DE10044925C2 - Process for making screens with mask mounting pins - Google Patents

Description

The invention relates to a method for producing one with at least one Adjustment pin for attaching perforated masks from the screen Windscreen and all-round screen bridge, the adjustment pin in the Screen bridge is introduced and a defined position relative to one or several reference points (hereinafter referred to as target position).

Screens are a major component of picture tubes for example TVs or monitors. To display colors you need TV and Monitor image tubes a shadow mask, which is omitted in black and white tubes.

Color picture tubes are cathode ray tubes, which additively all colors imaginable composed of the three basic colors red, green and blue. To do this three electrode guns for the Colors. The electric rays emitted by the electrode gun are partially over by the deflection unit arranged around the funnel neck directed the screen. But before the electron beams hit the screen they pass the shadow mask. The electron beams are like this focused that they cross each other when they pass through the shadow mask. In order to is achieved that the electron beams on the inner surface of the screen to coexist. The screen is made of phosphorescent fabrics coated for the three primary colors, which are used for the Lights are stimulated. The phosphorescent substances are in strips  applied vertically on the inside of the screen so that the three Electron beams only pass through a slit in the shadow mask stripes responsible for them. The electron beams continue distracted, so they are through the shadow mask to the next slot shadowed and can not reach the wrong fluorescent strip. For every slit in the shadow mask creates a pixel on the screen, the Color and brightness adjusted by the intensities of the electron beams becomes.

Since a shadow mask must be used in the color picture tube, the delivers Glass manufacturer not a complete glass bulb to the tube manufacturer, but two separate pieces of glass, the screen and the funnel. The screen picks up the shadow mask. For this, the screen bridge is already at Manufacture of the screen four or more, rarely three, small metal parts (Adjustment pins) melted down.

The method initially used is described in DE 17 89 070 B1, at which the adjustment pins subsequently positionally as part of the assembly of the Hole mask can be melted into the screen by using the adjustment pins at 340 ° -345 ° C with a glass powder and locally in the appropriate temperature plasticized screen bridge are pressed. However, this process has proven to be uneconomical, so that today Pins are melted directly during the manufacture of the screen.

The shadow mask is tied into the shade on the adjustment pins and adjusted.

DE 31 27 328 C2 shows an automatic device Position the shadow mask in a frame in the  Screen walkway, wherein the mask frame unit has a plurality of springs each have an opening, each in operative engagement with one metallic pin, which is embedded in the screen web, can be brought.

After attaching and adjusting the shadow mask on the screen, this becomes Unit then transported to apply the coating. Here is the Hole mask first knocked out again and the screen a washing process subjected. However, both parts remain assigned to each other and are in the separated state transported in parallel. It starts after washing Cover with the first, for example the green dye. For this the horizontal screen rotated and the liquid dye in poured the screen. Then the dye is dried and the Punched the shadow mask back on. The unit then comes out of the screen and shadow mask on an exposure machine, in which there is a light source that irradiates the shadow mask and the screen exactly as it did later the electron gun responsible for this color also in the finished picture tube does. The part of the beam irradiated through the slits of the shadow mask phosphorescent dye hardens during this process. After that the Removed the shadow mask again and its uncured part of the washed out phosphorescent dye in a further washing process. As a result of this process  the color strips responsible for this particular color remain on the Back of the screen. The same procedure is then used for the other colors, e.g. B. blue and red, performed again. Because the light sources in the exposure machines for the other two colors as well as the corresponding electron guns are staggered, arise finally, adjacent color stripes.

As already mentioned, at the beginning of the process each screen becomes one Hole mask assigned. The shadow mask remains on the screen over the assigned throughout the process and is also permanently installed at the end. This is due to the fact that the adjustment pins during the production of the Screen blanks are melted down if the glass is still one Has temperature of 400 to 500 ° C. Until the glass is at room temperature cooled down, there can still be changes in length in millimeter to Centimeter range occur. This gets big fluctuations in the Adjustment pin position. Since also the individual screens depending on Do not cool the cooling line evenly and also the adjustment pins with the help different pine melting machines are used, is the spread additionally increased. On the other hand, when coating the screen be ensured that the shadow mask is always arranged in the same place is because several coating steps have to be carried out in succession. It is therefore imperative that a screen has a Shadow mask is assigned. So that all coating steps always with the same mask can be run for the same screen For example, both parts are provided with barcodes and clocked on and synchronized transport routes. This means a lot great logistical effort.

The object of the present invention is therefore to find a method for which this logistical effort is reduced.  

