JPS63136444A - Shadow mask structure - Google Patents

Abstract

PURPOSE:To reduce a landing error in operation by forming a mask frame of a low expansion metal whose coefficient of average thermal expansion is a specific value or below in the range of fixed temperatures. CONSTITUTION:A shadow mask 22 is made of amber, and a mask frame 23 is made of a material whose coefficient of average thermal expansion is 45X10<-7>/ deg.C or below in the range of temperatures 30 deg.C to 300 deg.C and is 75X10<-7>/ deg.C or below in the range of temperatures 30 deg.C to 450 deg.C. A mask 22 is welded on one side of the frame 23 while tension is applied to the mask 22. An end of a frame supporter 25 is fixed on the other side of the frame 23, and the supporter is fixed with a panel pin of a color cathode-ray tube by means of a pin hole 26. Even if this shadow mask structure is corporated in a high finess color cathode-ray tube and is operated, for a long time since the start of operation, a beam landing error is reduced and excellent color purity is available.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a shadow mask structure, and in particular, when it is incorporated into a color picture tube used at high power, it has good color purity reproduction characteristics. The present invention relates to a shadow mask structure that can be used as a shadow mask.

(Prior art) Generally, in a shadow mask type color picture tube,
The electron beam emitted from the electron gun forms part of the shadow mask.
After passing through the apertures, the light hits the phosphor layers that emit light in three colors, red, green, and blue, formed on the inner surface of the panel facing the shadow mask, causing each of the phosphor layers to emit light. It has become.

Therefore, in order to achieve good color reproduction, the relative positional relationship between the many apertures V of the shadow mask and the three color phosphor layers corresponding to each of these apertures must be in a predetermined matching relationship, and the electron beam passing through the apertures must be aligned. must land accurately on a predetermined phosphor layer.

However, the shadow mask transmittance of the electron beam is usually 15
% to 20%, and most of the electron beams impinge on the shadow mask, causing the shadow mask to heat and expand. This heating expansion becomes particularly large when the anode voltage and beam current of the color picture tube are increased in order to obtain a bright screen, and as a result, the landing position of the electron beam on the phosphor layer changes greatly, resulting in color purity. This will cause deterioration.

Next, an example of a normal shadow mask type color receiving tube will be explained with reference to FIGS. 4 and 5.

That is, there is a panel (2) on which a fluorescent screen (2) consisting of a band-shaped or dot-shaped phosphor layer that emits light in three colors of red, green, and blue is adhered to the inner surface, and panels (2) and (2) are arranged at predetermined intervals on this fluorescent screen (2). A shadow mask structure (1) consisting of a shadow mask (3) provided, a mask frame (a) to which this shadow mask (3) is fixed, and a frame support (6) that supports this mask frame (a) on a panel pin. ) and an electron gun (9) provided within the neck (8).

In such a color picture tube, when the shadow mask (3) is heated by the impact of most of the electron beam (A), the temperature of this shadow mask (■) rises and expands, and this heat is further transferred to the mask. As the electron beam (11) is transmitted from the frame 6) and frame support 0 to the panel 0), a temperature difference occurs in each part and the parts are deformed, and the position where the electron beam (11) lands on the phosphor screen ■ through the aperture. A landing error occurs in which the plane is displaced from a predetermined position.

This landing error changes over time, and the shadow mask (3) undergoes rapid thermal expansion immediately after operation or when a locally bright portion occurs on the screen.

However, the temperature of the mask frame (3), which has a relatively large heat capacity, does not rise quickly, so the shadow mask (3)
3'), that is, it bulges out toward the phosphor screen (3). As a result, the electron beam ω) passing through the same aperture is (1
1'), and the landing position also changes from 02) to (12).
'), causing a landing error.

Furthermore, if the color picture tube continues to operate, after a sufficiently long period of time, the mask frame () will also undergo thermal expansion, so that the landing position will be displaced in the opposite direction to that immediately after the above-mentioned operation.

