JPH09198462A - Bar code reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a miniaturized bar code reader reduced in dead space by providing a folded mirror for reflecting scanning beams from a scanning means between the scanning means and a pattern mirror, and positioning the scanning means and the pattern mirror on one side of the folded mirror together. SOLUTION: A laser diode 12 as a reading light source, a polarization mirror 16, a rotary polygon mirror 18 as the scanning means, a folded mirror 20 and pattern mirrors 24 and 28, etc., are fixed on a common chassis. In this configuration, the folded mirror 20 for reflecting the reflected light from the rotary polygon mirror 18 is provided between the rotary polygon mirror 18 and the pattern mirrors 24 and 28. Besides, the rotary polygon mirror 18 and the pattern mirrors 24 and 28 are installed on one side of the folded mirror 20 together. Therefore, the rotary polygon mirror 18 can be arranged in a useless space which exists closer to the pattern mirrors 24 and 28 in a conventional device, so that a casing can be reduced by the space where the rotary polygon mirror 18 has been housed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bar code reading device for reading a bar code attached to or printed on a product at a point of sale operation in a department store or a supermarket.

[0002]

2. Description of the Related Art Bar code readers include stationary type in addition to pen type and hand-held type having a scanning unit in their hands. In a stationary bar code reader, an operator holds a product, for example, in his hand and moves it so that the bar code attached to the product traverses in front of the reading window of the bar code reader. The barcode reading device emits a laser beam to be scanned from a reading window, receives reflected light due to a barcode pattern, and reads information recorded in the barcode based on a change in intensity thereof.

[0003]

The stationary bar code reader is classified into a vertical type in which the reading window is arranged substantially vertically and a horizontal type in which the reading window is arranged substantially horizontally.

Recently, a horizontal bar code reader is sometimes used by being embedded in a counter. The barcode reading device used in this way is desired to be small enough to be embedded in a counter. In addition, it is desirable that the bottom be thin so that the bottom does not hit the operator's legs when the operator is seated in place.

In the conventional bar code readers, the optical path length from the scanning means to the reading window and the size of the pattern mirror require a certain size because the scanning line area is wide. In other words, in order to secure the required optical path length or component size inside the device, there is a functionally useless space, that is, a dead space, corresponding thereto.

It is an object of the present invention to provide a small bar code reader having a small dead space.

[0007]

According to the present invention, a light source for emitting a light beam, a scanning means for oscillating the light beam from the light source to generate a scanning beam, and a plurality of pattern mirrors for reflecting the scanning beam in different directions. And a bending mirror for reflecting the scanning beam from the scanning means, wherein the scanning means and the pattern mirror both have a bending mirror between the scanning means and the pattern mirror. It is located on the side.

In this structure, since the scanning means and the pattern mirror are located on the same side with respect to the folding mirror,
The scanning means can be arranged in a useless space existing near the pattern mirror in the conventional apparatuses. Therefore, it is possible to reduce the size of the device by reducing the size of the housing by the portion that accommodates the scanning means in the conventional device.

More preferably, the present invention further comprises, between the light source and the scanning means, a deflection mirror for reflecting the light beam from the light source, and the light source, the scanning means and the pattern mirror are both folding mirrors. It is located on the side of.

In the above structure, the light source is arranged on the same side as the folding mirror with respect to the scanning means,
There is a possibility that a sufficient optical path length cannot be secured between the light source and the scanning means. This is because the housing on the side of the folding mirror is cut down based on the scanning means to reduce the size of the device, and the depth of the housing is small in that direction. If, in the above-mentioned configuration, a sufficient optical path length is secured between the light source and the scanning means, it is necessary to lengthen the case that has been cut down. However, in this configuration, since the deflection mirror is provided, the light source is arranged on the same side as the scanning unit and the pattern mirror with the folding mirror as a reference, so that the size of the light source and the scanning unit can be increased without enlarging the housing. A sufficient optical path length can be secured between them.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIGS. 1 and 2, the bar code reader 10 includes a laser diode 12 and a deflection mirror 1.
6, a rotary polygon mirror 18, a bending mirror 20, four pattern mirrors 22, 24, 26, 28, a condenser mirror 30, a Fresnel lens 32, a condenser lens 34, and a light receiving element 36. Each of these elements is fixed to a common chassis.

