JPH09282406A - Optical scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a reliable and inexpensive device equipped with two-dimensional scanning by fixing an optical element to a bracket arranged so as to vibrate by a comparatively low frequency by a wire with comparatively high elasticity. SOLUTION: A mirror 10 and steel wire springs 12 and 13 are fixed to a bracket 11. A bracket 14 is fixed to a bracket 15 by steel wire springs 16 and 17. In order to vibrate the whole unit, wire springs 19 and 20 are arranged. An electromagnetic coil 21 is periodically attracted by the corner of the bracket 11 and gives vibrating force 22 moving the mirror 10. Scanning in an X direction is comparatively fast due to the characteristic of the springs of comparatively high elasticity 12, 13, 16 and 17 and the characteristic of the mirror 10 and the mass of the brackets 11 and 14. On the other hand, scanning in a Y direction is comparatively slow due to the combination of the characteristic of the brackets 11, 14 and 15, the springs 19 and 20 and the mirror 10.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION In general, the present invention relates to optical scanning devices for use as optical scanners, such as bar code readers.

[0002]

2. Description of the Related Art A general optical scanner (for example, a bar
The code reader comprises a light source, preferably a laser light source, and a symbol (eg,
Bar code symbol). On the optical path to this symbol, the laser beam is directed to and reflected at a light reflecting mirror, which is typically a scan. The scanning element, by vibrating the mirror,
The laser beam will be repeatedly scanned in symbols. The light reflected by the symbol is collected by a scanner and detected by a photodetector such as a photodiode. The demodulation circuit and / or the algorithm of the microprocessor is demodulated based on the reflected light. As a result, the data represented by the bar code symbol is recovered.

[0003]

In the type of scanner known as two-dimensional, or 2D scanner, scanning involves two-dimensional tracing of a light beam across the symbol being read. The preferred pattern depends on the nature of the scanner and symbol used, but Lissajous figures and laser patterns are typical examples.

Generally, in a two-dimensional scanning pattern, the mirror is mounted so that it vibrates in two vertical directions. In the past, a separate drive mechanism was required to generate vibration in the X and Y directions, but modern scanning devices use a single signal magnetic coil to enable two-dimensional operation. Has been devised. US Pat. No. 5,168,1
Examples are given in No. 49 and No. 5,280,165. These are assigned to the assignee of the present invention,
It is incorporated here as a reference.

[0005]

SUMMARY OF THE INVENTION The present invention seeks to provide a reliable and inexpensive device with two-dimensional scanning. Further, in the present invention, the scanning cycle in the X direction is Y
It is an object of the present invention to provide a device that can be significantly different from the scanning period in the direction. It is also an object of the present invention to provide a code reader for performing scanning using torsional vibrations of optical elements. From the following detailed description of the invention, other objects, advantages and novel features of the invention will be apparent to those skilled in the art. Although the present invention has been described as the following preferred embodiments, the present invention is not limited thereto. A person of ordinary skill in the art who has the benefit of the teachings herein is within the scope of the invention as disclosed and claimed herein, in respect of which other applications and variations in other fields in which the invention may be highly effective. And will recognize embodiments.

In accordance with the present invention, there is provided an optical scanning device for using a scanner to read a code having portions of different light reflectance. The device of the present invention comprises the following requirements. (1) An optical scanning device for reading a code composed of portions having different light reflectances, and having the following configuration. a) Optical element. b) When the optical element is attached by first and second wires having a relatively high elastic modulus, and the optical element vibrates due to elastic movement of the first and second wires. , Mounting bracket with relatively low moment of inertia. c) Third and fourth having relatively high elasticity against vibration
Wire is attached to the mountain bracket, and when vibrating due to elastic displacement of the third and fourth wires, the optical element, the mounting bracket, and the first and second wires are A fixed frame that has a relatively high moment of inertia. d) Driving means arranged to vibrate at a relatively high frequency the optical element for the mounting bracket arranged to vibrate at a relatively low frequency with respect to the frame. (2) The optical scanning device is characterized by having the following configuration. a) Optical element. b) Mounting bracket. The optical element is attached for torsional vibrations with respect to the mounting bracket by first and second wires disposed between the optical element and the mounting bracket,
The optical element has a relatively low moment of inertia when vibrating due to the elastic displacement of the first and second wires. c) The mountain bracket is attached to the mountain bracket by third and fourth wires, which have relatively high elasticity against vibration, and when vibrating due to torsional elastic displacement of the third and fourth wires, A fixed frame in which the optical element, the mounting bracket, and the first and second wires have a relatively high moment of inertia. d) Driving means arranged to simultaneously vibrate the optical element of the mounting bracket arranged to vibrate at a relatively low frequency with respect to the frame at a relatively high frequency. (3) The optical scanning device has the following configuration. a) Frame. b) A scanning member having a predetermined moment of inertia. c) A first elongate mounting element adapted to mount the scanning member to the frame to create vibrations about the frame about a first axis extending along the first elongated element. d) The scanning member includes a light reflecting sub-member having a moment of inertia different from a predetermined moment of inertia of the scanning member and a light reflecting member. e) for mounting the light sub-reflecting member for vibrating the scanning member about a second axis that is substantially perpendicular to the first axis and extends along the second elongate element. Second
Slender mounting element. f) Based on the different moments of inertia, the first and second
A common drive unit adapted to couple to the scanning member to simultaneously vibrate the reflective member at first and second frequencies about each of the axes.

