JP3790904B2 - Bar code reader - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a barcode reader that reads a barcode attached to or printed on a product in a point-of-sale operation at a department store or a supermarket.
[0002]
[Prior art]
Bar code readers include a stationary type in addition to a pen type and a handheld type having a scanning unit in hand. The stationary bar code reader has a relatively large reading window, and emits a plurality of scanning beams therefrom. In general, the trajectory of a plurality of scanning beams on the reading window, that is, the scanning pattern, extends in a plurality of different directions.
[0003]
When reading the information of the barcode attached to the product, the operator moves the product by holding the product in his hand and directing the barcode attached to the product toward the reading window of the barcode reader. By this operation, the barcode attached to the product traverses the scanning beam, and the light reflected and scattered by the barcode enters the reader through the reading window and is condensed on the light receiving element. In the barcode reader, the barcode information is read based on the temporal change in the light intensity detected by the light receiving element.
[0004]
[Problems to be solved by the invention]
From the viewpoint of the user, the bar code reader preferably has a smaller occupation area, and therefore the bar code reader is desired to be downsized.
[0005]
In general, in a bar code reader, a light beam emitted from a light source is converted into a scanning beam whose direction changes with time by a scanning unit, and this scanning beam is reflected in different directions by a plurality of pattern mirrors, and is reflected on a reading window. A plurality of scanning beams are scanned in different directions and 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 is then collected on the light receiving element by the light collecting means such as a lens.
[0006]
By the way, the optical path length between optical elements such as a light source, a scanning unit, a pattern mirror, a reading window, a condensing unit, and a light receiving element, or the size of each, can be determined by, for example, a single one on the reading window. Appropriate dimensions are selected according to design values such as the length of the scanning beam trajectory (ie, the scanning line) and the number of scanning lines having different directions. Therefore, the size of the apparatus cannot be reduced by simply shortening the optical path length between the optical elements or the size of each.
[0007]
However, a functionally useless space, so-called dead space, is present in the inside of the device, and if this dead space can be reduced, the device can be downsized.
[0008]
The present invention has been made from such a viewpoint, and an object thereof is to provide a small-sized bar code reader with little dead space.
[0009]
[Means for Solving the Problems]
The present invention includes a light source that emits a light beam; Said Scanning means for generating a scanning beam by shaking a light beam from a light source; Said A plurality of pattern mirrors that reflect the scanning beam in different directions; Said In a barcode reader having a light receiving element for receiving reflected light from an object crossing a scanning beam, Said Scanning means and Said Between the light receiving elements, Said A folding mirror for reflecting the reflected light from the scanning means; Said Scanning means and Said With pattern mirror Said Both light receiving elements Said Located on one side of the folding mirror In the projection onto the plane perpendicular to the plane including the optical path from the scanning means via the folding mirror to the light receiving element, the scanning means and the light receiving element are arranged with the pattern mirror interposed therebetween. Have It is characterized by that.
[0010]
In this configuration, since the light receiving element is located on the same side as the scanning means and the pattern mirror with respect to the bending mirror, the light receiving element is disposed in a useless space that has existed near the pattern mirror in the conventional apparatus. can do. Therefore, it is possible to reduce the size of the apparatus by reducing the housing by the amount that accommodates the light receiving element in the conventional apparatus.
[0011]
The present invention Bar code reader by Is more preferably Said With light source Said During the scanning means, Said A deflection mirror for reflecting the light beam from the light source; Said With light source Said Scanning means and Said With pattern mirror Said The light receiving element is located on one side of the folding mirror. In the projection onto the plane including the optical path from the scanning unit to the light receiving element via the folding mirror, the light source is arranged closer to the scanning unit than the folding mirror. .
[0012]
In the above-described configuration, the light source is disposed on the same side as the folding mirror with respect to the scanning unit, and in some cases, in order to ensure a sufficient optical path length between the light source and the scanning unit, than the folding mirror. It will be placed far away. Such a positional relationship negates the advantage of bringing the light receiving element close to the pattern mirror. In order to cope 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 respect 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]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0014]
As shown in FIGS. 1 and 2, the barcode reader 10 includes a laser diode 12 as a light source, a deflecting mirror 16, a rotary polygon mirror 18 as a scanning means, four pattern mirrors 22, 24, 26, 28, A Fresnel lens 32, a bending mirror 33, a condenser lens 34, and a light receiving element 36 are included, and these optical elements are all fixed to a common chassis 200.
