JPH09198461A - 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 reflected light from a scanning means between the scanning means and a light receiving element, and positioning the scanning means, a pattern mirror and the light receiving element on one side of the folded mirror. SOLUTION: A laser diode 12 as a light source, a deflection mirror 16, a rotary polygon mirror 18 as the scanning means, pattern mirrors 22 and 26, a folded mirror 33 and a light receiving element 36, etc., are fixed on a common chassis 200. In this configuration, the folded mirror 33 for reflecting the reflected light from the rotary polygon mirror 18 is provided between the rotary polygon mirror 18 and the light receiving element 36. Besides, since the light receiving element 36 is positioned on the same side as the rotary polygon mirror 18 and the pattern mirrors 22 and 26 with respect to the folded mirror 33, the light receiving element 36 can be arranged in a useless space which, exists close to the pattern mirrors 22 and 26 in a conventional device. Thus, casing can be miniaturized by the space where the light receiving element 36 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. The stationary bar code reader has a relatively large reading window,
A plurality of scanning beams are emitted from there. Generally, the trajectories of a plurality of scanning beams on the reading window, that is, the scanning patterns, extend in a plurality of different directions.

When reading the information on the bar code attached to the product, the operator holds the product, for example, and directs the bar code on the product toward the reading window of the bar code reader.
Move goods. By this operation, the barcode attached to the product traverses the scanning beam, and the light reflected and scattered by the barcode enters the inside of the reading device through the reading window,
It is focused on the light receiving element. The bar code reader reads bar code information based on the temporal change in the light intensity detected by the light receiving element.

[0004]

From the user's point of view, the smaller the occupied area of the bar code reading device is, the more preferable it is. Therefore, the bar code reading device is desired to be miniaturized.

Generally, in a bar code reader, a light beam emitted from a light source is made into a scanning beam whose direction changes with time, and the scanning beam is reflected by a plurality of pattern mirrors in different directions to read it. It becomes a plurality of scanning beams which scan in different directions on the window and is emitted from the reading window. The light reflected and scattered by the bar code enters the inside of the apparatus through the reading window, is reflected by the pattern mirror, passes through the scanning means, and then is condensed on the light receiving element by the condensing means such as a lens.

By the way, the optical path length between the optical elements such as the light source, the scanning means, the pattern mirror, the reading window, the condensing means, the light receiving element, or the size of each, depends on design requirements, for example, on the reading window. Appropriate dimensions are selected according to the design value such as the length of the trajectory of one scanning beam (that is, the scanning line) and the number of scanning lines having different directions. Therefore, the size of the device cannot be reduced by simply shortening the optical path length or the size of each of the optical elements.

[0007] However, a functionally useless space, a so-called dead space, exists inside or outside the device, and if the dead space can be reduced, the device can be downsized.

The present invention has been made in view of such a point of view, and an object of the present invention is to provide a compact bar code reader having a small dead space.

[0009]

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 light receiving element for receiving reflected light from an object that traverses the scanning beam, further comprising a bending mirror for reflecting the reflected light from the scanning means between the scanning means and the light receiving element. The scanning means, the pattern mirror and the light receiving element are all located on one side of the folding mirror.

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

More preferably, the present invention further comprises a deflection mirror for reflecting the light beam from the light source between the light source and the scanning means, and the light source, the scanning means, the pattern mirror and the light receiving element are all folded together. A bar code reader characterized in that it is located on one side of a bending mirror.

In the above-mentioned structure, the light source is arranged on the same side as the folding mirror with respect to the scanning means, and in some cases, the folding is performed in order to secure a sufficient optical path length between the light source and the scanning means. It will be placed farther than the mirror. Such a positional relationship eliminates the advantage of bringing the light receiving element close to the pattern mirror. In order to deal with such a situation, in this configuration, a deflection mirror that reflects the light beam emitted from the light source is provided, and the light source is arranged on the same side as the scanning means, the pattern mirror, and the light receiving element with reference to the folding mirror. To do. As a result, a sufficient optical path length can be secured between the light source and the scanning means without enlarging the housing.

