is desired to perform focus adjustment on a portion other than the areas e1 to e13, for example, the conventional method (b) It is also possible to observe the size and shape of the spot at that location with human eyes.

In the example of FIG. 3, each of the focus adjustment areas e1 to e13 is divided into a first area and a second area which are respectively arranged in the horizontal direction by dividing the entire surface of the projection screen 2 in the vertical direction. ing. However, the present invention is not limited thereto, and the focus adjustment areas e <b> 1 to e <b> 13 may be divided into a first area and a second area which are respectively arranged in the vertical direction by dividing the entire surface of the projection screen 2 in the horizontal direction.

In the example of FIG. 3, the bright line b is projected on the entire surface of the projection screen 2 in the vertical and horizontal directions.
The bright line b may be projected in the vertical direction and the horizontal direction only in the area and the second area.

In each of the above examples, a CCD line sensor is used. However, a CCD area sensor or an image sensor (for example, a thin film sensor) other than the CCD sensor may be used.

In each of the above examples, bright lines are projected in the vertical and horizontal directions. However, dots (bright points) are projected, and the horizontal and vertical illuminance distributions of the dots are used to determine the horizontal and vertical directions of the dots. The width in each direction may be determined, and the spot diameter may be determined from the horizontal and vertical widths of the dot.

In each of the above examples, the spot diameter r is calculated from the horizontal and vertical widths H and V of the bright line. However, without calculating the spot diameter r, the widths H and V are minimized. The focus circuit may be adjusted so that the widths H and V are equal.

In each of the above examples, the horizontal and vertical widths of the bright line are obtained from the bright lines projected in the vertical and horizontal directions. However, the horizontal and vertical widths of the bright line projected from the vertical and horizontal directions are obtained. The contrast in the horizontal direction and the vertical direction may be obtained, and the focus circuit may be adjusted so that the horizontal and vertical contrasts are maximized.

In each of the above examples, the foggy filter is arranged in front of the projection screen. However, another appropriate member capable of diffusing light may be arranged in front of the projection screen.

Further, in each of the above examples, the present invention is applied to a CRT projection television in which a total of 13 locations, that is, a peripheral portion and a central portion on the projection screen are used as a focus adjustment area. It goes without saying that the present invention may be applied to a CRT projection type television in which a portion or a portion other than these portions has a focus adjustment area.

The focus adjustment in each of the above examples is performed by C
Needless to say, it may be performed not only at the stage of manufacturing the RT projection television but also at the time of maintenance. In each of the above examples, the present invention is applied to a CRT projection television. However, the invention may be applied to a CRT projection display device other than a television. Further, the present invention is not limited to the above embodiments,
It goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

[0062]

As described above, according to the focus adjusting method according to the present invention, the light projected onto each focus adjustment area is directly incident on the image sensor. The illuminance distribution is detected with a good S / N ratio. Therefore, the size and shape of the light beam spot can be accurately determined from the illuminance distribution.
Focus adjustment of the CRT projection display device can be performed with high accuracy.

Since the image sensor is very small and inexpensive, focus adjustment can be performed with simple equipment. In addition, since observation is not performed by human eyes, even if the projection screen becomes large, it is not difficult to measure the focus adjustment area above the projection screen, and it requires skill and time. Nor. Therefore, the focus adjustment operation can be easily performed, and the operation time can be reduced.

According to a second aspect of the present invention, there is provided a focus adjusting method according to the fourth aspect, wherein a diffuser for diffusing a bright line projected from the projector in front of the horizontal linear image sensor. If you place
This eliminates the need for high-precision positioning of the linear image sensor in the horizontal direction in the vertical direction. This also makes it easier to perform focus adjustment work.

Further, according to the focus adjustment method according to the fifth aspect of the present invention, even before the registration adjustment is performed, the R, G, and R signals can be displayed on one short linear image sensor.
The effect that all the bright lines B can be projected can also be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a focus adjustment method according to the present invention.

FIG. 2 is a diagram showing a foggy filter arranged in the example of FIG. 1 and its operation.

FIG. 3 is a diagram showing another example of the focus adjustment method according to the present invention.

FIG. 4 is a diagram for explaining a length of a side of each divided surface in the example of FIG. 3;

FIG. 5 is a diagram illustrating an example of a first area and a second area in the example of FIG. 3;

FIG. 6 is a diagram showing bright lines projected in the horizontal direction and their illuminance distributions.

FIG. 7 is a diagram showing bright lines projected in the vertical direction and their illuminance distributions.

FIG. 8 is a diagram for explaining the relationship between registration adjustment and focus adjustment.

FIG. 9 is a diagram illustrating an example of a method for projecting all the R, G, and B bright lines onto one linear image sensor before registration adjustment.

FIG. 10 is a diagram illustrating a focus adjustment method of a conventional CRT projection television.

FIG. 11 is a diagram illustrating a focus adjustment method of a conventional CRT projection television.

[Explanation of symbols]

Reference Signs List 1 projector, 2 projection screen, 5 foggy filter, S1a to S13a, S1b to S13b
CCD line sensor, e1 to e13 focus adjustment area, e1a first area, e1b second area, m1 to m16 projection screen division surface,
b bright line

Claims (5)

[Claims] 1. An image sensor is arranged in an area to be focused on a projection screen of a CRT projection display device, and an image is projected from the projector of the CRT projection display device on the area, A focus adjustment method for a CRT projection display device, wherein focus adjustment of the projector is performed based on an illuminance distribution of the image detected by a sensor. 2. The focus adjusting method for a CRT projection display device according to claim 1, wherein a linear image sensor oriented in a horizontal direction and a linear image sensor oriented in a vertical direction are arranged in the area. Of the linear image sensor arranged in the horizontal direction, the bright line is projected vertically, and the bright line is projected in the horizontal image sensor in the area at the arranged position of the linear image sensor, Focus adjustment of the projector is performed based on an illuminance distribution of the bright line detected by the linear image sensor oriented in the horizontal direction and an illuminance distribution of the bright line detected by the linear image sensor oriented in the vertical direction. Focus adjustment method in a CRT projection display device. 3. The focus adjustment method for a CRT projection display device according to claim 2, wherein the width of the bright line in the horizontal direction is based on an illuminance distribution of the bright line detected by the horizontal linear image sensor. And calculating a vertical width of the bright line based on an illuminance distribution of the bright line detected by the vertical linear image sensor. A focus adjustment method for a CRT projection display device, comprising: 4. A focus adjusting method in a CRT projection display device according to claim 2, wherein a diffusing means for diffusing a bright line projected from the projector is provided in front of the horizontal linear image sensor. A focus adjustment method in a CRT projection display device, comprising: 5. The method of claim 1, wherein an area to be focused on a projection screen of a CRT projection display device is divided into a first area and a second area arranged in either the vertical or horizontal direction. A linear image sensor oriented in the horizontal direction is arranged in the first area, a linear image sensor oriented in the vertical direction is arranged in the second area, and the projector of the CRT projection display device is arranged in the first area. And projecting a plurality of bright lines in the vertical direction at an interval shorter than the length of the linear image sensor in the horizontal direction, the length of the linear image sensor in the vertical direction from the projector in the second area. A plurality of bright lines are respectively projected in the horizontal direction at shorter intervals than the illuminance distribution of the bright lines detected by the horizontal linear image sensor and A focus adjustment method for a CRT projection display device, wherein the focus of the projector is adjusted based on the illuminance distribution of the bright line detected by a vertical linear image sensor.