JPH02183880A - symbol reading 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] <Industrial Application Field> The present invention scans a laser beam emitted from a laser oscillation device, directs the laser beam toward a distant object, and receives the reflected light. Among symbol reading devices that read characters, codes, and other symbols displayed on the surface of objects, in particular, so-called hand belt type symbols that can be read simply by holding the casing in your hand and pointing the tip of the cylinder toward a distant object surface. Regarding a reading device.

<Prior Art> As computers have become widely used in recent years, input/output devices connected to computers are required to have more diverse functions. for example,
Optical character readers (OCR) and barcode readers (BCR) that read characters and barcodes recorded on cards, packaging packages, etc. and instantly identify their contents can be carried and used anywhere. There is a need for devices to be smaller and lighter. In addition, there is also a need for a function that allows characters and codes to be read accurately, not only by simply touching the surface of the characters and codes, but also from a certain distance from the object to be read, or even when not facing the object directly. ing.

In order to realize the above functions, recent symbol reading devices:
Called the hand belt type, it has a handy pistol-shaped housing that includes a small laser oscillation device, a polygon mirror that scans the laser beam emitted from the laser oscillation device with a fixed angular width,
A structure is provided in which a light-receiving element that receives light reflected from an object to be read and a processing circuit that processes a light-receiving signal from the light-receiving element to identify the reading 1=j phenomenon are integrated.

According to this I+'+- construction symbol reading device, since a laser beam is used, it is possible to apply a small spot even at a distant position, and it is possible to read not only nearby objects but also distant objects. (reading depth is wide) and because the beam scans automatically, there is no need to touch and move the tip of the barrel like with pen-type symbol reading devices, just aim at the target to be read. This, coupled with the fact that it can be carried anywhere with the X-mount, makes it very easy to read objects that cannot be touched directly, such as codes printed on printed circuit boards. .

<Problems to be Solved by the Invention> In the hand belt type symbol reading device described above, the scanning angle width of the laser beam is regulated by the rotational movement range of one reflective surface of the polygon mirror.

However, in order to scan a target to be read with a laser beam, not all of the above-mentioned laser beams are required, depending on the distance from the target to be read. If the object to be read is very far away, the scanning angle of the laser beam required is minute, and even when reading is done with the beam irradiation aperture of the symbol reading device in contact with the object to be read,
The angle may be any angle that allows the beam aperture to be seen at most.

However, in the conventional symbol reading device, the scanning angle, which is regulated by the rotational movement angle of one reflective surface of the polygon mirror, is set to two to three times the angle at which the beam aperture is viewed. It is. For this reason, a problem arises in that the laser beam q=t is irradiated on useless parts and energy is wasted.

The reason for this is mainly on the side of the polygon mirror. In other words, in order to narrow the scanning angle width, the number of surfaces of the polygon mirror must be set to a considerably large number, or the polygon mirror is a minute optical component, and the precision required for its processing is required to be quite high. . Therefore, the increase in the number of pages is
This directly leads to finer machining accuracy, which in turn leads to increased costs.

The present invention has been made in view of the above problems, and it is possible to emit a laser beam only within the available H effective angle range without changing the design of the polygon mirror, thereby reducing energy consumption. The purpose is to provide a symbol reading device.

Means for Solving the Problems> The symbol reading device of the present invention for achieving the above objects has the following features:
an emission angle determination means for detecting whether the emission angle of the laser beam to be scanned is within the a-effect angle range; It has a laser drive control means for controlling the drive of a laser output device for irradiation.

Effect> According to the symbol reading device having the above configuration, when the emission angle of the laser beam is outside the effective emission angle, the laser output can be stopped or reduced by the laser output drive control circuit, so that the effective emission angle can be stopped or reduced. A laser beam with normal output can be emitted only within this angle.

