JPH06259593A - Information identifier - Google Patents

Abstract

PURPOSE:To provide an information reader such as a bar code reader, etc., in which light receiving quantity distribution of a light receiving element can be improved so as to be uniformalized and a reading error can be reduced. CONSTITUTION:A bar code 2 is irradiated with light from the light source 1 of a thin film EL element, and the optical path of reflected light from the bar code 2 is changed by a mirror 3, and it is converged on a lens 4, and is received by the light receiving element 5 such as a charge storage element (CCD), and it is converted to an electrical signal, then, information stored in the bar code is read by a decoder circuit. The thin film EL element is as follows. (1) An EL element whose surface confronting with an information display medium is formed in a curved surface with the center formed in recessed shape. (2) An EL element in which the film thickness of an EL element light emitting layer is thickened at both terminal parts of the element. (3) An EL element whose EL element light emitting surface is widened at both terminal parts of the element. (4) An EL element letting EL element light emitting surface be plural number and in which the total area of the light emitting surface is formed larger than a middle part at both terminal parts of the element. (5) An EL element in which lets the density of light emission center included in the EL element light emitting layer be different values at the middle part and both terminal parts of the element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information discriminating apparatus for discriminating or reading information such as bar code, mark, facsimile characters and figures.

[0002]

2. Description of the Related Art FIG. 1 shows a sectional view of a bar code reader. The bar code reader uses the light source 1 of the bar code reader to output light on a white background with black lines JAN / EAN, UPC.
The barcode 2 arranged according to the standard such as A is irradiated, and the reflected light in white and black is changed by the mirror 3 to change the optical path.
The light-receiving element 5 such as a charge storage element (CCD) receives the light, converts it into an electric signal, and a decoding circuit reads the information stored in the bar code. Reference numeral 6 is a bar coder housing.

The length in which the barcodes are arranged is as long as about 40 mm, and it is necessary to have a linear light source having a length of at least 40 mm and uniformly irradiating the barcode with light to obtain a high reflected light amount. Further, when the light receiving element receives reflected light on a white background, for example, it is not preferable that the central portion and both end portions of the bar code have different light receiving amounts, and a light source capable of obtaining a uniform light receiving amount. It is desired to do.

Conventionally, a red light emitting diode (LE) having an emission wavelength of 660 nm has been used as a light source of a bar code as shown in FIG.
D) A plurality of 7 arranged in a line is used.
FIG. 2 is a perspective view of the opening facing the bar code 2 of the bar code reader of FIG. 1 as viewed from below. As an LED arranging method, a series resistance is added to the LEDs as in Japanese Patent Publication No. 2-17270 to try to reduce the central part of the illuminance of the strip-shaped illumination on the bar code as compared with the both ends. There is a technique.

[0005]

However, the LED
In the light source in which a plurality of 7 are arranged in a line, since the LED is a point light source, the directivity of light emission is high, the illuminance at the lower part is high, and it is difficult to obtain a smooth reflected light amount distribution, which causes a reading error. . As a solution to this problem, it is common to electrically correct the output signal of the light receiving element,
In this case, there is a problem that the circuit part becomes expensive. This non-uniformity increases as the LED is closer to the bar code. In addition, the further the distance, the better the uniformity,
There is a problem that the size of the bar code reader becomes large. Further, since the amount of reflected light decreases in proportion to the square of the distance, a reading error is likely to occur, and it is necessary to increase the amount of light from the light source in order to avoid this problem.
Approximately 60 cd / m required as the amount of reflected light in the direction normal to the surface
^In order to obtain ² , the luminescence amount of the LED needs to be tens of thousands cd / m ² measured by a luminance meter. Therefore, there is a problem that power consumption increases. In addition, when a bar code reading test was actually performed on various products, the bar code was read.
It was found that in many cases, the code surface was not flat but was convex, and the amount of light reflected from the bar code was often insufficient at both ends of the bar code. The present invention provides an information identification device such as a bar code reader that improves the reflected light amount distribution so that the received light amount distribution of the light receiving element becomes uniform and reduces reading errors.

