Optical reading apparatus

Abstract: An optical reading apparatus comprising: an optical head body (250) having a reading opening portion (256) therein; a slit sheet (240) having a slit-shaped light transmissive portion (241) and disposed adjacent to said reading opening portion of said optical head body; a light emitting device (220) for emitting light toward an object to be detected through said light transmissive portion of said slit sheet and said reading opening portion of said optical head body; and a light receiving device (221) for receiving light from said object to be detected through said reading opening of said optical head body and said light transmissive portion of said slit sheet, wherein a sheet pressing member (230) made of opaque material is disposed which presses said slit sheet against a portion, in the vicinity of said reading opening portion, of an inside face of said optical head body, said sheet pressing member has a light restriction hole (233) corresponding to said light transmissive portion (241) of said slit sheet, the other side of said light restriction hole corresponds to a light emitting portion of said light emitting device and a light receiving portion of said light receiving device, and a portion, in the vicinity of said light transmissive portion, of said slit sheet is covered with one end face of said sheet pressing member.

Description: The present invention relates to an optical reading apparatus for reading data recorded on an object, preferably using a fluorescent material which emits light when it is stimulated with infrared rays, from an object on which the latent image has been formed. In recent years, control of articles by means of bar codes has been performed widely in various industrial fields while centering the PDS (Point Of Sales) in the distribution field. Along with this, a suggestion has been made that a non-visible bar code, that is, a latent image bar code is put on in terms of the improving design and security (see, for example, Japanese Patent Application Laid-Open No. 52-80906). As for manufacturing of the latent image bar code, a method has been suggested (see, for example, Japanese Patent Application Laid-Open No. 53-9607) in which a ribbon containing fluorescent gains is made to be transferred to paper by impact so that the latent image bar code is printed on to the paper. At present, if the latent image bar code of the foregoing type is formed on an ID card for use as a credit card or the like, there arise a problem of unsatisfactory durability, such as the wear resistance and chemical resistance against, for example, alcohol. It will come to be difficult to read, the latent image bar code as the card is repeatedly used. Therefore, the code of the foregoing type has a disadvantage that the card cannot be used for a long time. Further, a latent image reading apparatus has been known (see for example Japanese Patent Application Laid-Open No. 52-80906 and Japanese Patent Application Laid-Open No. 53-9600) in which data recorded in the form of a latent image, of a florescent substance that emits light when it is stimulated by infrared rays, is read from paper on which the latent image has been formed. An optical reading apparatus according to the preamble of claim 1 is known from FR-A-2 555 337. Since the excited light obtainable from the latent image is very weak, if infrared rays from the infrared ray source is not efficiently applied to the latent image or if the excited light from the latent image is not efficiently incident upon a light detection device disposed in the reading apparatus, a high level of reading signal cannot be obtained and a reading error becomes liable to occur. In order to overcome a problem of the foregoing type, the conventional reading apparatus has been formed, as shown in Fig. 6 or Fig. 7, in such a manner that an excellent-directivity infrared ray source and a light detection device are used. Fig. 6 is a view which illustrates an example of a conventional latent image reading apparatus mainly composed of a card 101 having a latent image 102 printed on the top surface thereof, an infrared ray source 103 for irradiating the latent-image printed portion of the card 101, a stem 104 for holding the infrared ray source 103, a light detection device 105, a filter 106 disposed in front of a light receiving surface of the light detection device 5 and permitting only light emitted from the latent image 102 to pass therethrough, a light-conductive member 107, such as an optical fiber, which leads light emitted from the latent image 102 to the filter 106, and a terminal 108 for reproducing data from an output signal from the light detection device 105. In this latent image reading apparatus, the stem 104 is disposed in a manner inclined relative to the normal direction of the card 101 in order to dispose the infrared ray source 103 adjacent to the card 101 as much as possible while preventing an interference with the conductive member 107. It is advantageous to minimize inclination angle  to improve the light emitting efficiency and the light receiving efficiency. However, a large inclination angle is actually likely to become larger than 