This problem is solved by a generic method, in which as Justierpin semi-finished parts are used, the at least one section made of solid material, which is inserted into the screen bridge protrudes from the screen bridge and its cross-sectional area at least equal to the cross-sectional area of a shadow mask hole for receiving the Justierpins and in addition the area that is the scatter of the position of the Adjusting pins around the target position corresponds. After the introduction of the at least one adjustment pin is the solid material section such finished that its cross-sectional area is equal to the cross-sectional area of the corresponding hole mask hole and the adjustment pin is the target position occupies.

At least one adjustment pin is inserted into the screen bridge is not finished. Usually it will be more than one Actuate adjustment pin. The process according to the invention can be done either in the Use a way that all adjustment pins or even at least one of several adjustment pins are finished. To very tight tolerances in the To be able to maintain the desired position, all existing ones should advantageously be used Adjustment pins are finished. With less stringent requirements, it can are enough to use only one conventional adjustment pin and only that to finish an adjustment pin. For example, this can be enough to to compensate for process-related spreading of the adjustment position. The location of the or the reference points and the position of the adjustment pins relative to the Reference points, d. H. the target positions are determined by the individual Color tube manufacturers given.

The semi-finished part used as an adjustment pin is designed such that in the screen brought state of the section that from the The screen protrudes from solid material. This section out Solid material is dimensioned such that its cross-sectional area is equal to that Cross-sectional area of a shadow mask bore for receiving the alignment pin  plus an oversize. This measurement corresponds at least to the spread of the Position of the adjustment pin and the target position, depending on the type of insertion depends. The oversize is preferably chosen to be as large as possible by the To minimize scrap significantly.

If the insertion process is now complete and it is certain that the position of the adjustment pin in the screen bridge no longer changes automatically the full material section of the adjustment pin will be finished. The cross-sectional area of the solid material section is now on the Cross-sectional area of the corresponding shadow mask hole that the adjustment pin takes up, or possibly on a slightly smaller cross-sectional area brought. The adjustment pin should definitely be in the corresponding one Fit the hole mask hole. In addition, the position of the adjustment pin, or more specifically the full material section of the alignment pin relative to the or the reference points can be set very precisely.

This ensures that so tight with respect to the alignment pin position Tolerances can be met so that it becomes possible to use any screen can be combined with any shadow mask. Every coating step and the final assembly of the shadow mask can be done with any Screen hole mask combination can be performed. The license plate and Capture the screens and shadow masks as well as the synchronous execution a pair of shadow mask screens through the individual process stations eliminated.

For the committee u. a. matter how big the oversize at Cross-sectional area of the solid material section selected before finishing becomes. If you choose an allowance of ± a standard deviation of the Justierpinposition, one has a 68% probability that the Solid material section of the alignment pin can be finished in such a way that really the target position relative to the reference point (s)  is taken. If you want a probability of around 99% should reach at least two and a half stand deviations to get voted.

Preferably, the at least one adjustment pin is still warm Screen bridge melted down and finished only when cooled. Because the insertion with at least one adjustment pin by melting in the still warm screen bridge is connected with very little effort, because the deformability of the warm glass is exploited. The Changes in position of the adjustment pin, which are caused by the cooling of the Glases result from an appropriate measurement at the Cross-sectional area of the solid material section of the alignment pin balanced.

The adjustment pin has proven to be particularly advantageous and inexpensive to be finished by milling and / or turning. Depending on how Process steps are designed, which the screen with adjustment pins in will be exposed to further progress, it may be beneficial to the Treat adjustment surfaces, for example, a corrosion that the Tolerances in the position relative to the reference point (s) again would prevent it from deteriorating.

It has proven to be advantageous to use a semi-finished part as an adjusting pin in which the section that is inserted into the screen bridge is hollow is. It is meant by hollow that the adjustment pin to the side that in the Screen bridge is brought is open. To such adjustment pins in the Bringing the screen bridge requires less energy are used for the insertion of massive or not opened adjustment pins. In addition, hollow alignment pins have the advantage of a much larger one Contact area, namely inside and outside, between screen and Justierpinmaterial, so that the Justierpin is more effectively attached. Especially for the finishing and a precise setting of the target position is different  Proved advantage to use a semi-finished part as adjustment pin, which in is essentially cylindrical. In particular, the section of the alignment pin, that is inserted into the screen bridge, be cylindrical, especially if it is hollow.

The invention will now be described using exemplary embodiments in the following drawings are explained. Show:

Fig. 1a a suitable adjustment pin as semi-finished part in section,

FIG. 1b, the semi-finished part of Fig. 1a in top view,

Fig. 1c shows a finished adjustment pin in section,

Fig. 1d the adjustment pin of FIG. 1c, in plan view,

Fig. 1e a further processed adjustment pin in section,

Fig. 1f the adjustment pin of Figure 1e. In plan view,

Fig. 2a shows a screen with Justierpins and the position of the reference points,

FIG. 2b shows a section through Fig. 2a,

FIGS. 3a-3f conventional Justierpins.