The chassis on which each element is mounted is housed in the housing 52 after the optical adjustment is completed, and the inner window 40 is attached. The upper cover 5 having the outer window 42 attached to the housing 52
4 is attached.

As shown in FIG. 3, the outer window 42 has a gray coating 46 on the back surface of the glass 44, and a black coating 48 on the gray coating 46. The coatings 46 and 48 define the area of the exit window of the laser beam that is the reading light, and the contour thereof is determined in consideration of the appearance. For example, the support portion 5 that supports the rotating polygon mirror 18.
Selected as a shape that hides 2. In addition, it is preferable that the coating 46 that is visible from the outside be selected in a color that arouses the appearance, and that the coating 48 that is inside be selected in black in order to suppress reflection of light.

As shown in FIG. 1, the laser diode 1
2 is for emitting a laser beam which is a reading light,
It is housed in a holder 14 made of zinc die cast.
The surface of the holder 14 is preferably black alumite treated. The black alumite treatment suppresses internal reflection of stray light reflected by the inner window 40 and the outer window 42,
Contributes to improved reading accuracy.

The deflecting mirror 16 is composed of a circular flat mirror having a small diameter and is disposed in the reflecting surface of the condenser mirror 30, and reflects the laser beam emitted from the laser diode 12 toward the rotating polygon mirror 18. .

The rotary polygon mirror 18 is rotated by a motor 38, and each of the four reflecting surfaces has a different inclination angle with respect to the rotation axis of the motor 38. Therefore, the laser beam incident on the rotary polygon mirror 18 is reflected by the respective reflecting surfaces at different angles, and as a result, four scanning beams that periodically scan different trajectories are generated.

The folding mirror 20 uses the scanning beam generated by the rotary polygon mirror 18 as four pattern mirrors 22, 24,
Reflect toward 26 and 28. Four pattern mirrors 2
2, 24, 26 and 28 have different plane directions, so that one scanning beam is reflected by each pattern mirror in four different directions. That is, the four pattern mirrors 22, 24, 26, and 28 generate four scanning beams that scan in four different directions from one scanning beam.

The scanning beam reflected by the pattern mirror is transmitted through the inner window 40 and the outer window 42, and is read by the reader 10.
Is injected outside. Since four scanning beams are generated by the rotating polygon mirror 18, each of which is reflected in four different directions by the pattern mirror, a total of 16 scanning beams scan different trajectories on the outer window 42.

In FIG. 2, the scanning beams reflected by the pattern mirror 22 are shown by the symbols B22a and B22d, one for the innermost and one for the outermost. In reality, there are two scanning beams between the two scanning beams B2a and B22d.
Similarly, the scanning beams reflected by the pattern mirror 24 are denoted by reference numerals B24a and B24 respectively for the innermost and outermost scanning beams.
The innermost and outermost two beams of the scanning beam by the pattern mirror 26 are denoted by reference numerals B26a and B26d, and the innermost and outermost of the scanning beam by the pattern mirror 28 are denoted by reference numerals B28a and B28d. It is shown.

As can be seen from FIG. 2, the scan pattern is
The scanning beams reflected by the same pattern mirror are in a substantially parallel relationship, and the scanning beams reflected by different pattern mirrors clearly have different scanning directions.

When reading the information on the bar code attached to the product, the operator holds the product in his hand, directs the bar code toward the outer window 42, and moves the product to cross the outer window 42. As a result, the barcode traverses the scan pattern emitted from the outer window 42. At that time, the light reflected by the barcode passes through the outer window 42 and the inner window 40, is sequentially reflected by the pattern mirror, the bending mirror 20, and the rotary polygon mirror 18, and travels toward the condenser mirror 30.

The condensing mirror 30 has a concave mirror formed of a part of a spherical surface, reflects the beam from the rotary polygon mirror 18 toward the Fresnel lens 32, and converges the divergent beam into a converging beam. Change to.

The beam from the condenser mirror 30 passes through the Fresnel lens 32, and the condenser lens 34 causes the light receiving element 3 to pass.
The light is condensed on 6.

