JPH05314300A - Reader for latent image - Google Patents

Abstract

PURPOSE:To improve the assembly of the latent image reader and to make the device thin by devising the directivity of an infrared ray source and a photodetector and the arrangement of these members. CONSTITUTION:As an infrared ray source 3, an infrared light emitting diode is used with relative radiating strength higher than 80% at a position inclined from a normal direction at 35 deg. with respect to the radiating strength of infrared rays emitted in the normal direction of a light emitting plane. As a photodetector 5, a photodiode is used with relative photodetecting sensitivity higher than 80% to the light from the direction inclined at 15 deg. from the normal direction with respect to the photodetecting sensitivity of light made incident from the normal direction of a light receiving plane. These respective members are respectively set in the range of an angle within + or -10 deg. to the normal direction of the latent image 2 forming plane of a card 1 inserted into a card inserting part 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a latent image reading device for reading data recorded in a latent image from an object on which a latent image is formed by a phosphor that emits light by infrared stimulation.
In particular, the present invention relates to an array and characteristics of an infrared source that irradiates the latent image with infrared rays and a photo-detecting element that detects excitation light from the latent image.

[0002]

2. Description of the Related Art Conventionally, for example, JP-A-52-8090 is known.
6 and JP-A-53-9600, a paper on which a latent image is formed by a fluorescent substance that emits light by infrared stimulus, and data recorded on the paper with the latent image. There is known a latent image reading device for reading out.

The latent image is prepared by mixing 200 grams of yttrium sodium fluoride (NaYF ₄ ) phosphor activated by ytterbium and erbium with 160 grams of vinyl chloride resin and 40 grams of plasticizer,
It is obtained by printing an ink dispersed in 400 g of a solvent on, for example, white paper or plastic. When this type of latent image is irradiated with infrared rays by, for example, a gallium arsenide (GaAs) infrared light emitting diode, the ink emits light, and light having a wavelength different from that of the infrared rays is excited. The latent image reading device receives the excitation light from the ink, processes the signal, and reads the data recorded in the latent image.

Since the excitation light from the latent image is weak,
If the infrared image from the infrared source is efficiently applied to the latent image and the excitation light from the latent image is not efficiently incident on the photo-detecting element provided in the reading device, a large read signal level cannot be obtained and the reading is performed. It is easy to make an error.

In order to avoid such an inconvenience, a conventional latent image reading apparatus is constructed as shown in FIG. 6 or 7 by using an infrared ray source having a high directivity and a light detecting element.

FIG. 6 is a diagram showing a first example of a conventionally known latent image reading device, in which a card 1 having a latent image 2 printed on its upper surface and an infrared ray on the latent image printing portion of the card 1. Infrared source 3 for irradiating the infrared ray and a stem 4 for holding the infrared source 3
And the light detecting element 5, and a filter 6 arranged in front of the light receiving surface of the light detecting element 5 and transmitting only light emitted from the latent image 2.
And a light guide body 7 such as an optical fiber that guides the light emitted from the latent image 2 to the filter 6, and a terminal 8 that reproduces data from the output signal of the photodetection element 5. In this latent image reading device, the stem 4 is arranged so as to be inclined with respect to the normal line direction of the card 1 in order to arrange the infrared source 3 as close to the card 1 as possible while avoiding interference with the light guide 7. It is set up. It is advantageous to increase the light emitting efficiency and the light receiving efficiency by setting the inclination angle θ as small as possible, but in reality, the inclination angle θ is likely to be a large inclination angle of 30 to 40 degrees or more. Further, in this latent image reading device, in order to efficiently guide the light emission from the latent image 2 to the light detecting element 5, a light guide body 7 extending from the vicinity of the insertion portion of the card 1 to the arrangement portion of the filter 6 is provided. Has been done.

FIG. 7 is a diagram showing a second example of a conventionally known latent image reading device. In this device, the infrared irradiation efficiency from the infrared source 3 to the latent image printing section of the card 1 is shown. In order to make the height higher, a collimator lens 9 and a focus lens 10 are coaxially provided in front of the infrared source 3. Since the other parts are the same as those of the apparatus of FIG. 6, the corresponding parts are designated by the same reference numerals and the description thereof will be omitted.