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

FIG. 2 shows a laser beam output type hand belt type symbol reading device for reading symbols such as characters and bar codes. This symbol reader is a pistol-shaped 2
Inside the body (1) are a semiconductor laser oscillation device (2), an aberrational lens (3) that focuses the output light of the semiconductor laser oscillation device (2), and a rotating type that scans the output light over a fixed angular width. polygon mirror (4), polygon mirror (4)
a motor (11) that rotates the cylindrical lens (5), a cylindrical lens (5) that condenses the light emitted from the aperture (13), which hits the reading target (6) placed a distance away and is reflected; A light receiving element (7) such as a photodiode that receives reflected light through a cylindrical lens (5), a polygon mirror (
4) A scanning detection light receiving element (12a) that is installed at the end of the effective scanning angle range of the reflected light reflected from the surface and directly receives the reflected light, and a semiconductor laser oscillation device (2) according to the control procedure of the present invention. In addition to controlling the laser output of the light receiving element (7), the output signal of the light receiving element (7) is waveform-shaped and binarized.
A board (9) is housed on which is mounted a signal j'-4 which corresponds to the shape of, for example, a bar code to be read, and a processing section that identifies the contents of the bar code based on this signal. The code (lO) coming out of the housing (1) is a signal code for providing the output signal of the processing unit (9) to the outside, and the lever (8) is a reading switch of the symbol reading device. There is.

FIG. 1 shows a semiconductor laser oscillation device (2) based on a scanning detection signal supplied from a scanning detection light receiving element (12a).
FIG. 2 is a functional block diagram showing a configuration for controlling the output of the device. In the figure, (12b) is a scanning detection light receiving element (12a).
); (12el) is a CPU that causes a timer (12c2) to count a certain period of time T after receiving the output signal from the amplifier circuit (12b);
15) controls the drive switch of the semiconductor laser oscillation device (2) on/off based on the output signal transmitted from the CPU (12el), and turns on/off the drive switch of the semiconductor laser oscillation device (2).
) is a laser drive control circuit that oscillates and stops oscillation. The fixed time T counted by the timer (12c2) is the point in time when the laser beam reflected from the -reflecting surface of the rotating polygon mirror (4) finishes passing through the aperture (13) (the optical path (1) in FIG. , b)) until the point in time when the laser beam reflected from the next reflecting surface reaches the aperture (13) (see optical path (La) in FIG. 1).

The CPU (12cl) and the timer (12c2) constitute a processing circuit (12c), and the scanning detection light receiving element (
12a) The amplifier circuit (12b) and the processing circuit (12e) constitute the emission angle determination means described in the claims, and the laser drive control circuit (15) constitutes the laser drive control means.

Next, the operation of the symbol reading device having the above configuration will be explained.

In the above symbol reading device, when the lever (8) is operated, the polygon mirror (4) is driven by the motor (11).
At the same time, the semiconductor laser oscillation device (2)
A laser beam is irradiated from the The irradiated laser beam hits one of the reflective surfaces of the rotating polygon mirror (4) and is reflected, and the reflected light is scanned over a constant angle in accordance with the rotational movement of the reflective surface. This scanned beam passes through the aperture (13) and is irradiated onto the object to be read (6). The light reflected from the reading target (6) is received by the light receiving element (7),
The electrical output signal is detected and amplified by a processing circuit provided in the processing section (9), and then binarized. By being binarized, the signal becomes a rectangular square corresponding to the shape of the barcode, and its pulse interval, pulse width, etc. are read to identify the content of the barcode.

The laser beam that hits the reflective surface of the polygon mirror (4) and is scanned also enters the scanning detection light receiving element (12a) at a time point near the end of scanning.

The scanning detection light-receiving element (12a) is switched on in response to the incidence of this laser beam, and transmits an electric signal corresponding to this switch-on to the amplifier circuit (12b). The amplifier circuit (12b) amplifies the electrical signal and transmits it to the processing circuit (12c) connected to the next stage. When the processing circuit (12c) receives the signal, it transmits a control signal to stop the laser oscillation to the laser drive control circuit (15), and starts counting a certain period of time T by the timer (12c2). The laser drive control circuit (15) that has received the control signal stops the laser oscillation of the semiconductor laser oscillation device (2). As a result, the laser beam is
The laser beam disappears when entering the range shown by ■ from the range shown by .