The scanning beams reflected by the outer pattern mirrors 22 and 24 and the scanning beams reflected by the inner pattern mirrors 26 and 28 have different intensities due to the difference in optical path length. Therefore, the light incident on the light receiving element 36 has different intensities depending on whether it is reflected by the outer pattern mirrors 22 and 24 or reflected by the inner pattern mirrors 26 and 28. The Fresnel lens 32 is provided to equalize the light intensity reflected by the outer pattern mirrors 22 and 24 and the light intensity reflected by the inner pattern mirrors 26 and 28.

A light receiving element 36 having a size of about 2.7 mm square is generally used, but the light receiving element 36 is preferably small in size for low noise and high-speed response. Adjustment becomes difficult. Therefore, in order to facilitate the optical adjustment, it is preferable to use a large-sized light receiving element within the allowable range.

A mechanism for adjusting the emission direction of the laser diode 12 will be described with reference to FIG.

As shown in FIG. 4, the holder 14 is supported on the upper end of the supporting column 62, and the supporting column 62 stands on a substantially crank-shaped base 64. A circular groove 66 is formed at a corner portion of the base 64, and the circular groove 66 is fitted to the cylindrical protruding portion 202 provided on the chassis 200 with the coil spring 82 interposed therebetween. A hole 6 is formed in the center of the circular groove 66.
8 is formed through which the screw 76 is screwed into the chassis 200.

The end of the base 64 opposite to the holder 14 has a chevron-shaped projection 2 formed on the chassis 200.
It is supported by 04, in which two slots 70 and 72 are formed. Slotted holes 70 and 72 are screws 7
6 extends along the circumference of a circle centered on
And 80 pass through slots 70 and 72, respectively, into chassis 20.
It is screwed to 0. (In FIG. 4A, the screws 78 and 80 are shown in cross section to show the slots 70 and 72.
(A) shows the heads of screws 78 and 80) Base 6
4 has a rectangular through hole 74 formed therein,
A groove 206 is formed at 00 in a position corresponding to this.

The base 64 can pivot about the screw 76 within a slight angular range. Thereby, the emission direction of the laser beam in the XY plane can be adjusted.
This adjustment is performed by inserting a tool such as a flat-blade screwdriver into the through hole 74 with the screws 78 and 80 loosened, inserting the groove 206 at the tip thereof, and tilting the tool to rotate the base 64.

Further, the angle of the base 64 can be changed with the contact point with the projecting portion 204 as a fulcrum. This allows
The emission direction of the laser beam in the XZ plane can be adjusted. This adjustment is performed by tightening or loosening the screw 76 while changing the inclination of the base 64 with the screws 78 and 80 loosened.

After the adjustment is completed, the screws 78 and 80 are tightened to fix the base 64 to the chassis 200.

Next, a mechanism for adjusting the focusing position with respect to the light receiving element 36 will be described with reference to FIG.

The element support member 100 includes a fixed end portion 102,
It has an elastically deformable bending portion 108, an arm portion 110, and an element housing portion 120, which are made of an integral part formed by injection molding of plastic or the like. Further, a cover 128 is attached to the element housing portion 120. A rectangular opening 130 is formed in the cover 138.

The element support member 100 has a fixed end portion 102 fixed to the chassis 200 by two screws 132 and 134. A long hole 11 that is long in the Y direction is formed in the arm portion 110.
2 is formed, and the screw 136 is screwed into the chassis 200 through the long hole 112. An eccentric screw 138 is provided on the chassis 200, and the eccentric screw 138 is housed in a circular hole 116 formed in the arm portion 110.
A long hole 112 and a circular hole 116 are provided below the arm portion 110.
A V-shaped groove 114 is formed between them, a concave portion 118 is formed outside the circular hole 116, and a concave portion 208 facing the same is also formed in the chassis 200, and a coil spring 140 is accommodated between them.

A recess 122 is formed in the element housing 120, and a long hole 124 elongated in the Y direction is formed in the bottom of the recess 122. The screw 142 passes through the long hole 124 and is screwed into the chassis 200. The element housing portion 120 is further formed with a long hole 126 elongated in the Y direction, and the guide pin 2 formed on the chassis 200 is formed in the long hole 126.
10 passes.