3u degrees to 40 degrees. Further, the latent image reading apparatus is enabled to efficiently lead the light emitted from the latent image 102 into the light detection device 105 by disposing the lightconductive member 107 extending from a portion where the card 101 is passed to a portion where the filer 106 is disposed. Fig. 7 is a view which illustrates a second example of the conventionally known latent image reading apparatus. This apparatus has the arrangement to improve the efficiency of irradiating the latent image-printed portion of the card 101 by the infrared ray source 103 by coaxially disposing a collimator lens 109 and a focusing lens 110 in front of the infrared ray source 103. Since the residual portions are the same as those of the apparatus shown in Fig. 7, the corresponding portions are given the same reference numerals and their descriptions are omitted here. An actual apparatus is assembled by a process in which a mold serving as a member holder is made by a plastic molded part, followed by inserting and fixing members such as the infrared ray source 103, the stem 104, the light detection device 105, the filter 106 and the light-conductive member 107. Therefore, the conventional apparatus has a vertical hole and an inclined hole so that the light detection device 105, the filter 106 and the light conductive member 107 are coaxially inserted into the vertical hole to be fixed therein, while the infrared ray source 103 and the stem 104 (and further the collimator lens 109 and the focusing lens 110 in the apparatus shown in Fig. 18) are coaxially inserted into the inclined hole to be fixed therein. However, an operation for inserting the infrared ray source 103 and the stem 104 into the inclined hole suffers from an excessively unsatisfactory working efficiency as compared with an operation for inserting the other members into the vertical hole. Further, the fact that the infrared ray source 103 is fastened in the inclined manner necessitates that its lead wire should be formed to be bent vertically upwards at the time of connecting the infrared ray source 103 to a power supply or the like (omitted from illustration). From this view point, the assembling work is troublesome. Further, since the number of parts is too large to complete easily the assembling work. As a result, the conventional latent image reading apparatus has disadvantages of unsatisfactory assemblability and mass productivity, resulting in a problem of high cost. In addition, the conventional latent image reading apparatus comprises the conductive member 107 as a necessary element. Therefore, a length L from the light receiving surface of the light detection device 105 to the latent image forming surface of the card 101 becomes long, and therefore, a thickness of the apparatus becomes large. Also a system for reading a non-visible latent image mark formed by printing a bar code or the like with ink made of fluorescent material is disclosed in Japanese Patent Application Laid-Open No. 1-211089 or Japanese Patent Application Laid-Open No. 53-9600. It should be noted that Japanese Patent Application No. 3-163694 (U.S. Patent Application Serial No. 07/722,186 and European Patent Application No. 9108120), claiming priorities of Japanese Patent Application No. 2-173655, Japanese Patent Application No. 2-178207 and Japanese Patent Application No. 2-282881 have disclosed technologies, about a detection mark, a method of detecting the mark and a detection apparatus, for the purpose of stably detecting the shape of the mark formed on a card while maintaining an excellent measuring accuracy. An aim of the present invention is to overcome at least partially the foregoing problems experienced with the conventional technology. A second aim of the present invention is to provide an optical reading apparatus which exhibits excellent assemblability and mass-productivity. According to the present invention, there is provided an optical reading apparatus comprising: an optical head body having a reading opening portion therein; a slit sheet having a slit-shaped light transmissive portion and disposed adjacent to the reading opening portion of the optical head body; a light emitting device for emitting light toward an object to be detected through the light transmissive portion of the slit sheet and the reading opening portion of the optical head body; and a light receiving device for receiving light from the object to be detected through the reading opening of the optical head body and the light transmissive portion of the slit sheet, wherein a sheet pressing member made of opaque material is disposed to press the slit sheet against a portion in the vicinity of the reading opening portion on an inside of the optical head body, the sheet pressing member has a light restriction hole corresponding to the light transmissive portion of the slit sheet, the other side of the light restriction hole corresponds to the light emitting portion of the light emitting device and the light receiving portion of the light receiving device, and a portion in the vicinity of the light transmissive porsion of the slit sheet is covered by one face of the sheet pressing