[0008]

By the way, in an actual device, a mold which is a member holder is prepared by using a plastic molded product, and the infrared source 3, the stem 4 and the light source are provided in a mounting hole formed in the mold. An assembling method of inserting and fixing the detection element 5, the filter 6, the light guide 7, and the like is adopted. Therefore, in the conventional device, the mold is provided with the vertical hole and the inclined hole, and the photodetector 5, the filter 6, and the light guide 7 are coaxially inserted and fixed in the vertical hole. Infrared source 3 and stem 4
(In addition to this, in the device of FIG. 7, the collimator lens 9 and the focus lens 10) are coaxially inserted and fixed.

However, the work of inserting the infrared source 3 and the stem 4 into the inclined hole is extremely inferior in work efficiency to the work of inserting other members into the vertical hole. Further, since the infrared source 3 is mounted so as to be inclined, when connecting the infrared source 3 to a power source or the like (not shown), the lead wire of the infrared source 3 must be bent and bent vertically upward. Assembly work is troublesome. Furthermore, the assembly work is troublesome due to the large number of parts. Therefore, the conventional latent image reading device has disadvantages that the assembling property and the mass productivity are poor and the cost is high. In addition, since the conventional latent image reading device uses the light guide body 7 as an essential component, the distance L from the light receiving surface of the light detecting element 5 to the latent image forming surface of the card 1 becomes long, and the device is thick. There is a disadvantage that it takes shape.

The present invention has been made in order to solve the disadvantages of the prior art, and an object thereof is to provide a latent image reading apparatus which is thin and excellent in assembling property and mass productivity. is there.

[0011]

In order to achieve the above object, the present invention provides an insertion portion for an object on which a latent image is formed by a phosphor that emits light by infrared stimulus, and the insertion portion inserted in the insertion portion. In an apparatus for reading a latent image, which comprises an infrared source for irradiating the latent image forming surface of an object with infrared rays and a photo-detecting element for receiving excitation light from the latent image, the infrared source serves as a normal direction of a light emitting surface. An infrared light emitting diode having a relative radiation intensity of 80% or more at a position inclined by 35 degrees from the normal direction with respect to the radiation intensity of infrared rays emitted to A photodiode having a relative light-receiving sensitivity of 80% or more with respect to the light from a direction inclined by 15 degrees from the normal direction with respect to the light-receiving sensitivity of light incident from the line direction is used. Photodio The de, with respect to the normal direction of the latent image forming surface of an object inserted into the insertion portion, is set to the angle range within each ± 10 degrees.

[0012]

[Operation] When an infrared light emitting diode having low directivity is used,
It is possible to irradiate strong infrared rays not only in the normal direction of the light emitting surface but also over a wide range of the latent image forming surface. Further, when a photodiode having a low directivity is used, it is possible to receive not only the normal direction of the light receiving surface but also the excitation light of the latent image incident from a wide range around the photodiode. Therefore, it is not necessary to incline and face each of these members as in the prior art using the infrared light emitting diode and the photodiode having high directivity, and to set them parallel to the normal direction of the latent image forming surface. Will be possible. On the other hand, if a photodiode having too low directivity, for example, a photodiode having a relative light receiving sensitivity of 80% or more with respect to light from a direction inclined by 45 degrees with respect to the normal direction of the light receiving surface is used, Since the reflection component increases and the S / N decreases, it is desirable that the directivity is at least higher than this. According to the experiment, when the infrared light emitting diode and the photodiode having the characteristics shown in the above-mentioned means are set in parallel to the normal line direction of the latent image forming surface, the read signal level equivalent to that of the prior art is obtained. Further, even if there was a mounting error of about ± 10 degrees with respect to the normal direction of the latent image forming surface, a read signal level of a practically sufficient magnitude was obtained.