Even after the laser oscillation of the semiconductor laser oscillation device (2) stops, the polygon mirror (4) continues to rotate. However, even if the next reflective surface of the polygon mirror (4) comes to face the semiconductor laser oscillation device (2), when the oscillation of the semiconductor laser oscillation device (2) has stopped, the next laser beam cannot be activated. Unable to start scan. Therefore, the processing circuit (1
2c) waits for the count up of the above-mentioned fixed time T,
A control signal for starting laser emission is sent to the laser drive control circuit (15). The laser drive control circuit (15) receiving this control signal starts laser oscillation of the semiconductor laser oscillation device (2). Since the certain time T is defined as described above, laser oscillation is restarted from the end of the aperture (13) (see optical path (La) in FIG. 1). In other words, the laser beam is irradiated only within the effective angle range (range indicated by 1 in the figure) emitted from the aperture (13),
In other angle ranges (the range indicated by ■ in the figure), oscillation is stopped.

In this way, since the laser beam can be irradiated only within the effective angle range I, the laser beam will not be irradiated to the part outside the effective angle range (I) as in the conventional case. Therefore, unnecessary consumption of TU force for oscillating the laser beam can be prevented.

FIG. 3 shows a second embodiment of the symbol reading device according to the present invention.

The difference from the embodiment shown in FIG. 1 is that a scanning detection light receiving element (
12a) and a timer (12c2), a photoreflector (21) and a photoreflector (21) are arranged to face the reflective surface of the polygon mirror (4).
) level determination circuit (22) that determines the output signal level of
This is due to the fact that we adopted

Generally, if the laser drive control of the present invention is not performed, the laser beam will move as the polygon mirror (4) rotates. are scanned in this order. In other words, the optical path (L
Starting from c), it is scanned to (La), (Lb), and (Ld). Among these, if the laser beam is within the effective angle range I
There is a rotation angle range of the polygon mirror (4) that corresponds to when the polygon mirror (4) is being scanned.

Therefore, in this embodiment, when the polygon mirror (4) is within the above rotation angle range, the photoreflector (21)
was provided at a position facing the -reflection surface of the polygon mirror (4).

The photoreflector (21) is a light emitting element 'T-(21)I)
and a light-receiving element T- (21b), and a light-emitting element (2
When the light irradiated from 1a) is irradiated onto the polygon mirror (4), it is reflected by the -reflection surface of the polygon mirror (4) and is received by the light receiving element (21b). The light emitted from this light emitting element (21a) has an angle-to-intensity distribution in which the amount of irradiated light gradually decreases as the j1α radiation angle becomes more inclined than the amount of light irradiated onto the true II surface. I'm doing it.

The level determination circuit (22) reads the output signal vIl from the light receiving element (21b) and compares it with the reference value Vo. The base $ fi Vo is this polygon mirror (4)
is set to an appropriate value in order to determine whether or not is within the above rotation angle range, in other words, whether or not the laser beam is emitted within the effective angle range I. Light receiving element (2
When the output signal VIm from 1b) becomes larger than the base IllIMVo, the photoreflector (21) installed at the above position is opposite to or close to the -reflection surface of the polygon mirror (4). Therefore, it can be determined that the laser beam is within the nail effective angle range I. When the output signal vIQ from the light-receiving element (21b) is smaller than the reference value Vo, the photoreflector (21) is directly facing or close to the boundary between adjacent reflective surfaces of the polygon mirror (4). It can be determined that the laser beam is outside the effective angle range.

Therefore, when the output signal Vl from the light receiving element (21b) exceeds the reference value Vo, the level determination circuit (22) outputs a laser oscillation signal to the laser drive control circuit (15), and the output signal from the light receiving element (21b) The output signal V deception is the standard ii
If it is lower than V o, the level determination circuit (22) outputs a laser oscillation stop signal to the laser drive control circuit (15), thereby controlling the time during which the polygon mirror (4) is within the rotation angle range, that is, the laser drive control circuit (15). The laser beam is directed to the aperture (1) only when the beam is within the effective angle range I.
3).

