JPH09180644A - Color cathode-ray tube and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the strength of a shadow mask and improve the transmitance of an electron beam by specifying the shape of the slot hole of the shadow mask. SOLUTION: The surface side of a shadow mask 1 is covered with a resist film 9, a back face resist pattern 8 is formed on the back face side, etching is applied, and holes having a bridge section cross section are formed. The shadow mask 1 is washed and dried, the etched back holes are buried with an etching blocking agent Q, the back face side is protected with the resist film 9, a surface resist pattern 7 is formed on the surface side, etching is applied, and the etching blocking agent Q is removed. The shadow mask 1 is washed and dried, the surface holes on a fluorescent screen side are formed into a trapezoidal shape having two substantially parallel sides perpendicular to the longitudinal direction of slot holes 3, and the back holes on an electron gun side have cross sectional shapes of the trapezoidal slot holes 3 and bridge sections 4 in the opposite direction to the surface hole shape in this shadow mask 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color cathode ray tube having a slot type shadow mask, and in particular, the shape of the bridge portion of the shadow mask is devised to improve the electron beam transmittance while maintaining the strength of the shadow mask. The present invention relates to a color cathode ray tube.

[0002]

2. Description of the Related Art FIG. 6 shows a cross-sectional view of a main part of a basic structure of a conventional color cathode ray tube. As shown in FIG. 6, in the color cathode-ray tube 11, generally, a fluorescent screen 14 and a shadow mask 15 are arranged from the inner surface side of a face panel 13 which constitutes the front surface of the bulb 12, and a neck portion of the bulb 12 is arranged. The electron beam 17 emitted from the generated electron gun 16 is deflected by the magnetic field generated by the deflection yoke 18, and the shadow mask 15
By scanning the fluorescent screen 14 via the screen, an image is displayed on the fluorescent screen.

In order to improve the basic performance of the image display device, that is, the contrast and the brightness, the face panel 1
On the inner surface of 3, a black matrix film (not shown) filled with non-light-absorbing substances such as graphite is formed between the red, green and blue phosphor light emitting pixels, and is integrally formed with this black matrix film. The fluorescent screen 14, a metal back film (not shown) made of an aluminum film that reflects light in a separated form, and a shadow mask 15 are further provided.

In order to correspond to the present invention, only the shadow mask of the color cathode ray tube will be described here. The shadow mask has a large number of slot holes through which the electron beam passes. FIG. 7 is a partial plan view showing a region of an array of rectangular identical slots formed as a shadow mask. Generally, a large number of slot holes provided in the shadow mask are used for the front surface (fluorescent surface side) and the back surface (electron gun side) of the shadow mask material.
After forming a rectangular resist pattern,
It is formed by etching. The resist pattern is a rectangle having a major axis in the vertical axis direction and a minor axis in the horizontal axis direction of the screen.

As shown in FIG. 7, slot holes 23 are formed in the shadow mask 15, and the shadow mask 15 has a rectangular shape having a major axis in the vertical axis V direction and a minor axis in the horizontal axis H direction. The slot hole 23 is a rectangular surface hole 2 on the surface which is the phosphor screen side.
3a and a rectangular back hole 23b on the back surface on the electron gun side. The portion formed between the slot holes 23 arranged in the vertical V direction is the bridge portion 24.

FIG. 8 is a sectional view of the shadow mask as seen from the line AA and the line BB at the center of the slot hole 23 of the shadow mask 15 of FIG. 7, showing the sectional shapes of the slot hole 23 and the bridge portion 24. Is shown. These shapes are similar to the central portion and the peripheral portion of the shadow mask 15.

By the way, as shown in FIG.
The electron beam 17 emitted from 6 and deflected by the deflection yoke 18 passes through the slot hole 23 and causes the fluorescent screen 14 to emit light. However, as shown in FIG.
The transmittance of the electron beam due to the incident angle .theta. And the incident angle .theta. Is lowered because the electron beam 17 passes through the slot hole 23 and is projected on the phosphor screen 14 under the influence of the bridge portion 24.

In this case, the slot holes 23 have the same shape, and the incident angle θ increases as the distance from the central horizontal axis of the shadow mask 15 increases in the vertical direction. The projection width generated on the phosphor screen 14 under the influence of θ is increased. That is, in the upper and lower sides of the screen, the substantial projection width L1 that intercepts the electron beam 17 is larger than the projection width L2 in the center of the screen. This means that the transmittance measured in the incident direction of the electron beam 17 decreases as the distance from the central horizontal axis increases.

