JP2972411B2 - Optical reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical reading apparatus for displaying a hologram image for guiding the reading height and direction of a read object in a bar code reading apparatus or the like. A hologram is a thin-film optical element with a thickness of about several micrometers,
It is small and has a wavefront conversion function equal to or greater than that of lenses and prisms. Also, by using the duplication technique, a large amount of inexpensive optical elements can be expected.

For this reason, recently, applied devices using a hologram as an optical element instead of a lens, for example, P
Optical reading devices such as OS barcode readers have been researched and developed. On the other hand, in the barcode reader, the optimum reading height at which the reading rate is highest is determined. However, since there is no instruction indicating the optimum reading height, the operator does not always read the barcode of the product at the optimum position, and it is desired to improve this point.

[0003]

2. Description of the Related Art In a conventional bar code reader,
A laser beam emitted from a beam scanner built in the apparatus housing is emitted through a reading window, irradiates an object such as a product existing in a front upper space, and a bar code is read by detecting reflected light. ing.

In such a bar code reader, it is usual that the optimum reading height and direction are set within a certain height range from the reading window, and an object is passed from the optimum reading height and direction. Thus, a high reading rate can be obtained without failing in reading. However, because the optimal reading height cannot be indicated in the space through which the object passes,
An arrow indicating the passing direction is simply displayed on the reading window by printing or the like.

[0005] For this reason, the operator has not always read at a position where the reading rate is high, such as moving the product along the reading window surface of the apparatus. As means for solving this problem, the present inventors provide a hologram for displaying a three-dimensional image on a window surface of a reading window of a barcode reading device, and provide an optimum reading height and direction in a space in front of the reading window. An optical reading device has been proposed in which a guide display image such as an arrow graphic indicating the above is displayed using a hologram.

FIG. 8 shows an example of an optical reading apparatus of the prior application proposed by the inventors of the present invention. The reading window surface, which is the upper surface of the housing 1, has a reflective Lippmann hologram 2 on it.
Is installed. The Lippmann hologram 2 is formed by applying an emulsion onto a glass substrate, irradiating the emulsion with object light such as an arrow pattern and reference light, and performing interference exposure of two light beams.

An illumination lamp 3 is installed diagonally above the housing 1, and when a reference light 4 is applied to the Lippmann hologram 2,
An arrow figure 5 is displayed as a hologram image in a space having a height of about 10 cm of the housing 1. Therefore, the operator moves the product along the hologram image of arrow figure 5,
Barcodes can be read reliably. FIG. 9 shows the configuration of another device of the prior application proposed by the inventor of the present application. The housing 1 provided with the Lippmann hologram 2 on the reading window surface is vertically mounted on a check counter 6 and an arrow graphic 5 is displayed.

FIG. 9 shows another device configuration.
The illumination lamp 3 is attached to the housing 1. FIG.
FIG. 10 shows a further improved optical reading device of the prior application proposed by the inventors of the present application. As shown in FIG.
A light guide plate 8 having a reflection type Lippmann hologram 2 is provided on a reading window surface of the housing 1, and a light source 13 built in the housing 1 is provided.
The reference light 4 is totally reflected and propagated in the light guide plate 8 to irradiate the Lippmann hologram 2, and as a diffraction image, an arrow pattern 5 is displayed as the information of the housing 1 by 10 cm as shown in FIG. An image is formed as a hologram image in a space of the order.

Here, the reflection type Lippmann hologram 2 is, as shown in FIG.
The recording surface is irradiated with the reference light 4 through the lower prism 11 at an angle equal to or smaller than the critical angle, and at the same time, the object light 10 irradiating the arrow image 12 is irradiated from the upper side, and is created by interference exposure of two light beams. . In the apparatus shown in FIG. 10, it is not necessary to externally install an illumination lamp for irradiating the reference light 4.

FIGS. 11A and 11B show an optical reading apparatus using a transmission type Lippmann hologram 2 prepared by the method shown in FIG. 11C. FIG. 12 is an explanatory diagram of an optical system of a conventional bar code reader using a hologram window in a reading window. In FIG. 12, a He-Ne laser 1
The laser beam oscillated from 4 is horizontally scanned by the rotating polygon mirror 16, reflected by each of the three-sided mirrors 17 and then reflected upward by the bottom mirror 18 to form a scanning pattern in three directions crossing each other. The holograms 24a, 24b and 24c on the window 20 are incident.

The hollow window 20 converts an incident laser scanning pattern into a five-direction dynamic cross scanning pattern 21 in which three vertical scanning lines d and e plus three intersecting scanning lines a to c are emitted. . The signal scattered light reflected on the bar code is collected through a hollow window 20 and guided to a photodetector 22 via a three-sided mirror 17, a polygon mirror 16, and a concave mirror 15.