[0006]

DISCLOSURE OF THE INVENTION The present invention is an information comprising a light source for irradiating an information display medium with light, a light receiving element for receiving light from the information display medium, and an information processing section for processing an electric signal from the light receiving element. In the identification device, the light source is (1) an EL element in which the surface facing the information display medium is a curved surface having a concave center, and (2) an EL element in which the thickness of the EL element light emitting layer is thicker at both ends of the element. , (3) an EL element in which the EL element light emitting surface is widened at both ends of the element, (4) a plurality of EL element light emitting surfaces,
An EL device in which the total area of the light emitting surface is larger at both ends of the device than in the central part. (5) The concentration of the emission center contained in the EL device light emitting layer is different between the central part and both ends of the device. At least one of the EL elements described above is an information identifying device.

The present invention will be described below with reference to a bar code reader. FIG. 3 shows a first example of a thin film EL element used as a light source of the barcode reader of the present invention.
3A is a sectional view and FIG. 3B is a plan view. A glass plate or the like is used as the base material 8 of the thin film EL element. The glass plate has a curved surface with a concave center. Conductive film 9
Is preferably a transparent conductive film such as SnO ₂ , In ₂ O ₃ , indium tin oxide (ITO), aluminum,
A non-transparent metal film such as chromium or gold can also be used. The conductive film 9 is formed by an electron beam evaporation method, a resistance heating evaporation method, a sputtering method, a CVD (Chemical Vapor Depo) method.
It is formed by a method such as a position) method or a plasma CVD method.

The light emitting layer 10 is composed of a phosphor made of a host material containing a Group VI element such as ZnS, CaS, SrS, and ZnSe containing emission centers such as Mn and Tb.
Resistance heating evaporation method, sputtering method, MOCVD (Me
tal Organic CVD) method, ALE (Atom)
ic layer epitaxy) method or the like.

The conductive film 11 is a non-transparent metal film of aluminum, chromium, nickel, gold, silver or the like, SnO ₂ , In.
A transparent conductive film such as ₂ O ₃ or indium tin oxide (ITO) can be used. The conductive film 11 is formed by an electron beam evaporation method, a resistance heating evaporation method, a sputtering method, a CVD (Chemi) method.
It is formed by a cal vapor deposition method, a plasma CVD method, or the like.

The AC thin film element requires an insulating layer. The insulating layers 12 and 13 are made of TaO ₅ , Y ₂ O ₃ , SiO ₂ and A.
l ₂ O ₃ , Si ₃ N ₄ , AlN, SrTiO ₃ etc.,
Two or more layers of these layers may be laminated to form an insulating layer. The method of forming these layers is the same as the method of forming the transparent conductive film, such as electron beam evaporation method, resistance heating evaporation method, sputtering method, and C method.
VD (Chemical Vapor Deposition)
ion) method, plasma CVD method and the like. The insulating layers 12 and 13 are laminated between the conductive film 9 and the light emitting layer 10 and / or between the light emitting layer 10 and the conductive film 11. Light emission is obtained by applying an AC voltage between the conductive film 9 and the conductive film 11. When the conductive film 9 is a transparent conductive film, the light may be extracted through the transparent conductive film or the glass plate.
When the conductive film 9 is a non-transparent conductive film, it can be taken out from the end face of the device. In this case, the end face is curved. 14 is a back glass.

The thin film EL device thus obtained is
By making the surface facing the bar code a curved surface having a concave center, the reflected light amount of the bar code surface can be changed without changing the emitted light amount, and the bar received by the light receiving element can be changed. The amount of light reflected from the code surface can be made constant regardless of the position of the bar code. Transparent conductive film 9 and conductive film 13
According to the pattern, the shape of the light emitting surface can be freely optimized. Therefore, a linear light emission pattern can be easily obtained. Moreover, since it is composed of a thin film, a thin light source can be achieved. The same applies to the dispersion type EL element, which is a thin surface light source.

FIG. 4 shows a second example of the thin film EL element used as the light source of the bar code reader of the present invention. FIG. 4 (a) is a sectional view and FIG. 4 (b) is a plan view. is there.
A glass plate or the like is used as the base material 15 of the thin film EL element. The conductive film 16 is preferably a transparent conductive film of SnO ₂ , In ₂ O ₃ , indium tin oxide (ITO) or the like, and a non-transparent metal film of aluminum, chromium, gold or the like can also be used. The conductive film 16 is formed by electron beam evaporation, resistance heating evaporation,
Sputtering method, CVD (Chemical Vap)
or Deposition) method, plasma CVD method, or the like.