[0015]
The chassis 200 on which each optical element is mounted is housed in the housing 52 after the optical adjustment is completed. An upper cover 54 to which the reading window 42 is attached is attached to the housing 52.
[0016]
The laser diode 12 is housed in a zinc die-cast holder 60 and emits a laser beam toward the deflection mirror 16. The holder 60 is attached to the chassis 200 so that the laser beam emission direction can be adjusted. The mounting structure, that is, the adjusting mechanism will be described later. More preferably, the surface of the holder 60 is black anodized. The black alumite treatment suppresses internal reflections such as stray light generated when the laser beam is reflected by the reading window 42 and disturbance light entering from the reading window 42.
[0017]
The deflection mirror 16 is composed of a small rectangular plane mirror, and is attached to the center of the Fresnel lens 32 at an angle of 45 °. The deflection mirror 16 deflects the laser beam from the laser diode 12 by 90 ° by reflection and is directed toward the rotating polygon mirror 18. Dodge. The deflection mirror 16 is attached, for example, by adhering the deflection mirror 16 to the maximum side surface of the right-angled isosceles triangular attachment member 17 and fixing it to the center of the Fresnel lens 32 by adhesion.
[0018]
The rotary polygon mirror 18 serving as 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 laser beam incident on the rotating polygon mirror 18 is reflected at different angles on each reflecting surface, and four parallel scanning beams are generated that cross the pattern mirror along different trajectories.
[0019]
The four pattern mirrors 22, 26, 28, and 24 are both flat mirrors and are arranged in different directions. Accordingly, the scanning beams that cross the four pattern mirrors 22, 26, 28, and 24 are reflected in different directions by the respective pattern mirrors. In other words, one scanning beam generated by the rotary polygon mirror 18 is divided into four for each component reflected by each pattern mirror when crossing the four pattern mirrors, and each component has a different direction. To the reading window 42.
[0020]
That is, one scanning beam generated by the rotary polygon mirror 18 draws four scanning trajectories, that is, scanning lines running in different directions on the reading window 42. Since the rotary polygon mirror 18 generates four scanning beams that scan different orbits parallel to each other, sixteen scanning orbits appear on the reading window 42.
[0021]
The four scanning beams generated by the rotating polygon mirror 18 scan parallel trajectories, but the optical path length and angle from the rotating polygon mirror 18 through the pattern mirror to the reading window 42 differ depending on the trajectory. On the reading window 42, parallelism is not maintained even with scanning beams reflected by the same pattern mirror.
[0022]
In this way, sixteen scanning beams from the four pattern mirrors 22, 26, 28, 24 toward the reading window 42 are transmitted through the reading window 42 and emitted.
[0023]
When reading the information on the barcode attached to the product, the operator holds the product, moves the product with the barcode directed toward the reading window 42, and moves in front of the reading window 42 that emits the scanning beam. Cross. 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 enters the inside of the apparatus through the reading window 42. Reflected by the pattern mirrors 22, 26, 28 and 24 corresponding to the scanning beam hitting the code, reflected by the rotating polygon mirror 18, and directed toward the Fresnel lens 32.
[0024]
The Fresnel lens 32 has positive power and changes divergent light from the rotary polygon mirror 18 into focused light. In addition to the function of condensing the light from the rotary polygon mirror 18, the Fresnel lens 32 equalizes the intensity of the light reflected by the outer pattern mirrors 22 and 24 and the light reflected by the inner pattern mirrors 26 and 28. It also has a function to do. The optical path length from the rotary polygon mirror 18 to the reading window 42 is different between the case of passing through the outer pattern mirrors 22 and 24 and the case of passing through the inner pattern mirrors 26 and 28. Therefore, the intensity of the scanning beam emitted from the reading window 42 differs depending on whether the scanning beam passes through the outer or inner pattern mirror. Further, since the reflected and scattered light travels from the reading window 42 to the rotary polygon mirror 18 through the same optical path as the scanning beam, the difference in intensity is further increased. Eventually, the intensity of the light incident on the light receiving element 36 differs depending on whether it passes through the outer pattern mirrors 22 and 24 or the inner pattern mirrors 26 and 28. Such variation in light intensity depending on the path is not preferable for information reproduction. The Fresnel lens 32 corrects such intensity variation.
[0025]
The bending mirror 33 deflects the focused light from the Fresnel lens 32 by 90 ° by reflection and directs it toward the condensing lens 34. The condensing lens 34 further collects the incident focused light and forms a spot on the light receiving surface of the light receiving element 36.
