JPH0675374B2 - Shadow mask position measuring device for color cathode ray tube - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a shadow mask position measuring device for measuring the three-dimensional position of a shadow mask with respect to a panel of a color CRT equipped with a shadow mask.
For example, in the manufacturing process of a shadow mask type color cathode ray tube, it is used for deformation of a shadow mask and misregistration management.

[Conventional technology]

FIG. 7 is an explanatory view showing the positional relationship between a shadow mask type color cathode ray tube panel and a shadow mask. In FIG. 7, (1) is a panel having an inner surface coated with a phosphor, (2)
Is a shadow mask arranged with a space on the panel (1) surface, (3) is a mask spring, (4) is a panel pin, and (5) is a trajectory of an electron beam for causing a phosphor to emit light. (2a) shows a deformed state of the shadow mask (2), and (5a) shows an electron beam locus passing through the hole of the deformed shadow mask (2a). When the shadow mask (2) is deformed like (2a) due to some cause, the position moves through the hole of the shadow mask (2), and the trajectory of the electron beam passing through the same hole as the electron beam (5) passed through. Becomes like (5a).

FIG. 8 shows the states of the phosphor dots and the electron beam spot before and after the deformation of the shadow mask (2).
(A) is before deformation, (b) is after deformation. In the figure,
(6) is an electron beam spot, and (7) is a phosphor dot.

When the shadow mask is deformed and the matching state of the phosphor dots (7) and the electron beam spots (6) is disturbed as shown in FIG. 8 (b), color unevenness occurs.

As the resolution of color cathode ray tubes has recently increased and the pitch of the phosphor screen has become finer, the shadow mask has smaller holes and thinner thickness, which causes deformation during processing of the shadow mask and attachment / detachment of the shadow mask during the exposure process of the cathode ray tube. Since color irregularity easily occurs due to time deformation, positional deviation, etc., it is necessary to detect and manage color irregularity defects that were conventionally found by image quality inspection in the final process of cathode ray tube manufacturing during the manufacturing process. Has become. Therefore, it is desired to measure the three-dimensional position of the shadow mask with the shadow mask attached to the panel.

A conventional device for measuring the three-dimensional position of an object is, for example, a device shown in the principle diagram of FIG. 9 shown in the magazine 0plusE (February 1987, p72). In the figure, p is a non-contact type probe, (24) is a light source, (25) is a first lens system, and (221) is a light source (24) projected through the first lens system (25). A light beam, (26) a light spot formed by the light beam (221) formed on the surface of the object (30) to be measured, and (27) a reflected light from the light spot (26) to the second lens system (28). ) Through the detector,
(29) Indicates the measurement range of the probe P at the illustrated position.

Next, the measurement principle will be described. The light flux emitted from the light source (24) is made into a thin light beam (22
The object to be measured (30) within the measuring range (29) is narrowed down to 1)
Forming a small light spot (26) on the surface of the. The light spot (26) is imaged on the surface of the detector (27) by the second lens system (28), and the image formation position is the position of the light spot (26) on the surface of the DUT (30). Probe P
Has a fixed relationship with the distance in the vertical direction, and the distance to the object to be measured (30) can be obtained from the image forming position.

Conventionally, the measurement of the positional relationship between the panel and the shadow mask by such a three-dimensional measuring device is performed by fixing the panel (1) and the shadow mask (2) in a combined state on a measurement table as shown in FIG. The probe P of the three-dimensional measuring apparatus scans the light beam on the surface of the panel and the inside of the mask, respectively, and measures the respective distances. After the measurement, the three-dimensional positional relationship between the panel and the shadow mask is obtained by calculating the corresponding measured values on the surface of the panel and the inside of the shadow mask.

[Problems to be Solved by the Invention]

In the measurement of the positional relationship between the panel and the shadow mask by the conventional three-dimensional measuring device as described above, since the surface of the panel and the inside of the shadow mask are separately scanned by the probe for measurement, the surface of the panel and the shadow mask are measured. It is difficult to correspond the measurement points inside the mask with high accuracy, and it not only takes a long time for measurement but also the measurement accuracy is poor. Further, the non-contact type probe has a problem that it is necessary to correct the difference between the panel surface and the glass thickness depending on the measurement position. Further, the contact probe cannot be used because it deforms the shadow mask.