The light emitting layer 17 is made of a phosphor composed of a host material containing a Group VI element such as ZnS, CaS, SrS, ZnSe containing luminescence centers such as Mn and Tb, and the electron beam evaporation method,
Resistance heating evaporation method, sputtering method, MOCVD (Me
tal Organic CVD) method, ALE (Atom)
ic layer epitaxy) method or the like. The light emitting layer 17 has a large thickness at both ends of the device.

The conductive film 18 is a non-transparent metal film made of aluminum, chromium, nickel, gold, silver or the like, SnO ₂ , In.
A transparent conductive film such as ₂ O ₃ or indium tin oxide (ITO) can be used. The conductive film 18 is formed by an electron beam evaporation method, a resistance heating evaporation method, a sputtering method, a CVD (Chemi) method.
It is formed by a cal vapor deposition method, a plasma CVD method, or the like.

The AC thin film element requires an insulating layer, and the insulating layers 19 and 20 are made of TaO ₅ , Y ₂ O ₃ , SiO ₂ and A.
l ₂ O ₃ , Si ₃ N ₄ , AlN, SrTiO ₃ etc.,
Two or more layers of these layers may be laminated to form an insulating layer. The method of forming these layers is the same as the method of forming the transparent conductive film, such as electron beam evaporation method, resistance heating evaporation method, sputtering method, and C method.
VD (Chemical Vapor Deposition)
ion) method, plasma CVD method and the like. The insulating layers 19 and 20 are laminated between the conductive film 16 and the light emitting layer 17 and / or between the light emitting layer 17 and the conductive film 18. Conductive film 16
Light emission is obtained by applying an AC voltage between the conductive film 18 and the conductive film 18. Light may be extracted through a transparent conductive film or a glass plate when the conductive film 9 is a transparent conductive film, and may be extracted from an end face of the element when the conductive film 9 is a non-transparent conductive film. You can also 14 is a back glass.

The thin film EL device thus obtained is
By increasing the thickness of the light emitting layer 17 at both ends of the element, the applied voltage can be kept constant and the amount of light emitted from both ends of the element can be increased. The amount of reflected light from the bar code surface can be changed without changing the amount of emitted light so that the amount of light reflected by the light receiving element from the bar code surface is constant regardless of the position of the bar code. it can. The pattern of the transparent conductive film 16 and the conductive film 20 allows the shape of the light emitting surface to be freely optimized. Therefore, a linear light emission pattern can be easily obtained. Moreover, since it is composed of a thin film, a thin light source can be achieved. The same applies to the dispersion type EL element, which is a thin surface light source.

FIG. 5 shows a third example of the thin film EL element used as the light source of the bar code reader of the present invention. FIG. 5 (a) is a sectional view and FIG. 5 (b) is a plan view. is there.
A glass plate or the like is used as the base material 21 of the thin film EL element. The conductive film 22 is preferably a transparent conductive film of SnO ₂ , In ₂ O ₃ , indium tin oxide (ITO) or the like, and a non-transparent metal film of aluminum, chromium, gold or the like can also be used. The conductive film 22 is formed by an electron beam evaporation method, a resistance heating evaporation method,
Sputtering method, CVD (Chemical Vap)
or Deposition) method, plasma CVD method, or the like.

The light emitting layer 23 is made of a phosphor composed of a matrix containing a Group VI element such as ZnS, CaS, SrS and ZnSe containing luminescence centers such as Mn and Tb.
Resistance heating evaporation method, sputtering method, MOCVD (Me
tal Organic CVD) method, ALE (Atom)
ic layer epitaxy) method or the like.

The conductive film 24 is a non-transparent metal film made of aluminum, chromium, nickel, gold, silver or the like, SnO ₂ , In.
A transparent conductive film such as ₂ O ₃ or indium tin oxide (ITO) can be used. As shown in FIG. 5B, the conductive film 24 is formed by an electron beam evaporation method so that the area is widened at both ends.
Resistance heating evaporation method, sputtering method, CVD (Chem
It is formed by an ICP method, a plasma CVD method, or the like.