The element housing portion 120 has a Fresnel lens 3
2 and the condenser lens 34 are fixed, and these elements are covered with a cover 128. The light collecting element 36 is fixed to the analog substrate 146 fixed to the chassis 200 via the support member 144. Analog board 14
6 is equipped with various analog circuits required for this device.

With the screw 136 loosened, the eccentric screw 13
When 8 is rotated, the bending portion 108 is elastically deformed, and the portion beyond the bending portion (the arm portion 110 and the element housing portion 120) is Y-shaped.
Move in the direction. Therefore, the Fresnel lens 32 and the condenser lens 34 move in the Y direction with respect to the light receiving element 36 fixed to the chassis 200. That is, the eccentric screw 138
By turning, the Y
You can adjust the direction. After the adjustment, it is fixed by tightening the screw 136.

When the screw 142 is tightened or loosened, the element support member 100 is bent at a portion beyond the V groove 114, and the element housing portion 120 is displaced in substantially the Z direction. Therefore, the Fresnel lens 32 and the condenser lens 34 move in the Z direction with respect to the light receiving element 36 fixed to the chassis 200. In other words, by turning the screw 142, the light collecting position with respect to the light receiving element 36 can be adjusted in the Z direction.

The above-mentioned adjustment is performed while observing the position of the spot formed on the light receiving surface of the light receiving element 36 through the opening 130 formed in the cover 128. After the adjustment is completed, it is preferable to close the opening 130 by attaching a tape or the like.

By the way, the apparatus is provided with a speaker for notifying the operator that the reading of the bar code is completed. The speaker mounting structure will be described with reference to FIG.

As the speaker 150, it is preferable to use a waterproof speaker in consideration of drip-proof. Further, the front surface thereof is covered with a polyester film (for example, Myra (trademark)) 156 to prevent static electricity. The film 156 has an opening 158 for exposing the cone of the speaker 150.
Has a shape in which the lead wire 154 of the coil is hidden.

Generally, static electricity is scattered toward the metal portion around the speaker 150 and the lead wire 154 of the coil,
In this embodiment, the film 15 is formed on the front surface of the speaker 150.
6 is provided and the metal portion and the drawer 154 are not exposed to the outside, the static electricity is directed to the metal portion and the lead wire through the opening 158, and the amount thereof is the film 156.
It is obviously less than when there is no.

The speaker 150 has a housing 52 on the front surface.
Is attached in accordance with the portion provided with the plurality of slits, and the attachment is performed as follows. The front surface of the speaker 150 has an opening 158 in the film 156.
According to the above, the film is placed on the film 156, and the folding parts 160 on four sides are folded. A pair of facing guide members 56 having an L-shape is formed in the housing 52, and the speaker 150 wrapped with the film 156 is inserted into the groove defined by the pair of guide members 56. Then, a substantially W-shaped wire spring 162 is pushed in, both ends of which are elastically engaged with the guide member 56, and the central portion holds down the periphery of the magnet 152. As a result, the speaker 150 is firmly fixed to the housing 52. Moreover, the installation is easy.

As shown schematically in FIG. 7, the window 42
Around the area, electronic article surveillance (EAS: Electronic Art
The antenna wire 162 for the icle Surveillance Radio Frequency Device) system is arranged. In this system, a security tag including a resonance circuit is attached to a product in advance, and a detection device for detecting the security tag is generally installed at the exit. In addition, the antenna wire 162 is supplied with electric power that generates an electromagnetic field that causes an excessive induced current in the resonance circuit of the security tag. Japanese Patent Publication No. 7-500432 discloses an example of such a security tag. Crime prevention tags
For example, it is provided on the back side of the barcode sticker and is attached to the product together with the barcode sticker.

When a product is taken out by an illegal means, the detection device detects the resonance circuit of the security tag and notifies the clerk by an alarm or the like. On the other hand, when the product is taken out by a legitimate means, the product always passes near the window 42 of the barcode reading device for reading the barcode, and at that time, the resonance circuit of the security tag is connected by the antenna wire 162. It is not detected by the detection device because it is destroyed by the generated electromagnetic field.