The present invention has been made to solve the above problems, and the three-dimensional position of the shadow mask relative to the panel of the color cathode-ray tube can be accurately measured from one direction on the shadow mask side in a non-contact manner. The purpose is to obtain a measuring device.

[Means for Solving the Problems]

A shadow mask position measuring device for a color cathode-ray tube according to the present invention is at least perpendicular to the shadow mask of a shadow mask type color cathode-ray tube having a shadow mask arranged with a space on a panel surface coated with a phosphor. A movable stage formed so as to be movable in a predetermined direction, a projector that is fixed to the movable stage and projects slit light toward the shadow mask, and a projector that is fixed to the movable stage and has a predetermined length with respect to the optical axis of the projector. A television camera that is arranged so as to enclose the angle axis and captures an image of the projected slit light; and an illumination device that illuminates the shadow mask and forms an image of the hole of the shadow mask on the television camera. An image of the slit light on the shadow mask captured by the television camera and the shadow mask Calculating means for calculating the position of the hole of the shadow mask where the light of the slit is projected from the image, and when the television camera captures an image of the slit light on the shadow mask and on the panel surface. Comprising arithmetic means for computing the three-dimensional position of the shadow mask with respect to the panel from the amount of movement of the movable stage in the vertical direction when capturing an image of slit light and the arithmetic result of the arithmetic means. is there.

[Action]

The shadow mask position measuring apparatus for a color cathode ray tube according to the present invention is configured as described above, and slit light is projected toward the shadow mask to form a light image on the shadow mask surface, and at the same time, the shadow mask is formed. An image of light is also formed on the panel surface coated with the phosphor by the light passing through the hole. The moving stage is moved in the vertical direction, and the TV camera fixed to the moving stage captures images of the light on the shadow mask surface and the panel surface, respectively, and then the moving stage moves in the vertical direction. The vertical position of the shadow mask with respect to the panel is obtained from the moving force, and the shadow mask is illuminated by an illuminating device to form an image of the hole of the shadow mask on the television camera, and its screen is displayed. The position in the horizontal direction of the hole of the shadow mask on which the slit light is projected is obtained as described above, and the three-dimensional position of the shadow mask is measured from these positional relationships.

Example of Invention

An embodiment of the present invention will be described below with reference to the drawings. First
In the figure, (8) is a jig for positioning the panel (1) of a shadow mask type color CRT having a shadow mask (2), and (9) is the shadow mask provided so as to face the shadow mask (2). A moving stage formed so as to be movable horizontally and vertically with respect to (2),
(10) is a projector which is fixed to the moving stage (9) and projects slit light toward the shadow mask (2),
(11) is a television camera fixed to the moving stage (9) and arranged such that the optical axis (23) is inclined by a predetermined angle θ with respect to the optical axis (22) of the projector (10), Is an illuminating device that illuminates the shadow mask (2) from the front surface of the panel (1), (13) is a drive circuit of the projector (10), (1
4) is a drive circuit of the moving stage (9), and (15) is an arithmetic processing circuit, and the slit light image and the shadow mask (2) on the shadow mask (2) captured by the television camera (11). ) And the position of the hole of the shadow mask (2) on which the slit light is projected, and the television camera (11) captures an image of the slit light on the shadow mask (2). And the amount of movement of the moving stage (9) in the vertical direction with respect to the shadow mask (2) when the slit light image on the surface of the panel (1) is taken and the shadow mask obtained by the above calculation. The three-dimensional position of the shadow mask (2) with respect to the panel (1) is calculated from the position of the hole (2). (1
6) is a control circuit for controlling the entire device, and (17) is a display circuit for legalizing the calculation result.