As a remedy for such a problem, a manufacturing method was studied as a means for forming the bridge portion 24. For example, by deeply etching from the surface,
As a result of studying eliminating the flat portion of the bridge portion 24 on the front side and lowering the height of the bridge portion 24 in the plate thickness direction, as a result, the peripheral portion of the screen that is farther in the vertical direction from the central horizontal axis of the shadow mask 1 is transparent. Although the problem that the rate was lowered was improved, the problem that the mechanical strength of the shadow mask was significantly decreased occurred, and it could not be put to practical use.

To solve the same problem, JP-A-50-1421
In Japanese Patent Laid-Open No. 60, by shifting the positional relationship between the front hole and the back hole of the shadow mask in accordance with the electron beam incident angle,
It is disclosed that the transmittance of an electron beam is increased, the phosphor screen brightness is improved, or the bridge strength is improved. However, although the publication describes what it should be, there is no description of specific implementation.

Further, as disclosed in Japanese Patent Laid-Open No. 7-114885, there is a problem in that the transmittance decreases due to an increase in the incident angle of the electron beam with respect to the horizontal direction of the shadow mask. It has been improved by taking.

[0012]

However, in the shadow mask 15 having the bridge portion 24 of the same shape as described above, when the electron beam 17 passes through each slit hole 23 provided in the shadow mask 15, The projection width L1 by the bridge portion 24 increases as the distance from the central horizontal axis of the shadow mask 15 increases in the vertical direction. That is, there is a problem that the transmittance measured from the incident direction of the electron beam 17 decreases as the incident angle θ of the electron beam 17 to each slot hole 23 increases.

Therefore, the present invention has been proposed in view of the above problems, and its object is to provide a means for reducing the projection width of the bridge portion when the electron beam passes through the slot hole, that is, With respect to the vertical component of the shadow mask, by providing a bridge shape that suppresses a decrease in the transmittance measured from the incident direction with an increase in the incident angle and a method for manufacturing the bridge shape, the transmittance is improved and the color purity and contrast are improved. It is to provide a color cathode ray tube.

[0014]

SUMMARY OF THE INVENTION According to the present invention, an in-line array electron gun and a slot hole vertically long in a direction perpendicular to a scanning line of an electron beam from the electron gun have a constant vertical pitch via a bridge portion. In a color cathode ray tube having a shadow mask in which a row of slot holes connected in parallel in the horizontal direction are arranged, and a stripe-shaped fluorescent screen which is arranged so as to face the shadow mask and is continuous in the vertical direction, a shadow mask The front hole shape on the phosphor screen side is a trapezoidal shape having two substantially parallel sides orthogonal to the slot hole longitudinal direction, and the back hole shape on the electron gun side is the front hole shape. An inverted trapezoidal color cathode ray tube is provided.

Further, there is provided a color cathode ray tube in which two substantially parallel sides forming the front hole shape of the slot hole are longer sides on the side far from the horizontal axis of the shadow mask center.

Also provided is a color cathode ray tube in which the difference between the lengths of two substantially parallel sides of a trapezoid having the front hole shape of a slot hole increases with distance from the central horizontal axis of the shadow mask, and a manufacturing method thereof.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In general, a shadow mask of a color cathode ray tube has a large number of slot holes through which an electron beam passes, which are regularly arranged. An embodiment of the present invention will be described with reference to FIGS. In each figure,
1 is a shadow mask, 3 is a slot hole, 3a is a trapezoidal front hole, 3b is a trapezoidal back hole, 4 is a bridge portion connecting the slot holes, 5 is an electron beam, 6 is a fluorescent screen, and 7 and 8 are slots. It is a trapezoidal front and back side resist pattern for forming holes and bridges.

FIG. 1 is a partial plan view showing a region of a slot hole array formed in a shadow mask according to the present invention. FIG. 1A shows the slot hole arrangement near the upper side portion, and FIG. 1B shows the slot arrangement near the central horizontal axis. As shown in the figure, the slot hole 3 formed in the shadow mask 1 has a rectangular shape having a long side in the vertical axis V direction and a short side in the horizontal axis H direction of the shadow mask 1 in which the slot hole 3 is formed. Has become. The slot hole 3 is composed of a trapezoidal front hole 3a on the front side which is the phosphor screen side and a trapezoidal back hole 3b on the back side which is the electron gun side. Further, the space between the slot holes 3 arranged in the vertical axis V direction is called a bridge portion 4. Although FIG. 1A shows the slot hole 3 near the upper side portion, the slot hole 3 near the lower side portion is formed in line symmetry with the upper side portion with respect to the central horizontal axis.

