JPH02278391A - Symbol reading device - Google Patents

Abstract

PURPOSE:To save weight and volume to be occupied by a mirror, and in addition, to realize a symbol reading device easy to manufacture by disusing the mirror by rotating or reciprocating directly a laser light source. CONSTITUTION:When a switch 5 is operated, a scanning table 3 is reciprocated by being driven by a solenoid 4, and simultaneously, a laser beam is emitted from a laser diode 7. The irradiating laser beam is reciprocated and distributed extending over a definite angle correspondingly to the reciprocating motion of the scanning table 3. A label 2 is irradiated by this distributed beam having passed through the opening part of the nozzle of a laser scanning head 1, and light reflected from the label 2 is received by a light receiving sensor 8. Thus, the label can be scanned by the laser beam directly even if the mirror is not used, and time to assemble the mirror can be saved, and the weight and the volume of the mirror can be saved.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention scans a laser beam emitted from a laser light source, directs the laser beam toward a distant object, and receives the reflected light. The present invention relates to a symbol reading device that reads symbols such as characters and codes displayed on the surface of an object.

<Prior art> In recent years, optical character readers (OCR) and barcode readers (BCR) have been developed to read characters and barcodes recorded on cards, packaging packages, etc. and instantly identify their contents.
Symbol reading devices such as the following are used.

Furthermore, recently, various hand belt type symbol reading devices have been developed that can be read simply by holding the housing in the hand and pointing the tip of the cylinder toward a distant target surface (for example, Japanese Patent Publication No. 63-60435). ). According to this, even if the barcode is a certain distance from the object to be read, by simply aiming and pressing the trigger button, the barcode can be read by emitting a laser beam and receiving the reflected light.

This symbol reading device includes a handy pistol-shaped laser scanning head, a laser light source, a movable mirror that scans the laser beam emitted from the laser light source over a fixed angular width, a light receiving element that receives the light reflected from the object to be read, and It has a structure in which a processing circuit, etc. that processes the light reception signal from the light receiving element and identifies the object to be read is integrated.

Since a symbol reading device with this structure uses a laser beam, it is possible to obtain a small spot even at a distant location, and it is possible to read not only nearby objects but also distant objects (the reading depth is In addition, since the beam is automatically scanned using a movable mirror, there is no need to move the tip of the cylinder in contact with the surface to be read, unlike in pen-type symbol reading devices, just aim at the target to be read. In addition to the fact that it is handy and can be carried anywhere, it is also possible to perform reading operations very easily even on objects that cannot be touched directly, such as codes printed on printed circuit boards. .

<Problems to be Solved by the Invention> In the symbol reading device described above, in order to scan the laser beam from a laser light source built into the laser scanning head, the laser beam is reflected by a mirror that vibrates back and forth.

However, since the beam is scanned by slight variations in the mirror angle, it is necessary to incorporate a mirror with a precision-machined mirror surface with high accuracy, which poses problems in that it is costly and requires time and effort to assemble.

Rotating polygon mirrors are also used (for example, see US Patent No. 3,899,687), but processing polygon mirrors requires extremely fine precision, and furthermore, polygon mirrors weigh and occupy a large volume. So,
The drawback is that the laser scanning head is large and heavy to carry.

The present invention has been made in view of the above problems, and
The purpose is to provide a symbol reading device that can reduce the number of parts and assembly steps, and can be made smaller and lighter than conventional devices.

Means for Solving the Problems> The symbol reading device of the present invention for achieving the above objects has the following features:
It has a scanning means that directly rotates or reciprocates the laser light source.

The scanning means may rotate or reciprocate the laser light source and the light receiving means in the same direction.

Effect> By directly rotating or reciprocating the laser light source, the laser beam can be directly scanned without using a mirror, saving the effort of assembling the mirror and saving the weight and volume of the mirror.

In particular, when the laser light source and light receiving means are moved simultaneously,
The light-receiving means always faces the direction of the spot of the laser beam hitting the target surface, which can prevent angular differences in light-receiving sensitivity from occurring.

<Example> Embodiments will be described in detail below with reference to the accompanying drawings showing examples.

FIG. 1 shows a laser beam output type hand belt type symbol reading device for reading symbols such as characters and bar codes. This symbol reading device includes a laser diode (7) in a pistol-shaped laser scanning head (1).
) and a scanning table (3) incorporating a light receiving sensor (8),
It is provided so that it can be rotated reciprocally by a solenoid (4). Furthermore, the output signal of the light receiving sensor (8) is waveform-shaped and binarized at an appropriate slice level to obtain a signal corresponding to the black and white of the barcode to be read attached to the label (2). A processing circuit (6) is provided for identifying the content of the barcode.The code (14) emerging from the laser scanning head (1) is a signal for providing the output signal of the processing circuit (6) to the outside. The switch (5) is a reading trigger switch for the symbol reading device.

To explain in more detail, the scanning table (3) includes a laser diode (7) and a light receiving sensor (8), as shown in the cross-sectional view of FIG.
) are installed parallel to each other, and a lens (9) that focuses the laser beam to a diameter of 0.1-0.2 mm is placed facing the output surface of the laser diode (7), and the light receiving sensor (8) A lens (10) is arranged facing the surface to collect as much light reflected from the label (2) as possible. In addition,
The degree of parallelism between the laser diode (7) and the light receiving sensor (8) is not very strict, and it is sufficient that they face approximately the same direction.