Next, the operation will be described. First, the shadow mask type color cathode ray tube panel (1) is fixed to the positioning jig (8), and the driving circuit (14) of the moving stage (9) moves the moving stage (9) to the slit light from the projector (10). The first positioning is performed so that the light is exactly projected onto the measurement point of the shadow mask (2). Drive circuit (13) for floodlight (10)
The television camera (11) is focused on the slit image on the shadow mask mask (2) that projects the slit light from the light projector (10) perpendicularly to the shadow mask (2). The distance between the surface of the panel (1) coated with the phosphor and the shadow mask (2) is determined as follows according to the principle of triangulation shown in FIG. That is, the slit image (20) on the shadow mask (2) by the slit light projected from the projector (10) and the hole (18) of the shadow mask (2).
The slit image (21) by the slit light that has passed through
Seen from the projector (10) side, it looks like Fig. 3. When the slit image (20) is captured by the television camera (11) having an optical axis inclined by an angle θ with respect to the optical axis of the projector (10), the screen of the television camera (11) shows, for example, FIG. It becomes like the statue (20a). c is the center line of the screen of the television camera (11). Here, if the intersection of the optical axis (22) of the projector (10) and the optical axis (23) of the television camera (11) is on the surface of the shadow mask (2), the television camera (11) In the screen, the slit image (2
The image of 0) is observed on the center line c. However, the intersection of the optical axes (22) and (23) is the shadow mask (2).
Even if the deviation is slightly above or below the surface of the, if the deviation is within the measurement range of the television camera (11), the image of the slit image (20) is the image of the television camera (1).
Observed clearly on the left or right side of the center line c on the screen of 1). The image (20a) in FIG. 4 (a) shows the above general example. In FIG. 4 (a), the distance Δm between the center line c and the image (20a) is obtained. Here, the right side is plus and the left side is minus from the center line c. Next, when the moving stage (9) is raised vertically, the slit image (21) on the surface of the panel (1) coated with the phosphor is
When it comes within the measurement range of the television camera (11), it is clearly observed on the screen of the television camera (11) and becomes, for example, an image (21a) of FIG. 4 (b). TV camera (1
The distance Δp between the center line c of the screen in 1) and the image (21a) above is
The moving stage (9) is kept vertical until the distance (m) between the image (20a) of the slit image (20) on the screen of the television camera (11) and the center line c of the screen of the television camera (11) becomes equal to. Move it in the direction and position it for the second time. The amount of movement L of the moving stage (9) at the time of performing the first and second positionings of this measurement is obtained, and the panel (1) surface coated with the phosphor and the shadow mask (2) are obtained.
Becomes a distance Δz between.

Further, the distance Δz between the panel (1) and the shadow mask (2) may be obtained as follows. That is, after obtaining the position Δm on the screen of the television camera (11) of the image (20a) obtained by capturing the slit image (20) on the shadow mask (2) with the television camera (11), the phosphor is The slit image on the panel (1) is moved vertically by moving the moving stage (9) by a distance equal to a predetermined design value q of the distance between the shadow mask (2) and the coated panel (1) surface. (21) is imaged by the television camera (11). The distance Δp of the image (21a) from the center line c on the screen of the television camera (11)
Ask for. The arithmetic processing circuit (15) separates the distance (Δm) between the image (20a) and the image (21a) on the screen of the TV camera (11).
The length Δq in the direction perpendicular to the surface of the panel (1) corresponding to −Δp) is calculated, and the distance Δz of the shadow mask (2) to the surface of the panel (1) is calculated as (q + Δq).
Is required.

Next, the illumination device (12) is turned on by a command from the control circuit (16), and the image of the hole of the shadow mask (2) is captured by the television camera (11) as shown in FIG. The center (18c) on the shadow mask (2) on which the slit light is projected from the projector (10) is the television camera (1).
On the screen of 1), the distances Δx and Δy from the vertical center line c and the horizontal center line d of the screen are obtained to determine the horizontal position of the shadow mask (2) with respect to the surface of the panel (1). I'm gimme. Here, the upper side of the center line d is positive and the lower side is negative. By moving the moving stage (9), positioning the projector (10) at the next measurement point on the shadow mask (2), performing the same measurement as above, and repeating the measurement in sequence. , It is possible to obtain the three-dimensional positions of a plurality of measurement points.