[0013]

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 which is a light source, a deflection mirror 16, a rotary polygon mirror 18 which is a scanning means, and four pattern mirrors 22, 24 and 26. , 28, Fresnel lens 32, bending mirror 33, condenser lens 34, light receiving element 3
6, and these optical elements are fixed to a common chassis 200.

The chassis 200 on which each optical element is mounted is
After the optical adjustment is completed, it is stored in the housing 52. An upper cover 54 to which the reading window 42 is attached is attached to the housing 52.

The laser diode 12 is housed in a holder 60 made of zinc die cast, and the deflection mirror 1
A laser beam is emitted toward 6. Holder 60
Is attached to the chassis 200 so that the emission direction of the laser beam can be adjusted. The mounting structure, that is, the adjusting mechanism will be described later. It is more preferable that the surface of the holder 60 is black alumite treated.
In the black alumite treatment, the laser beam is used as the reading window 4
It suppresses internal reflection of stray light that is reflected by 2 and disturbance light that has entered through the reading window 42.

The deflecting mirror 16 is composed of a small rectangular plane mirror and is attached to the central portion of the Fresnel lens 32 with an inclination of 45 °. The deflecting mirror 16 deflects the laser beam from the laser diode 12 by 90 ° and reflects the rotating polygon mirror. Send to 18. The deflection mirror 16 is attached by, for example, adhering the deflection mirror 16 to the largest side surface of the attachment member 17 in the shape of a right-angled isosceles triangular prism, and fixing it to the central portion of the Fresnel lens 32 by adhesion.

The rotating polygon mirror 18, which is a scanning means, has four reflecting surfaces around it and is rotated by a motor 38. Since the laser beam from the deflecting mirror 16 is reflected by the reflecting surface whose surface direction changes with time, it becomes a scanning beam whose direction changes with time and crosses the four pattern mirrors 22, 26, 28, 24. To do. Further, the four reflecting surfaces of the rotary polygon mirror 18 have different inclinations with respect to the rotation axis of the motor 38. Therefore, the rotary polygon mirror 18
The laser beam incident on is reflected by each reflecting surface at different angles, and four scanning beams parallel to each other are generated across the pattern mirror in different trajectories.

The four pattern mirrors 22, 26, 28,
24 are both plane mirrors, and are arranged in different directions. Therefore, the scanning beams that traverse the four pattern mirrors 22, 26, 28, and 24 are reflected by the respective pattern mirrors in different directions. In other words, one scanning beam generated by the rotary polygon mirror 18 is divided into four for each of the components reflected by each pattern mirror when traversing the four pattern mirrors,
Each component becomes a scanning beam that travels in a different direction toward the reading window 42.

That is, one scanning beam generated by the rotary polygon mirror 18 draws four scanning trajectories, that is, scanning lines, which run in different directions on the reading window 42. Since the rotary polygon mirror 18 generates four scanning beams which scan different trajectories parallel to each other, sixteen scanning trajectories appear on the reading window 42.

The four scanning beams generated by the rotary polygon mirror 18 scan trajectories parallel to each other.
Since the optical path length and the angle from 8 to the reading window 42 via the pattern mirror vary depending on the orbit, the reading window 42
In the above, the parallelism is not maintained even with the scanning beam reflected by the same pattern mirror.

In this way, the four pattern mirrors 2 are
Sixteen scanning beams from 2, 26, 28, 24 toward the reading window 42 are transmitted through the reading window 42 and emitted.

When reading the information on the bar code attached to the product, the operator holds the product in his hand, moves the product toward the reading window 42, and moves the product to the reading window 42 which emits a scanning beam. Cross in front of. This operation may be performed by sliding the product on the table on which the reading device is placed. As a result, the bar code attached to the product traverses the scanning beam emitted from the reading window 42, and the light reflected and scattered by the bar code at that time enters the inside of the device through the reading window 42 and enters the bar. The pattern mirrors 22, 26, 28, 24 corresponding to the scanning beam striking the code are reflected, and the rotary polygon mirror 18 is reflected.
Head to 2.