member. Since the sheet pressing member is arranged such that a portion in the vicinity of the light transmissive portion of the slit sheet is covered by one face of the sheet pressing member, light reflected from the foregoing portion can be eliminated. Therefore, the S/N can be improved as compared with that obtainable from the conventional structure, and therefore, the reading reliability can be improved. Optionally, the sheet pressing member is arranged such that its other face covers the end surfaces of the light emitting device and light receiving device except for the light emitting portion and light receiving portion, whereby the reading reliability can further be improved. Further optionally, the sheet pressing member also serves as the device holder for holding the light emitting device and the light receiving device, number of elements (parts) of the whole apparatus can be decreased, whereby the assembling process can be simplified, and the size and the cost can be reduced. Preferably, the portion of the slit sheet except for the light transmissive portion is made of the opaque layer, so that the light reflection prevention effect in the foregoing portion can further be improved. Further, air tightness can be maintained. The foregoing and other aims, features and advantages of the invention will be made clearer from the following description of non-limiting embodiments of with accompanying drawings in which: Fig. 1 is a sectional view which illustrates an essential portion of an apparatus for reading the latent image described for reference; Fig. 2 is a sectional view taken along line XIII-XIII of Fig. 1; Fig. 3 is a characteristic diagram which shows the radiation directivity of an infrared ray emitting diode; Fig. 4 is a characteristic diagram which shows the radiation directivity of various photo-diodes; Fig. 5 is a plan view which illustrates a card described for reference; Fig. 6 is a view which illustrates a conventional apparatus for reading a latent image; Fig 7 is a view which illustrates another example of the conventional apparatus for reading the latent image; Fig. 8 is a schematic view of a bar code reader having an optical reading apparatus; Fig. 9 is an exploded perspective view of an optical reading apparatus according to an embodiment of the present invention; Fig. 10 is a front sectional view of an optical reading apparatus according to an embodiment of the present invention; Fig. 11 is a side sectional view of an optical reading apparatus according to an embodiment of the present invention; Fig. 12 is a plan view of an optical reading apparatus, according to an embodiment of the present invention, in a state where its head cover is removed; Fig. 13 is a front elevational view of the head cover; Fig. 14 is a side elevational view of the head cover; Fig. 15 is a bottom view of the head cover; Fig. 16 is a front elevational view of a sheet pressing member; Fig. 17 is a side sectional view of the sheet pressing member; Fig. 18 is a plan view of the sheet pressing member; Fig. 19 is a bottom view of the sheet pressing member; Fig. 20 is a plan view which illustrates an example of a slit sheet; Fig. 21 is plan view which illustrates another example of the slit sheet; Fig. 22 is a front elevational view of the slit sheet in a state where the slit sheet made of a thin metal plate is warped as is done in actual use; Fig. 23 is a front elevational view of an optical head body; Fig. 24 is a front sectional view of the optical head body; Fig. 25 is a plan view of the optical head body; Fig. 26 is a bottom view of the optical head body; Fig. 27 is a sectional view for illustrating disadvantage of the optical reading apparatus shown in Fig. 1 ; A reference apparatus will be described with reference to Figs. 1 to 5. Fig. 1 is a sectional view of an essential portion of a reference apparatus for reading the latent image. Fig. 2 is a sectional view taken along line XIII-XIII of Fig. 1. Fig. 3 is a diagram which illustrates the radiation directivity characteristics of an infrared ray emitting diode used in this apparatus. Fig. 4 is a diagram which illustrates the radiation directivity characteristics of various photo-diodes. Fig. 5 is a plan view of a card used in this apparatus. Referring to the drawings, reference numerals 111 represents a mold, 112 represents a card insertion portion, 113 represents a hole for mounting the infrared ray emitting diode, 114 represents a hole for mounting the photo-diode, 115 represents a filter setting portion, 116 represents a through hole, 117 represents a slit plate setting portion, 118 represents a slit plate, and 119 represents a slit formed in the slit plate 118. Residual elements corresponding to those shown in Figs. 6 and 7 are given the same reference numerals. As shown in Fig. 1, the mold 111 comprises integrally the card insertion portion 112 through which a card 101 (which may be as described in EP-A-0,611,666) having a predetermined shape as exemplified in Fig. 5 and a latent image formed therein is inserted as desired, the hole 113 for mounting therein the infrared ray emitting diode 103, the hole 114 for mounting therein the photo-diode 103, the portion 115 