JP3674588B2 - Bar code reader - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a barcode reader that optically reads a barcode.
[0002]
[Prior art]
FIG. 4 is a schematic diagram showing the configuration of a general bar code reader. In the illustrated barcode reading apparatus, the light from the light emitting element 100 is stopped by the light emitting lens 101, and this light is reflected by the scan mirror 201 of the scan unit 200 to irradiate the barcode 300. At this time, in order to irradiate (scan) light over the entire area of the barcode 300, the scan mirror 201 is swung.
[0003]
As drive means for swinging the scan mirror 201, a swing shaft (rotation shaft) 204 is provided at a substantially intermediate portion in the longitudinal direction of the scan mirror 201, so that the scan mirror 201 is swung around the swing shaft 204. A magnet (permanent magnet) 202 is attached to the scan mirror 201 at a position shifted in the longitudinal direction of the mirror from the swing shaft 204 while being supported movably, and one end side of the magnet 202 is inserted into the drive coil 203. It has become.
[0004]
In this oscillating drive means, by energizing the drive coil 203 (for example, flowing positive and negative currents at a constant cycle), a magnetic field is generated in the axial direction of the drive coil 203 and the magnetic field polarity (direction of the magnetic field). Are periodically reversed by the positive / negative of the current. As a result, the magnet 202 repeats the magnetic attraction / repulsion action with respect to the drive coil 203, and the scan mirror 201 swings about the swing shaft 204 in conjunction with this.
[0005]
On the other hand, the light irradiated on the surface of the barcode 300 returns to the scan mirror 201 again with a change in the amount of light of the barcode 300 in black and white while being irregularly reflected, and the reflected light is collected by the light receiving lens 401. Light collected by the light receiving lens 401 is received by the light receiving element 400. The light receiving element 400 electrically converts the change in the amount of received light and outputs it. In order to improve reading accuracy, a band-pass filter (BPF) 402 is provided on the front surface of the light receiving element 400 to prevent the collection of unnecessary light (natural light, etc.) other than the emitted light frequency. Further, the light emitting element 100 and the light receiving element 400 may be arranged three-dimensionally in addition to being arranged in a plane as illustrated.
[0006]
[Problems to be solved by the invention]
By the way, in the conventional barcode reading apparatus, an oscillation member that swings around the oscillation shaft 204 by adding an elastic member such as a leaf spring or silicone to the oscillation shaft 204 portion of the scan mirror 201 in the scan unit 200. The resonance frequency of the mechanism (including the scan mirror 201) is determined.
[0007]
However, when manufacturing the bar code reader, the dimensions and weight of the components vary, and this influence may cause the resonance frequency of the swing mechanism to vary when the assembly of the apparatus is completed. Therefore, a desired resonance frequency may not be obtained. Further, due to variations in the relative position of the scan mirror 201 and the swing shaft 204, the mounting position of the magnet 202, etc., the stationary posture of the scan mirror 201 when the drive coil 203 is not energized (neutral point during mirror swing) There was also the inconvenience that it fluctuated.
[0008]
[Means for Solving the Problems]
A bar code reader according to the present invention holds a scan mirror, is supported by a swinging member that is swingable about a swinging shaft, is mounted on the swinging member, and is substantially the same as the swinging shaft. A first magnet that forms a magnet magnetic field in an orthogonal direction, a swing drive unit that swings the swing member by a magnetic attraction / repulsion action of the magnet magnetic field formed by the first magnet, and a first A magnetic attraction force is applied between magnetic poles different from each other, and a first direction in which the magnitude of the magnetic attraction force is varied and a second direction in which the balance of the magnetic attraction force is varied. The second magnet is provided so as to be capable of changing the position.
[0009]
In the barcode reading apparatus having the above configuration, the position of the second magnet is changed in the first direction to change the magnitude of the magnetic attractive force acting between the first magnet and the scan mirror and the swinging movement. The resonance frequency of the swing mechanism including the member changes. Further, by changing the position of the second magnet in the second direction and changing the balance of the magnetic attractive force acting between the first magnets, The static posture changes.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0011]
FIG. 1 is a perspective view showing a configuration of a scan unit applied to a barcode reading apparatus according to an embodiment of the present invention. 2 is a side view including a partially broken section when the scan unit of FIG. 1 is viewed from the direction of arrow J, and FIG. 3 is a front view of the scan unit of FIG. 1 when viewed from the direction of arrow K. FIG.