Further, FIG. 3 shows a state in which the scanning table (3) is attached to the solenoid (4). The solenoid (4) is generally called a rotary solenoid, and when current flows through it, it rotates at a certain angle (4).
00), and when the current is stopped, it returns to its original position due to the force of the spring. Therefore, by turning on and off the current flowing through the solenoid (4), the scanning table (3) is turned on and off by the solenoid (4).
It reciprocates as shown by arrow A around the axis 4).

In the symbol reading device, when the switch (5) is operated, the scanning table (3) is reciprocated by driving the solenoid (4), and a laser beam is irradiated from the laser diode (10,000).The irradiated laser beam is scanned back and forth over a certain angle in response to the reciprocating movement of the scanning table (3).This scanned beam passes through the opening at the tip of the laser scanning head (1) and is directed onto the label (2). The irradiated light reflected from the label (2) is received by the light receiving sensor (8).

As described above, since there is no mirror for scanning the beam of the laser diode (7), it is possible to achieve a reduction in size and weight and to simplify assembly.

In addition, since the light receiving sensor (8) follows the same direction as the laser diode q) as described above, the light receiving sensor (8) always tracks the label (2).
It can directly face the laser spot above.

Therefore, compared to the conventional case where the light receiving sensor (8) is fixed facing the front direction of the laser scanning head (1), the reflection intensity from the center of the label (2) and the The difference with the reflection intensity from the edge can be reduced.

This relationship will be explained in detail using FIG. Figure 6 (a
) indicates the positional relationship between the light-receiving sensor (8) and the label ('2J). Conventionally, the light-receiving sensor (8) was placed almost directly in front of the center (Q) of the label (2).For this reason, , the received light intensity of the light receiving sensor (8) is indicated by the broken line (X) in Fig. 6(b).
As shown in , it is large at the center (Q) and large at the ends (P) (
R) becomes smaller.

Therefore, by making the light receiving sensor (8) follow the same direction as the laser diode (7) as described above, the reflected spot can always be seen in front, and the received light intensity is determined by the solid line in Fig. 6(b). It will look like (Y) with both ends raised. In other words, the reception sensitivity is improved by the amount that both ends are raised, leading to an improvement in the reading depth.

It should be noted that the present invention is not limited to the above-described embodiment, and for example, a scanning table (3a) as shown in FIG. 4 may be used instead of the rotary type solenoid (4). This scanning table (3a) is made of a magnetic material, and the scanning table (11)
It is possible to rotate around the center. Then, actuating piece (3b
), and by alternately attracting this actuating piece (3b) to the electromagnet (12) or (13), the scanning stage (3a
) can be reciprocated.

Furthermore, as shown in FIG. 5, the scanning table (3C) is formed into a columnar shape, its central axis is connected to the shaft of the motor (4a), and the electrode (7a) of the laser diode (7) is connected to the scanning table (3C). )
The contact electrode (7b) may be attached in a ring shape around the periphery of the contact electrode (7b), and the laser beam may be scanned by rotating the motor (4a) in one direction.

Furthermore, in the above description, the scanning table (3) has been rotated or reciprocated in forward and reverse directions, but it is also possible to reciprocate linearly using a linear motor, a magnet, or the like.

It is also possible to attach only the laser diode (7) to the scanning table (3), and fix the light receiving sensor (8) so that it faces the front of the laser scanning head (1) without placing it on the scanning table (3). good. According to this, although it is not possible to reduce the difference between the reflection intensity from the center of the label (2) and the reflection intensity from the edges of the label (2), (3) is lighter and the solenoid (
4) The load can be reduced.

Other - Various design changes may be made without changing the gist of the present invention, such as using a laser tube instead of the laser diode (7) or applying it to a stationary symbol reading device other than a hunt belt type. is possible.

<Effects of the Invention> As described above, according to the present invention, by directly rotating or reciprocating the laser light source, the mirror, which was indispensable in the past, is no longer necessary, so the weight occupied by the mirror is reduced.
It is possible to realize a symbol reading device that saves space and is easy to manufacture.

Furthermore, since precision mirrors are expensive, eliminating the mirror can significantly reduce costs.

Furthermore, by moving the laser light source and the light receiving means in the same direction, it is possible to improve the sensitivity toward the edge of the reading surface, resulting in a deeper reading depth and accurate reading even when the reading surface is dark. Be able to read.

[Brief explanation of drawings]

Figure 1 is a perspective view showing the internal state of the symbol reading device, Figure 2 is a sectional view showing the structure of the scanning table, Figure 3 is a perspective view showing the scanning table attached to the solenoid, and Figure 4 is the scanning A plan view showing an example in which the scanning table is driven by an electromagnet, FIG. 5 is a perspective view showing an example in which the scanning table is driven by a rotary motor, and FIG. 6 (a) is a plan view showing the arrangement relationship between the light receiving sensor and the read label. , FIG. 6(b) is a graph of the amount of received light. (1)...Laser scanning head, (2)...Reading label, (3) (3a) (3c
)...Scanning table, (4)...Solenoid, (4a)...
...Motor, (7)...Laser diode, (8)...
...Light receiving sensor, (+2) (13)...Electromagnet

Claims (1)

[Claims] 1. A symbol attached to a target surface by scanning a laser beam output from a laser light source, receiving the light reflected from the target surface by a light receiving means, and converting it into an electrical signal. What is claimed is: 1. A symbol reading device for reading a symbol, comprising a scanning means for directly rotating or reciprocating a laser light source. 2. The symbol reading device according to claim 1, wherein the laser light source, the light receiving means, and the scanning means are built into a hand-held housing. 3. Claim 1, wherein the scanning means rotates or reciprocates the laser light source and the light receiving means in the same direction.
The symbol reading device described.