for setting a filter 106, the through hold 116 communicated with the mounting holes 113 and 114, and the portion 117 for setting the slit plate. The mounting hole 113 for the infrared ray emitting diode 103 and the mounting hole 114 for the photo-diode 105 are opened to extend parallel to each other in normal direction N-N' with respect to the top surface (the surface of the card 101 in which the latent image 102 is formed) of the card insertion portion 112. The mounting holes 113 and 114 respectively and selectively receive therein the infrared ray emitting diode 103 and the photo-diode 105. The mounting holes 113 and 114 do not need to be formed in the structly normal direction N-N' but may be mounted in the direction with an error of a degree less than 10 ± degrees. The mounting holes 113 and 114 and the through hole 116 are, of course, located on a passage through which substantially the central portion (portion Y-Y' shown in Fig. 5 ) of the latent image 102 passes when the card 101 is inserted into the card insertion portion 112 in a predetermined direction (orientation). The infrared ray emitting diode 103 to be employed has a relative radiation intensity of 80% or more at a direction (orientation) inclined by 60 degrees from the normal direction assuming that the normal direction of the light emission surface is zero degree and the radiation intensity of infrared rays to be emitted in the normal direction is 100% as shown in Fig. 3. The infrared ray emitting diode of the type having such radiation directivity characteristics is exemplified by a 0.8 µm band infrared ray emitting diode HE8807SG having a GaAlAs single hetero-junction structure manufactured by Hitachi, Ltd. As the photo-diode 105, a photo-diode having a relative light receiving sensitivity of about 80% at an orientation inclined from the normal direction by 30 degrees as designated by symbol B of four types of light receiving sensitivities A1, B1, C1 and D1 shown in Fig. 15 is used assuming that the normal direction of the light receiving surface is zero degrees and the light receiving sensitivity of light incident from the normal direction is 100%. The photo-diode of the type having such directivity characteristics is exemplified by a photo-diode TO-18 manufactured by Hamamatsu Photonics Co., Ltd. The slit plate 118 having the slit 119 as shown in Fig. 2 is fastened to the slit plate setting portion 117. The slit width s is determined to be the same, preferably slightly narrower than the width of the thinnest bar code in a case where the latent image 102 is formed according to the bar code system as shown in Fig. 5. Within a range where the resolving power of the bar code is not affected, the slit width s of the slit 119 may be wider than the width of the thinnest bar code. As a result, the resolving power of the reading apparatus can be restricted, and therefore data recorded in the bar code can be correctly read out. The slit 119 is, of course, opened in a direction perpendicular to an imaginary line Y-Y' passing through substantially the central portion of the latent image 102 (an extension direction of each bar code) as shown in Fig. 2. It is preferable that the clearance C from the slit plate 118 to the surface, in which the latent image 102 is formed, is adjusted to be 3 mm or less to meet a desire of the thickness reduction. Because of a similar reason, it is preferable that the distance D from the light emission surface of the infrared ray emitting diode 103 to the surface, in which the latent image 102 is formed, be adjusted to be 5 mm or less. The filter 106 made of material, which permits only light emitted from the latent image 102 to pass therethrough, is mounted to the filter setting portion 115. As a result, the reflected infrared rays (background light) reflected by the card 101 and the light emitted from the latent image 102 can be distinguished from each other. Therefore, data can be read out at a high S/N ratio. Although a terminal for reproducing data from an output signal from the photo-diode 105 is fastened to the upper portion of the mold 111, it is a known fact and it is not included in the an essential part of the present invention. Therefore, its description is omitted here. Since the latent image reading apparatus according to the embodiment comprises, as the infrared ray source and the light detection device, the infrared ray emitting diode 103 exhibiting the directivity and the photo-diode 105 having a relatively low directivity, the elements 103 and 105 can be set in parallel to the normal direction of the surface in which the latent image 102 is formed. Therefore, the work for assembling the elements 103 and 105 can be completed by only inserting the elements into the mounting holes 113 and 114 opened vertically. Further, the work for bending lead wires of the electric parts can be omitted from the process while omitting the light conductive member and the lens group from the structure. Therefore, the number of parts can be decreased, causing the assemblability and mass-productivity of the latent image reading apparatus to significantly be improved. In addition, as the light conductive member 107, and the lens