Therefore, the assembly of the members can be completed simply by inserting the members into the vertical holes, the bending of the lead wires of the electric parts is unnecessary, and the light guide and the lens group are not necessary, and the number of parts is reduced. Therefore, the assembling property and the mass productivity of the latent image reading device are significantly improved. Further, since the light guide 7 and the lens group can be omitted, the distance from the light receiving surface of the light detecting element to the latent image forming surface can be shortened, and the device can be made thin.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 is a sectional view of a main part of a latent image reading apparatus according to an embodiment, FIG. 2 is a sectional view taken along line XX of FIG. 1, and FIG. 3 is a radiation directivity characteristic diagram of an infrared light emitting diode applied to the embodiment. 4 is the radiation pattern of various photodiodes,
FIG. 5 is a plan view of a card applied to the embodiment. In these figures, 11 is a mold, 12 is a card insertion part, 13 is an infrared light emitting diode mounting hole, 14 is a photodiode mounting hole, 15 is a filter setting part, 16 is a through hole, and 17 is a slit plate. Setting part, 18 is a slit plate,
Reference numeral 19 denotes a slit formed in the slit plate 18, and other members corresponding to those shown in FIGS. 6 and 7 have the same reference numerals.

As shown in FIG. 1, a card insertion portion 12 into which a card 1 having a predetermined shape as shown in FIG. 5 can be removably inserted, and a mounting hole 13 for an infrared light emitting diode 3 are provided in a mold 11. The mounting hole 14 for the photodiode 5, the setting portion 15 for the filter 6, the through hole 16 for connecting the mounting holes 13, 14 and the setting portion 17 for the slit plate are integrally formed. The mounting hole 13 of the infrared light emitting diode 3 and the mounting hole 14 of the photodiode 5 are provided in the card insertion portion 12
Direction N-N of the upper surface (the surface on which the latent image 2 of the card 1 is formed)
It is opened in parallel with each other, and the infrared light emitting diode 3 and the photodiode 5 are selectively installed in each of the mounting holes 13 and 14. In addition, these mounting holes 13 and 14 are
It does not need to be formed strictly in the normal direction N-N ', and is ± 1
Errors up to 0 degrees are acceptable. Of course, these mounting holes 13 and 14, and the above-mentioned through hole 16 are provided in the substantially central portion of the latent image 2 (see FIG. 5) when the card 1 is inserted into the card insertion portion 12 in a predetermined direction. (Y-Y 'part) is set on the route.

As shown in FIG. 3, the infrared light emitting diode 3 has a normal line direction of the light emitting surface of 0 degree, and an infrared ray emitted in that direction has a radiation intensity of 100%. An infrared light emitting diode having a relative radiation intensity of 80% or more at a position inclined by 60 degrees is used. As an infrared light emitting diode having such radiation directivity characteristics,
For example, HE8807SG, which is a 0.8 μm band infrared light emitting diode having a GaAlAs single heterojunction structure manufactured by Hitachi, Ltd., is available.

In the photodiode 5, as shown by the symbol B in FIG. 4, when the normal direction of the light receiving surface is 0 degree and the light receiving sensitivity of light incident from that direction is 100%,
A photodiode having a relative light receiving sensitivity of about 80% at a position inclined by 30 degrees from the normal direction is used. As a photodiode having such a directional characteristic, there is, for example, a TO-18 type photodiode manufactured by Hamamatsu Photonics KK.

A slit plate 18 having a slit 19 as shown in FIG. 2 is attached to the slit plate setting portion 17. When the latent image 2 is formed by the bar code system as shown in FIG. 5, the slit width s is equal to, or more preferably, slightly narrower than the width of the narrowest bar code. Formed in. Note that the slit width s of the slit 19 may be formed to be slightly wider than the width of the narrowest barcode, as long as the resolution of the barcode is not impaired. As a result, the resolution of the reading device is regulated, and the data recorded on the barcode can be read without error. Of course, this slit 19
2 is opened in a direction (extending direction of each bar code) orthogonal to an imaginary line Y-Y 'passing through a substantially central portion of the latent image 2, as shown in FIG.

The clearance C between the slit plate 18 and the surface on which the latent image 2 is formed is 3 mm due to the demand for thinning.
It is preferable to make the following adjustments. For the same reason, the distance D from the light emitting surface of the infrared light emitting diode 3 to the surface on which the latent image 2 is formed is preferably adjusted to 5 mm or less.

The filter setting section 15 includes a filter 6 formed of a substance that transmits only the light excited from the latent image 2.
Is attached. As a result, the reflected infrared light (background light) from the card 1 and the excitation light from the latent image 2 are discriminated from each other, and data reading with a high S / N ratio becomes possible.

A terminal for reproducing data from the output signal of the photodiode 5 is attached to the upper part of the mold 11. This is a well-known matter and is not the gist of the present invention. Omit it.