The antenna wire 162 is, as shown in FIG.
Interface unit 164 provided on the lower side of the housing 52
Is pulled out from the housing 52. A wall portion 166 is provided beside the drawn-out portion of the antenna wire 162, and a space 168 is formed. The antenna wire 162 is EA
When S is not used, it is housed in this space 168.

A connector 174 for connecting necessary wiring is exposed on the interface section 164.
The cover 170 is flush with the housing 52 after the wiring is connected.
Is attached. The connector 170 is provided on the cover 170.
A groove 172 for drawing out the wiring connected to the No. 4 and the EAS antenna wire 162 is formed. The groove 172 is made up of three parts 172a, 172b, 172c that are continuous with each other, and each of these parts 172a, 172b, 172c.
Are formed on three mutually orthogonal wall portions of the cover 170 and face three directions. Thereby, the wiring and the antenna wire 162 can be pulled out in the most suitable direction among the three directions depending on the installation environment of the device, the positional relationship with the external device, and the like.

As shown in FIG. 9, the chassis 200 includes
An analog board 146 on which various analog circuits are mounted is fixed, and a connector 1 for connection with an external device is provided.
The decode board 176 to which 74 is attached is engaged. The decode substrate 176 is not fixed to the chassis 200 and is only caught by the claws 178, so that the degree of freedom of position with respect to the chassis 200 is high. Although not shown in FIG. 9, the chassis 200 includes
Necessary optical elements such as the laser diode 12 are attached. After the optical adjustment is completed, the chassis 200, the analog board 146, and the decode board 176 are integrally formed into the housing 5.
2, the decoding board 176 is fixed to the housing 52 with screws 180, and the chassis 200 and the analog board 146 are fixed to the housing 52 with screws 182 separately from the decoding board 176.

As described above, since the chassis 200 and the analog board 146 are fixed to the housing 52 separately from the decode board 176, the decode board 1 is inserted and removed when the wiring is inserted into and removed from the connector 174 fixed to the decode board 176.
Although 76 may sway or be displaced, the mutual positional relationship between the chassis 200 and the optically adjusted optical elements mounted on the analog board 146 does not shift.

Next, the control of the motor will be described.

When power is supplied to the main body, the rotary polygon mirror 1
The motor 38 of No. 8 starts. At the time of starting the motor 38, slow start control is used in order to reduce the inrush current flowing into the motor 38 at the time of starting.

FIG. 10 shows a configuration example of the motor rotation control circuit. The motor circuit control unit 310 includes a CPU 310a that controls the operation of the entire system and an MPU 310b that controls the operation of each circuit.

MPU3 for controlling the rotation of the motor 38
In 10b, the CPU 310a uses the power-on reset circuit 3
After detecting the reset signal of 13, the motor rotation permission signal is received. The motor drive signal output from the MPU 310b is a PWM signal, which is supplied to the control input terminal 38a of the motor 38 via the filter circuit 311 having the RC configuration.

The rotation of the motor 38 is controlled by the MPU 310.
This is performed by varying the duty ratio of the pulse of the PWM signal output from b so that the target frequency can be obtained. This duty ratio variable information is output to the rotation synchronization signal output terminal 38 which is output in proportion to the rotation speed of the motor 38.
It is obtained by referring to the frequency (time) of b by the CPU 310a, and the duty ratio of the PWM signal is changed until the difference becomes equal to the target value, and when it matches, it is fixed to that value.

FIG. 11 shows the PWM signal of the motor 38, and FIG. 12 shows the control operation flow. When the motor 38 is started for the first time, the frequency of the PWM signal is switched to f1 to improve the initial motion sensitivity of the motor 38 and gradually continue the rotation at a low speed. When the CPU 310a detects the signal from the rotation synchronizing signal output terminal 38b that the rotation of the motor 38 has exceeded a certain level, this time the frequency of the PWM control signal is switched to f2 and the rotation of the motor 38 is pulled to the rated rotation. Take control. The magnitude relationship between the frequencies of the PWM signals is f1 >> f2. When it is determined that the frequency is lower than the target frequency at the time of switching the frequency, in order to increase the rotation speed of the motor 38, the H of the frequency f2 is increased.
The duty ratio of the section is gradually increased. In addition, when decelerating the speed of the motor 38, the reverse operation is performed,
The control is stable at the duty ratio at which the rated speed is reached.