FIG. 2 is a sectional view of the shadow mask as seen from the YY line at the center of the slot hole 3 of the shadow mask 1 of FIG. FIG. 2 shows a trapezoidal surface hole 3 after etching.
slot hole 3 formed by a and trapezoidal back hole 3b
And the completed cross-sectional shape of the bridge portion 4. The cross-sectional shape of these bridge portions 4 is such that the incident angle θ of the electron beam 5 as shown in FIG. It is designed to gradually incline according to.

FIG. 3 is a plan view showing the shape of the resist pattern according to the present invention. As shown in FIG. 2, in FIG. 3, in order to form the slit hole 3 and the bridge portion 4 of this cross-sectional shape, for example, the trapezoidal front hole 3 of the shadow mask 1 is formed.
a is a front surface resist pattern 7 and a back surface resist pattern 8 for forming the trapezoidal back hole 3b. FIG.
3A is the upper side, FIG. 3B is the vicinity of the central horizontal axis, and FIG.
(C) shows each resist pattern shape on the lower side. The back surface resist pattern 8 has a rectangular resist pattern in which the direction of the front surface resist pattern 7 is reversed. As described above, the slot hole 3 and the bridge portion 4 of the shadow mask 1 according to the present invention are manufactured by etching by the so-called two-step etching method.

The manufacturing method will be described more specifically by referring to FIG. 4 and showing the upper and lower sides of the shadow mask 1, in particular. As shown in FIG. 4A, first, the front surface side of the shadow mask 1 is covered with a resist film 9, and the back surface side is formed with a back surface resist pattern 8, and then etching is performed.
At this time, in the backside resist pattern 8 formed on the shadow mask 1, the longer side has a lower etching resistance than the shorter side, and the etching proceeds deeper and wider. As a result, holes are etched which have a sectional shape as shown in FIG.
Next, after washing and drying, as shown in FIG. 4B, the etched back hole is filled with the etching stopper Q, the back surface side is protected by the resist film 9, and the front surface side is formed with the front surface resist pattern 7. Then, etching is performed. Similar to the case of the back surface etching, the etching enters deeper and wider in the vicinity of the longer side of the front surface resist pattern 7, so that this cross-sectional shape is shown in FIG.
(B).

For example, most of the sloped portions of the cross-sectional shape of the bridge portion of the upper and lower sides near the central horizontal axis are formed with deep and wide etching curves at the time of surface hole etching, and from the central horizontal axis of the same bridge portion. Most of the distant inclined portion has a deep and wide etching curve formed during back hole etching, and the inclinations of these deep and wide etching curves are formed to be substantially parallel to the electron beam incident angle. After that, if the etching inhibitor Q is removed and washed and dried,
The shadow mask 1 having the cross-sectional shapes of the slot hole 3 and the bridge portion 4 as shown in (c) is completed.

Further, by increasing the difference in length between the two sides of the trapezoid parallel to each other with increasing distance from the central horizontal axis, the inclination of the bridge portion can be gradually inclined. Needless to say, the shape of the bridge portion and the shape of the slot hole of the shadow mask can be controlled by adjusting the position and shape of the trapezoidal shape on the resist pattern.

As a result, the projection width of the electron beam in the bridge portion 4 becomes narrower than in the conventional case, and the transmittance measured in the electron beam incident direction is improved. Moreover, since the flat portion of the bridge portion is secured on both the front surface and the back surface, the bridge portion 4 having sufficient strength can be formed without causing a significant decrease in mechanical strength of the bridge portion 4.