In the latent image reading apparatus of the above-described embodiment, the infrared light emitting diode 3 having a low directivity and the photodiode 5 having a relatively low directivity are used as an infrared source and a light detecting element. , 5 can be set in parallel to the normal direction of the surface on which the latent image 2 is formed. Therefore, assembly of these members 3 and 5 can be completed simply by inserting the members into the mounting holes 13 and 14 which are vertically formed, and the bending of the lead wire of the electric component is unnecessary, and the light guide and the lens are not required. Since the group is unnecessary and the number of parts is reduced, the assembling property and the mass productivity of the latent image reading device can be greatly improved.
Further, since the light guide 7 and the lens groups 9 and 10 can be omitted, the distance from the light receiving surface of the photodiode 5 to the latent image forming surface can be shortened, and the device can be made thin.

In the above embodiment, the latent image reading device has been described by taking the card reader as an example.
By appropriately changing the shape of the card insertion part 12,
It can be a device for reading a latent image formed on an arbitrary object. Further, in the above-mentioned embodiment, the reading device of the card in which the latent image of the bar code system is formed has been described as an example, but the present invention can be applied to the reading device in which the latent image is formed by any other system. Furthermore, although the slit plate 18 is set on the upper surface of the card insertion portion 12 in the above-described embodiment, it may be set on the lower surface of the filter 6 instead.

[0024]

As described above, according to the present invention,
Since the infrared light emitting diode having a low directivity and the photodiode having a relatively low directivity are used as the infrared source and the light detecting element, it is possible to set each of these members parallel to the normal direction of the latent image forming surface. As a result, the assembling property and mass productivity of the latent image reading device are significantly improved. Further, since the light guide and the lens group can be omitted as compared with the prior art, the distance from the light receiving surface of the photodiode to the latent image forming surface can be shortened and the latent image reading device can be thinned.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts of a latent image reading device according to an embodiment. FIG. 3, FIG. 4 and FIG. 5 are cross-sectional views of essential parts of the magneto-optical recording medium according to the first embodiment.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is a radiation directivity characteristic diagram of an infrared light emitting diode applied to an example.

FIG. 4 is a radiation directivity characteristic diagram of various photodiodes.

FIG. 5 is a plan view of a card applied to the embodiment.

FIG. 6 is an explanatory diagram of a latent image reading device according to a conventional example.

FIG. 7 is an explanatory diagram showing another example of the latent image reading device according to the conventional example.

[Explanation of symbols]

 1 Card 2 Latent Image 3 Infrared Source 5 Photodetector 6 Filter 11 Mold 12 Card Insertion Section 13 Infrared Light Emitting Diode Setting Section 14 Photodiode Setting Section 15 Filter Setting Section 16 Through Hole 17 Slit Plate Setting Section 18 Slit Plate 19 slits

Claims (4)

[Claims] 1. An insertion part of an object on which a latent image is formed by a phosphor that emits light by infrared stimulus, an infrared source for irradiating the latent image forming surface of the object inserted in the insertion part with infrared light, In a latent image reading device including a photodetection element for receiving excitation light from a latent image, the infrared source serves as the infrared source with respect to a radiation intensity of infrared rays emitted in a normal direction of a light emitting surface. An infrared light emitting diode having a relative radiant intensity of 80% or more at a position inclined by 35 degrees from is used, and the light detection element is used as the light detecting element with respect to the light receiving sensitivity of light incident from the direction normal to the light receiving surface. Using a photodiode having a relative light receiving sensitivity of 80% or more for light from a direction inclined by 15 degrees from the line direction, the infrared light emitting diode and the photodiode are formed into a latent image of an object inserted in the insertion portion. Surface law An apparatus for reading a latent image, characterized in that the angle ranges are set within ± 10 degrees with respect to the line direction. 2. The slit according to claim 1, between the infrared light emitting diode and the photodiode and the latent image forming surface of the object, a slit for restricting an infrared irradiation range to the object is formed. A latent image reading device, wherein the clearance between the slit and the latent image forming surface of the object is adjusted to 3 mm or less. 3. The latent image reading device according to claim 1, wherein the distance from the light emitting surface of the infrared source to the latent image forming surface of the object is 5 mm or less. 4. The latent image reading device according to claim 1, wherein the object is a card on which a barcode type latent image is formed.