[0012]
The illustrated scan unit 11 is mainly configured to include a swing member 12, a first magnet 13, a drive coil 14, a scan mirror 15, and a second magnet 17. The swing member 12 is formed in a substantially triangular shape (right triangle) in a side view, and a flat plate-like scan mirror 15 is integrally held on the swing member 12. The scan mirror 15 is attached to the inclined surface 12A (see FIG. 2) of the swing member 12 in a fixed state using, for example, an adhesive. The scan mirror 15 has a reflection surface 15A for reflecting light (laser light or the like) emitted from a light emitting element (not shown) toward the barcode, and the direction (tilt angle) of the reflection surface 15A is set to the swing member 12. The light reflected by the reflecting surface 15A is scanned (scanned) in the barcode arrangement direction.
[0013]
On both sides of the oscillating member 12, oscillating shafts 16 are provided so as to protrude coaxially outside the oscillating member 12. The swinging member 12 is supported so as to be swingable about the swinging shaft 16 by supporting the swinging shafts 16 on both sides thereof by bearings (not shown) of the housing 18. The housing 18 serves as a case for housing the scan unit 11, and is formed by integral molding of resin, for example. For example, when the rocking member 12 is integrally formed of resin, the rocking shaft 16 may be formed integrally with the rocking member 12 or may be incorporated into the rocking member 12 by press fitting or the like. The former is preferable in reducing the number of parts.
[0014]
Further, a first magnet 13 is attached (fixed) to the lower surface of the swing member 12 (the surface that makes an acute angle with the inclined surface 12A) using, for example, an adhesive. The first magnet 13 is a permanent magnet obtained by magnetizing a ferromagnetic material, and is formed in a bar shape having a square cross section. Further, the first magnet 13 has a magnet configuration in which an intermediate portion in the longitudinal direction (axial direction) is used as a boundary portion of the magnetic pole property, one end is an N pole, and the other end is an S pole. When mounting the first magnet 13 on the bottom surface of the swing member 12, the mounting direction of the first magnet 13 is set to a direction substantially orthogonal to the swing shaft 16, and the first magnet 13 is formed accordingly. The direction of the magnet magnetic field is also set in a direction substantially orthogonal to the swing shaft 16. In addition, the pole-boundary boundary portion of the first magnet 13 passes through the center (axial core) of the swing shaft 16 and is on a virtual line (swing shaft) that is substantially perpendicular to the surface on which the first magnet 13 is mounted. 16 on an imaginary line vertically lowered from the center of 16 to the bottom surface of the swinging member 12.
[0015]
On the other hand, the drive coil 14 corresponds to the swing drive unit in the present invention, and is disposed in a state of facing the first magnet 13 with a gap between the drive coil 14 and the first magnet 13. The drive coil 14 is formed by winding a coil wire in one direction, and the swinging member 12 is magnetically attracted and repelled by the magnetic field formed by the first magnet 13 in the gap portion. The function of swinging (swing drive function) is achieved. When a positive / negative (alternating current) current is passed through the driving coil 14, a driving magnetic field corresponding to the direction of the current is generated so as to pass through the center of the coil winding. The direction of this driving magnetic field is in a direction (vertical direction in FIG. 2) substantially perpendicular to the direction of the magnetic field of the magnet by the first magnet 13 (horizontal direction in FIG. 2), and the central axis of the swing shaft 16 The direction (the left-right direction in FIG. 3) is also set in a direction (vertical direction in FIG. 3) substantially orthogonal to the direction (the left-right direction in FIG. 3).
[0016]
The second magnet 17 is a permanent magnet obtained by magnetizing a ferromagnetic material in the same manner as the first magnet 13 and is formed in a bar shape having a square cross section. The second magnet 17 is disposed so as to face the first magnet 13 through the drive coil 14. The mounting direction of the second magnet 17 is set in a direction substantially orthogonal to the swing shaft 16 as in the case of the first magnet 13, and the direction of the magnet magnetic field formed by the second magnet 17 according to this is also set. It is set in a direction substantially orthogonal to the swing shaft 16. Further, in the initial setting state, the boundary portion of the magnetic pole property of the second magnet 14 passes through the center (axial center) of the rocking shaft 16 and the first magnet 13 in the same manner as the first magnet 13. Are arranged so as to be located on a virtual line (substantially perpendicular to the bottom surface of the rocking member 12 from the center of the rocking shaft 16) that is substantially perpendicular to the surface on which the is mounted. However, the magnetic poles (N pole, S pole) of the second magnet 17 are arranged in the opposite direction to the magnetic poles (N pole, S pole) of the first magnet 13. As a result, the magnetic attractive force acts between the magnetic poles different from each other at the facing portion between the first magnet 13 and the second magnet 17.
