JPH02220019A - Information reader - Google Patents

Abstract

PURPOSE:To reduce the vignetting of the quantity of photodetection of a reflected beam by separating an irradiating beam and the reflected beam by an optical path separation member which has areas for transmission and reflection. CONSTITUTION:The light emitted by a semiconductor laser 3 is converged by a 1st condenser lens 4 and converted into the irradiating beam (a), which is reflected by a partial reflecting mirror 6. The partial reflecting mirror 6 has the reflecting part 7, which is nearly equal in diameter to the irradiating beam (a), at its center part and the transmission part 8 is formed over the entire peripheral surface of the reflection part 7. The irradiating beam (a) is therefore reflected by the reflection part 7 which is nearly equal in diameter to the beam and the reflected beam (b) is transmitted through the transmission part 8 formed over its entire peripheral surface and photodetected by a photodetector 14. Consequently, the vignetting range of the photodetection luminous flux of the reflected beam (b) which is photodetected is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an information reading device used in a barcode reader or the like.

2. Description of the Related Art Conventionally, as an information reading device used in a bar code reader or the like, there is one using a focusing hologram disk, for example, as disclosed in Japanese Patent Application Laid-Open No. 117333/1983. This involves transmitting light emitted from a laser light source through a focusing hologram disk, irradiating the transmitted and focused light onto the barcode surface that is the irradiated surface, and scanning that surface. The information recorded on the barcode surface is read by transmitting the light reflected by the code surface through the focusing hologram disk again, and causing a photodetector to detect the focused light.

In addition to an information reading device using a retroreflective optical system using such a focusing hologram disk, there is also an information reading device configured with a feedback optical system in which the hologram for optical scanning and the hologram for focusing are the same. be.

Problems to be Solved by the Invention All of these information reading devices use a hologram disk, and by using the hologram disk in this way, the focusing function of the irradiation beam irradiated on the barcode surface and its It combines a deflection function that uses reflective mirrors in the optical path, a function to receive reflected beams for return from the barcode surface, and a rask scanning function, thereby reducing the number of S items and making it easier to read. It is possible to achieve improvements in reliability, etc. However, in a device having such a configuration, there is a limit to how compact the device itself can be made, and in particular, there has been no improvement in terms of making it thinner.

In addition, as a general method for separating the optical path between the irradiated beam and the reflected beam in the conventional apparatus as described above,
As shown in FIG. 11, a carpenter's perforated mirror 2 is installed in the center so as to be inclined with respect to the incident optical path of the irradiation beam a, and in this state, the irradiation beam a is passed through the hole 1. , by reflecting the reflected beam b by the perforated mirror 2, the amount of light received by the reflected beam b is read. However, in this case, since the hole 1 is located at the center of the perforated mirror 2, most of the light beam at the central position where the amount of light received is highest is vignetted. (vignetting area P)
As a result, a problem arises in that the amount of received luminous flux decreases and the light utilization efficiency decreases.

Means for Solving the Problem Therefore, in order to solve such problems, claim 1
The described invention includes a first condenser lens that converts light emitted by a semiconductor laser into a condensed irradiation beam, and a beam shaping member that shapes the irradiation beam that has passed through the first condenser lens. , providing a hologram disk for deflecting the irradiation beam, and providing an optical path separating member in which a region is formed in the center and the periphery to separate the irradiation beam from the semiconductor laser and the reflected beam from the irradiated surface; A second condenser lens was provided to condense the reflected beam separated by the optical path separation member, and a light receiving element was provided to detect the reflected beam condensed by the second condenser lens.

The invention according to claim 2 provides a beam shaping method that includes a first condenser lens that converts the light emitted by the semiconductor laser into a condensed irradiation beam, and that shapes the irradiation beam that has passed through the first condensing lens. a hologram disk for deflecting the irradiation beam; an irradiation optical system for changing the optical path of the irradiation beam before and after entering the hologram disk; and an optical path separating member in which a region is formed to separate the irradiation beam from the semiconductor laser,
A second condensing 1/lens was provided to condense the reflected beam separated by the optical path separating member, and a light receiving element was provided to detect the reflected beam condensed by the second condensing lens.

In the invention as claimed in claim 1, since the irradiation beam and the reflected beam are separated by the optical path separation member having a region for transmitting and reflecting, the reflected beam is smaller than when a conventional perforated mirror is used. It is possible to reduce vignetting in the amount of light received. Furthermore, by using a semiconductor laser instead of the He-Ne laser that has been conventionally used as a laser light source, and beam-shaping the light emitted from the semiconductor laser using a beam-shaping member,
A large reading depth can be obtained even in a short focus irradiation beam optical system.