Here, for example, the relative transmittance with respect to the electron beam incident angle θ at the central portion and the upper side portion of the screen was simulated and compared. FIG. 5 is an explanatory diagram of the shape of the bridge portion 4 formed on the shadow mask 1 and the transmittance with respect to the incident angle θ. The transmittance when there is no bridge portion 4 is set to 100, and what percentage is reduced by the bridge portion 4 is compared. First, when the plate thickness of the shadow mask 1 is 0.1 mm, the vertical pitch of the slot holes 3 is 0.5 mm, and the width of the orthogonal projection of the bridge portion 4 on the plane parallel to the shadow mask 1 is 0.1 mm, the upper side of the screen is displayed. The vertical component of the incident angle θ of the electron beam 5 on the section is about 20 degrees, and in the case of the present invention, as shown in FIG. 5, the projection widths by the bridge section 4 are L1 = 0.07 mm and L2 = 0, respectively. It becomes 1 mm. Similarly, in the case of the conventional shadow mask of the same size, as shown in FIG. 7, L1 = 0.12 mm, L2 =
It becomes 0.1 mm. As a result, when the relative transmittances of the present invention and the conventional example are compared, it is as shown in Table 1, and at the upper side of the screen, the relative transmittance of 76% is 86%, which can be improved by 10%. It should be noted that specifically, the shape and size of the bridge portion of the shadow mask on the lower side of the screen may be appropriately selected to make the electron beam transmittance of the entire screen uniform.

[0026]

[Table 1]

[0027]

As described above, according to the color cathode ray tube of the present invention, in the resist pattern for forming the slot hole and the bridge portion of the shadow mask, the front hole shape has a longer side on the side far from the central horizontal axis. By making the trapezoidal shape with a square shape and the shape for the back hole an inverted trapezoidal shape, the inclination of the bridge portion can be made suitable for the incident angle of the electron beam while maintaining the height of the bridge portion. As a result, while maintaining the shadow mask strength, the transmittance measured in the incident direction of the electron beam was improved at the upper and lower sides of the screen to realize a color cathode ray tube with improved color purity and contrast. .

[Brief description of the drawings]

FIG. 1 is a partial plan view showing an area of a slot hole arrangement of a shadow mask according to the present invention (a) a slot hole arrangement on an upper side portion (b) a slot hole arrangement on a lower side portion

FIG. 2 is a cross-sectional view of the shadow mask as seen from the line YY of FIG.

FIG. 3 is a plan view showing the shape of a resist pattern according to the present invention. (A) Front surface resist pattern (b) Back surface resist pattern

FIG. 4 is a manufacturing explanatory view showing a method for forming a slot hole and a bridge portion according to the present invention. (A) Front side forming method (b) Back side forming method (c) Finished shadow mask

FIG. 5 is an explanatory view of the transmittance according to the incident angle of the electron beam according to the present invention. (A) Projection width by the bridge portion at the upper side portion (b) Projection width by the bridge portion at the central portion

FIG. 6 is a sectional view of a main part of a color cathode ray tube.

FIG. 7 is a partial plan view showing a region of a conventional shadow mask slot hole array.

FIG. 8 is a cross-sectional view of the shadow mask as seen from line AA and line BB in FIG.

9A and 9B are explanatory diagrams of the transmittance according to a conventional electron beam incident angle. (A) Projection width by the bridge portion at the upper side portion (b) Projection width by the bridge portion at the central portion

[Explanation of symbols]

 1 Shadow Mask 3 Slot Hole 3a Trapezoidal Front Hole 3b Trapezoidal Back Hole 4 Bridge Part 5 Electron Beam 6 Fluorescent Surface 7 Surface Resist Pattern 8 Backside Resist Pattern L1 Bridge Part Projection Width L2 at Upper Side (Lower Side) Bridge at Central Part Partial projection width

Claims (3)

[Claims] 1. An in-line arrayed electron gun and a slot hole row in which vertically elongated slot holes are connected in a vertical direction with respect to a scanning line of an electron beam from the electron gun at a constant vertical pitch via a bridge portion. Shadow masks arranged side by side,
In a color cathode ray tube provided with a stripe-shaped phosphor screen which is arranged so as to face the shadow mask and is continuous in the vertical direction, the slot hole shape is such that the front hole on the phosphor screen side is orthogonal to the slot hole longitudinal direction. A color cathode ray tube having a trapezoidal shape having two sides that are substantially parallel to each other, and a back hole on the electron gun side having a trapezoidal shape in a direction opposite to a front hole shape. 2. The color according to claim 1, wherein two substantially parallel sides forming the front hole shape of the slot hole are longer sides on the side farther from the central horizontal axis of the shadow mask. Cathode ray tube. 3. The difference between the lengths of two substantially parallel trapezoidal sides forming the front hole shape of the slot hole is increased as the distance from the central horizontal axis of the shadow mask increases. The described color cathode ray tube.