[0007]

DETAILED DESCRIPTION OF THE INVENTION From FIG. 1, generally, 100 is
2 illustrates a handheld gun-shaped scanner head having a barrel 120 and a handle 140. The head 100 need not necessarily be gun-shaped, as any suitable design, such as box-shaped, may be used. The manually operable trigger 160 has the barrel 120 located above the front portion of the handle 140. As can be seen from the above patent and the application provided here as a reference, a typical light source component, a laser, is incorporated inside the head 100. However,
It is not always necessary to use a laser as a light source. A window 180 facing a code such as a bar code to be read
A light beam from a light source is emitted along an optical path that is arranged so as to penetrate through.

The scanner component is mounted within the head 100 and is capable of manipulating the scanning of the symbol and / or photodetector field of view. The scanner component includes at least one light reflector located in the transmission path and / or the return path. The light reflector is preferably driven by a motorized drive to vibrate in other peripheral directions at a frequency that resonates with the scanner component.

The photodetector produces an electrical analog signal indicative of the various intensities of the reflected light. This analog signal is
It is converted into a digital signal by the A / D conversion circuit.
This digital signal is transmitted to the decoding module 220 arranged outside the head 100 according to the first embodiment.
Dielectric along the electrical cable 200. Here, the decoding module 220 decodes the digital signal into symbol display data. The external host device 240, which is usually a computer, is mainly used as a device for storing data generated by the decryption module 220 and stored for continuous processing.

The user aims the head at the symbol and pulls the trigger 160 to begin reading the symbol. The trigger 160 is an electric switch that operates the driving means. The symbol is multiple times per second, for example 40 per second.
It is repeatedly scanned once. As soon as the symbol has been successfully decoded and read, the scan is automatically terminated, after which the scanner leads to the next symbol to be read.

Furthermore, in the present invention, the head need not be a portable handheld type, but may be fixed. Furthermore, the head may be manually operated with a trigger or continuously operated by a direct connection to a power source. The vibration is only about 1 second. With multi-vibration,
It has a high probability of successfully decoding dirty printed symbols. The tuned reflector has a predetermined, known, generally uniform angular velocity that is predetermined to improve system safety. FIG. 2 is a schematic diagram of an embodiment of a scanner component of a bar code reader according to the present invention. This diagram does not illustrate practical embodiments, but illustrates the basic idea of the invention. As shown in FIG. 2, an optical element such as a mirror 10 is mounted for vibration on the first mounting bracket 11. Also, the first mounting bracket 11 is mounted for vibration on the second mounting 14 by springs, such as first and second wires 12, 13 of high tensor steel wire. . The springs 12 and 13 connect the mirror 10 to the second bracket 14
Vibrates in a first direction (X direction).

The second bracket 14 is sequentially attached to the mounting bracket 15 by steel wire springs 16 and 17 in the x direction. Mirror 10
And springs 12, 13, 16 and 17, and the first,
A third group of wire springs 19, 20 is arranged to oscillate the entire unit with the second brackets 14, 15 in the second direction (Y direction). The drive device 21 provides an oscillating force 22 which displaces each of the springs and moves an optical element for producing a deflection of the scanning light beam in the XY directions.

One of the most different features of the present invention is
The brackets 11, 14 and 15 are flat.
All these elements are generally square and are arranged in the same plane. Springs 12, 13, which have a relatively high elastic modulus,
16 and 17 characteristics, mirror 10 and bracket 1
Due to the mass characteristics of 1,14, the scanning in the X direction is
Relatively fast. On the other hand, scanning in the Y direction is relatively slow due to the combination of mass characteristics of the first, second and third brackets, the spring and the mirror. Here, the mass of the mirror is relatively large.

The driving force 22 may include an overlapping position of the vibration signals separated into two, a high-frequency signal for promoting vibration in the X direction, and a low-frequency signal for promoting vibration in the Y direction. From the above description, the frequency of vibration in the Y direction is the sum of the elastic moduli of the springs 19 and 20 and the masses that move in the Y direction (in this case, the combination of the brackets 11, 14 and 15, the mass of the spring and the mirror). You can see that it depends on and. The frequency of vibration in the X direction is
3, 16 and 17 length, diameter and modulus, and mirror 1
0 and the mass moving in the X direction including the brackets 11 and 14.

It will be appreciated by those skilled in the art that, more specifically, the frequency of the X, Y scan depends on the moment of inertia rather than the mass. The actual mechanical characteristics of the device are somewhat more complicated than the above, if there is a rotating element when the spring is flexible as in translation. However, the general principle is applicable, and it
The associated mass and length to meet the requirements for vibration in the X and Y directions,
It eases the skill of technicians in the field of choosing diameter and modulus.

