JPH03225316A - Laser beam scanning device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a laser beam scanning device used for optically reading optical cards and the like.

2. Description of the Related Art A first example of a conventional optical scanning device is disclosed in Japanese Patent Application Laid-open No. 156293/1983, for example. As shown in FIGS. 5 and 8, a polygon mirror 1 is rotated by a motor 2, the light incident on the mirror 3 is horizontally scanned, and a plurality of mirrors 4 are irradiated with the light. The light reflected by the plurality of mirrors 4 is guided to one common mirror 5 provided on the bottom surface, and is reflected by this to draw a plurality of scanning NAs 6 that intersect with each other, thereby reading information. This is what I decided to do. Note that FIG. 5 is a side view schematically showing the optical path in FIG. 8.

Further, as a second conventional example, there is one disclosed in Japanese Patent Laid-Open No. 52-95239. As shown in FIG. 9, this method involves making light incident on reflective surfaces 8 of polygon mirrors 7 formed at greatly different angles of inclination, and transmitting the light reflected by these reflective surfaces 8 to separate mirrors. 9
The reflected light is drawn on a reading surface 10 provided at a distant position to draw a plurality of scanning lines 11 that intersect with each other, thereby reading information.

Problems to be Solved by the Invention In the case of the first conventional example, the light is circulated in the horizontal direction and then reflected upward by the common mirror 5, so that a thinner structure can be achieved. In order to obtain a constant scanning width, the width of the mirror 4 in the lateral direction is required, which poses a problem in that the device becomes larger.

In the case of the second conventional example, each corner face of the polygon mirror 7 needs to be tilted significantly, and therefore, unless the position of the mirror 9 placed opposite to these is adjusted, each scanning line 11
The path length to a certain reading surface 10 is different, and each scanning line 11 is focused on a different position. Therefore, when using such a device as a barcode reader, the sixth
As shown in Figure (a), the reading area differs for each scanning line 11. Moreover, as shown in FIG. 6(b),
Adjust the position of each mirror 9, and the path length to the reading surface 10 (
In the case where the optical path lengths are made equal, the entire optical system must be expanded laterally to some extent, which tends to increase the size of the device. Furthermore, the emission directions of the scanning Mll and the scanning line 11 are greatly different, and they intersect with each other at a large angle, and after this intersection, they rapidly separate, resulting in a reduction in the reading rate.

Furthermore, when manufacturing a polygon mirror 7 with each reflective surface 8 tilted upward or downward by cutting, it is not possible to line up several of these surfaces at the same time and manufacture them in one go.
It is troublesome because each piece must be cut separately. On the other hand, when attempting to manufacture the polygon mirror 7 from plastic by injection molding, a mold 12 as shown in FIG. 7 is required. There is a problem in that it cannot be separated from the mold, and as a result, it cannot be manufactured by injection molding and must be manufactured by cutting as described above, making it impossible to reduce costs. .

Furthermore, when the reflective surfaces 8 of the polygon mirrors 7 are formed by tilting them in the same direction, a recursive optical system (a method that detects the signal light that returns in the opposite direction to the output optical path) that is resistant to disturbance light cannot detect the reflected light. Since a certain area is required for the surface 8, the inclination of the mirror surface must be made significantly different in order to make the light incident on the large mirror 9 located at different heights. The problem arises that the emission directions of the scanning lines 11 intersect with each other at a large angle in the middle of the optical path.

Means for Solving the Problems Therefore, in order to solve such problems, the present invention shapes the emitted light emitted from the laser light source, applies the shaped light to the reflective surface of a rotating mirror, A laser beam that reads information recorded on the reading surface by irradiating the light scanned by the rotating mirror onto the reading surface through a plurality of mirrors and detecting the reflected light from the reading surface. In the scanning device, the reflective surface of the rotary mirror is formed by tilting at a certain angle so that the light travels diagonally downward in a direction opposite to the direction of light emitted from the laser light source and directed toward the rotary mirror. A plurality of mirrors are provided to guide the light reflected by the inclined reflecting surface onto the reading surface.

In addition, the output light emitted from the laser light source is shaped, the shaped light is incident on the reflective surface of a rotating mirror, and the light scanned by the rotating mirror is passed through a plurality of mirrors to the reading surface. In a laser beam scanning device that reads information recorded on the reading surface by irradiating the light upward and detecting the reflected light from the reading surface, the direction of the emitted light emitted from the laser light source and directed toward the rotating mirror; The rotary mirror is disposed horizontally so that the rotation axis is in a parallel direction, and a mirror is provided so that the emitted light is incident on the reflective surface of the rotary mirror placed laterally, and the mirror is provided so that the light is transmitted through the mirror. The reflecting surface of the rotating mirror is formed to be inclined at a certain angle so that the incident light travels in a direction opposite to the exit direction of the emitted light, and the reflecting surface is reflected by the inclined reflecting surface. A plurality of mirrors were arranged on the optical path of the light, and an inclined mirror was provided to guide the light reflected by the plurality of mirrors onto the reading surface.