[0012]

However, in such a conventional optical reading device such as a bar code reading device which spatially displays a hologram image indicating the optimum reading height and direction, Since a hologram was installed on the reading window of the device to display a three-dimensional image, the device became thicker. The conditions for creating the hologram and the conditions for reproducing the 3D image are restricted, and a part of the transmitted light by the 3D image display hologram becomes stray light, which is returned to the photodetector for reading the barcode information, which adversely affects the reading of the product. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a hologram for displaying a three-dimensional image indicating an optimum reading height and direction without adversely affecting an optical system for reading an object. It is an object of the present invention to provide an optical reader capable of improving the efficiency of a checkout operation and improving the reading rate.

[0014]

FIG. 1 is a diagram illustrating the principle of the present invention. First, according to the present invention, a light beam emitted from a beam scanner of a reading optical system built in a housing 1 is emitted from a predetermined reading window 20 to irradiate an object existing in a space in front of the reading window 20 with the light beam. The present invention is directed to an optical reader that detects reflected light from an object and reads characteristics of the object.

According to the present invention, such an optical reader is provided in a space in front of a reading window 20 by irradiating a reference light beam 4 using a beam scanner of a reading optical system inside a housing 1. A hologram 2 for displaying a guide display image 5 indicating at least one of the optimum reading height and direction is provided. Here, the reproducing light source 25 for irradiating the reference light beam 4 may be provided inside the reading optical system or may be provided outside.

As the reproducing light source 25, a laser light source, a light emitting diode or a fluorescent tube can be used. Further, the irradiation range of the hologram 2 is expanded by irradiating the hologram 2 with the reference light beam 4 from the reproduction light source 25 via at least one mirror. On the other hand, a polygon mirror rotated at a constant speed is used as a beam scanner of the reading optical system. In this polygon mirror, the guide display image is given a width by making the inclination of each mirror surface different.

The beam scanner may be a galvanomirror that is reciprocated at a constant period. Alternatively, the hologram 2 may be irradiated as a reference light beam 4 on a part of the scanning range with the scanning light from the reading light source reflected by the beam scanner without providing the dedicated reproduction light source 25.

Further, the hologram 2 is created by multiple exposure, and reproduces and displays at least two or more types of guide display images 5.

[0019]

According to the optical reading apparatus of the present invention having such a configuration, the hologram 2 for displaying a hologram three-dimensional image for guide display is provided on the housing 1 separated from the reading window 20.
The reading window 20 as a hollow window is not thickened, and the restrictions on the conditions for creating the hollow window and the mutual field of the three-dimensional image reproduction system can be eliminated.

Further, since the scanning beam for reading does not enter the hologram 2 for displaying a three-dimensional image, stray light due to the scanning beam transmitted through the hologram 2 for displaying a three-dimensional image does not occur, so that the adverse effect on the reading optical system is reliably prevented. Can be prevented. Further, by irradiating the hologram 2 incorporated in the reading optical system with the reference light from the reproduction light source 25, a guide display image 5 as a hologram diffraction image is displayed in a space of about 10 cm in front of the reading window 20, and this guide display is performed. Looking at the image 5, the operator can move the product within the optimal reading range, and the reading rate can be greatly improved.

[0021]

FIG. 2 is a block diagram showing a first embodiment of the present invention. In FIG. 2, a hollow window 20 constituting a reading surface is provided at the upper part of the housing of the barcode reading device, and a reading optical system is provided inside the housing below the hollow window 20.

The reading optical system is He-Ne as a reading light source.
Laser 14, concave mirror 15, polygon mirror 16 having a pentagonal mirror surface rotated at a constant speed, three mirrors 1
A three-sided mirror 17 composed of 7a, 17b, and 17c, a bottom mirror 18, and a photodetector 22 are further provided. FIG. 3 shows a reflection path of the scanning beam for reading in the reading optical system of FIG. 4. The laser beam from the He-Ne laser 14 is incident on the polygon mirror 16 at the center of the concave mirror 15. The scanning beam is horizontally rotated at the position of the three-sided mirror 17 by the polygon mirror 16. Accordingly, as shown in FIG. 3, beams from the polygon mirror 16 to the three-sided mirror 17 in the order of the mirrors 17a to 17c enter the scanning pattern shown by the solid line.

The scanning beam which has entered the three-sided mirror 17 is reflected by the bottom-side mirror 18 and draws a scanning pattern of three overlapping beams on the bottom-side mirror 18. The scanning beam that has entered the bottom mirror 18 is reflected upward and enters three holograms provided on the hollow window 20, respectively. More specifically, as shown in FIG. 13, three holograms 24a, 24b, and 24c are arranged in the hollow window 20 so as to intersect at the center, and the scanning beam reflected by the bottom mirror 18 is used as the holograms 24a and 24b. , 24c
The holograms 24a to 24a-2
By the hologram diffraction of 4c, a 5-directional dynamic cross scanning pattern 21 including two vertical scanning patterns is formed in a predetermined space on the hollow window 20.