The amount of variation in this landing position is on the order of tens to hundreds of degrees, which causes deterioration of color purity. Furthermore, as the anode voltage of the color picture tube increases and the beam current increases in an attempt to obtain a bright screen, the thermal expansion of the shadow mask (2) also increases, resulting in a larger landing error and a significant deterioration in color purity.

On the other hand, in order to realize a high-definition image, it is necessary to reduce the distance between the apertures of the shadow mask (3) and increase the number of picture elements. This reduces the spacing between the three color phosphor layers deposited on the phosphor screen (1) and the landing tolerance of each phosphor layer.

Therefore, high-definition color picture tubes require more accurate beam landing.

Various proposals have been made to reduce the above-mentioned beam landing error. For example, the shadow mask may be blackened or coated with black to improve heat dissipation and reduce the temperature rise of the shadow mask, or the thickness and length of the side wall of the shadow mask may be adjusted, or holes or cutouts may be provided. There are structures that reduce heat capacity and equalize heat, and structures that use low thermal expansion materials. However, these measures were insufficient for applications that require high brightness and are used under bright outside light, such as in aircraft or vehicles.

As a structure to solve this problem, A High Brightness Shadow Mask Color C, R, T Fore Cockpit Display Digest of Paper Or 1983. A color picture tube equipped with an improved shadow mask structure was announced at the Symposium of Society for Information Display 9.5.

As shown in Figure 6, this color 4 picture tube is equipped with a flat shadow mask 03) fixed to a mask frame (4) under tension, and the thermal expansion of this shadow mask 03) is absorbed by relaxing the tension. This color picture tube has a shadow mask structure (1P) that does not deform even at high brightness.Compared to conventional color picture tubes with dome-shaped shadow masks, the landing error has been significantly improved. It is reported that.

In this type of shadow mask structure, there is a step in which it is heated to 400'C to 500C during the manufacturing process of color picture tubes, and this heating can significantly reduce the tension of the shadow mask.

Such a color picture tube in which tension is applied to the shadow mask has a balance between tension relaxation due to thermal expansion of the shadow mask and stress in the mask frame in response to an increase in input to the shadow mask. Therefore, the thermal expansion of the shadow mask becomes large, and when it becomes loose, the beam landing will shift by a large amount.

The beam landing tolerance for a shadow mask type color picture tube is determined at the time of design, and conditions must be within this range and under tension on the shadow mask.

When this type of shadow mask type color picture tube is operated, the collision occurs due to the collision of electron beams immediately after operation. Thermal expansion of the shadow mask is absorbed by the tension relaxation of the shadow mask, so no landing error occurs, but if it is operated continuously for a long time, a landing error will occur due to the thermal expansion of the mask frame, and this landing error will be used at high inputs. The more you do it, the bigger it gets.

(Problems to be Solved by the Invention) Immediately after operation of a high-definition shadow mask type color picture tube used at high input, a landing error occurs due to thermal expansion of the shadow mask, and color purity deteriorates. Furthermore, if the color picture tube continues to operate, landing errors will also occur due to thermal expansion of the mask frame.

In order to reduce the landing error immediately after the color picture tube operates, it is possible to use a shadow mask structure in which tension is applied to the shadow mask, but even with this method, the landing error cannot be reduced during long-term operation. There is a problem.

The present invention solves this problem and provides a high-precision shadow mask type color picture tube used with high input.
- It is an object of the present invention to provide a shadow mask structure capable of reducing landing errors immediately after the operation and during the operation for a long period of time.

[Structure of the invention]

(Means for solving the problem) In a shadow mask structure mainly composed of a shadow mask and a mask frame supporting this shadow mask, the mask frame is made of a metal material with low thermal expansion, and the angle of 30° to
The average coefficient of thermal expansion up to 300℃ is 45X 10-7 /
'C or less, and the average coefficient of thermal expansion from 30° to 450°C is 75×10-7/”C or less.

