JP3195011B2 - CRT with reading mark and method of manufacturing the mark - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube having a reading mark and a method of manufacturing the mark, and more particularly, to a method for preventing a mark provided on a side surface of a glass panel from being deteriorated in various steps of manufacturing a cathode ray tube. The present invention relates to a cathode ray tube having a read mark on which the mark is formed, and a method of manufacturing the mark.

[0002]

2. Description of the Related Art In general, many types of cathode ray tubes are manufactured by sequentially or appropriately selecting various types of cathode ray tubes using a common cathode ray tube manufacturing process path. Then, in the manufacturing process path, a certain 1
When manufacturing two types of cathode ray tubes, the manufacturing is performed by combining one processed component used for the one type with another processed part also used for the one type one after another.

Conventionally, in the above-mentioned cathode ray tube manufacturing process, the parts used by the cathode ray tube to be assembled by the manufacturing worker are:
By looking at the mark attached to the part or the part itself, an appropriate one is selected and assembled or processed. However, as CRTs to be manufactured have become larger or have higher definition, it has become more difficult for manufacturers to respond to the task of selectively transporting parts and performing precision work. Processing and automatic assembly are being measured.

[0004] In this case, in order to achieve the above-mentioned automatic processing and automatic assembling of the entire manufacturing process, it is necessary to clarify what kind of cathode ray tube is currently being manufactured, and During the manufacture of a CRT, the type of the CRT is attached to the side of the glass panel in order to accurately select the parts that match the type of CRT and assemble it, or to perform processing that matches this type of CRT. Is also provided.

[0005] By the way, as a cathode ray tube having a machine reading mark, especially a bar code on the side surface of a glass panel, for example, Japanese Utility Model Laid-Open No. 60-136465, US Pat. No. 4,374,451, US Pat. No. 4,377,890, and US Pat. No. 4,515,867. Of these, the one disclosed in Japanese Utility Model Laid-Open No.
This is called the former method), on the side of the glass panel,
A bar code having a different number for each cathode ray tube or a number incremented for each tube is printed using a heat-resistant substance.
No. 1, U.S. Pat. No. 4,377,890, U.S. Pat.
No. 5867 (hereinafter referred to as the latter means) are disclosed at the beginning of the cathode ray tube manufacturing process.
A double layer is formed on the side of the glass panel using two types of water glass paints having different compositions, and then a laser beam is irradiated from above on this layer to form a bar code. This bar code is read mechanically during the subsequent manufacturing process of a cathode ray tube, and is then used for management of the manufacturing process by computer processing.

Since the bar code is mainly used for managing and recording the state of the cathode ray tube during the manufacturing process, it is usually formed on the side surface of the glass panel at the beginning of the cathode ray tube manufacturing process. Is done. However, in the manufacturing process, after forming a barcode, the glass panel is subjected to a treatment with a relatively high heat or a treatment with various acids. Sometimes it disappeared.

For this reason, conventionally, when forming a bar code, bar code printing using a heat-resistant substance is performed as in the former method, or as in the latter method.
A bar code was formed by a laser beam.

[0008]

However, even in the former method, it is inevitable that the bar code formed on the glass panel is deteriorated in the subsequent cathode ray tube manufacturing process. The problem of bar codes disappearing still remains.

In the latter means, although the bar code formed on the glass panel can be temporarily prevented from being deteriorated or disappearing in the subsequent cathode ray tube manufacturing process, the bar code is formed using a laser beam. Since it is formed, the manufacturing process becomes complicated, and the manufacturing equipment becomes expensive, so that there is a problem that the unit cost of manufacturing the CRT increases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a main object of the present invention is to provide a CRT with a mark in which a formed mark is not deteriorated or erased in a subsequent manufacturing process, and a method of manufacturing the mark. It is in.

It is a secondary object of the present invention to provide a cathode ray tube manufacturing apparatus capable of inexpensively obtaining the cathode ray tube with the mark which is not deteriorated or erased.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned main object, the present invention provides an undercoat layer of a white or similar color heat-resistant and acid-resistant paint on a side surface of a glass panel of a cathode ray tube, and A mark portion made of a heat-resistant ink having a good contrast color with respect to the color of the base printed thereon, or a reading mark formed of a transparent heat-resistant and acid-resistant overcoat layer coated on the mark portion, or ,
There is provided a first means provided with a reading mark from which the overcoat layer is omitted.

Further, in order to achieve the above-mentioned main object, the present invention relates to a glass panel of a cathode ray tube,
A base made of a heat-resistant and acid-resistant paint of a white color or a similar color is applied, and then a reading mark is formed on the base by an ink jet recording apparatus containing a heat-resistant ink having a good contrast color with respect to the color of the base. And finally, a top coat made of a transparent heat-resistant and acid-resistant paint is applied on the mark, or a second coat in which the top coat step is omitted.
Means.

Further, in order to achieve the above-mentioned secondary object, the present invention has been provided and conveyed to the glass panel conveyance path and the shadow mask conveyance path of the juxtaposed cathode ray tube, respectively. Type confirmation means for confirming the specification type of the glass panel and the shadow mask; mask transfer assembling means for transferring the shadow mask on the shadow mask conveyance path to the glass panel conveyance path and incorporating the shadow mask on the glass panel of the corresponding specification type; An underlayer forming means for forming an underlayer on a side surface of the glass panel in which a mask is incorporated; a mark forming means for forming a reading mark portion on the underlayer; A topcoat layer forming means for forming a transparent topcoat layer on the glass panel, and a fluorescent lamp downstream of the topcoat layer forming means in the glass panel transport path. Surface forming means comprises a third means provided it is.

[0015]

[Function] Even when a bar code formed on the side surface of a glass panel of a cathode ray tube is printed using a heat-resistant and acid-resistant substance (ink), the bar code still deteriorates or disappears in the subsequent manufacturing process of the cathode ray tube. About why
The present inventors have pursued the cause by repeatedly performing various experiments. As a result, the main cause of the ink once firmly adhering to the glass panel surface dropping off from the glass panel surface is an acid, particularly, the ink is dissolved when the bar code attached portion comes into contact with hydrofluoric acid, and the ink dissolves. Instead of the ink peeling off the glass panel surface, hydrofluoric acid reaches the glass panel surface below it through the very thin layer of the ink, the glass panel surface is dissolved in hydrofluoric acid, Has been found to be peeled off from the glass panel surface.

Therefore, in the present invention, first, a base layer made of a heat-resistant and acid-resistant paint resistant to hydrofluoric acid is formed, and a reading mark is printed thereon with a heat-resistant ink using an ink jet recording apparatus. Then, an overcoat layer made of a transparent heat- and acid-resistant paint was further formed thereon.

The read mark formed as described above was tested for acid resistance against hydrofluoric acid. As a result, the read mark consisting of the three layers of the underlayer, the mark portion, and the overcoat layer was almost deteriorated. No good results were obtained. Also, the read mark composed of two layers, the underlayer and the mark portion, was inferior to the three-layer mark, but did not show any significant deterioration, and was found to be sufficiently within the practical range. The reason that the deterioration does not proceed in this way is that the hydrofluoric acid is prevented from reaching the glass panel surface by the overcoat layer and the underlayer, in particular, the underlayer, whereby the glass panel surface is not melted, and the ink is exposed to the glass panel. It is considered that this was because the film was not peeled off from the panel surface.

As described above, according to the present invention, the reading mark formed during the manufacturing process of the cathode ray tube is not deteriorated or erased in the subsequent manufacturing process, so that the subsequent manufacturing process is not performed. In the process, there is no possibility that the mark cannot be read or the mark is erroneously read, and after the mark is formed, the mark can be effectively used in various places.

Also, during the manufacturing process of the cathode ray tube, the above-described underlayer coating means for newly applying the mark, or the underlayer coating means and the overcoat layer coating means as described above are added. However, since these means only need to be of an ordinary configuration, the manufacturing apparatus does not become complicated or expensive, and the unit price of the cathode ray tube does not increase.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of a CRT in which a reading mark according to the present invention is provided on a glass panel surface, and FIG. 2 shows a configuration of the glass panel surface provided with the reading mark. It is an expanded sectional view shown.