According to this control method, the MPU 3 of the motor circuit control means 310 is provided during the beginning of starting the motor 38.
The low-speed torque is increased by shifting the frequency of the PWM signal from 10b to a high range, and the initial motion sensitivity is improved.
The motor 38 gradually increases its rotation speed and eventually reaches a steady rotation speed. Since the number of rotations of the motor 38 in the steady rotation is extremely high, the corners of the rotary polygon mirror 18 are cut off or the air resistance of the edge portion of the rotary polygon mirror 18 is reduced in order to further reduce the drive current of the motor 38. Cover with a cover to reduce wind loss. When the rotation of the motor 38 reaches a predetermined rotation number, the rotation detection circuit 314 outputs a lighting permission signal for the laser diode 12 to an LD control circuit (not shown),
The laser diode 12 emits light. The laser diode 12 is supported by a supporting means which also functions as a heat sink, and its terminal is connected to a printed circuit board which also functions as a detachable connector.

The laser light emitted from the laser diode 12 is reflected by the rotating polygon mirror 18 of the scanning device and is irradiated by the pattern mirrors 22, 24, 26 and 28 in the direction determined by the angle, and a plurality of scanning patterns are obtained. Is generated. The angles of the mutually adjacent surfaces of the rotary polygon mirror 18 are different. Therefore, each pattern mirror 2
Multiple translated scan patterns are generated for 2, 24, 26, 28. The irregular reflection light of the laser light scanned on the bar code symbol becomes optical information corresponding to the information, returns in the opposite direction to the irradiation direction, and passes through the pattern mirrors 22, 24, 26, 28 and the rotary polygon mirror 18. And is focused on the light receiving element 36. In front of the light receiving element 36, a Fresnel lens 32 and a convex lens 34 are provided as a light collecting means.

Optical information is converted into an electric signal by the light receiving element 36, unnecessary noise is removed by an amplifier circuit and a filter circuit, and the signal is amplified into a binarizable signal. In this amplifier circuit stage, the same kind of amplifier circuits are connected in multiple stages (cascade connection) in order to largely attenuate the unnecessary signal band.
In this embodiment, five-stage multistage connection (cascade connection) is performed. The basic configuration of the amplifier is shown in FIG. 13 (A), and its frequency characteristic is shown in FIG. 13 (B). This amplifier circuit is a bandpass type (bandpass filter) amplifier circuit.
It has a band stop band of 6 dB / oct. 12 to 18 dB / oc with one amplification blocker depending on cost and mounting space
Although it is possible to construct a similar amplifier circuit by combining LPFs and HPFs having a large band stop band of t,
In some cases, the correct signal amplitude may not be obtained, or the characteristics may not be sharp, due to the signal band to be handled, insufficient drive capacity of the amplification element itself, and the like. Particularly, in the case of a bar code reader, since a pulse signal is handled, if the group delay time undulates for the above-mentioned reason, the pulse signal is not correctly transmitted, and pulse distortion easily occurs, which is not preferable.

In general, the frequency characteristic of the amplifier circuit in the bar code reader may be passed from direct current (DC), so it is necessary to separate unnecessary low frequency from the signal frequency band. If this frequency cannot be separated, it will lead to a problem that correct reading cannot be performed due to the influence of disturbance. Therefore, it is necessary to reduce unnecessary low-frequency frequencies to a level that does not affect the signal frequency band before the binarization process. Therefore, as shown in FIG. 14, this circuit configuration is configured such that amplifier circuits having the same type of frequency characteristics are connected in series in multiple stages (cascade connection) so that the phase characteristics can be maintained without impairing the tracking characteristics of the frequency characteristics of each element itself. It is expected that the effect of suppressing the deterioration of the frequency band will be minimized and the unnecessary frequency band will be attenuated more.