Although the slot hole type shadow mask has been described in the above embodiment, in the case of the round hole shadow mask as shown in FIG. 6, the shadow mask position can be measured in exactly the same manner as in the above embodiment. Further, the illumination of the shadow mask (2) by the illumination device (12) may be transmitted light from the panel (1) side or reflected light from the side facing the shadow mask (2).

〔The invention's effect〕

As described above, according to the present invention, the shadow mask position measuring addition of the color cathode ray tube includes the shadow mask type color cathode ray tube having the shadow mask arranged with a space on the panel surface coated with the phosphor. A moving stage is provided facing the shadow mask so as to be movable in at least a vertical direction with respect to the shadow mask, and a projector that projects slit light toward the shadow mask and a predetermined axis with respect to the optical axis of the projector. A television camera having an optical axis inclined is fixed to the moving stage, and an image of the slit light on the projected shadow mask and an image of the slit light on the panel surface are captured by the television camera. At this time, the moving amount of the moving stage in the vertical direction is obtained, and an illumination device is provided to prove the shadow mask and The image of the hole of the mask is formed on the television camera, and the slit light is projected from the image of the slit light on the shadow mask and the image of the shadow mask captured by the television camera. Since the position of the hole of the shadow mask is calculated and obtained, the three-dimensional position of the shadow mask with respect to the panel can be measured with the shadow mask still attached to the panel. In the manufacturing process of the type color cathode ray tube, the shadow mask position measurement of the same panel with the shadow mask attached is performed for each process, and the measured values are compared, so that the deformation of the shadow mask and the displacement of the panel may occur. There is an effect that can be detected.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing a shadow mask position measuring device for a color cathode-ray tube according to an embodiment of the present invention, FIGS. 2 to 5 are explanatory views for explaining the measuring principle of the present invention, and FIG. 6 is a round shape. FIG. 7 is an explanatory view of the hole shadow mask, FIG. 7 is an explanatory view showing the positional relationship between the panel of the shadow mask type color cathode ray tube and the shadow mask, and FIG. 8 is an explanatory view showing the state of the phosphor screen before and after the deformation of the shadow mask. ) Indicates before deformation, and (b) indicates after deformation. FIG. 9 is an explanatory view showing the measuring principle of the three-dimensional measuring device. In the figure, (1) is a panel, (2) is a shadow mask, (8) is a panel (1) positioning jig, (9) is a moving stage, (10) is a slit light projector, and (11) is a television camera. , (12) is a lighting device, (13) is a drive circuit for the projector (10), (14) is a drive circuit for the moving stage (9), and (1
5) is an arithmetic processing circuit, (16) is a control circuit for controlling the whole, (17) is a measurement result display circuit, (18) is a hole of the shadow mask (2), (18c) is a television camera (11) screen The center of the image of the hole in the upper shadow mask (2), (19) the phosphor, (20) the image of the slit light on the shadow mask (2), (20a) the television of the image of the slit light (20) Camera (1
1) Image on screen, (21) is phosphor (19) of panel (1)
Image of slit light on the surface, (21a) is image of slit light (2
The image on the screen of the television camera (11) of 1), (22) shows the optical axis of the projector (10), and (23) shows the optical axis of the television camera (11). In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A shadow mask type color cathode ray tube having a shadow mask arranged at a distance from a panel surface coated with a phosphor, the shadow mask type color cathode-ray tube being opposed to the shadow mask and being at least perpendicular to the shadow mask. A movable stage formed so as to be movable in a predetermined direction, a projector that is fixed to the movable stage and projects slit light toward the shadow mask, and a projector that is fixed to the movable stage and has a predetermined length with respect to the optical axis of the projector. A television camera that is arranged with an angled optical axis and captures an image of the projected slit light, and an illumination device that illuminates the shadow mask and forms an image of the hole of the shadow mask on the television camera. From the image of the slit light on the shadow mask and the image of the shadow mask captured by the television camera, Calculation means for calculating the position of the hole of the shadow mask on which the slit light is projected, and the time when the television camera captures the image of the slit light on the shadow mask and the image of the slit light on the panel surface. And a calculation means for calculating the three-dimensional position of the shadow mask with respect to the panel based on the movement amount of the movement stage in the vertical direction when capturing an image and the calculation result of the calculation means. CRT shadow mask position measuring device.