group 109 and 110 can be omitted from the structure, the distance from the light receiving surface of the photo-diode 105 to the latent image forming surface can be shortened, and therefore the apparatus can be thinned. Although the latent image reading apparatus has been described in the form of a card reader, appropriate change of the card insertion portion 112 enables to have an apparatus for reading a latent image formed on an arbitrary article. Although the description has been made while taking the case of the apparatus for reading the card having the bar code type latent image thereon, the apparatus can be a reading apparatus for an other type of latent image. The structure according to the apparatus in which the slit plate 118 is disposed on the upper surface of the card insertion portion 112 may be replaced by a structure in which it is disposed on the lower surface of the filter 106. As described above, since the reference apparatus comprises, as the infrared ray source and the light detection device, the infrared ray emitting diode exhibiting a high directivity and the photo-diode having a relatively low directivity, these elements can be set in parallel to the normal direction of the surface in which the latent image is formed. Therefore, the assembability and the mass-productivity can be significantly improved. Further, the light conductive member and the lens group from can be omitted when compared with the conventional technology. Therefore, the distance from the light receiving surface of the photo-diode to the latent image forming surface can be shortened, and therefore the apparatus can be thinned. It has been found that the reading apparatus shown in Fig. 1 etc. is desired to be further improved. This will now be described with reference to Fig. 27. Since the slit sheet or slit plate 118 has been secured to the molded optical head body 111 by using the adhesive agent as shown in Fig. 37 , it takes a long time to wait for drying the adhesive agent. Therefore, the working efficiency is unsatisfactory and there arises a risk that the slit sheet 118 is deviated at the time of the adhesion. Further, the fact that the portions, in the vicinity of the slit 119, of the surface of the slit sheet 118 is exposed, light beams L1 and L2 reflected by the portions are also received by the photo-diode 105 which is the reflecting type photo-sensor. Therefore, a predetermined S/N value cannot be obtained, and accordingly, satisfactory reliability cannot be realized. Then, a reading apparatus capable of overcoming this problem will now be described. Embodiment Fig. 8 is a schematic view of a bar code reader having an optical reading apparatus. Referring to Fig. 8 , reference numeral 206 represents a bar code reader body, 207 represents a printed circuit board mounted on the inside of the bar code reader body 207, and 208 represents an insertion groove for a member, such as a pre-paid card, to be detected. An optical reading apparatus 200A is disposed to face the insertion groove 208. Fig. 9 is an exploded perspective view of the optical reading apparatus according to this embodiment. Referring to Fig. 9 , reference numeral 210 represents a head cover comprising four leg portions 211 projecting downwards, each of the four leg portions 211 having an engagement claw 212 at an inside of the distal end portion thereof. Reference numeral 220 represents a light emitting device, 221 represents a light receiving device, the two devices forming a reflecting-type photo-sensor. Reference numeral 230 represents an opaque sheet pressing member colored in, for example, black, and comprising device holder portions 231 and 232, into which lower ends of the light emitting device 220 and the light receiving device 221 respectively are inserted to be held, slit-shaped light restricting holes 233 formed in lower surfaces of the device holder portions 231 and 232, and engagement pieces 234 at both end thereof. Reference numeral 240 represents a slit sheet having a light transmissive (transmitting) portion 241 at the central portion thereof and positioning holes 242 formed in such a manner that two positioning holes are respectively formed in front of the light transmitting portion 241 and at a rear side of the same when viewed from the front position. Reference numeral 250 represents an optical head body comprising mounting holes 252 respectively formed in the central portions of flanges 251 respectively projecting forwards and rearwards, recessed engagement portions 253 formed in four positions of a bottom portion thereof to receive to stop the engagement claws 212, engagement grooves 54 into which the engagement pieces 234 are inserted, positioning pins 255 inserted into the positioning holes 242, an opening portion 256 for reading formed in the bottom of the central portion thereof, and so on. Fig. 10 is front sectional view of the optical reading apparatus according to this embodiment. As shown in Fig. 10 , the slit sheet 240 is mechanically held between the sheet pressing member 230 having a substantially circular-arc-shaped bottom surface and a tapered surface of the optical head body 250 to be warped in such a manner that the central