When binarizing the read signal amplified by the analog amplifying stage, it is necessary to prevent binarization of an inappropriate signal, for example, by specular reflection light from the bar code surface or excessive ambient light. An overvoltage detection circuit is provided to suppress an excessive signal level that is much larger than the above information. This overvoltage detection circuit has two independent thresholds for positive and negative signal levels, outputs an overvoltage detection signal independently for positive and negative signal amplitudes above the threshold, and outputs a binary signal by a binarization circuit. The binarized data output inhibiting means is controlled to prevent the information of the digitized pulse train from being erroneously transmitted to the decoding processing means. This is to prevent erroneous reading from occurring due to erroneous binarization due to the above influence.

The read signal is, as shown in FIG.
It is preferably within the dynamic range of the analog circuit, and in this case, the peak is detected and binarized. As shown in FIG. 15B, when the signal is amplified beyond the dynamic range of the analog amplifier circuit, the signal is saturated and the peak cannot be detected, so that a correct binary signal is generated. Becomes difficult. To detect the signal saturation of the analog circuit, as shown in FIG. 16 (A), the logical sum (OR circuit) of the output signals OUT1 and OUT2 of the comparator circuit in which the positive and negative thresholds can be set independently is taken. As shown in FIG. 16B, an H pulse is output each time an overvoltage is detected in the final stage of the analog amplifier circuit. This pulse signal is connected between the binarization processing means 380 and the decoding processing means 381 shown in FIG. 17 via the binarized data output inhibiting means 382. The binarized data output prohibiting means 382 is a one-shot circuit configured to output a pulse width of a constant cycle, which is composed of a gate circuit, some passive elements, and active elements. When the H pulse is detected from the above-mentioned overvoltage detection means (FIG. 16), the data line of the binarized signal is short-circuited to GND via the resistor 383 for a certain period, and the communication of the binarized data to the decoding processing means 380 is cut off. To do.

The amplified signal is binarized by the binarization circuit, input to the decoding circuit and decoded. When the decoding is completed, the operator can be notified by the notification means such as a speaker or the light emitting means such as an LED to notify the operator that the decoding was successful.

One piece of information is decrypted, the next information is subsequently entered, and the same is decrypted. Regarding this decoding means, as an auxiliary means for further increasing the decoding accuracy, as a means for initializing the scanning pattern, an initialization signal for the scanning pattern is used as the starting point of the first scanning pattern generated by the first pattern mirror (for example, 22). To obtain a signal for detecting. As a concrete means, the means for detecting the position of the pole of the rotor of the motor is provided so that it can be taken out as a rotation synchronizing signal.
From this, it is possible to extract the signal when the scanning line is at the start position of the first pattern mirror, and it is also possible to generate a read synchronization signal for each scan line by software processing, and read on the same line. It is effective for speeding up the decoding process because there is no need to read the data that has been read.

When the read information cannot be detected even after a lapse of a certain time after the series of information is finished, the current consumption is reduced,
The laser diode is switched from continuous lighting to flashing lighting to keep the motor running at a low speed in order to prolong the life of the laser and ensure high reliability of the motor. This controls the laser diode lighting control circuit and the motor drive control circuit through the CPU 310a. In this state, if the next bar code information can be detected, the continuous lighting state of the laser diode and the steady rotation of the motor can be restored by the information from the decoding circuit.

Although the embodiments have been described with reference to the drawings, the present invention is not limited to the above-described embodiments, and various modifications can be made.

For example, in the embodiment, the Fresnel lens 32 is used to equalize the intensities of the scanning patterns reflected by the outer pattern mirrors 22 and 24 and the scanning patterns reflected by the inner pattern mirrors 26 and 28. However, instead of providing the Fresnel lens 32, the mirror surface of the condenser mirror 30 may be changed from a spherical mirror to an elliptical mirror.

Alternatively, as another method, the outer pattern mirrors 22 and 24 and the inner pattern mirrors 26 and 28 are used.
You may change the reflectance with and. For example, the reflectance of the outer pattern mirrors 22 and 24 is 92%, and the reflectance of the inner pattern mirrors 26 and 28 is 78%.