FIG. 4 is a diagram showing still another embodiment, in which a polygon mirror (
4), a light-absorbing rotation angle display mark (4a) is placed on the upper end surface of the polygon mirror (4).
) are drawn radially. And polygon mirror (4
) A photoreflector (31) is provided opposite the upper end surface of the photoreflector (31). The photoreflector (31) rotates when the polygon mirror (4) is at a rotation angle corresponding to the effective emission angle range I of the laser beam.
is directly above the rotation angle display mark (4a) (or
The rotation angle display mark (4a) may be directly above the adjacent rotation angle display marks (4a). The photoreflector (31) includes a light emitting element (31a) and a light receiving element (31b).
), but the difference from the photoreflector (21) in Figure 3 is that the amount of light emitted from the light emitting element (31a) 4i has a sharp peak only toward the front. be. Therefore, even if the polygon mirror (4) rotates at high speed, the rotation angle display mark (4a) drawn on the upper end surface of the polygon mirror (4) can be accurately detected.

When the polygon mirror (4) rotates, the light receiving strand (31b)
The received light signal is sent to the signal detection circuit (32), which shapes the received light signal waveform and sends it to the laser drive control circuit (15).
15) starts the semiconductor laser oscillation device (2) based on this signal.
) laser oscillation can be driven and stopped. Therefore, the laser beam can be emitted from the aperture (13) only during the time when the laser beam is within the effective angle range l.

As explained above using a few examples,
Since laser oscillation is stopped when the laser beam is not emitted from the aperture (13), the energy required for laser oscillation can be saved. Conversely, if it is possible to consume the same amount of energy required for driving the laser as in the past, it is possible to increase the output of the laser light that irradiates the effective angle range.

It should be noted that the present invention is not limited to the above embodiments. For example, in the above embodiments, when the laser beam is outside the effective angle range, the laser oscillation is stopped, or
It is also possible to suppress laser oscillation to a certain level without completely stopping it. Furthermore, it goes without saying that the present invention is applicable not only to barcode reading devices but also to OCR and the like. Various design changes can be made without changing the gist of the invention.

<Effects of the Invention> As described above, according to the symbol reading device of the present invention, it is possible to detect whether the scanning angle of the laser beam is within the H effective angle range and prevent the laser beam from moving outside the effective angle range. Since emission can be restricted, wasteful power consumption of the laser oscillation device due to laser beam emission can be reduced, and the life of the laser oscillation device can be extended.

[Brief explanation of the drawing]

Fig. 1 is a mechanical diagram of main parts of a symbol reading device showing a first embodiment of the present invention, Fig. 2 is a perspective view showing the internal structure of the symbol reading device, and Fig. 3 shows a second embodiment. Mechanical diagram of main parts of symbol reading device FIG. 4 is a mechanical diagram of main parts of a symbol reading device showing a third embodiment. (1)...Housing, (2)...Laser oscillation device, (6
)... Barcode, (H)... Opening, (12)
. . . Output angle determining means, (12a) . . . Light receiving element r for scanning detection, (12b) . .
・Amplification circuit, (12c)...Processing circuit, (15)...
・Laser drive control circuit, (21)(31)...Photoreflector, (22)・
...Level judgment circuit, (32)...Signal detection circuit Patent applicant Sumitomo Electric Industries, Ltd. Agent

Claims (1)

[Claims] 1. Scanning a laser beam output from a laser oscillation device built into a handheld housing, and directing the laser beam onto a target surface through an opening formed at the tip of the housing. In a symbol reading device that reads symbols on a target surface by emitting light toward the target surface and receiving reflected light from the target surface, it is determined whether the output angle of the scanned laser beam is within the effective angle range. It has an emission angle determination means for detecting the emission angle, and a laser drive control means for controlling the drive of the laser output device so as to irradiate the laser beam only when the emission angle of the laser beam is determined to be within the effective emission angle. A symbol reading device featuring: