GB2176144A

GB2176144A - Recording information on disc

Info

Publication number: GB2176144A
Application number: GB08610362A
Authority: GB
Inventors: Kazuyuki Suganuma; Takashi Ujihara; Yoshikazu Sakashita
Original assignee: Pioneer Video Corp; Pioneer Electronic Corp
Current assignee: Pioneer Video Corp; Pioneer Corp
Priority date: 1985-04-26
Filing date: 1986-04-28
Publication date: 1986-12-17
Also published as: GB2176144B; JPH0375947B2; GB8610362D0; JPS61248250A

Abstract

A process for imprinting additional information, such as bar codes (Figures 2, 3), on an already imprinted stamp 5 to be used for pressing a plastic disc at the final stage of manufacture, allows information to be added pertinent to the specific daughter stamp 5, as well as information common to all. The additional information is formed in an empty area of the stamp, eg by an optical mechanical process. <IMAGE>

Description

SPECIFICATION Method for recording secondary information on a disc Background Field of the invention This invention relates to a method for manufacturing a recording disc.

Background art It is well known in the art to manufacture recording discs, in which secondary information can be recorded on areas of the recording disc outside the primary recording area. The secondary information can be recorded in the form of character codes, bar codes and the like. The secondary information may contain a short description of the contents of the audio or video information recorded in the primary area. The contents of the primary area will be called the performance information. Japanese Patent Publication 58-211343, for instance, disclose a method of recording character and bar codes corresponding to the description of the contents of performance information.The character and bar codes are simultaneously recorded with the performance information by means of any cutting apparatus now available in a secondary photoresist information area of a glass master disc in the socalled cutting process. The photoresist film applied to the surface of the master disc is exposed to light as a result of which audio as well as video data is recorded thereon. In such a conventional method, the arcuate bar code prepared by conforming the longer direction of the bar codes to the radial direction of the optical recording disc is mechanically marked so as to render unnecessary the use of a special bar code reader for linearly scanning and deciphering the bar code. This process also permits an ordinary bar code reader to decipher the code when the optical recording disc has been rotated.

However, the conventional method simultaneously records on the primary and secondary areas and thus allows the marking of bar and character codes corresponding to the contents of a perform ance recording only on a one-to-one basis, thus making it difficult to incorporate information perti nent to the second or third generation stamp used in the final manufacturing process. Such pertinent information may be dates of manufacture, manufacturing plants and the like.which do not corre spond to the contents of the performance recording. Accordingly, the information thus re corded is unsatisfactory for use in controlling the manufacturing operation and the products.

Summary of the invention An object of the present invention is to provide a recording disc carrying a pattern corresponding both to performance recording information and to a recognition pattern corresponding to information pertinent to the stamp itself, in which the perform ance recording information and the recognition pattern are combined immediately before the recording disc is pressed into shape.

In the method of manufacturing recording discs according to the present invention, bar codes corresponding to performance information are recorded on a stamp before it is used to press the product into shape. Furthermore, recognition patterns pertinent to the stamp are marked in non-recording areas by proper mechanical or optical means in a separate process. In the final process, glass master discs with photoresist films applied thereto are pressed into the recording discs by the stamp through intermediate manufacturing steps.

Thereby the recognition patterns corresponding to the contents of the recorded performance information and those corresponding to the particular information pertinent to the stamp itself are both formed on the recording discs thus pressed into shape by the stamp. In consequence, information useful for process and product control becomes readable from the finished discs.

Brief description of the drawings Figure 1 shows the steps of the procedure for manufacturing optical discs, with a sectional view in each stamp.

Figure 2 shows the construction of a bar code writing apparatus useful with the present invention.

Figure 3 (a) and (b) show stamps marked with bar codes embodying the present invention.

Figure 4 and 5 show the construction of readers for reading the bar codes marked on the finished optical discs.

Detailed description of the preferred embodiments Referring now to the accompanying drawings, and embodiment of the present invention will be described. Figure 1 shows the steps of procedure for manufacturing an optical recording disc. A master disc 1 has a photo-sensitive fluid, called photoresist 1b, applied to the polished flat surface of its glass disc 1a. The master disc 1 is placed in a recording apparatus called a cutting machine (not shown) and a laser beam modulated according to video and audio signals to be recorded irradiates the master disc 1 so as to expose the photoresist 1b to light. The master disc 1 so exposed to light is a recording disc 2. The master recording disc 2 is used to make a master stamp 3 through nickel electroforming.Thereafter, the master stamp 3 is used to make a mother stamp 4, and then the mother stamp is used to make several daughter stamps 5, all by the well known nickel electroforming technique. The multiple generations of stamps 3, 4 and 5 are used in order to protect the master stamp 3.

The daughter stamps 5 are used to make a large number of press molded transparent plastic discs 6, on which are deposited aluminum reflective films for reflecting laser beam when images and sound are reproduced. The transparent plastic protective films 7a are applied over the aluminum coated discs 6 to produce completed optical recording discs 7.