Further, it is preferable to appropriately select the angle direction of the laser diode. The laser light is through windows 40 and 42
For the scanning direction. This is because the ratio of S-polarized light components to the windows 40 and 42 differs depending on the scanning direction. Therefore, the polarization direction of the laser light, that is, the laser diode, is adjusted so that the transmittance of the scanning pattern reflected by the outer pattern mirrors 22 and 24 becomes equal to the transmittance of the scanning pattern reflected by the inner pattern mirrors 26 and 28. It is more preferable to select the angle direction of 12 optical axes.

The scanning pattern appearing on the outer window 42 may be asymmetric with respect to the housing 52. For example, the scanning pattern shown in FIG. 2 may be rotated by a predetermined angle. This is achieved by changing the mounting direction of the chassis on which all the elements are mounted with respect to the housing 52, or by changing the plane direction of the pattern mirrors 22, 24, 26, 28.

[0071]

According to the present invention, by providing the folding mirror, the scanning means is arranged in the space near the pattern mirror, which has been wasted up to now. Therefore, the scanning means is accommodated until then. Since it is not necessary to secure a large space, and the housing can be made smaller by that much, a small barcode reading device can be obtained.

[Brief description of drawings]

FIG. 1 is a side sectional view of a barcode reading device according to an embodiment of the present invention.

FIG. 2 is a top view of the barcode reading device shown in FIG.

FIG. 3A is a top view of the outer window, and FIG.
It is sectional drawing in line 3B.

4A is a top view of a laser diode position adjusting mechanism, and FIG. 4B is a sectional view taken along line 4B-4B thereof.

FIG. 5A is a top view of the position adjusting mechanism of the light receiving element,
5B is a sectional view taken along line 5B-5B, and FIG.
It is sectional drawing in the C-5C line.

6A is a perspective view of the speaker, FIG. 6B is a front view of the speaker, and FIG. 6C is a side sectional view of the speaker.

FIG. 7 is a diagram schematically showing an antenna line for an EAS system.

FIG. 8 is a perspective view showing an interface section and a cover.

9A is a side view showing a chassis, an analog substrate, and a decoding substrate, and FIG. 9B is a perspective view showing a connection between the chassis and the decoding substrate.

FIG. 10 is a diagram of a configuration example of a motor rotation control circuit.

FIG. 11 is a diagram showing a motor drive signal.

12 is a diagram showing an operation flow of control by the circuit of FIG.

FIG. 13A is a diagram showing a basic configuration of an amplifier,
(B) is a diagram showing the frequency characteristic.

14A is a diagram showing a configuration in which the amplifiers of FIG. 13A are connected in series in multiple stages, and FIG. 14B is a diagram showing frequency characteristics thereof.

15A is a diagram showing a good read signal, and FIG. 15B is a diagram showing an undesired read signal.

FIG. 16A is a diagram showing a configuration of an overvoltage detection unit,
(B) is a diagram showing the output characteristic.

FIG. 17 is a diagram showing a configuration of a binarized data output prohibiting unit.

[Explanation of symbols]

 12 laser diode 16 deflection mirror 18 rotating polygon mirror 20 folding mirror 22, 24, 26, 28 pattern mirror 30 condensing mirror 36 light receiving element

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Eiji Miki 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Co., Ltd. (72) Akiki Kimura 2-43-2 Hatagaya, Shibuya-ku, Tokyo No. Olympus Optical Co., Ltd. (72) Inventor Masaki Iwata 2-43-2 Hatagaya, Shibuya-ku, Tokyo No. 2 Olympus Optical Co., Ltd. (72) Inventor Kubo Hidenobu 2-chome Hatagaya, Shibuya-ku, Tokyo 43 No. 2 Olympus Optical Industry Co., Ltd.

Claims (2)

[Claims] 1. A bar code reading apparatus having a light source for emitting a light beam, a scanning means for oscillating the light beam from the light source to generate a scanning beam, and a plurality of pattern mirrors for reflecting the scanning beam in different directions. Further, a bending mirror for reflecting the scanning beam from the scanning means is further provided between the scanning means and the pattern mirror, and both the scanning means and the pattern mirror are positioned on one side of the folding mirror. Characteristic bar code reader. 2. A deflecting mirror for reflecting a light beam from the light source is further provided between the light source and the scanning means, and the light source, the scanning means and the pattern mirror are both folding mirrors. A bar code reader which is located on the side.