The Fresnel lens 32 has a positive power and converts the divergent light from the rotary polygon mirror 18 into focused light. The Fresnel lens 32 has the function of condensing the light from the rotary polygon mirror 18, and the light reflected by the outer pattern mirrors 22 and 24 and the light reflected by the inner pattern mirrors 26 and 28 have the same intensity. It also has a function to do. The optical path length from the rotary polygon mirror 18 to the reading window 42 differs depending on whether the light passes through the outer pattern mirrors 22 and 24 or the inner pattern mirrors 26 and 28. Therefore, the intensity of the scanning beam emitted from the reading window 42 differs depending on which of the outer and inner pattern mirrors passes. Further, since the reflected and scattered light passes through the same optical path as the scanning beam while it reaches the rotary polygon mirror 18 from the reading window 42, the difference in intensity becomes larger. After all, the light receiving element 36
The intensity of the light incident on is different depending on whether it has passed through the outer pattern mirrors 22 and 24 or the inner pattern mirrors 26 and 28. Such variations in light intensity depending on the path are not preferable for information reproduction. The Fresnel lens 32 corrects such variations in intensity.

The folding mirror 33 is a Fresnel lens 32.
The focused light from the light is deflected by 90 ° by reflection, and the condenser lens 3
Move to 4. The condenser lens 34 further condenses the incident focused light to form a spot on the light receiving surface of the light receiving element 36.

As the light receiving element 36, one having a size of 2.7 mm square is often used. The light receiving element 36 is preferably as small as possible for low noise and high-speed response, but on the other hand, optical adjustment becomes difficult. Therefore, it is preferable to use a large-sized light receiving element 36 within an allowable range in order to facilitate optical adjustment.

Here, the mounting structure of the holder 60 of the laser diode 12 to the chassis 200, that is, the adjusting mechanism of the emitting direction of the laser beam will be described with reference to FIG.

As shown in FIG. 3, the laser diode 1
A large number of heat radiation fins 6 are attached to the holder 60 which holds 2
2 are provided. Holder 60 has three through holes 6
4 are formed, a screw 70 is passed through each through hole 64, and all three screws 70 are screwed into the chassis 200. On the inner surface of the holder 60, that is, on the surface facing the chassis 200, a circular groove 66 is formed substantially in the center of the three through holes 64. The chassis 200 also has a similar groove at a position facing the circular groove 66. Circular groove 204
Are formed. A coil spring 72 is provided between the circular groove 66 of the holder 60 and the circular groove 204 of the chassis 200.
Are stored in a compressed state.

According to such a mounting structure, the inclination of the holder 60 with respect to the surface of the portion of the chassis 200 facing the holder 60 can be changed in an arbitrary direction by adjusting the tightening degree of the screw 70. Therefore, the direction of the laser beam emitted from the laser diode 12 can be adjusted to an arbitrary direction by tightening or loosening the appropriate screw 70.

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 front surface of the speaker 150 is a housing 52.
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.

Further, as schematically shown in FIG.
Around the window 42, electronic article surveillance (EAS: Electron
The antenna wire 162 for the ic Article 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. The security tag is provided on the back side of the barcode sticker, for example.
It is attached to the product along with the barcode sticker.

When the 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.

As shown in FIG. 5B, the antenna wire 162 is passed through a tube 58 provided in an intermediate cover 53 provided between the housing 52 and the upper cover 54, and as shown in FIG. Then, the interface unit 164 provided on the lower side of the housing 52 is pulled out of the housing 52. The cylinder 58, through which the antenna wire 162 passes, extends to the vicinity of the interface section 164, which reduces the intrusion of dust into the inside of the device. 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 accommodated in this space 168 when it is not used.

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.

Next, the control of the motor will be described.
When starting the motor 38, in order to reduce the inrush current, the motor 38 is started up at a low speed. A control circuit therefor is shown in FIG. Motor circuit control means 310
Is a CPU 310a that controls the operation of the entire system,
It has an MPU 310b for controlling the operation of each circuit.