Further, in the invention as set forth in claim 2, by using a semiconductor laser, a hologram disk, and an irradiation optical system in combination, the apparatus can be made more compact. Also,
Since the irradiation beam and the reflected beam are separated by an optical path separation member having a region for transmission and reflection,
It is possible to reduce vignetting in the amount of received reflected beam compared to when a conventional perforated mirror is used. moreover,
By using a semiconductor laser instead of the He-Ne laser that has been commonly used as a laser light source, and by shaping the light emitted from the semiconductor laser using a beam shaping member, a short focus irradiation beam can be created. The reading depth can also be increased in the optical system.

Embodiment An embodiment of the invention set forth in claim 1 will be described with reference to FIGS. 1 to 4. First, the basic configuration of the information reading device will be explained based on FIG. The light emitted from the semiconductor laser 3 is focused by a first condensing lens 4 and converted into an irradiation beam a, and this irradiation beam a is beam-shaped by a mask 5 as a beam shaping member, and partially reflected by an optical path separating member. It is reflected by mirror 6. Here, as shown in FIG. 3, the partially reflecting mirror 6 has a reflecting part 7 formed in its center with approximately the same diameter as the irradiation beam a, and extends over the entire circumference of this reflecting part 7. A transparent portion 8 is formed therein. Therefore, in this case, the irradiation beam a is reflected by the reflection portion 7 of the partial reflection mirror 6, has its optical path changed, and is guided to the hologram disk 9.

This hologram disk 9, as shown in FIG.
It consists of six sectors 0, and is rotated at high speed by a motor 1 installed below. The hologram disk 9 has each sector 0 (
For example, since the diffraction angle is different for each sector (Sa, Sb%, S, C), the irradiation beam a passing through it becomes a separate optical path for each sector 0. The irradiation beam a transmitted through the hologram disk 9 and separated into a plurality of beams is irradiated onto the surface of the barcode 12 as the irradiated surface. In this case, the scanning direction of the irradiation beams a is perpendicular to the plane of the paper in FIG. 1, and scanning in this manner is called "self-rusk scanning." By performing such self-rusk scanning, the information recorded on the barcode 12 can be read more reliably.

Then, the reflected beam b from the barcode 12 surface is
The light enters the hologram disk 9 again due to the retroreflection function of the hologram disk 9.

The reflected beam b, which has become reverse diffracted light due to this incidence, passes through the transmission part 8 of the partial reflection mirror 6, and is then condensed by the second condensing lens 13, and the amount of received light is detected by the light receiving element 14. Thereby, the information recorded on the barcode 12 surface can be read. Note that the surface shape of the second condensing lens 13 is a horizontally elongated shape as shown in FIG. 4 when viewed from the side on which the reflected beam b enters.

In the information reading device basically configured as described above, the irradiation beam a is reflected by the reflection section 7 of the partial reflection mirror 6, and the reflected beam b is transmitted through the transmission section 8 around it.
A detailed illustration of the passing state is shown in Fig. 1O. As a result, the irradiation beam a is reflected by the reflection section 7 having an area of approximately the same diameter as the irradiation beam a, while the reflected beam b is transmitted through the transmission section 8 formed on the entire surface around it and is received by the light receiving element 14. Therefore, it can be seen that the vignetting area Q of the received light beam of the reflected beam b is much smaller than the conventional vignetting area P (see FIG. 11). Therefore, as a result, the light receiving element 14
Since the total amount of light beams received can be larger than that of the conventional method, it is possible to further increase the light utilization efficiency.

In addition, He-
A semiconductor laser 3 is used instead of the Ne laser, and the light emitted from the laser is beam-shaped using a mask 5, so that even in a short-focus irradiation beam optical system like this embodiment, the reading depth can be sufficiently increased. It is possible to make it larger.

Next, an embodiment of the invention according to claim 2 will be described based on FIG. This shows the basic configuration in the same way as FIG. The optical path of a is changed so that it is guided to the barcode 12. By changing the optical path of the irradiation beam a that has passed through the hologram disk 9 in this way, the degree of freedom in designing the scanning optical system can be further increased.

Next, an actual assembly of the information reading device having the basic configuration described in the previous two embodiments will be explained based on FIGS. 6(a), (b), and (c). In this case, in FIG. 6(b), the LD unit 16 constituting the semiconductor laser 3 is located on the upper side in the drawing, and the heat sink (not shown) of the LD unit 16 is located outside the holding member 17. Further, the irradiation beam a emitted from the semiconductor laser 3 of the LD unit 16 is shown in FIG.
In C), after passing through a first condensing lens and a mask (not shown), the mirror M1 and the reflecting part 7 of the partially reflecting mirror 6
, mirror M2, hologram disk 9, mirror M3. M
4. The light is emitted from the window 18 to the outside through the M5 in order, and is irradiated onto the barcode 12 surface. The reflected beam b from the barcode 12 surface is reflected by mirror M5. M4. M
3. The light is received by the light receiving element 14 through the hologram disk 9, the mirror M2, the transmitting part 8 of the partial reflection mirror 6, the second condensing lens 13, and the mirror M6 in this order.