According to the invention, in the step prior to that where the transparent disc 6 is pressed into shape, a bar code 8, shown in Figure 2, is recorded on the daughter stamp 5. The bar code 8 corresponds to information relevant to the contents previously recorded on the daughter stamp 5, e.g., a software name code or information relevant to the daughter stamp 5 itself, e.g., a date of manufacture, a stamp control number and the like. The bar code is marked on the daughter stamp 6 using a special bar code writing apparatus shown in Figure 2. As is obvious from Figure 3(a) and 3(b), the surface of the daughter stamp 5 is divided into secondary areas 5a and 5c on which performance information is not recorded and a primary area 5b on which performance information is recorded.

The bar code 8 is marked in the inner secondary area 5a that is free of performance information.

The marking method is shown in Figure 2. A laser beam LB generated by a laser beam generator 9 is passed through a shutter 10 and reflected by an X polarizers 11 and a Y polarizer 12. The so reflected beam is then converged by a lens 13 in the inner secondary area 5a of the daughter stamp 5. The aperture of the shutter 10 and the rotation angles of the X and Y polarizers 11 and 12 are con troiled by a control device 14 so that a plurality of polygonal bar codes 8 are marked by the laser melting the metallic stamp 5. The laser inscriber of Figure 2 is well known in the art and is described in Japanese Patent Publication 58-211343. Alternatively, a mechanical scriber or other means could be used Each of the plurality of bar codes 8 com prises a group of words shows in Figure 3(a) and 3(b).The center lines C1 and C2 of the different bar codes 8 form a rotated line.

The transparent disc 6 is then press molded by the marked daughter stamp 5 and contains both the bar codes 8 and the performance information.

Thereafter, in the conventional process, the trans parent disc 6 is covered with aluminum and with the transparent plastic protective film 7a to be come the finished optical recording disc 7.

The bar code 8 marked on the optical recording disc 7 is read out in such a manner that, as shown in Figure 4, when the optical recording disc 7 is conveyed by a conveyed 15 to a predetermined position, an optical sensor 16 detects the end of the optical recording disc 7 and causes the con veyer 15 to stop. As shown in Figure 5, a cylinder 17 subsequently extends to cause a rotatable spin dle 18 to rise, enter the center hole of the optical recording disc 7, raise the optical recording disc 7 from the conveyer 15 and press it against a disc driver 19, which is driven by a motor 21 to rotate the optical recording disc 7.A well-known bar code sensor 22 is so installed as to scan the polygonal bar codes 8, convert the light and shaded regions, i.e., changes in reflectance of the bar codes 8, into electric signals and send them to a bar code de coder 23. The bar code decoder 23 decodes the electric signals received and supplies them to a control device (not shown) in the next stage.

Although the bar codes 8 as a distinguishing pat tern are-formed in the secondary area 5a of the daughter stamp 5 not containing performance information according to the above embodiment, the distinguishing pattern is not limited to bar codes but what can be deciphered automatically, either mechanically or optically. It may also be formed in any area of the daughter stamp 5 and need not always be in the inner secondary area 5a, provided that the previously recorded performance information given is not impaired when the stamp 5 is marked. Although the bar codes 8 as a whole are polygonal, they need not always be polygonal and may be arcuate or linear.

According to the present invention, distinguishing patterns in the form of codes representing information on the contents of recorded performances are mechanically or optically formed in the area of optical recording discs not recorded with performance information, whereby the contents on the discs can be deciphered by mechanical or optical means. The bar code display means are imprinted on daughter stamp immediately before the step wherein optical recording discs are pressed into shape and this makes it possible to incorporate not only information corresponding to the recording contents common to all daughter stamp but also what is related to control codes specific to each stamp. Thus process and product control becomes systematic and efficient.

Use of a special bar code marking apparatus for writing bar codes ensures highly clear marking and enables even inexpensive bar code readers to decipher them readily and at low cost.

Claims

1. A method of recording a recording disc, comprising the steps of; a afirst forming step for forming in # first area on a side of a stamp recording information; a second forming step, subsequent to and in a different process from said first forming step, for forming a distinguishing pattern in a second area on said side of said stamp; and pressing by means of said stamp a plastic material into a shape containing on a first side thereof said recording information and said distinguishing pattern.

2. A method as recited in Claim 1, wherein said first forming step comprises; depositing a photoresist film on a surface of a substrate; recording with light said recording information on said photoresistfilm; developing said recorded photoresistfilm; evaporating a metal film on said developed photoresist film; and removing said metal film.

3. A method as recited in Claim 1, wherein said second area is outside said first area.

4. A method as recited in Claim 1, wherein said distinguishing pattern comprises at least one bar code.

5. A method as recited in Claim 4, in which said distinguishing pattern comprises a plurality of bar codes arranged on respective non-parallel center lines.

6. A method as recited in Claim 1, wherein said second forming step comprises directing a beam of light onto said second area.

7. A method as recited in Claim 6, wherein said directing step includes reflecting said beam from two polarizing reflectors and separately rotating each of said two reflectors.

8. A method as recited in Claim 2, wherein said second forming step comprises directing a beam of light onto said second area.

9. A method as recited in Claim 8, wherein said directing step includes reflecting said beam from two polarizing reflectors and separately rotating each of said two reflectors.

10. A method of recited in Claim 1, wherein said first forming step comprises recording said recording information on a free-standing first medium and forming said stamp from said first medium.