Fig. 1a shows an adjustment pin 3 'according to the invention before the finishing. The adjustment pin 3 'is essentially cylindrical. It has a solid material section 7 on its upper side 5 . Below this, a hollow section 9 connects to the underside 6 of the adjusting pin 3 . This hollow section 9 is the section of the adjustment pin 3 'which has not yet been finished and which is introduced into the screen bridge.

So that the semi-finished part 3 'can be introduced more easily into the screen web, the hollow section 9 is open towards the bottom 6 . The solid material section 7 is dimensioned such that its cross-sectional area (see also top view in FIG. 1b) corresponds to the cross-sectional area of the slot in the shadow mask that will accommodate the alignment pin, plus an additional allowance that corresponds to the spread of the pin position.

In Fig. 1c an adjustment pin 3 is shown in section and in Fig. 1d in plan view after the finishing. The solid material section 7 has been machined in such a way that its cross-sectional area corresponds to the cross-sectional area of the slot in the shadow mask that will accommodate it, or machined so that its diameter corresponds to a predetermined reference diameter RD. The position of the solid material section 7 relative to the hollow section 9 has been selected such that it corresponds to the target position relative to predetermined reference points. The solid material section 7 is brought into a slightly conical shape in order to prevent the alignment pin 3 and the shadow mask from tilting.

In Fig. 1e in section and Fig. 1f in plan view, another finished adjustment pin 3 is shown, the overall position of which had shifted during the cooling process after melting into the screen bridge such that the position of the processed solid material section 7 in relation to the hollow section 9 on the edge of the Hollow section had to be selected to meet the target position with respect to the predetermined reference points.

If one carries out the method according to the invention in such a way that the adjustment pins in still warm screen bridge can be melted and then by turning and / or milling can be processed, tolerances down to 20 µm be respected. This is comparable to conventional tolerances which are approx. 0.5 to 0.7 mm.

In Fig. 2a, a screen 1 is shown with a circumferential web 2 and windshield 8 . In addition, three reference points 4 are shown on the web 2 and four reference points AD on the inner contour of the windshield 8 . The reference points AD span a plane to which the adjustment pins 3 have a defined distance. The position of the adjustment pins 3 in the plane is defined relative to the reference points 4 .

In Fig. 2b is a section through the FIG. 1 along the line II shown. It can be seen from the illustration in FIG. 2 b that the adjustment pins 3 are arranged at a defined distance from the screen web edge 12 and in particular from the reference points AD (only D shown here).

In Figs. 3a to 3f each conventional as-section and a top view Justierpins 3 are "shown. This Justierpins are already finished when they are melted down in the screen web. In the conventional Justierpins 3" of the reference diameter RD either by reference balls 11 (FIG . 3a, b 10 (FIG) or reference truncated cones. 3c defined to 3f). Since the position of the reference diameter RD with respect to the overall pin 3 "is predetermined from the beginning, the position of the reference diameter RD relative to the reference points also changes when the position of the total pin 3 " changes. An exception is therefore that a reference diameter is at the target position with respect to the reference points. It is therefore necessary to assign a shadow mask to each individual screen at the beginning of the coating process, to adapt the screen and the shadow mask to one another and to maintain the coordinated unit of screen and shadow mask until the final assembly of the shadow mask on the screen. This costly and complex logistical problem is remedied by the present invention.

Claims (6)

1. A method for producing a screen provided with at least one adjustment pin for fastening perforated masks from the front screen and the circumferential screen bridge, the at least one adjustment pin being inserted into the screen bridge and assuming a defined position relative to one or more reference points (hereinafter referred to as the target position) , characterized in that
Semi-finished parts are used as alignment pins, which have at least one section made of solid material, which protrudes from the screen bridge when it is inserted into the screen bridge and whose cross-sectional area is at least equal to the cross-sectional area of a shadow mask hole for receiving the alignment pin and additionally the area that is used to scatter the position of the Adjustment pins around the target position;
after the introduction of the at least one adjusting pin, the solid material section of which is finished in such a way that its cross-sectional area is at most equal to the cross-sectional area of the corresponding shadow mask bore and the at least one adjusting pin assumes the desired position. 2. The method according to claim 1, characterized in that the at least one adjustment pin in the warm screen bridge is melted down and finished in the cooled state. 3. The method according to claim 1 or 2, characterized in that the Adjustment pin is finished by milling and / or turning.   4. The method according to any one of claims 1 to 3, characterized in that the adjustment pin is surface treated. 5. The method according to any one of claims 1 to 4, characterized in that a semi-finished part is used as the adjustment pin, in which the section which is inserted into the screen bridge is hollow. 6. The method according to any one of claims 1 to 5, characterized in that a semi-finished part is used as adjustment pin, which in is essentially cylindrical.