The AC thin film element needs an insulating layer, and the insulating layers 12 and 13 are made of TaO ₅ , Y ₂ O ₃ , SiO ₂ and A.
l ₂ O ₃ , Si ₃ N ₄ , AlN, SrTiO ₃ etc.,
Two or more layers of these layers may be laminated to form an insulating layer. The method of forming these layers is the same as the method of forming the transparent conductive film, such as electron beam evaporation method, resistance heating evaporation method, sputtering method, and C method.
VD (Chemical Vapor Deposition)
ion) method, plasma CVD method and the like. The insulating layers 25 and 26 are stacked between the conductive film 22 and the light emitting layer 23 and / or between the light emitting layer 23 and the conductive film 24. Conductive film 21
Light emission is obtained by applying an AC voltage between the conductive film 24 and the conductive film 24. Light may be extracted through the transparent conductive film or the glass plate when the conductive film 22 is a transparent conductive film, and may be extracted from the end face of the element when the conductive film 9 is a non-transparent conductive film. You can also 14 is a back glass.

The thin film EL device thus obtained is
By widening the EL element light emitting surface at both ends of the element, the applied voltage can be kept constant and the amount of light emitted from both ends of the element can be increased. In this way, it is possible to change the flash without changing the amount of emitted light.
By changing the amount of reflected light from the code surface, the amount of reflected light received by the light receiving element from the bar code surface can be made constant regardless of the position of the bar code. Transparent conductive film 22 and conductive film 2
The pattern of 6 allows the shape of the light emitting surface to be freely optimized. Therefore, a linear light emission pattern can be easily obtained. Moreover, since it is composed of a thin film, a thin light source can be achieved. The same applies to the dispersion type EL element, which is a thin surface light source.

FIG. 6 shows a fourth example of a thin film EL element used as a light source of the bar code reader of the present invention, and is a plan view. The cross section of the thin film EL element of the fourth example is
It is essentially the same as the thin film EL device of the third example. In the thin film EL element of the fourth example, a conductive film 27 and a conductive film 28 are formed as shown in FIG. 6 so that the EL element has a plurality of light emitting surfaces and the total area of the light emitting surfaces is at both ends of the element. So that it is larger than the central part.

The thin film EL element thus obtained is
By the pattern of the conductive film 27 and the conductive film 28, the shape and number of light emitting surfaces can be freely optimized. By doing so, it is possible to increase the amount of light emitted from both ends of the device while keeping the applied voltage constant.

The cross section of the thin film EL element of the fifth example is essentially the same as that of the thin film EL element of the third example. In the thin-film EL device of the fifth example, the concentrations of the luminescence centers contained in the EL device luminescent layer are set to have different values in the central part and both ends of the device. In this EL element, the amount of emitted light changes depending on the concentration of the emission center. In this way, the amount of light emitted from both ends of the device can be increased by keeping the applied voltage constant.

The EL element used in the present invention is a thin film EL
There are elements and dispersed EL elements, and either of them can be used in the present invention. The voltage application method may be either alternating current or direct current. The light source of the present invention may combine a plurality of methods of (1) to (5) EL elements. In the present invention, the information display medium may be not only a bar code, but also a mark sheet, a character or a figure. Further, in the information identifying apparatus of the present invention, the light received by the light receiving element from the information display medium may be the reflected light from the information display medium or the transmitted light of the information display medium.

[0026]

When the EL element is flat and uniform, the illuminance of the strip-shaped illumination section on the bar code 2 is substantially the same at both ends and at the center. When this EL element is used in a bar code reader as shown in FIG. 7, the amount of light incident on the lens 4 from both ends becomes smaller than the amount of light reaching the lens 4 from the central part. This is because at both ends of the bar code, the solid angle .beta. Looking into the lens from both ends is smaller than the solid angle .alpha. Looking into the lens from the central part, and the amount of light used from the bar code surface with constant illuminance is reduced. It depends. Therefore, the amount of light reaching the light receiving element is smaller from both ends of the bar code than in the central part. For this reason, the base rail of the output signal of the light receiving element is not flat. On the other hand, in the EL device of the present invention, the illuminance of the bar code surface from the EL device is not changed at both ends of the bar code, as shown in FIG. Large, bar
The amount of reflected light from the bar code surface is changed so that it becomes small at the center of the board, and the amount of reflected light from the bar code surface received by the light receiving element is constant regardless of the position of the bar code. You can