[0026]
In general, a light receiving element 36 of about 2.7 mm square is often used. The light receiving element 36 is desirably as small as possible for low noise and high speed response, but on the other hand, optical adjustment becomes severe. Therefore, it is preferable to use a large light receiving element 36 within an allowable range in order to facilitate optical adjustment.
[0027]
Here, a structure for attaching the holder 60 of the laser diode 12 to the chassis 200, that is, a mechanism for adjusting the laser beam emission direction will be described with reference to FIG.
[0028]
As shown in FIG. 3, the holder 60 holding the laser diode 12 is provided with a number of heat radiation fins 62. The holder 60 has through holes 64 formed at three locations, and screws 70 are passed through the through holes 64, and all the three screws 70 are screwed into the chassis 200. On the inner surface of the holder 60, that is, the surface facing the chassis 200, a circular groove 66 is formed at substantially the center of the three through holes 64. The chassis 200 is similarly positioned at a position facing the circular groove 66. A circular groove 204 is formed. A coil spring 72 is accommodated in a compressed state between the circular groove 66 of the holder 60 and the circular groove 204 of the chassis 200.
[0029]
According to such an attachment structure, the inclination of the holder 60 with respect to the surface of the portion facing the holder 60 of the chassis 200 can be changed in an arbitrary direction by adjusting the tightening degree of the arbitrary 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 an appropriate screw 70.
[0030]
By the way, the apparatus is provided with a speaker for informing the operator that the reading of the barcode is completed. The speaker mounting structure will be described with reference to FIG.
[0031]
The speaker 150 is preferably a waterproof speaker in consideration of drip-proof. Further, in order to prevent static electricity, the front surface thereof is covered with a polyester film (for example, Mylar (trade name)) 156. An opening 158 for exposing the cone of the speaker 150 is formed in the film 156, and the opening 158 has a shape in which the lead wire 154 of the coil is hidden.
[0032]
In general, static electricity flies toward the metal portion around the speaker 150 and the lead wire 154 of the coil, but in this embodiment, a film 156 is provided on the front surface of the speaker 150 so that the metal portion and the drawer 154 are exposed to the outside. Therefore, static electricity will flow through the opening 158 toward the metal part and the lead line, and the amount thereof is clearly less than that without the film 156.
[0033]
The speaker 150 is attached so that the front surface thereof is aligned with a portion of the housing 52 provided with a plurality of slits, and the attachment is performed as follows. The speaker 150 is placed on the film 156 with its front face aligned with the opening 158 of the film 156, and the four-side folded portions 160 are folded back. A pair of facing L-shaped guide members 56 are formed in the housing 52, and the speaker 150 wrapped with the film 156 is inserted into a groove defined by the pair of guide members 56. Subsequently, a substantially W-shaped wire spring 162 is pushed in, and both ends thereof are engaged with the guide member 56 by elasticity, and the central portion suppresses the periphery of the magnet 152. Thereby, the speaker 150 is firmly fixed to the housing 52. Moreover, installation is easy.
[0034]
Further, as schematically shown in FIG. 5A, an antenna line 162 for an electronic article surveillance (EAS) system is disposed around the window 42. 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 an outlet. 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 National Patent Publication No. 7-500432 discloses an example of such a security tag. The security tag is provided, for example, on the back side of a bar code seal, and is attached to a product together with the bar code seal.
[0035]
When the product is taken out by unauthorized means, the detection device detects the resonance circuit of the security tag and notifies the store clerk by an alarm or the like. On the other hand, when the product is taken out by legitimate means, the product always passes near the window 42 of the bar code reader for reading the bar code, and at that time, the resonance circuit of the security tag is connected by the antenna line 162. Since it is destroyed by the generated electromagnetic field, it is not detected by the detection device.
[0036]
As shown in FIG. 5B, the antenna wire 162 is passed through a cylinder 58 provided in the intermediate cover 53 provided between the casing 52 and the upper cover 54, and as shown in FIG. The interface unit 164 provided on the lower side of the body 52 is pulled out of the housing 52. The tube 58 through which the antenna line 162 passes extends to the vicinity of the interface unit 164, thereby reducing intrusion of dust into the apparatus. A wall portion 166 is provided near the location where the antenna line 162 is drawn, and a space 168 is formed. The antenna line 162 is accommodated in this space 168 when not in use.