When the CPU 310a detects the reset signal of the power-on reset circuit 313, it outputs a motor rotation permission signal to the MPU 310b, and the MPU 310b
In response to this, the motor drive signal is output. The motor drive signal is a PWM signal and the filter circuit 3 of RC configuration
It is supplied to the control input terminal 38 a of the motor 38 via 11.

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. As the variable information of the duty ratio, the frequency (time) of the rotation synchronization signal output from the rotation synchronization signal output terminal 38b and proportional to the rotation speed of the motor 38 is calculated by the CPU 310.
The duty ratio of the PWM signal is changed until the difference is equal to the target value, and the difference is fixed at that value.

FIG. 8 shows the PWM signal of the motor 38, and FIG. 9 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 that the rotation of the motor 38 has exceeded a certain level, based on the rotation synchronization signal, the CPU 310a sets the frequency of the PWM control signal to f.
Switch to 2 and use the motor 38 to pull in the rated rotation.
Rotation control. Here, the magnitude relationship of 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, the duty ratio in the H section of the frequency f2 is gradually increased in order to increase the rotation speed of the motor 38. Further, when the speed of the motor 38 is reduced, the reverse operation is performed, and the control is stabilized at the duty ratio that makes the rated rotation speed.

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 rotation speed of the motor 38 in the steady rotation is extremely high, the corners of the rotary polygon mirror 18 are cut off to reduce the drive current of the motor 38, and the air resistance (wind loss of the edge portion of the rotary polygon mirror 18 is reduced. It is preferable to cover the circumference with a cover to reduce the above. 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 rotary polygon mirror 18 of the scanning means, and is irradiated by the pattern mirrors 22, 24, 26 and 28 in the direction determined by the angle, and a plurality of scanning lines. Generate a scan pattern consisting of The angles of the mutually adjacent surfaces of the rotary polygon mirror 18 are different. Therefore, a plurality of translated scan patterns are generated for each pattern mirror 22, 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 condenser lens 34 are provided as a condenser 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 circuit is shown in FIG. 10 (A), and its frequency characteristic is shown in FIG. 10 (B). This amplifier circuit
It is a band-pass type (band-pass filter) amplifier circuit and has a band stop band of 6 dB / oct. Depending on the cost and mounting space, 12-18 dB /
It is possible to construct a similar amplifier circuit by combining LPFs and HPFs having a large oct band stop band, but the correct signal amplitude cannot be obtained due to the signal band to be handled, insufficient drive capability of the amplifier element itself, or the like. The characteristics may not be sharp. Particularly, in the case of a bar code reader, since a pulse signal is handled, if the group delay time undulates due to the above reasons, the pulse signal is not correctly transmitted, and pulse distortion is likely to occur, 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. 11, this circuit configuration has phase characteristics without impairing the trackability of the frequency characteristics of each element by connecting amplifier circuits having the same kind of frequency characteristics in series in multiple stages (cascade connection). 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 the binarization of an unsuitable signal, for example, by regular 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. When amplified above the dynamic range of the analog circuit, the signal is saturated and the peak cannot be detected, as shown in FIG. 12B, making it difficult to generate a correct binary signal. Become. As shown in FIG. 13A, the detection of the signal saturation of the analog circuit is performed by taking 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 independently set. As shown in FIG. 13B, an H pulse is output each time an overvoltage is detected in the final stage of the analog amplifier circuit.

As shown in FIG. 14, the overvoltage detecting means 370 is connected between the binarizing processing means 380 and the decoding processing means 381 via the binarized data output inhibiting means 382. The binarized data output prohibiting means 382 is a one-shot circuit that outputs a pulse width of a constant cycle composed of a gate circuit, some passive elements, and active elements, and receives an H pulse from the overvoltage detecting means 370. Then, the data line of the binarized signal is connected to G via the resistor 383 for a certain period.
Short to ND. As a result, the communication of the binarized data to the decoding processing unit 380 is interrupted during the above-mentioned fixed period.

The amplified signal is binarized by the binarization processing means 380, input to the decoding processing means 381 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 decoded, the next information is subsequently entered, and the same information is decoded. 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 completion of the series of information, the current consumption is reduced,
The laser diode 12 has a long life, and the motor 3
8 laser diode 12 to ensure high reliability
Is switched from continuous lighting to blinking lighting, and the motor 38 is kept in a low speed rotation state. 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 information from the decoding circuit
It is possible to return to the continuous lighting state of the laser diode and the steady rotation of the motor again.