[0027]

【Example】

Example 1 An example of the first example will be described with reference to FIG. As the substrate 8, a curved barium borosilicate glass having a width of 6 mm, a length of 70 mm and a thickness of 1.1 mm (manufactured by Corning, trade name # 7059) was used. The radius of curvature is 70 mm. As the transparent conductive film 9, ITO is formed by an electron beam evaporation method using a metal mask to have a width of 1.5 as shown in FIG.
mm, length 60 mm from one end, and film thickness 200 nm. Then, Si ₃ N ₄ is added to 20 by plasma CVD method.
It was deposited as a 0 nm first insulating layer 12. Next, the light emitting layer 10
ZnS added with 0.8 mol% of Mn as an electron beam
The film was deposited to a thickness of 600 nm by the vapor deposition method, and then heat-treated in air at 500 ° C. for 1 hour. Next, Ta ₂ O ₅ of 400 is formed as the second insulating layer 13 by a sputtering method.
nm deposited. Next, 200 nm of aluminum was formed as the back electrode 11 by an electron beam evaporation method using a metal mask, with an electrode width of 1 mm and a length of 60 mm from one side opposite to the transparent conductive film 9. Since ZnS is vulnerable to moisture, moisture-proof sealing is performed next. Width 6 mm, length 60 mm, thickness 1.1
mm glass barium borosilicate glass (trade name: # 7059, manufactured by Corning Incorporated) is used as the rear glass 14 and sealed with an epoxy adhesive. Next, the lead wire is taken out from the terminals at both ends with silver paste, and the lead wire is incorporated into the housing 6 of the bar code reader to obtain the bar code reader shown in FIG.

Embodiment 2 An embodiment of the second example will be described with reference to FIG. As the substrate 15, a curved barium borosilicate glass having a width of 6 mm, a length of 70 mm and a thickness of 1.1 mm (manufactured by Corning, trade name # 7059) was used. ITO as the transparent conductive film 16
Was deposited by an electron beam evaporation method using a metal mask to a width of 1.5 mm, a length of 60 mm from one end, and a thickness of 200 nm as shown in FIG. 4 (b). Next, plasma C
Si ₃ N ₄ was deposited as a 200 nm first insulating layer 19 by the VD method. Next, Mn is used as the light emitting layer 17 with 0.8mo
ZnS added with 1% was deposited by electron beam evaporation to a thickness of 500 nm at the center and 900 nm at both ends, and then heat-treated in air at 500 ° C. for 1 hour. Second
As the insulating layer 20, Ta ₂ O ₅ was deposited to 400 nm by the sputtering method. Next, as the back electrode 18, an electrode width of 1 mm was formed by an electron beam evaporation method using a metal mask.
Aluminum was deposited in a thickness of 200 nm with a length of 60 mm from one side opposite to that of the transparent conductive film 16. Since ZnS is vulnerable to moisture, moisture-proof sealing is performed next. Barium borosilicate glass (product name # 7059, manufactured by Corning Incorporated) having a width of 6 mm, a length of 60 mm and a thickness of 1.1 mm is sealed as the rear glass 14 with an epoxy adhesive. Next, the lead wire is taken out from the terminals at both ends with silver paste, and the lead wire is incorporated into the housing 6 of the bar code reader to obtain the bar code reader shown in FIG.