Referring again to FIG. 2, according to the present invention, in the reading optical system, for example, a reproduction light source 25 using a laser semiconductor and a guide display image are provided in a space of about 10 cm in front of the hollow window 20. 5 is provided with a Lippmann hologram 2 for drawing 5 by hologram diffracted light. FIG. 4 shows FIG.
FIG. 8 is an explanatory diagram showing a display state of a display line 5b in a guide display image 5 according to the example of FIG.

FIG. 4 shows a state where the reference light beam from the reproducing light source 25 is reflected by the polygon mirror 16 and the central mirror 17b of the three-sided mirror 17 is irradiated with the beam. The reference light beam reflected by the mirror 17b is a Lipman hologram 2 for displaying a stereoscopic image.
The beam is scanned. In response to the scanning of the reference light beam, the hologram diffracted light is emitted from the Lippmann hologram 2 to the front upper space via the hollow window 20 and draws a display line 5b which is a part of the guide display image 5. Here, the display line 5b is indicated by two lines, which indicates a state in which the display line 5b is displayed with a certain width due to a change in the optical path due to a variation in the horizontal plane during the rotation of the polygon mirror 16. Of course, the inclination of the mirror surface may be positively changed.

FIG. 5 shows a display state of the display line 5c in the guide display image 5 of FIG. At this time, the reference light beam from the reproduction light source 25 is reflected by the polygon mirror 16 and the reference light beam is incident on the mirror 17c on the right side of the three-sided mirror 17, and the reference light beam is reflected by the mirror 17c to form a three-dimensional image. The light enters the Lippmann hologram 2 for display. For this reason, the hologram diffracted light due to the irradiation of the reference light beam is emitted from the Lippmann hologram 2 into the hollow window 20.
And the display line 5c constituting a part of the guide display image 5 is displayed in a space in front of the hollow window 20 with a certain width due to variation in the horizontal rotation of the polygon mirror 16.

FIG. 6 shows a display line 5a of the guide display image 5 of FIG.
The reference light beam from the reproducing light source 25 is reflected by the polygon mirror 16, and in this state, the beam is incident on the right side 17a of the three-sided mirror.
The reference light beam incident on the mirror 17a is reflected by the Lippmann hologram 2 for displaying a three-dimensional image, and upon receiving the reference light beam, hologram diffracted light is emitted from the Lippmann hologram 2 to the front space via the hollow window 20. , The display line 5 a is displayed with a width corresponding to the variation in the horizontal rotation of the polygon mirror 16.

The scanning of the Lippmann hologram 2 for displaying a stereoscopic image by the polygon mirror 16 by the reference light beam shown in FIGS. 4, 5 and 6 is continuously performed.
As shown in FIG. 2, a guide display image 5 indicating the optimal reading height and direction of a product can be displayed at a predetermined position in the front space of the hollow window 20. Further, in the embodiment of FIG.
Since the hollow window 20 and the Lippmann hologram 2 for displaying a stereoscopic image are separately provided, the conditions are not mutually restricted when both are created.

Further, the hollow window 20 by the reading optical system is used.
Is not incident on the Lippmann hologram 2 for displaying a stereoscopic image located below the reading optical system, but the scanning beam is incident on the Lippmann hologram 2 and stray light is emitted. It is possible to reliably prevent the reading of the scattered light from being affected. FIG. 7 is a plan view of a reading optical system according to a second embodiment of the present invention.

In FIG. 7, mirrors 28a and 28b for displaying a stereoscopic image are newly provided on both sides of the three-sided mirror 17 using the mirrors 17a to 17c. The polygon mirror 16 differs from the first embodiment of FIG. 2 in that a four-sided mirror is used. Further, in the second embodiment shown in FIG. 7, the reproduction light source 25 is not provided, and the He-
A stereoscopic image is displayed on the Lippmann hologram 2 using the scanning beam from the Ne laser 14.

Referring to the operation of FIG. 7, when the scanning beam scans the range of the mirrors 17a to 17b of the three-sided mirror 17 by the constant rotation of the polygon mirror 16,
As shown in FIG. 3, a scan pattern is formed on the object by the hollow window 20. On the other hand, when the scanning beam from the polygon mirror 16 is scanning the mirrors 28a and 28b for displaying a stereoscopic image provided following the three-sided mirror 17, the scanning beam from the mirror 28a is used for displaying the stereoscopic image. A predetermined position of the Lippmann hologram 2 is irradiated, and a guide display line 5 a is displayed in the front space via the hollow window 20. When the scanning beam is incident on another position of the Lippmann hologram 2 by scanning the mirror 28b, the guide display line 5b is displayed in the upper space via the hollow window 20.