In these figures, 1 is a glass panel,
1a is a glass panel upper surface, 1b is a glass panel side surface, 1
c is a panel mold match line, 2 is a reading mark, 2
a is a base layer, 2b is a mark portion, 2c is an overcoat layer, 3 is a seal edge (seal surface), 4 is a shadow mask, 5 is a funnel portion, and 6 is a neck portion.

A fluorescent screen is formed on the inner surface of the upper surface 1a of the glass panel 1, and a portion where the fluorescent screen exists constitutes an image display effective surface. On one side surface 1b of the glass panel 1, a reading mark 2 composed of a base layer 2a, a mark portion 2b, and an overcoat layer 2c is provided. Inside the glass panel 1, a shadow mask 4 is arranged facing the fluorescent screen. Is done. The glass panel 1 and the funnel 5 are connected by frit glass at the sealing surface 3, and an electron gun is built in a neck 6 continuous with the funnel 5. In this case, the reading mark 2 may be a bar code alone or a bar code and a number, character, symbol, or the like related thereto. Note that the cathode ray tube according to the above configuration is such that the electron beam emitted from the electron gun is projected on the phosphor screen, whereby the phosphor screen emits light and a desired image is displayed on the effective surface. Performs the same operation as the above operation.

FIG. 3 is a structural diagram showing a process portion for attaching the reading mark 2 and a process portion immediately before the process portion in the cathode ray tube manufacturing apparatus.

In FIG. 3, 7 is a glass panel conveyor, 8 is a shadow mask conveyor, 9 is a shadow mask conveyor, 10 is a glass panel and shadow mask assembler, 11 is a panel mask assembly (PMA) conveyor, 12 Is a glass panel checking device, 13 is a shadow mask checking device, 14 is a heater for heating, 15 is a base layer coating device, 16 is an ink jet recording device, 17 is an overcoat layer coating device, and 18 is a panel mask assembly (P
MA), and the same components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals. In addition,
Here, the panel mask assembly (PMA) 18 means a state in which the panel and the shadow mask are assembled.

The glass panel transport conveyor 7 and the shadow mask transport conveyor 8 are arranged substantially side by side.
And a glass panel and shadow mask assembling machine 10. The types of the glass panel 1 and the shadow mask 4 which have been conveyed respectively near the end portions of the glass panel conveying conveyor 7 and the shadow mask conveying conveyor 8,
A glass panel checking device 12 and a shadow mask checking device 13 for determining characteristics and the like are arranged, and a heating heater 14 is appropriately arranged along the glass panel conveying conveyor 7. The PMA transport conveyor 11 is arranged so as to be continuous with the glass panel transport conveyor 7 with the glass panel and shadow mask assembling machine 10 as a starting point, and the PMA 18 is transported thereon. This PMA transport conveyor 11
A base layer coating device 15, an ink jet recording device 16, a heat treatment furnace 19, and an overcoat layer coating device 17 are arranged in this order along with a heater 14 for heating.

In the cathode ray tube manufacturing apparatus having the above configuration, the following operation is performed.

The glass panel conveyor 7 has a panel storage (not shown) on the upstream side (upper side in the figure).
The glass panels 1 of various types are sequentially conveyed according to a predetermined program, and the conveyed glass panels 1 are heated by the heater 14 for heating. The transmissivity of the surface, the reflectance on the surface of the panel effective surface, the posture of the panel, and the like are confirmed. Further, the shadow mask 4 corresponding to the type of the glass panel 1 is stored in the shadow mask transport conveyor 8 from a mask storage (not shown) which stores the assembled shadow mask 4 on the upstream side (upper side in the figure). Are transported in order in synchronization with the transport of the glass panel 1 according to the above.
In 3, the types such as mask outer shape, mask hole size, mask hole interval, mask hole shape, and mask direction are checked.

When the glass panel checking device 12 and the shadow mask checking device 13 confirm that the type of the glass panel 1 and the type specification of the shadow mask 4 match, the glass panel 1 and the shadow mask are checked. The shadow mask 4 transferred via the transfer machine 9 is simultaneously supplied to the glass panel and the shadow mask assembling machine 10, respectively, where the shadow mask 4 is automatically incorporated into the glass panel 1 and the PMA 18
Is formed. After being discharged from the glass panel and shadow mask assembling machine 10, the PMA 18 is transported by the PMA transport conveyor 11.