Embodiment 3 An embodiment of the third example will be described with reference to FIG. As the substrate 21, a barium borosilicate glass having a width of 6 mm, a length of 70 mm and a thickness of 1.1 mm (made by Corning, trade name # 70
59) was used. As the transparent conductive film 22, ITO is formed by an electron beam evaporation method using a metal mask, as shown in FIG.
As shown in, width is 1.5mm, length is 60m from one end
m and a thickness of 200 nm. Then, Si ₃ N ₄ was deposited as a 200 nm first insulating layer 25 by plasma CVD. Next, ZnS containing 0.8 mol% of Mn was deposited as the light emitting layer 23 to a thickness of 700 nm by the electron beam evaporation method, and then heat treatment was performed in air at 500 ° C. for 1 hour. Next, Ta ₂ O ₅ was deposited to 400 nm as the second insulating layer 25 by the sputtering method. Next, as the back electrode 24, as shown in FIG. 5B, the length is transparent so that the central part has an electrode width of 1 mm and both ends have an electrode width of 5 mm by an electron beam evaporation method using a metal mask. Conductive film 16
Aluminum from 200 nm with 60 mm from one side opposite to
A film was formed. Since ZnS is vulnerable to moisture, moisture-proof sealing is performed next. Width 6 mm, length 60 mm, thickness 1.1 mm barium borosilicate glass (product name # 705, manufactured by Corning Incorporated)
9) is used as the back glass 14 and is sealed with an epoxy adhesive. Next, the lead wire is taken out from the terminals at both ends with silver paste, and the lead wire is incorporated into the housing 6 of the bar code reader to obtain the bar code reader shown in FIG.

Embodiment 4 An embodiment of the fourth example will be described with reference to FIG. As a substrate, a barium borosilicate glass having a width of 6 mm, a length of 70 mm and a thickness of 1.1 mm (manufactured by Corning, trade name # 705)
9) was used. As the transparent conductive film 27, ITO is used as an electronic beam.
As shown in FIG. 6, a width of 1.5 mm, a length of 60 mm from one end, and a thickness of 2 using a metal mask by a vapor deposition method.
The film was formed to a thickness of 00 nm. Next, by the plasma CVD method, S
200 nm of i ₃ N ₄ was deposited as a first insulating layer. Next, ZnS containing 0.8 mol% of Mn added as a light emitting layer was deposited to 700 nm by an electron beam evaporation method, and then heat treatment was performed in air at 500 ° C. for 1 hour. Second
Ta ₂ O ₅ was used as an insulating layer by sputtering to 40
0 nm was deposited. Next, the back electrode 28 is formed by an electron beam evaporation method using a metal mask so that the back electrode 28 has the electrode pattern shown in FIG. A film was formed. ZnS
Is vulnerable to moisture, so a moisture-proof sealing is performed next. Barium borosilicate glass (product name # 7059, manufactured by Corning Incorporated) having a width of 6 mm, a length of 60 mm and a thickness of 1.1 mm is sealed as the rear glass 14 with an epoxy adhesive. Next, the lead wire is taken out from the terminals at both ends with silver paste, and the lead wire is incorporated into the housing 6 of the bar code reader to obtain the bar code reader shown in FIG.

Example 5 A substrate having a width of 6 mm, a length of 70 mm and a thickness of 1.1 mm
The curved barium borosilicate glass (trade name: # 7059, manufactured by Corning Incorporated) was used. I as a transparent conductive film
TO was formed by an electron beam evaporation method using a metal mask to have a width of 1.5 mm, a length of 60 mm from one end, and a thickness of 2
The film was formed to a thickness of 00 nm. Next, by the plasma CVD method, S
200 nm of i ₃ N ₄ was deposited as a first insulating layer. Next, ZnS, which is the base material of the light emitting layer, was deposited to a thickness of 500 nm by an electron beam vapor deposition method, and then Mn was vapor deposited from below the element normal direction by a resistance heating vapor deposition method. As a result, the Mn film thickness in the central part of the device became thicker than that at both ends. This Mn is 500 ° C
It was diffused into ZnS by heat treatment for 1 hour. Then, as a second insulating layer, T is formed by a sputtering method.
400 nm of a ₂ O ₅ was deposited. Next, the electrode width is 1 m by the electron beam evaporation method using a metal mask as the back electrode.
Aluminum was deposited in a thickness of 200 nm with a length m and a length of 60 mm from one side opposite to the transparent conductive film. Since ZnS is vulnerable to moisture, moisture-proof sealing is performed next. Barium borosilicate glass (product name # 7059, manufactured by Corning Incorporated) having a width of 6 mm, a length of 60 mm and a thickness of 1.1 mm is sealed as the rear glass 14 with an epoxy adhesive. Next, the lead wire is taken out from the terminals at both ends with silver paste, and the lead wire is incorporated into the housing 6 of the bar code reader to obtain the bar code reader shown in FIG.