light transmitting portion 241 facing the light restricting hole 233 projects downwards to be pressed against the reading opening portion 256. Portions in the vicinity of the light transmitting portion 241 of the slit sheet 240 is covered with the bottom surface of the sheet pressing member 230. Further, the top surface of the sheet pressing member 230 covers an end surface of the light emitting device 220 except for the light emission surface and an end surface of the light receiving device 221 except for the light receiving portion. The light emitting device 220 and the light receiving device 221 are pressed from upper sides by pressing pins 213 formed to extend downward from an inner surface of the head cover 210 so that upward loosening is prevented. Fig. 11 is a side sectional view of the optical reading apparatus according to this embodiment. Terminals 220a of the light emitting device 220 and terminals 221a of the light receiving device 221 project out of opening portions 214 of the head cover 210. Fig. 12 is a plan view which illustrates a state of the optical reading apparatus from which the head cover 210 is removed. Fig. 13 is a front elevational view of the head cover 210. Fig. 14 is a side elevational view which illustrates the head cover 210. Fig. 15 is a bottom view of the head cover 210. In these drawings, the four leg portions 211, the four engagement claws 212, the two pressing pins 213 and the two opening portions 214 respectively are illustrated. Fig. 16 is a front elevational view which illustrates the sheet pressing member 230. Fig. 17 is a side sectional view of the sheet pressing member 230 illustrating a high cylindrical device-holding portion 231a, a low cylindrical device-holding portion 232a and the slit-like light restricting hole 233 formed below the device holding portions 231a and 232a. Fig. 18 is a plan view of the sheet pressing member 230, and Fig. 19 is a bottom view of the same. Fig. 20 is a plan view of an example of the slit sheet 240. In this example, a transparent plastic base film made of, for example, polyethylene terephthalate (PET) covered isexcept for the light transmissive portion 241, with an opaque layer 241a composed of a black printed layer. Fig. 21 is a plan view of another example of the slit sheet 240. In this example, a thin metal plate made of, for example, stainless steel is used while forming, by punching, the light transmissive portion 241 and the positioning holes 242. In the case where the slit sheet 240 made of the thin metal plate is used, it is used in a previously warped state as shown in Fig. 22. Fig. 23 is a front elevational view of the optical head body 250, in which the mounting holes 252 formed in the flanges portions 251 are designated by dashed lines. Fig. 24 is a front sectional view of the optical head body 250, in which the flange portions 251, the mounting holes 252, the recessed mounting portions 253, the positioning pins 255 and the reading opening portion 256 and the like are illustrated. Fig. 25 is a plan view of the optical head body 250, in which the flange portions 251, the mounting holes 252, the engagement grooves 54, the positioning pins 255 and the reading opening portion 256 and the like are illustrated. Fig. 26 is a bottom view of the optical head body 250, in which the flange portions 251, the mounting holes 252, the recessed engagement portions 253 and the reading opening portion 256 and the like are illustrated. When the fluorescent mark (the latent image mark) is read by the optical reading apparatus according to the present invention, following applications can be contemplated and following characteristics are attained. (1) Factory Automation (FA) Field Partial management at the time of assembling automobiles: that is, model types, export destinations, manufactured dates, and lots and so forth can be managed by using the fluorescent marks (the latent image marks), which are not easily visible, without affecting the appearance. (2) If a mark is formed in a black substance, for example, a black tire, or a transparent material such as glass, which cannot be read out in case of the conventional reflecting-type bar code, the mark can be read. (3) If characters or a designed form is printed on the fluorescent mark (the latent image mark), the fluorescent mark (the latent image mark) can be read out. Therefore, a small space, such as a price label or a tag of a commodity can be effectively used. (4) Because of the same reasons as those of (1) and (3), the present invention is effective when it is used in commodities such as cosmetics or drugs, to which a designs are attached greater importance, or various decorative boxes or packages that should give high quality feeling. (5) Even in an environment in which the conventional reflecting type bar code cannot be used due to contamination by oil or dust in a plant or a work shop or the like, the fluorescent mark (the latent image mark) can be read out. (6) Because of the same reasons as those of (1) and (3), the management information needed by the manufacturer can be put, as a hidden code, for the physical distribution management and the slip management, on the statements of delivery (usually the statement of delivery has a format specified by a customer and has only information that is needed by the customer). (7) Information can be, as a hidden code, pun on a card-like structure to ne used as a game card (a bar code game). In particular, forming of a hiding layer or a laminated layer enables the hidden code to be completely invisible. (8) Because of the same reasons as those of (1) and (3), use of the fluorescent mark to manage books or libraries will not affect the design quality. (9) Since the fluorescent mark cannot easily be forged, altered or changed, it can be used to manage person's entrance and withdraw, the attendance management (the time recorder) or used as a key card in a hotel. (10) Forgery, alteration or change of securities or stock certificates can be prevented. (11) Forgery, alteration or change of credit cards, cash cards or telephone cards can be prevented. (12) Forgery, alteration or change of student identification cards or ID cards can be prevented while reducing the size and the occupying space (13) Forgery, alteration or change of stamp cards or point cards can be prevented. Further, the needed size and the space can be reduced. (14) Forgery, alteration or change of betting tickets on, for example, horses or bicycles, can be prevented. (15) It can be used in a pinball machine premium exchange system to prevent forgery, alteration or change. The optical reading apparatus of the invention is arranged in such a manner that a portion, around the through hole portion, of the slit sheet is covered with a surface of the sheet pressing member. Therefore, reflection light from the foregoing portion can be eliminated, resulting in that the S/N can be improved. As a result, reading reliability can be improved. A preferred feature of the invention is that the other surface of the sheet pressing member covers the end surfaces of the light emitting device and the light receiving device except for the light emitting portion and the light receiving portion. Therefore, reading reliability can further be improved. A further preferred feature of the invention is that the sheet pressing member also serves as the device holder for holding the light emitting device and the light receiving device. Therefore, the size of the overall body of the apparatus can be reduced and the structure of the same can be simplified. Also optionally according to the invention the slit may be formed by the opaque layer except for the portion of the through hole. Therefore, the effect of preventing the light reflection in the foregoing portion can further be improved.

Claims: An optical reading apparatus comprising: an optical head body (250) having a reading opening portion (256) therein; a slit sheet (240) having a slit-shaped light transmissive portion (241) and disposed adjacent to said reading opening portion of said optical head body; a light emitting device (220) for emitting light toward an object to be detected through said light transmissive portion of said slit sheet and said reading opening portion of said optical head body; and a light receiving device (221) for receiving light from said object to be detected through said reading opening of said optical head body and said light transmissive portion of said slit sheet, characterised by a sheet pressing member (230) made of opaque material which presses said slit sheet against a portion, in the vicinity of said reading opening portion, of an inside face of said optical head body, said sheet pressing member has a light restriction hole (233) corresponding to said light transmissive portion (241) of said slit sheet, the other side of said light restriction hole corresponds to a light emitting portion of said light emitting device and a light receiving portion of said light receiving device, and a portion, in the vicinity of said light transmissive portion, of said slit sheet is covered with one face of said sheet pressing member. An optical reading apparatus according to claim 1, wherein another face of said sheet pressing member (230) covers an end face of said light emitting device (220) except for said light emitting portion and an end face of said light receiving device (221) except for said light receiving portion. An optical reading apparatus according to claim 1 or 2, wherein said sheet pressing member (230) also serves as a device holder for holding said light emitting device (220) and said light receiving device (221). An optical reading apparatus according to claim 1, 2 or 3, wherein said slit sheet (240) is composed of a transparent base film (241) and an opaque layer (241a) printed on a surface of said base film, and a portion in which no opaque layer is printed is made to be said light transmissive portion. An optical reading apparatus according to claim 1, 2, 3 or 4, wherein said object to be detected has a fluorescent mark.

Inventors: ITOH AKIHIKO, MATSUMOTO TAIJI, NISHIDA MASATO, OHIWA TSUNEMI, OSHIMA TOSHIO, TAKEUCHI YOJI, ITOH, AKIHIKO, MATSUMOTO, TAIJI, NISHIDA, MASATO, OHIWA, TSUNEMI, OSHIMA, TOSHIO, TAKEUCHI, YOJI
Applicants: HITACHI MAXELL, HITACHI MAXELL LTD.
Application year: 1993
Main classification: G06K7
IPC codes: G06K7