[0017]
The second magnet 17 is sandwiched between a pair of guide portions 19 formed integrally with the housing 18. The pair of guide portions 19 protrudes outward through the air core portion of the drive coil 14 and supports the second magnet 17 in a state of sandwiching the second magnet 17 from both sides. In this support state, the second magnet 17 contacts and separates from the first magnet 13 (the vertical direction in FIGS. 2 and 3) and the magnetic field central axis direction of the first magnet 13 (the left and right in FIG. 2). The position can be changed in each direction. The positional fluctuation of the second magnet 17 is guided by a pair of guide members 19 that support the second magnet 17. Further, when the position varies in each direction, the position of the second magnet 17 is adjusted (finely adjusted) using a position adjusting jig (not shown) or the like.
[0018]
Next, the operation of the scan unit 11 having the above configuration will be described. First, the stationary posture of the scan mirror 15 attached to the swing member 12 is held by a magnetic attractive force acting between the first magnet 13 and the second magnet 17. When positive and negative currents are passed through the drive coil 14 from this state at a constant period, a drive magnetic field corresponding to the direction of the current is generated in the direction of the central axis of the drive coil 14. At this time, when the drive coil 14 generates an upward drive magnetic field in FIG. 2, a magnetic repulsive force acts on the N pole of the first magnet 13 and a magnetic attractive force acts on the S pole. Due to this magnetic attraction / repulsion action, a moment Z is generated in the swing member 12 to rotate about the swing shaft 16. Further, when the direction of the driving magnetic field is reversed due to the reversal of the current flowing in the driving coil 14, a moment is generated to rotate the swing member 12 in the opposite direction. Thus, the swing member 12 swings according to the frequency of the current (alternating current) flowing through the drive coil 14 together with the scan mirror 15 held by the swing member 12.
[0019]
In the scan unit 11 operating in this way, when the position of the second magnet 17 is changed in the vertical direction (corresponding to the first direction) in FIG. 2 while the drive coil 14 is not energized (non-driven state). Accordingly, the distance L between the first magnet 13 and the second magnet 17 changes. Therefore, the magnitude of the magnetic attractive force acting between the first and second magnets 13 and 17 also changes. That is, when the position of the second magnet 17 is moved upward in FIG. 2, the distance L between the first and second magnets 13, 17 is shortened, and accordingly, the first, second magnets 13, The magnetic attractive force acting between 17 increases. Further, when the position of the second magnet 17 is moved downward in FIG. 2, the distance L between the first and second magnets 13 and 17 becomes longer, and accordingly, the first and second magnets 13 and 13 are accordingly changed. The magnetic attractive force acting between 17 is reduced.
[0020]
The magnetic attractive force acting between the first and second magnets 13 and 17 in this way is a spring against the swinging member 12 when the swinging member 12 is swung by energizing the drive coil 14. It acts elastically like this. Therefore, by changing the position of the second magnet 17 in the vertical direction in FIG. 2 and changing the magnitude of the magnetic attractive force acting between the first and second magnets 13 and 17, the scan mirror 15 and the swing member The resonance frequency of the rocking mechanism including 12 can be changed. As a result, it is possible to arbitrarily adjust the resonance frequency of the swing mechanism in the apparatus manufacturing process.
[0021]
Further, if the position of the second magnet 17 is changed in the left-right direction (corresponding to the second direction) in FIG. 2 in a state where the drive coil 14 is not energized (non-driven state), the first magnet is changed accordingly. The magnetic pole positions of the magnet 13 and the second magnet 17 change relatively. Therefore, the balance of the magnetic attractive force acting between the first and second magnets 13 and 17 also changes. That is, if the position of the second magnet 17 is changed in the right direction in FIG. 2, the magnetic pole position of the second magnet 17 is moved in the right direction relative to the magnetic pole position of the first magnet 13. The swinging member 12 swings in the clockwise direction due to the change in the balance of the magnetic attraction force accompanying this. In addition, if the position of the second magnet 17 is changed in the left direction in FIG. 2, the magnetic pole position of the second magnet 17 moves relative to the magnetic pole position of the first magnet 13. The swinging member 12 swings counterclockwise due to the change in the balance of the magnetic attractive force accompanying this.
[0022]
Thus, the magnetic attractive force acting between the first and second magnets 13 and 17 acts as a holding force for holding the stationary posture (tilt angle) of the scan mirror 15 without energizing the drive coil 14. . Therefore, the stationary posture of the scan mirror 15 is changed by changing the balance of the magnetic attractive force acting between the first and second magnets 13 and 17 by moving the second magnet 17 in the left-right direction in FIG. Can be made. Therefore, it is possible to arbitrarily adjust the stationary posture of the scan mirror 15 during the apparatus manufacturing process.
[0023]
Incidentally, at the stage where the resonance frequency adjustment of the oscillating mechanism by the position fluctuation of the second magnet 17 and the stationary posture adjustment of the scan mirror 15 are completed, the second magnet 17 is attached to the pair of guide portions 19 using an adhesive or the like. Fixed.