(Function) ′ In a shadow mask to which tension is applied, the thermal expansion of the shadow mask immediately after the color picture tube is operated is absorbed by the tension relaxation of the shadow mask, so that the landing error is reduced. In order to obtain this effect, it is necessary that a predetermined tension is applied to the shadow mask after the heat treatment step in the color picture tube manufacturing process, and it is necessary to suppress a decrease in the tension of the shadow mask due to the heat treatment. The reason for this decrease in tension due to heat treatment is considered to be that the yield strength of the shadow mask at high temperatures is lower than the yield strength at room temperature. Therefore, so that the tension of the shadow mask at high temperatures is smaller than its yield strength, the mask frame is made of a material that has a smaller thermal expansion than the shadow mask at high temperatures and has a tension-relieving effect commensurate with the decrease in yield strength.
Average coefficient of thermal expansion from ° to 300 °C is 45X 10-7
The best results have been obtained by using materials with an average coefficient of thermal expansion of 75 x 10-7/°C or less from 30° to 450°C.

Next, when the color picture tube is operated for a long time, the landing error is reduced because the mask frame has a small coefficient of thermal expansion at low temperatures. The landing margin error for high-definition tubes is about 20-30-30, but the mask frame has a margin error of 30-30.
If a material with a thermal expansion coefficient of 45x10-7/°C or less at 0'C is used, for example, a 6"x6" color picture tube can be used with an input of up to 45W.

(Embodiment) An embodiment of the shadow mask structure of the present invention will be described with reference to FIG.

That is, the shadow mask 0 is welded under tension to one side of the mask frame (23) to form a shadow mask groove, and the frame support (25) is welded to the other side of the mask frame (23). ) is fixed at one end, and is fixed to a panel pin of a color picture tube through a pin hole (26) provided near the other end.

A feature is that the tension applied to the shadow mask C, the mask frame (23), and the frame support (25) are each made of a combination of low thermal expansion materials.

More specifically, the shadow mask (2) is made of amber with a thickness of 50 mm, and the mask frame (23) is made of Ni containing 42% Ni with a thickness of 1.2 M.

Fe alloys have particularly low thermal expansion, for example, the average coefficient of thermal expansion is 45X 10-7/°C from 30° to 300'C.
75X 10-7 from 30° to 450°C
A shadow mask structure was assembled using a metal material (extremely low thermal expansion metal) with a temperature of /'C or less.When such a shadow mask structure was heated at 450'C and the tension of the shadow mask was measured, the result of heat treatment was The amount of decrease in tension between the front and rear was 10%.This was about 50% when the material of the mask frame (23) was made of amber, which rarely occurred, but the tension remaining in the shadow mask (2) It was found that the color picture tube incorporating this shadow mask structure required phosphor screen power to achieve high brightness compared to a color picture tube equipped with a conventional dome-shaped shadow mask. It was found that the landing error was about the same even when the input was increased by a factor of 10.

The reason why the tension reduction side before and after this heat treatment was 10% is because tension relaxation occurred due to the difference in thermal expansion characteristics with Amber (an extremely low thermal expansion metal) of this example, and the tension of Shadow Mask Q was reduced by 10%. It is thought that the decrease was 10%.

This thermal expansion characteristic is shown in Figure 2, where the horizontal axis is temperature and the vertical axis is the elongation (Δρ/fl>) at each temperature from the maximum temperature, and Fe is a straight line as shown in (31). For F
The amber ultra-low thermal expansion metal made of e-Ni alloy has a bending point as shown in (32) and (33), and the lower temperature side of this bending point shows a lower expansion coefficient, and the higher temperature side shows a higher expansion coefficient. There is.

According to Figure 2, the elongation of amber at 450'C is approximately 35
XIO-4, whereas ultra-low thermal expansion metals are approximately 28x
10-4, and it is thought that the tension of the shadow mask was relaxed due to the difference between the two, and the decrease in tension due to heat treatment was suppressed.

Next, the operation of the color picture tube will be described.