[0037]
A connector 174 for connecting necessary wiring is exposed on the interface unit 164, and a cover 170 that is flush with the housing 52 is attached after the wiring is connected. The cover 170 is formed with a groove 172 for drawing out the wiring connected to the connector 174 and the EAS antenna line 162. The groove 172 includes three portions 172a, 172b, and 172c that are continuous with each other, and these portions 172a, 172b, and 172c are formed on three mutually orthogonal wall portions of the cover 170 and face in three directions. Yes. Thereby, the wiring and the antenna line 162 can be drawn out in the most appropriate direction among the three directions according to the installation environment of the apparatus, the positional relationship with the external apparatus, and the like.
[0038]
Next, motor control will be described. When starting the motor 38, the motor 38 is started up from a low rotational speed in order to reduce the inrush current. A control circuit for this purpose is shown in FIG. The motor circuit control means 310 includes a CPU 310a that controls the operation of the entire system and an MPU 310b that controls the operation of each circuit.
[0039]
When detecting the reset signal of the power-on reset circuit 313, the CPU 310a outputs a motor rotation permission signal to the MPU 310b, and the MPU 310b receives this and outputs a motor drive signal. The motor drive signal is a PWM signal, and is supplied to the control input terminal 38a of the motor 38 via the RC configuration filter circuit 311.
[0040]
The rotation control of the motor 38 is performed by changing the duty ratio of the pulse of the PWM signal output from the MPU 310b so that a target frequency can be obtained. The variable information of the duty ratio is obtained by referring to the frequency (time) of the rotation synchronization signal output from the rotation synchronization signal output terminal 38b in proportion to the rotation speed of the motor 38, and the difference is the target value. The duty ratio of the PWM signal is changed until it becomes equal to and is fixed to that value at the point where they coincide.
[0041]
The PWM signal of the motor 38 is shown in FIG. 8, and the operation flow of control is shown in FIG. When starting the motor 38 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 to continue the rotation gradually at a low speed. When the CPU 310a detects that the rotation of the motor 38 has reached a certain level or more based on the rotation synchronization signal, the CPU 310a switches the frequency of the PWM control signal to f2 and controls the rotation of the motor 38 so as to draw the rated rotation. . Here, the magnitude relation of the frequency of the PWM signal 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 of the H section of the frequency f2 is gradually increased in order to increase the rotational 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 at which the rated rotational speed is obtained.
[0042]
This control method increases the low-speed torque by shifting the frequency of the PWM signal from the MPU 310b of the motor circuit control means 310 to a high frequency during the first time when the motor 38 starts to start, thereby improving the initial motion sensitivity. The motor 38 gradually increases in rotational speed and eventually reaches a steady rotational speed. Since the rotation speed of the motor 38 in the steady rotation is very high, the corners of the rotary polygon mirror 18 are cut off to reduce the drive current of the motor 38, or the air resistance (windage loss) at the edge of the rotary polygon mirror 18 is reduced. ) Is preferably covered with a cover. When the rotation of the motor 38 reaches a predetermined number of rotations, the rotation detection circuit 314 outputs a lighting permission signal for the laser diode 12 to the LD control circuit (not shown), and the laser diode 12 emits light. The laser diode 12 is supported by support means that also serves as a heat sink, and its terminal is connected to a printed circuit board that also serves as a detachable connector.
[0043]
The laser beam emitted from the laser diode 12 is reflected by the rotary polygon mirror 18 of the scanning means, irradiated by the pattern mirrors 22, 24, 26, and 28 in the direction determined by the angle, and is formed of a plurality of scanning lines. Generate a pattern. The angles of adjacent surfaces of the rotary polygon mirror 18 are different. Accordingly, a plurality of parallel scanning patterns are generated for each pattern mirror 22, 24, 26, 28. The irregularly reflected light of the laser beam scanned on the bar code symbol becomes optical information corresponding to the information, and returns to the opposite direction of irradiation and passes through the pattern mirrors 22, 24, 26 and 28, and the rotary polygon mirror 18. And condensed on the light receiving element 36. In front of the light receiving element 36, a Fresnel lens 32 and a condensing lens 34 are provided as condensing means.