[0024]
From the above, in the barcode reading apparatus according to the present embodiment, even if a desired resonance frequency cannot be obtained due to variations in the dimensions and weight of components, for example, at the final stage of the assembly process. A desired resonance frequency can be obtained by appropriately changing the position of the second magnet 17 in the first direction (vertical direction in FIG. 2). Therefore, handling becomes very easy. In particular, in order to efficiently operate the magnetic circuit for oscillating the mirror, it is preferable that the resonance frequency and the driving frequency of the oscillating member coincide with each other. By adjusting the resonance frequency of the oscillating mechanism, the magnetic circuit can be operated efficiently. Thereby, since the resonance frequency is optimized, the operating efficiency of the magnetic circuit can be increased and the power consumption can be reduced. In addition, even when the scan unit 11 is assembled using similar components, it is possible to obtain different resonance frequencies due to the position variation of the second magnet 17.
[0025]
Further, even if the relative position between the scan mirror 15 and the swinging shaft 16 and the mounting position of the first magnet 13 vary, the second magnet 17 is moved in the second direction (FIG. 2) at the final stage of the assembly process. By appropriately changing the position in the left and right directions), the scanning mirror 15 can be stopped in a desired posture while the driving coil 14 is not driven, and the swinging member 12 can be started to swing from the resting posture.
[0026]
In the above embodiment, the stationary posture of the scan mirror 15 can be adjusted by changing the position of the second magnet 17 in the direction of the magnetic field center axis of the first magnet 13. However, the present invention is not limited to this. Not limited to this, the second magnet 17 is supported so as to be able to rotate around the boundary portion of its own magnetic pole property, and the position of the second magnet 17 can be changed in the rotation direction around the boundary portion of the magnetic pole property. Even in this case, by changing the position of the second magnet 17 in the rotation direction, the balance of the magnetic attractive force acting between the first and second magnets 13 and 17 is changed, and as a result, the scan mirror 15 in the same manner as described above. Can be adjusted.
[0027]
【The invention's effect】
As described above, according to the present invention, the position of the second magnet is changed in the first direction to change the magnitude of the magnetic attractive force acting between the second magnet and the scan mirror and the swinging force. The resonance frequency of the rocking mechanism including the moving member can be changed. Further, by changing the position of the second magnet in the second direction and changing the balance of the magnetic attractive force acting between the first magnets, The stationary posture can be changed. As a result, it is possible to arbitrarily adjust the resonance frequency of the swing mechanism and the stationary posture of the scan mirror. As a result, it is possible to set the resonance frequency of the oscillating mechanism and the stationary posture of the scan mirror to the optimum conditions even if there are manufacturing variations (variations in component dimensions, weight, mounting position, etc.).
[Brief description of the drawings]
FIG. 1 is a perspective view showing a configuration of a scan unit applied to a barcode reading apparatus according to an embodiment of the present invention.
2 is a side view including a partially broken surface when the scan unit of FIG. 1 is viewed from the direction of arrow J. FIG.
FIG. 3 is a front view of the scan unit of FIG. 1 when viewed from the K direction.
FIG. 4 is a schematic diagram showing a configuration of a general barcode reader.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Scan unit, 12 ... Swing member, 13 ... 1st magnet, 14 ... Drive coil, 15 ... Scan mirror, 16 ... Swing shaft, 17 ... 2nd magnet, 18 ... Housing, 19 ... Guide part

Claims (3)

A swing member that holds the scan mirror and is supported so as to be swingable about a swing shaft;
A first magnet that is mounted on the swing member and that forms a magnet magnetic field in a direction substantially perpendicular to the swing axis;
A swing drive unit that swings the swing member by magnetic attraction and repulsion with the magnet magnetic field formed by the first magnet;
A first direction in which a magnetic attraction force is applied between magnetic poles different from each other with respect to the first magnet and a magnitude of the magnetic attraction force is varied, and a second direction in which the balance of the magnetic attraction force is varied. And a second magnet provided in such a manner that its position can be varied. The second magnet is disposed in a state of facing the first magnet via the swing driving unit, and is in contact with and away from the first magnet and a magnetic field of the first magnet. 2. The bar code reader according to claim 1, wherein the bar code reader is provided so as to be capable of changing its position in the central axis direction. The second magnet is disposed in a state of facing the first magnet via the swing drive unit, and a direction in which the second magnet is brought into contact with and separated from the first magnet and an attachment of the second magnet. 2. The bar code reader according to claim 1, wherein the bar code reader is provided so as to be capable of changing its position in the rotation direction around the magnetic pole boundary.

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