[0032]

In the information identifying apparatus of the present invention, since it is not necessary to partially change the amount of light emitted from the light source, it is sufficient to simply make the entire element emit light, and the structure is simple and the cost is low. Further, by using this EL element, it is possible to obtain a highly sensitive one in which the light amount distribution of the reflected light and the transmitted light from the information display medium is uniform, and the reading error can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a bar coder.

FIG. 2 is a perspective view from below of an opening of a bar-co-reader.

FIG. 3 (a) is a cross-sectional view of a first thin film EL element of the present invention,
(B) It is a top view of the 1st thin film EL element of this invention.

FIG. 4 (a) is a cross-sectional view of a second thin film EL element of the present invention,
(B) It is a top view of the 2nd thin film EL element of this invention.

FIG. 5 (a) is a sectional view of a third thin film EL element of the present invention,
(B) It is a top view of the 3rd thin film EL element of this invention.

FIG. 6 is a plan view of a fourth thin film EL element of the present invention.

FIG. 7 is a schematic cross-sectional view illustrating a state of reflected light from a bar code.

FIG. 8 is a graph showing an illuminance distribution of the thin film EL element of the present invention.

[Explanation of symbols]

 1. Light source 2. Bar code 3. Mirror 4. Lens 5. Light receiving element 6. Housing 8. Glass substrate 9. Conductive film 10. Light emitting layer 11. Conductive film 12. Insulation layer 13. Insulation layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ken Yoshida 48 Wadai, Tsukuba City, Ibaraki Prefecture, Hitachi Chemical Co., Ltd. Tsukuba Development Laboratory (72) Inventor Kenzo Susa 48 Wadai, Tsukuba City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Incorporated company Tsukuba R & D Laboratory (72) Inventor Toshitaka Suzuki 1-28-32 Ishinasaka-cho, Hitachi (72) Inventor Mitsuru Watanabe 4-37-17 Hongo, Bunkyo-ku, Tokyo 72) Inventor Tsuneo Izumi 4-37-17 Hongo, Bunkyo-ku, Tokyo In stock company Nurong (72) Inventor Takashi Sagawa 4-37-17 Hongo, Bunkyo-ku, Tokyo In stock company Nuron

Claims (4)

[Claims] 1. An information identification device comprising a light source for irradiating an information display medium with light, a light receiving element for receiving light from the information display medium, and an information processing section for processing an electrical signal from the light receiving element. An information identification device comprising at least one of the following EL elements (1) to (5). (1) An EL element in which the surface facing the information display medium is a curved surface having a concave center. (2) EL element An EL element in which the thickness of the light emitting layer is increased at both ends of the element. (3) EL element An EL element in which the light emitting surface is widened at both ends of the element. (4) EL element An EL element having a plurality of light emitting surfaces so that the total area of the light emitting surfaces is larger at both end portions of the element than in the central portion. (5) EL element An EL element in which the concentration of the light emission center contained in the light emitting layer has different values in the central portion and both end portions of the element. 2. The information identification device according to claim 1, wherein the light from the information display medium is reflected light from the information display medium. 3. A light source for irradiating a bar code with light, a light receiving element for receiving reflected light from the bar code, and a decoding circuit for decoding an electric signal from the light receiving element to process information recorded on the bar code. A bar code reader comprising: a bar code reader, wherein the light source is at least one of the following EL elements (1) to (5). (1) An EL element in which the surface facing the information display medium is a curved surface having a concave center. (2) EL element An EL element in which the thickness of the light emitting layer is increased at both ends of the element. (3) EL element An EL element in which the light emitting surface is widened at both ends of the element. (4) EL element An EL element having a plurality of light emitting surfaces so that the total area of the light emitting surfaces is larger at both end portions of the element than in the central portion. (5) EL element An EL element in which the concentration of the light emission center contained in the light emitting layer has different values in the central portion and both end portions of the element. 4. The EL element is a thin film EL element.
3 The information identification device or bar code reader described in each item.