That is, in FIG. 3, the shadow mask Q21 is balanced with the mask frame (23) curved inward as shown by the broken line (23'). Therefore, when the shadow mask 20 thermally expands, it moves as shown by the arrow (29) in the figure, and the tension on the shadow mask 112 is relaxed. When considering this, it occurs in proportion to the heat capacity of the shadow mask @ and the mask frame (23).In other words, the heat capacity of the shadow mask (2) is small, and the change indicated by the arrow (29) occurs in a short time. Since the frame (23) has a large heat capacity, it takes a long time for the temperature to rise compared to the shadow mask (2), several tens of times more.Therefore, if high brightness input occurs in a short time, the tension of the shadow mask (2) will increase. When applied for a long time, thermal expansion of the mask frame (23) occurs.In this case, the stress of the mask frame (23) is reduced due to the stress relationship balanced with the tension of the shadow mask (22). This increases the tension of the shadow mask (2) due to thermal expansion, which increases the input limit that causes it to loosen.In other words, in the case of the embodiment, the heat of the mask frame (23) made of an extremely low thermal expansion metal increases. The expansion acts to give tension to the shadow mask @ made of amber. This is because the thermal expansion curves of both are on the low temperature side, and the extremely low thermal expansion metal has a larger thermal expansion than the amber.

The landing error due to thermal expansion of the mask frame is reduced as the thermal expansion coefficient of the mask frame becomes smaller. 30° to 300 of what is commonly known as 4270i
The standard for the coefficient of thermal expansion in °C is 40 to 50xx 10-7 /
°C, 45 to 65X10-7/'C, etc., and there is a difference of 25X10-7/'C between the maximum and minimum, which results in a landing error of more than 201 seats for color picture tubes used at high inputs. It makes a difference.

In conventional low to medium input color picture tubes, the temperature rise in the mask frame is low, and this level of difference in thermal expansion coefficients has not been a problem. However, in a high-definition color picture tube used at high input, the landing tolerance is exceeded due to its design.

Therefore, in order to fully obtain the effects of the present invention, it is necessary to
The thermal expansion coefficient at 0'C is 45X 10-7/'C or less, and the thermal expansion coefficient at 30° to 450°C is 75X 10-
The mask frame must be made of a material of 7/'C or less.

In the above explanation, amber is used for the shadow mask and an extremely low thermal expansion metal is used for the mask frame, but other combinations may be used, and the material of the mask frame is not limited.

〔Effect of the invention〕

As described above, according to the present invention, even if the present invention is incorporated into a high-definition color picture tube used under extremely high input conditions under bright external light such as on board an aircraft, the beam will continue to be emitted for a long time immediately after the color picture tube is operated. It is possible to provide a shadow mask structure that can realize a color picture tube with less landing error and good color purity.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of the shadow mask structure of the present invention, FIG. 2 is a thermal expansion curve diagram of Fe, amber, and extremely low thermal expansion metals, and FIG. 3 is a diagram of the shadow mask structure of FIG. 1. An explanatory diagram showing deformation during heating, Fig. 4 is a sectional view showing a color picture tube equipped with a conventional shadow mask structure, Fig. 5 is an explanatory diagram showing a beam landing state, and Fig. 6 is an explanatory diagram showing another conventional shadow mask structure. FIG. 2 is a sectional view of a main part of a color picture tube equipped with a mask structure. 3.22...Shadow mask 4.23...Mask frame 6.25...Frame support

Claims (2)

[Claims] (1) In a shadow mask structure mainly composed of a shadow mask and a mask frame that supports this shadow mask, the metal material used for the mask frame is
The average coefficient of thermal expansion from 0° to 300°C is 45 x 10^-
^7/°C or less, and an average coefficient of thermal expansion from 30° to 450°C is 75×10^-^7/°C or less. (2) The metal material used for the shadow mask is 30° to 4
The average coefficient of thermal expansion up to 50℃ is 80 x 10^-^7/℃
The shadow mask structure according to claim 1, characterized in that it is made of the above materials.