Here, the PMA 18 is first conveyed to the place where the underlayer coating device 15 is arranged. Here, a white paint exhibiting heat and acid resistance, for example, a polymer , is applied to one side 1 b of the glass panel 1. Mainly composed of polysiloxane resin
Kansai Paint “Campecera No. 155”
(Trade name) is applied using a select coat (trade name) manufactured by Nordson Corporation or a normal spray, and the base layer 2a
To form The underlayer 2a thus formed is dried by the heater 14 while the PMA 18 is being conveyed. Next, the PMA 18 is conveyed to the location where the ink jet recording apparatus 16 is disposed. Here, a heat-resistant brown ink, such as methyl ethyl ketone , having a good contrast with the color of the underlayer 2a is provided on the underlayer 2a. Mainly resin
The mark 2b is printed using the inkjet recording ink "JP-T24" (trade name) manufactured by Hitachi, Ltd. as a component using the inkjet recording apparatus "FX series" (trade name) also manufactured by Hitachi, Ltd. Then, the underlayer 2a
The PMA 18 on which the mark 2b is formed is
Is transported to the place where the overcoating layer coating device 17 is disposed. Here, a transparent heat-resistant and acid-resistant paint, for example, a high-molecular-weight polysiloxane resin is used as a main component on the mark 2b.
A process of forming the reading mark 2 provided on the side surface 1b of the glass panel 1 by applying "Kanpe Sera ZC120" (trade name) manufactured by Kansai Paint Co., Ltd. using the same device as the above-described device for applying the underlayer 2a. Is completed. In this case, the reason why the ink is passed through the heat treatment furnace 19 in the above-described process is to prevent the ink of the mark 2b from bleeding when the overcoating is performed.

Further, in the PMA transport conveyor 11, after the step of forming the reading mark 2 (downstream),
Means (not shown) for forming a phosphor screen are arranged.

Next, FIG. 4 shows a side view 1 of the glass panel 1.
FIG. 4 is a configuration diagram showing a specific arrangement of read marks 2 formed on a line b.

In FIG. 4, reference numeral 20 denotes a reinforcing band of the glass panel 1, and other components which are the same as those shown in FIGS.

The mark 2 for reading has a height h in the bar code of 15 mm or more and the width of the thick bar is 0.5 to 2.0 mm. The reason for such selection is the thickness (thinness) of a bar recordable in the ink jet recording apparatus 16, the required information amount, and the thickness (thinness) of a bar required for reading.
This is because it is determined that the above values are appropriate. The position where the reading mark 2 (bar code) is provided is such that the lower limit line w is at a position separated from the sealing edge (sealing surface) of the glass panel 1 by 5 mm or more, preferably about 10 mm, and the reinforcing band is provided. The reading mark 2 (bar code) is formed at a position where the reading mark 2 (bar code) is not concealed by the reinforcing band 20 when the mounting member 20 is mounted. With such an arrangement of the reading marks 2 (bar codes), the reading marks 2 (bar codes) can be easily read even after the cathode ray tube has been incorporated into an actual product.

However, depending on the type of the cathode ray tube, almost the entire area of the side surface 1b of the glass panel 1 is a reinforcing band.
In some cases, the position where the reading mark 2 (bar code) is to be applied may be freely selected within a range not exceeding the mold match line 1c.

In addition, although not shown in FIG. 3,
The glass panel checking device 12 and the shadow mask checking device 13 are provided with a storage means. The storing means stores the type of the reading mark 2 formed on the glass panel 1 and the type of the reading devices 12 and 13. The contents of the confirmation, the time when the mark 2 was formed in the process of forming the reading mark 2, the number of the manufacturing apparatus that formed the mark 2, and the like are stored. For mark readers arranged in each process section on the transport path of the processed cathode ray tube, various information corresponding to the contents of the mark formed on the processed cathode ray tube transported on the transport path, for example,
Provide processing conditions and inspection conditions and the like specific to the processed cathode ray tube, and, from the mark reader, the inspection content for the cathode ray tube to be processed and the arrival time of the cathode ray tube to be processed by the inspection department, etc. Mark 2
Is stored in correspondence with. By providing such a storage means, wherein not only can be processed CRT is automatically executes The required various processing and testing in the production developing, said even after completion of the workpiece CRT, its It can be used as data for follow-up survey of the history of production of cathode ray tubes and the like.