As a result, the emitted light is reflected by the reflecting surface of the rotating mirror that forms a certain angle, so that it travels diagonally downward in the opposite direction to the emitting direction, and is reflected by multiple mirrors, causing the rotating mirror to reflect. A scanning line is drawn upwards, which allows the path length (optical path length) of the emitted light to be folded in half and scanned almost reciprocally, ensuring a constant scanning width with a simpler configuration than before. In addition, it is possible to downsize the device.

Further, by arranging the rotating mirror laterally so that the rotation axis is parallel to the direction in which the emitted light is emitted, the device can be made thinner.

Embodiment A first embodiment of the present invention will be explained based on FIG. A polygon mirror 13 serving as a rotating mirror has a reflective surface 14 formed thereon, and is connected to a motor 16 via a rotating shaft 15 . In this case, the reflective surface 14 is formed at a certain angle so that the light travels obliquely downward in the opposite direction to the emission direction A of the emitted light 17 emitted from a laser light source (not shown) and directed toward the polygon mirror 13. It is formed at an angle. Further, a plurality of mirrors 18 are arranged below the polygon mirror 13 so as to guide the light reflected by the reflection surface 14 onto a reading surface (not shown).

In such a configuration, the emitted light 17 is reflected by the reflective surface 14 having a constant inclination angle, travels diagonally downward in the direction opposite to the emitted direction A, and is reflected by the plurality of mirrors 18. After that, the scanning lines move toward the upper side of the polygon mirror 13, and scanning lines that intersect with each other can be drawn above the polygon mirror 13.

Therefore, the emitted light 17 is directed to the reflective surface 14 of the polygon mirror 13.
The light is directed downward by the mirror 18, then reflected by the mirror 18, and then directed upward. By folding the path length (optical path length) in half and using it by reciprocating almost, as in the conventional method (see Figs. 6 and 8), It is possible to secure a scanning line with a constant scanning width without making the path length long or wide.
As a result, the space for the entire optical system can be omitted and the device can be made smaller.

Next, a modification of the first embodiment will be explained based on FIG. 2. This is because the light reflected by the reflective surface 14 of the polygon mirror 13 passes through a plurality of mirrors 18 provided below.
A common mirror 19 is disposed on the optical path toward the mirrors 18, that is, on the bottom surface located further below the mirrors 18. Therefore, the reason for providing the common mirror 19 will now be described.

When using this device as a laser barcode scanner,
Generally, a recursive optical system is often used to avoid the influence of disturbance light. In this case, it is necessary to receive the light that is scanned and scattered on the reading surface by a mirror having a certain wide area to ensure the intensity of the received light. Therefore, the mirror 18 used in the middle of the path length (optical path/length) needs to be made to have a wider area than the scanning width to be secured.

For this reason, as shown in FIG. 4, when mirrors 18 of different sizes are scanned, the intensity of the received light decreases, and some locations become unusable for actual optical signal reading. The closer the mirror is to the polygon mirror 13, the larger the area becomes, and conversely, the further away from the polygon mirror 13, the smaller the area becomes. For this reason, by first reflecting the light reflected by the reflective surface 14 on the common mirror 19 and then reflecting it on the plurality of mirrors 18, a wide scanning line width is ensured with a wide intersection angle. It becomes possible to do so.

Next, a second embodiment of the present invention will be described based on FIG. The polygon mirror 13 is disposed horizontally so that the rotation axis 15 is parallel to the emission direction A of the emitted light 17 emitted from a laser light source (not shown) and directed toward the polygon mirror 13. A mirror 20 is provided so that the emitted light 17 is incident on the reflective surface 14 of the polygon mirror 13 placed laterally. Further, the reflective surface 14 of the polygon mirror 13 is formed to be inclined at a certain angle so that the light incident through the mirror 20 travels in a direction opposite to the output direction A of the output light 17. . A plurality of mirrors 18 are disposed on the optical path of the light reflected by the inclined reflecting surface 14.

Further, an inclined mirror 22 is disposed within the device 21 so as to guide the light reflected by the plurality of mirrors 18 onto an external reading surface.

In such a configuration, the emitted light 17 travels in the opposite direction to the emitted direction A by being reflected by the reflective surface 14 of the polygon mirror 13 via the mirror 20, and is reflected by the plurality of mirrors 18. The light then travels again in the same direction as the emission direction A, is reflected by the tilted mirror 22, and is thereby emitted to the outside of the device 21.