As described above, in the second embodiment shown in FIG.
Using the laser light source of the reading optical system, the reading and scanning of the object can be performed simultaneously with the display of the guide display image indicating the optimum reading height and direction using the Lippmann hologram 2 without providing the reproduction light source 25. In the above embodiment, a laser light source is taken as an example of the reproduction light source 25 for displaying the guide display image 5 by the Lippmann hologram 2, but a light emitting diode (LED) or a fluorescent tube is used as a light source. Is also good.

In the above-described embodiment, the polygon mirror 16 rotated at a constant speed is used as an example of the beam scanner of the reading optical system. A dynamically rotated galvanomirror may be used. Further, in the above embodiment, the three-way mirror 17 is provided on the path for irradiating the reference light beam 4 from the reproducing light source 25 to the Lippmann hologram 2 and is reflected to increase the optical path length, thereby increasing the optical path length. Thereby, the irradiation range of the reference light beam to the Lippmann hologram 2 can be lengthened, and the display image for guide can be made a sufficiently large display image by the hologram diffraction light.

[0034]

As described above, according to the present invention, a hologram for displaying a guide display image indicating an optimum reading height and direction is provided on a reading optical system branched from a reading surface such as a hollow window. Therefore, the reading window is not thickened, and the mutual restrictions on the creation conditions and the reproduction conditions when using a hollow window for the reading window can be eliminated.

Since the scanning beam for reading does not enter the hologram for displaying a three-dimensional image, stray light due to the scanning beam for reading transmitted through the hologram for displaying a three-dimensional image is not generated, and the three-dimensional image for guiding is formed by the hologram. Even if the image is displayed, the adverse effect on the reading optical system can be reliably prevented. Furthermore, since a hologram image indicating the optimum reading height and direction is displayed in a predetermined space in front of the reading surface, the operation of the operator can be facilitated and the reading rate can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a configuration diagram of a first embodiment of the present invention.

FIG. 3 is an explanatory diagram of a reflection path of a scanning beam of the reading optical system of FIG. 2;

FIG. 4 is an explanatory diagram of a guide display image due to reflection by a three-sided mirror 7b in FIG. 2;

FIG. 5 is an explanatory diagram of a guide display image due to reflection by a three-sided mirror 7c in FIG. 2;

FIG. 6 is an explanatory diagram of a guide display image due to reflection by the three-sided mirror 7a in FIG. 2;

FIG. 7 is a configuration diagram of a second embodiment of the present invention.

FIG. 8 is an explanatory view showing an example of the invention of the prior application.

FIG. 9 is an explanatory view showing another example of the invention of the prior application.

FIG. 10 is an explanatory view showing another example of the invention of the prior application.

FIG. 11 is an explanatory view of the invention of the prior application in which a light source for the reproduction reference light is built

FIG. 12 is an explanatory diagram showing another example of the prior invention incorporating a light source for reproduction reference light.

FIG. 13 is an explanatory diagram of a reading optical system in a conventional barcode reading device using a hologram window.

[Explanation of symbols]

 1: housing 2: hologram (Lipman hologram) 5: guide display image (arrow figure) 14: He-Ne laser 15: concave mirror 16: polygon mirror 17: three-sided mirror 17a to 17c: mirror 18: bottom mirror 20: holo Window 22: photodetectors 24a to 24b: hologram (for scanning pattern) 25: light source for reproduction 28a, 28b: mirror

Continuing from the front page (72) Inventor Hironing Yoshikawa 1015 Uedanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Co., Ltd. Field surveyed (Int.Cl. ⁶ , DB name) G06K 7/10 G03H 1/22

Claims (4)

(57) [Claims] A light beam emitted from a beam scanner of a reading optical system built in a housing is emitted from a predetermined reading window to irradiate an object existing in a space above the reading window. In an optical reading device for detecting reflected light from an object and reading characteristics of the object, reading is performed by irradiating a reference light beam 4 into the inside of the housing 1 using a beam scanner of the reading optical system. An optical reading device, comprising: a hologram 2 for displaying a guide display image 5 indicating at least one of an optimum reading height and a direction in a space above a window 20. 2. An optical reader according to claim 1, wherein:
An optical reading device, wherein a reference light beam from a reproduction light source 25 is applied to the hologram 2 via at least one mirror. 3. The optical reading device according to claim 1, wherein
An optical reader according to claim 1, wherein said beam scanner is a polygon mirror rotated at a constant speed. 4. The optical reading device according to claim 1, wherein
An optical reading apparatus, wherein the hologram 2 is created by multiple exposure, and reproduces and displays at least two or more types of guide display images 5.