As described above, according to this embodiment, when forming the reading mark 2 on the side surface 1b of the glass panel 1, first, the base layer 2a is formed by applying a heat-resistant and acid-resistant white paint. Next, a mark portion 2b made of a heat-resistant ink is printed thereon using an ink-jet recording device, and an overcoat layer 2c is formed thereon by applying a transparent heat-resistant and acid-resistant paint. When all of the manufacturing steps after the step of forming the reading mark 2 were passed, the reading mark 2 was not deteriorated, and almost no change was observed as compared with the state when the reading mark 2 was provided.

In the above embodiment, the underlayer 2a
And the heat-resistant and acid-resistant paint used for the formation of the overcoat layer 2c merely exemplify those suitable for the formation thereof.
The paint used for forming the overcoat layer 2c is not limited to the above. Further, in the above-described embodiment, those mentioned as the appliances for applying the paint are also merely examples of those suitable as the painting appliances, and in the present invention, other appliances may be used. Of course. Further, in the above-described embodiment, the inks forming the mark portions 2b and the ink jet recording devices are merely examples of those suitable for forming the mark portions 2b. In the present invention, other inks are used. Needless to say, an inkjet recording device may be used. In addition, in the present invention, as for the color of the underlayer 2a and the color of the ink forming the mark portion 2b, the former is white or a light color similar thereto, and the latter is a contrast with the color of the underlayer 2a. Of course, any color may be selected as long as the color is relatively dark.

Although not shown, as another embodiment, the same effect as in the above-described embodiment can be achieved also in the above-described embodiment in which the overcoat layer applying device 17 is removed. Things. In this embodiment, the deterioration rate of the reading mark 2 is larger than that of the above-mentioned embodiment, but the value is considerably smaller than the deterioration rate of the conventional one that does not use a base, and there is no practical problem. It is not enough.

[0040]

As described above, according to the present invention,
During the manufacturing process of the CRT, the glass panel 1
The reading mark 2 formed on the side surface 1b is formed by a base layer 2a made of a heat and acid resistant paint, a mark portion 2b printed with a heat resistant ink, and an overcoat layer 2c made of a transparent heat and acid resistant paint, or The mark is formed by the base layer 2a and the mark portion 2b, so that the mark is not read in the subsequent manufacturing process without being deteriorated or erased in the subsequent manufacturing process of the cathode ray tube. There is an effect that the mark does not exist or the mark is erroneously read.

According to the present invention, the undercoating device 15 and the overcoating coating device 17 for newly providing the read mark 2 during the manufacturing process of the cathode ray tube, or the undercoating device 15 or Even if only each of them is added, the devices 15 and 17 need only have an ordinary configuration, so that the CRT manufacturing apparatus does not become complicated or expensive, and the unit price of the CRT increases. There is no effect.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a CRT in which a reading mark according to the present invention is provided on a glass panel surface.

FIG. 2 is an enlarged cross-sectional view illustrating a configuration of a glass panel surface to which a reading mark is provided.

FIG. 3 is a configuration diagram showing a process portion for providing a reading mark and a process portion immediately before the process mark in the cathode ray tube manufacturing apparatus.

FIG. 4 is a configuration diagram showing a specific arrangement of reading marks 2 formed on a side surface 1b of the glass panel 1.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Glass panel 1a Glass panel upper surface (effective surface) 1b Glass panel side surface 1c Panel mold match line 2 Reading mark 2a Underlayer 2b Mark part 2c Topcoat layer 3 Seal edge (seal surface) 4 Shadow mask 5 Funnel part 6 Neck part 7 Glass panel transfer conveyor 8 Shadow mask transfer conveyor 9 Shadow mask transfer machine 10 Glass panel and shadow mask assembly machine 11 Panel mask assembly (PMA) transfer conveyor 12 Glass panel check device 13 Shadow mask check device 14 Heater for heating 15 Underlayer coating device 16 Inkjet recording device 17 Overcoat layer coating device 18 Panel mask assembly (PMA) 19 Heat treatment furnace 20 Reinforcement band