[0044]
The optical information is converted into an electrical signal by the light receiving element 36, and unnecessary noise is removed by the amplifier circuit and the filter circuit, and the signal is amplified to a binary signal. In this amplifier circuit stage, the same kind of amplifier circuits are connected in multiple stages (cascade connection) in order to greatly attenuate the unnecessary signal band. In this embodiment, five-stage multistage connection (cascade connection) is used. FIG. 10A shows the basic configuration of the amplifier circuit, and FIG. 10B shows its frequency characteristics. This amplifying circuit is a band-pass type (band-pass filter) amplifying circuit and has a band stop band of 6 dB / oct. Although it is possible to construct a similar amplifier circuit with a combination of LPF and HPF having a large band stop band of 12 to 18 dB / oct with one amplification block depending on cost, mounting space, etc., the signal band handled, the amplification element itself The correct signal amplitude may not be obtained or the characteristics may not be sharp due to lack of drive capability. In particular, in the case of a bar code reader, since a pulse signal is handled, if undulation occurs in the group delay time due to the above reasons, the transmission of the pulse signal is not performed correctly, and pulse distortion is likely to occur, which is not preferable.
[0045]
In general, the frequency characteristics of an amplifier circuit in a bar code reader may be passed from a direct current (DC), and therefore it is necessary to separate unnecessary low frequency from the signal frequency band. If this frequency separation is not possible, it will cause a problem that correct reading cannot be performed due to the influence of disturbance. Therefore, it is necessary to attenuate to a level at which a low frequency unnecessary in the previous stage of binarization processing does not affect the signal frequency band. Therefore, as shown in FIG. 11, the present circuit configuration has a multi-stage connection (cascade connection) of amplifier circuits having the same type of frequency characteristics, so that the phase characteristics can be obtained without impairing the followability of the frequency characteristics of each element itself. It is possible to expect the effect of minimizing the deterioration of noise and attenuating unnecessary frequency bands more greatly.
[0046]
When binarizing the read signal amplified by the analog amplification stage, as a means for not binarizing an inappropriate signal, for example, from the necessary information due to specular reflection light from the barcode surface or excessive disturbance light In addition, an overvoltage detection circuit for suppressing an excessively large signal level is provided. This overvoltage detection circuit has two independent thresholds for the signal level positively and negatively, and outputs an overvoltage detection signal independently for positive and negative signal amplitudes greater than or equal to the threshold value. The binarized data output prohibiting 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 misreading from occurring by binarizing by mistake due to the above effect.
[0047]
As shown in FIG. 12A, the read signal is preferably within the dynamic range of the analog circuit. In this case, the peak is detected and binarized. When amplified beyond the dynamic range of the analog circuit, as shown in FIG. 12B, the signal saturates and peaks cannot be detected, making it difficult to generate a correct binary signal. Become. As shown in FIG. 13A, detection of signal saturation in 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 positive and negative threshold values can be set independently. As shown in FIG. 13B, an H pulse is output each time an overvoltage is detected at the final stage of the analog amplifier circuit.
[0048]
As shown in FIG. 14, the overvoltage detection unit 370 is connected between the binarization processing unit 380 and the decoding processing unit 381 via the binarized data output prohibiting unit 382. The binarized data output prohibiting means 382 is a one-shot circuit that outputs a pulse width of a constant period composed of a gate circuit, several passive elements, and an active element, and receives an H pulse from the overvoltage detection means 370. Then, the data line of the binarized signal is short-circuited to GND via the resistor 383 for a certain period. As a result, the communication of the binarized data to the decoding processing means 380 is interrupted for the above-mentioned fixed period.
[0049]
The amplified signal is binarized by the binarization processing unit 380 and input to the decoding processing unit 381 for decoding. When the decoding is completed, the operator can be notified that the decoding has been completed by a notification means such as a speaker, or can be notified by a light emitting means such as an LED.
[0050]
One piece of information is decoded and then the next piece of information is entered and decoded in the same way. With respect to this decoding means, as an auxiliary means for increasing the decoding accuracy, as a means for initializing the scanning pattern, the origin of the first scanning pattern generated by the first pattern mirror (for example, 22) is used to generate the scanning pattern initialization signal. A signal for detecting this is obtained. As a specific means, a means for detecting the position of the pole of the rotor of the motor can be provided so that it can be taken out as a synchronous signal for rotation. As a result, a signal when the scanning line is at the start position of the first pattern mirror can be taken out, and further, a reading synchronization signal for each scanning line can be generated by software processing. It is not necessary to read the data again, which is effective for speeding up the decoding process.