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

For example, in the embodiment, the Fresnel lens 32 has the function of equalizing the intensity of the light passing through the outer pattern mirrors 22 and 24 and the intensity of the light passing through the inner pattern mirrors 26 and 28. Fresnel lens 32
The pattern mirrors 22 and 24 on the outer side and the pattern mirrors 26 and 28 on the inner side are simply provided with the light collecting function.
You may deal with it by changing the reflectance with and. For example, the reflectance of the outer pattern mirrors 22 and 24 is set to 92%,
The reflectance of the inner pattern mirrors 26 and 28 is set to 78%.

Further, it is preferable to appropriately select the angle direction of the laser diode 12. Laser light is read window 42
For the scanning direction. This is because the S-polarized component with respect to the reading window 42 differs depending on the scanning direction. Therefore, the polarization direction of the laser light emitted from the laser diode 12, that is, the mounting angle of the laser diode 12 around the optical axis is set to the transmittance of the scanning beam passing through the outer pattern mirrors 22 and 24 and the inner pattern mirrors 26 and 28. It is more preferable to select so that the transmittances of the scanning beams passing through are equal.

The plurality of (sixteen) scanning lines or scanning patterns appearing in the reading window 42 may be asymmetric with respect to the housing 52. For example, the scanning pattern is as shown in FIG.
The symmetrical center line may be inclined. This is the chassis 5 of the chassis 200 with all optical elements mounted.
It is realized by changing the mounting direction with respect to 2, or by changing the surface directions of the pattern mirrors 22, 24, 26, 28.

[0056]

According to the present invention, by providing the folding mirror, the light receiving element is arranged in the space near the pattern mirror which has been wasted up to now. A space for housing is not necessary, the housing can be made smaller accordingly, and the barcode reading device can be downsized.

[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.

3A is a top view of a laser diode position adjusting mechanism, and FIG. 3B is a front view thereof.

4A is a perspective view of a speaker, FIG. 4B is a front view of the speaker, and FIG. 4C is a side sectional view of the speaker.

5A is a perspective view schematically showing the arrangement of antenna lines for an EAS system, and FIG. 5B is a diagram showing a pipe through which the antenna lines pass.

FIG. 6 is a perspective view showing an interface section and a cover.

FIG. 7 is a diagram of a configuration example of a motor rotation control circuit.

FIG. 8 is a diagram showing a motor drive signal.

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

FIG. 10A is a diagram showing a basic configuration of an amplifier circuit,
(B) is a diagram showing the frequency characteristic.

11A is a diagram showing a configuration in which the amplifier circuits of FIG. 10A are connected in multiple stages in series, and FIG. 11B is a diagram showing frequency characteristics thereof.

FIG. 12A is a diagram showing a good read signal, and FIG. 12B is a diagram showing an undesired read signal.

FIG. 13A is a diagram showing a configuration of an overvoltage detection unit,
(B) is a diagram showing the output characteristic.

FIG. 14 is a diagram showing a configuration of a binarized data output inhibiting unit.

[Explanation of symbols]

 12 laser diode 16 deflection mirror 18 rotary polygon mirror 22, 24, 26, 28 pattern mirror 33 bending 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 Co., Ltd. (72) Inventor Teruaki Sugada 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd.

Claims (2)

[Claims] 1. 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, a plurality of pattern mirrors for reflecting the scanning beam in different directions, and an object traversing the scanning beam. In a bar code reader having a light receiving element for receiving the reflected light from the scanning means, a bending mirror for reflecting the reflected light from the scanning means is further provided between the scanning means and the light receiving element. And a light-receiving element are both positioned on one side of the folding mirror. 2. A deflecting mirror for reflecting a light beam from a light source is further provided between the light source and the scanning means, and the light source, the scanning means, the pattern mirror and the light receiving element are bent together. A bar code reader characterized by being located on one side of a mirror.