Continuation of the front page (56) References JP-A-2-82433 (JP, A) JP-A-61-193342 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01J 29 / 86 H01J 9/24

Claims (17)

(57) [Claims] The side surface of the 1. A cathode ray tube glass panel, resistant
A base layer of a heat-acid resistant paint , printed on the base layer
A CRT with a reading mark, comprising: a mark portion made of a heat-resistant ink; and a reading mark made of a transparent heat-resistant and acid-resistant overcoat layer coated on the mark portion. 2. The method according to claim 1, wherein the underlayer is white or a similar color.
2. The cathode ray tube with a reading mark according to claim 1, wherein: 3. A cathode ray tube with read mark according to claim 1, wherein the mark portion is a bar code. 4. The mark portion includes at least a bar code.
And the bar code has a wide bar width of 0.5
CRT with read mark according to claim 1, characterized in that the optimum 2.0 mm. 5. The mark portion is visually read with a bar code.
2. A cathode ray tube with a reading mark according to claim 1, wherein the cathode ray tube is made of a character or a symbol . 6. The glass tube of the CRT according to claim 1 ,
The place where the barcode is installed is the seal of the CRT
At least 5.0mm from the edge
On the seal edge side from the
6. A browsing device with a reading mark according to claim 2, wherein
Pipe. 7. The undercoat layer and the overcoat layer are made of a polymer.
Characterized in that the main component is a polysiloxane resin
A CRT with a reading mark according to claim 1. 8. The undercoat layer and the overcoat layer are made of a polymer
Type polysiloxane resin as a main component,
Is that methyl ethyl ketone resin is the main component
The brown with the mark for reading according to claim 1 characterized by the above-mentioned.
tube. 9. The white side of the glass panel of the cathode ray tube
A base layer of heat or acid resistant paint of a color or similar
Marks made of heat-resistant ink printed on the underlayer
A reading mark comprising:
CRT with marking for taking. 10. The mark part is a bar code.
10. A browsing device with a reading mark according to claim 9, wherein:
Pipe. 11. The mark part is at least a bar code.
And the bar code has a wide bar width of 0.5
10 to 2.0 mm.
CRT with reading mark. 12. The mark portion includes a bar code and a visual reading.
A contract that is made up of characters or symbols that can be
A CRT with a reading mark according to claim 9. 13. A side surface of a glass panel of the cathode ray tube.
The place where the bar code is installed is
At least 5.0mm from the edge and reinforced
Note that the position is closer to the seal edge than the band arrangement position.
13. With a reading mark according to claim 10 to 12
CRT. 14. The underlayer is a polymer type polysiloxane.
The resin according to claim 9, wherein the resin is a main component.
CRT with reading mark. 15. The polymer layer according to claim 15, wherein the underlayer is a polymer type polysiloxane.
Resin is the main component, and the heat-resistant ink is methyl
Claims characterized in that a tyl ketone resin is a main component.
Item 9. A CRT with a reading mark according to Item 9. 16. On the side of a glass panel of a cathode ray tube,
First, apply a base made of heat and acid resistant paint, then
Inkjet containing heat-resistant ink on the base
After printing the reading mark by the recording device,
Apply a clear coat of heat-resistant and acid-resistant paint on the coating
A method for manufacturing a cathode ray tube, comprising the steps of: 17. A glass panel transport path and a shadow mask transport path for cathode ray tubes arranged side by side, and type checking means provided on each of the two transport paths and for checking the specification type of the glass panel and the shadow mask being transported, Means for transferring a shadow mask on the shadow mask transfer path to the glass panel transfer path, and a mask transfer assembling means for assembling into a glass panel of a corresponding specification type; and a heat-resistant and acid-resistant paint on a side surface of the glass panel in which the shadow mask is incorporated . An underlayer forming means for forming an underlayer, and
A mark forming means for forming a reading mark portion by heat-resistant ink, transparent heat-resistant to the reading mark portion on
An apparatus for manufacturing a cathode ray tube with a reading mark, comprising: an overcoat layer forming means for forming an acidic overcoat layer; and a fluorescent surface forming means provided downstream of the overcoat layer forming means in the glass panel transport path.