At this time, if the item to be read is a special item, such as a cigarette, which is thin and long and is used on a table in a store, the reading system must also be a similar thin item. Ru. Therefore, by arranging the scanner horizontally and directing the scanning line upward using the tilted mirror 22 as in this embodiment, it is possible to deal with the above-mentioned special articles. Also in this case, since the path length is folded in half, the space for the optical system can be omitted and the optical system can be made smaller.

If the polygon mirror 13 as described above is made of plastic by injection molding, the motor 16
It is possible to reduce the load and reduce costs. In this case, as described in the problem to be solved by the invention, if the mirror surfaces were formed tilted in opposite directions, if the mold 12 is used as shown in FIG. It becomes impossible to separate. For this reason, the reflective surfaces 14 formed on the polygon mirror 13 are made to face in the same direction. Therefore, by manufacturing the polygon mirror 13 having the reflective surfaces 14 facing in the same direction from plastic by injection molding, it is possible to obtain a lightweight device at low cost. In this case, by setting the inclination angle of the reflective surface 14 to a small angle, it is also possible to draw several mutually parallel scanning lines.

Further, the surfaces of the mirrors 18 and 22 can be made by vapor-depositing aluminum or the like, or by pasting existing mirrors. The mirrors 18 that receive the light scanned from the polygon mirror 13 do not need to be arranged circumferentially, but can be arranged three-dimensionally in various states according to the pattern desired to be created. In addition, the polygon mirror 13
In addition to being used in barcode readers, it can also be used in other optical systems, such as laser printers.

Effects of the Invention In the present invention, the emitted light is reflected by the reflecting surface of a rotating mirror that forms a certain angle, so that the emitted light travels diagonally downward in the opposite direction to the emitted direction, and is reflected by a plurality of mirrors. A scanning line is drawn above the rotating mirror, which allows the path length (optical path length) of the emitted light to be folded in half and scanned almost reciprocatingly, making it possible to achieve constant scanning with a simpler configuration than before. This makes it possible to secure the width and downsize the device.

Furthermore, by arranging the rotating mirror laterally so that the rotation axis is parallel to the direction in which the emitted light is emitted, the device can be made thinner.

[Brief explanation of drawings]

Fig. 1 is a side view showing a first embodiment of the present invention, Fig. 2 is a side view showing a modification thereof, Fig. 3 is a side view showing a second embodiment, and Fig. 4 is a side view showing a rotating mirror. FIG. 5 is a perspective view showing the shape of the mirrors disposed around it, FIG. 5 is a side view schematically showing the optical path of the scanning line in the first conventional example, and FIG. 6 is the arrangement of the mirrors to adjust the optical path length. An explanatory diagram showing a state in which the
Fig. 7 is a longitudinal side view showing the appearance of a mold when producing a rotating mirror by injection molding, Fig. 8 is a perspective view showing the first conventional example, and Fig. 9 is a perspective view showing the second conventional example. It is a diagram. 13...Rotating mirror 14...Reflecting surface, 17...Outgoing light, 18...Mirror, 22...Tilt mirror Applicant: Ricoh Co., Ltd.] Figure 7 Blade a Figure Z Figure 34] Figure 10 Bacteria (a) (b) 7 illustrations per piece”Z

Claims (1)

[Claims] 1. A plurality of light beams are provided in which the output light emitted from the laser light source is shaped, the shaped light is made incident on the reflective surface of a rotating mirror, and the light is scanned by the rotating mirror. In a laser beam scanning device that reads information recorded on the reading surface by illuminating the reading surface through a mirror and detecting reflected light from the reading surface, the laser beam is emitted from the laser light source and directed toward the rotating mirror. The reflecting surface of the rotary mirror is formed to be inclined at a certain angle so that the light travels obliquely downward in a direction opposite to the direction in which the emitted light is emitted, and the reflecting surface is reflected by the inclined reflecting surface. 1. A laser beam scanning device comprising a plurality of mirrors that guide the light onto the reading surface. 2. Shape the output light emitted from the laser light source, make the shaped light incident on the reflective surface of a rotating mirror, and send the light scanned by the rotating mirror to the reading surface via a plurality of mirrors. In a laser beam scanning device that reads information recorded on the reading surface by irradiating the light upward and detecting the reflected light from the reading surface, the direction of the emitted light emitted from the laser light source and directed toward the rotating mirror; The rotary mirror is disposed horizontally so that the rotation axis is in a parallel direction, and a mirror is provided so that the emitted light is incident on the reflective surface of the rotary mirror placed laterally, and the mirror is provided so that the light is transmitted through the mirror. The reflecting surface of the rotating mirror is formed to be inclined at a certain angle so that the incident light travels in a direction opposite to the emission direction of the emitted light, and the reflecting surface is reflected by the inclined reflecting surface. A laser beam scanning device comprising: a plurality of mirrors disposed on an optical path of light; and an inclined mirror that guides light reflected by the plurality of mirrors onto the reading surface.