By using the LD unit 16 having the semiconductor laser 3, the hologram disk 9, and the mirrors M1 to M6 in an integrated configuration in this way, it is possible to obtain a thinner and more compact device.

Next, a modification of the information reading device shown in FIG. 6 described above will be explained based on FIGS. 7 to 9. Here, a modification of the diffraction optical path of the irradiation beam a that passes through the hologram disk 9 and is irradiated onto the surface of the barcode 12 is shown.

First, FIG. 7 shows an oblique irradiation type device in which the irradiation beam a that has passed through the hologram disk 9 is guided directly to the barcode 12 surface. It can be done.

Further, FIG. 8 shows an example of the vertical irradiation type, and FIG. 9 shows an example of the horizontal irradiation type.
By changing the irradiation direction, it becomes possible to further increase the degree of freedom in design when assembling the device.

Note that the optical path separation member in the embodiments described so far is
° In both cases, a partially reflecting mirror 6 was used in which a reflecting part 7 was formed in the center and a transmitting part 8 was formed around it, but the invention is not limited to this. It is also possible to use a partially transmitting mirror, in which a transmitting portion is formed at the top and a reflecting portion is formed around the transmitting portion, as the optical path separation member.

Effects of the Invention The invention described in claim 1 separates the irradiated beam and the reflected beam by an optical path separation member having a region for transmitting and reflecting. It is possible to further reduce vignetting in the amount of light received by the reflected beam, thereby further reducing the amount of light received by the light receiving element, thereby further increasing light utilization efficiency. In addition, by using a semiconductor laser instead of the He-Ne laser that has been commonly used as a laser light source and beam-shaping the light emitted from the semiconductor laser using a beam-shaping member, short focus The irradiation beam optical system also allows for a large reading depth. Furthermore, by combining and integrating the semiconductor laser, the hologram disk, and the irradiation optical system, the device can be made thinner and more compact.

According to the second aspect of the invention, the semiconductor laser, the hologram disk, and the irradiation optical system are combined and integrated to make the device thinner and more compact. In addition, since the irradiated beam and reflected beam are separated by an optical path separation member in which a region for transmission and reflection is formed, vignetting in the amount of received reflected beam is reduced compared to when a conventional perforated mirror is used. This makes it possible to further reduce the amount of light received by the light receiving element, thereby further increasing light utilization efficiency. Furthermore, by using a semiconductor laser instead of the He-Ne laser that has been commonly used as a laser light source and beam-shaping the light emitted from the semiconductor laser using a beam-shaping member, short focus The irradiation beam optical system also allows for a large reading depth.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the invention as claimed in claim 1,
Fig. 2 is a plan view of the hologram disk, Fig. 3 is a front view of the partially reflecting mirror, Fig. 4 is a front view of the second condensing lens,
FIG. 5 is a configuration diagram showing an embodiment of the invention as claimed in claim 2;
Fig. 6(a) is a side view of the unitized information reading device, Fig. 6(b) is its plan view, Fig. 6(C) is its front view, and Figs. 7 to 9 are information reading devices. FIG. 10 is an optical path diagram showing an optical path separating means using an optical path separating member of the present invention, and FIG. 11 is an optical path diagram showing a conventional optical path separating means. 3... Semiconductor laser, 4... First condensing lens, 5...
... Beam shaping member, 6... Optical path separation member, 7...
Reflection part, 8... Transmission part, 9... Hologram disk, 12... Irradiated surface, 13... Second condensing lens, 1
4... Light receiving element, 15... Irradiation optical system, a... Irradiation beam, b... Reflected beam

Claims (1)

[Claims] 1. A semiconductor laser, a first condensing lens that converts the light emitted by the semiconductor laser into a condensed irradiation beam, and the irradiation beam that has passed through the first condensing lens. a beam shaping member for shaping, a hologram disk for deflecting the irradiation beam, and an optical path in which a region is formed in the center and its periphery to separate the irradiation beam from the semiconductor laser and the reflected beam from the irradiated surface. A separating member, a second condensing lens that condenses the reflected beam separated by the optical path separating member, and a light receiving element that detects the reflected beam condensed by the second condensing lens. Characteristic information reading device. 2. A semiconductor laser, a first condenser lens that converts the light emitted by the semiconductor laser into a condensed irradiation beam, and a beam shaping member that shapes the irradiation beam that has passed through the first condenser lens. , a hologram disk that deflects the irradiation beam, and an irradiation optical system that changes the optical path of the irradiation beam before and after entering the hologram disk;
an optical path separation member in which a region is formed in the center and its periphery to separate the irradiation beam from the semiconductor laser and the reflected beam from the irradiated surface; and the reflected beam separated by the optical path separation member is focused. An information reading device comprising: a second condensing lens; and a light receiving element that detects the reflected beam condensed by the second condensing lens.