[0051]
When a series of information is completed and read information cannot be detected even after a lapse of a certain time, the laser diode 12 is used to reduce current consumption, extend the life of the laser diode 12, and ensure high reliability of the motor 38. Is switched from continuous lighting to blinking lighting so that 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 can be used to return to the continuous lighting state of the laser diode and the steady rotation of the motor again.
[0052]
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.
[0053]
For example, in the embodiment, the Fresnel lens 32 has a function of equalizing the intensity of the light passing through the outer pattern mirrors 22 and 24 and the light passing through the inner pattern mirrors 26 and 28. However, this may be dealt with by changing the reflectance between the outer pattern mirrors 22 and 24 and the inner pattern mirrors 26 and 28 by simply providing a condensing function. For example, the reflectance of the outer pattern mirrors 22 and 24 is set to 92%, and the reflectance of the inner pattern mirrors 26 and 28 is set to 78%.
[0054]
Further, it is preferable to appropriately select the angle direction of the laser diode 12. The transmittance of the laser light with respect to the reading window 42 varies depending on the scanning direction. This is because the S polarization component with respect to the reading window 42 differs depending on the scanning direction. Accordingly, the polarization direction of the laser light emitted from the laser diode 12, that is, the mounting angle around the optical axis of the laser diode 12, the transmittance of the scanning beam via the outer pattern mirrors 22 and 24, and the inner pattern mirrors 26 and 28 are set. It is further preferable to select the scanning beams to pass through the same.
[0055]
A plurality (sixteen) scanning lines, that is, scanning patterns appearing in the reading window 42 may be asymmetric with respect to the housing 52. For example, the scanning pattern may be one in which the symmetric center line is inclined in FIG. This is realized by changing the mounting direction of the chassis 200 on which all the optical elements are mounted with respect to the casing 52, or by changing the surface direction of the pattern mirrors 22, 24, 26, and 28.
[0056]
【The invention's effect】
According to the present invention, by providing the bending mirror, the light receiving element is disposed in the space near the pattern mirror that has been wasted so far. Can be made smaller, and the barcode reader can be downsized.
[Brief description of the drawings]
FIG. 1 is a side sectional view of a barcode reader according to an embodiment of the present invention.
FIG. 2 is a top view of the barcode reader shown in FIG.
3A is a top view of a laser diode position adjustment 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 wires for an EAS system, and FIG. 5B is a diagram showing a tube through which the antenna wires pass.
FIG. 6 is a perspective view showing an interface unit and a cover.
FIG. 7 is a diagram illustrating a configuration example of a motor rotation control circuit.
FIG. 8 is a diagram showing a motor drive signal.
FIG. 9 is a diagram showing an operation flow of control by the circuit of FIG. 7;
10A is a diagram illustrating a basic configuration of an amplifier circuit, and FIG. 10B is a diagram illustrating frequency characteristics thereof.
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 the frequency characteristics thereof.
12A is a diagram showing a good read signal, and FIG. 12B is a diagram showing an undesired read signal.
13A is a diagram showing a configuration of overvoltage detection means, and FIG. 13B is a diagram showing its output characteristics.
FIG. 14 is a diagram showing a configuration of binarized data output prohibiting means.
[Explanation of symbols]
12 Laser diode
16 Deflection mirror
18 rotating polygon mirror
22, 24, 26, 28 Pattern mirror
33 Bending mirror
36 Light receiving element

Claims (2)

A light source that emits a light beam;
Scanning means for generating a scanning beam by swinging a light beam from said light source,
A plurality of patterns mirror for reflecting said scanning beam in different directions,
In a barcode reader having a light receiving element that receives reflected light from an object crossing the scanning beam,
Between said scanning means and said light receiving element, further has a a fold mirror for reflecting the reflected light from the scanning means,
The light receiving element and the pattern mirror and said scanning means is positioned to both one side of the fold mirror,
In projection onto a plane perpendicular to a plane including an optical path from the scanning unit to the light receiving element via the bending mirror, the scanning unit and the light receiving element are arranged with the pattern mirror interposed therebetween. A bar code reader characterized by the above. Between said scanning means and said light source further includes a deflection mirror for reflecting the light beam from the light source,
The light source and is positioned on one side of the scanning means and the pattern mirror and the folding and light receiving elements are both mirrors,
Claims in a projection onto a plane including the optical path to the light receiving element via said fold mirror from the scanning means, wherein the light source being disposed in the vicinity of said scanning means than the fold mirror Item 2. The barcode reader according to Item 1 .

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