FIG. 3 shows a particular embodiment of a biaxial scan pattern device. Here, the scanning component is, for example, the light reflector or the mirror 10 fixedly mounted on the bracket 11. The electromagnetic coil 21 is a chassis 18
, Is fixedly attached. The electrical input provides an energy signal to the coil 27. In some applications it is desirable to scan the code in a raster scan pattern. In a raster scan pattern, a number of continuous, substantially horizontal, substantially parallel scan lines are generated from top to bottom to uniformly cover the desired scan area. In order to obtain a raster scanning pattern, mirrors are arranged which oscillate in mutually perpendicular planes. As shown in FIG. 2, the mirror is moved by this device of the holding means by virtue of angular oscillations in the first and second alternating rotational directions between the first and second scanning ends. It is installed. In addition, according to their shape and position, the internal springs 16,17 and 12,13 have
Generally, it vibrates in a high frequency range of about 200 to 800 Hz. On the other hand, the outer springs 19 and 20 generally vibrate in a low frequency range of about 5 to 100 Hz. It is preferable that these frequencies are 280 Hz and 20 Hz, respectively. The amplitude of the vibration required to scan the symbol is
Depending on the size of the symbol, it is generally at least 5-15 degrees with respect to the face of the brackets 11, 14 and 15.

In this device, whenever an AC drive signal is provided which is placed over the coil 21, the coil is periodically attracted at the corner of the bracket 14. The high frequency component of the drive signal is the spring 19,
20 is vibrated, preferably at the resonant frequency, causing the bracket 15 to vibrate at an angle with the scanning end. The low frequency components of the drive signal are springs 12, 13, 1
6 and 17 are angularly vibrated. As the light emitted from the laser is directed at reflector 10 while the spring vibrates simultaneously at each high and low frequency, a substantially horizontal continuous scan line in the X direction is generated and displaced in the Y direction. It As a result, a raster scan pattern is formed. The device of FIG. 3 is very simple and well designed with only one drive (coil) for vibration in two directions to form a raster scan pattern. There are no shafts or bearings, but flexible metal is used to extend product life.

Although the present invention has been described with respect to reading one-dimensional and two-dimensional bar codes, it is not limited to such an embodiment and may be applied to more complex code scanning applications. Also, the method of the present invention can be performed from another type of code, such as a letter, or
It would be possible to find applications for use as various machine vision devices or optical character recognition applications in the information derived from the surface characteristics of the scanned article.

In all of the various embodiments, the elements of the scanner may be assembled in a very compact package in which the entire scanner is constructed like a single printed circuit board or stacked module. Such modules can be interchangeably used as laser scanning elements for different types of variations of data acquisition systems.
Can be used. For example, the module may include a handheld scanner and table top mounted on a flexible arm or table mounting extension surface side or under the table top, or as a subcomponent of a more sophisticated data acquisition device. The scanner and the scanner may be used alternately. Control or data lines assisted by such components to electrically connect the module to maintain the connector supporting other elements of the data acquisition system are provided on the edge or extended surface of the module. It is connected to the installed electrical connector.

Each module may have specific scanning or decoding characteristics to support it (eg, operation at some working distance, certain semiotics or print density operation). The characteristics are also defined via manual setting of control switches that assist the module. Users may also employ the data acquisition system for scanning different types of articles. Also, the system may be employed for different applications with replaceable modules on the data capture device via the use of simple electrical connectors.

The scanning module described above is also implemented in an embedded data acquisition system that includes one or more components such as a key board, display, printer, data storage medium, application software or data base. You may Also, such a system can be used with a low power radio broadcast from a portable terminal to a fixed receiver, via a modem or ISDN interface, to the data acquisition system and other components of the LAN or telephone switching network. May include a communication interface that enables communication of the.

Each of the above features, or combinations of two or more, may be found to be useful applications in different types of scanners and bar code readers than those described above. Although the present invention is illustrated and described in its embodiments as a two-dimensional optical scanning device, it is not intended to be limited to the details shown. Thus, various modifications or structural changes do not depart from the spirit of the invention.

Except for a deeper analysis, the above description fully illustrates the gist of the present invention, so that a third party can easily apply it to various applications by applying the current knowledge. From the point of view of the prior art, the functions capable of constructing the general or professional characteristics of the present invention sufficiently and essentially can be applied without omission. Therefore,
Such applications are intended to fall within the scope of the following claims.

[0024]

According to the present invention, it is possible to provide a reliable and inexpensive apparatus having two-dimensional scanning.

[Brief description of drawings]

FIG. 1 is a front perspective view of a handheld bar code reader including a scanner according to the present invention.

FIG. 2 is a schematic diagram employing the present invention.

FIG. 3 is a perspective view of an embodiment of a scanning device according to the present invention.

[Explanation of symbols]

 10 Mirror 12 Wire 13 Second Wire 14 Second Bracket 15 Third Bracket 16 Wire 17 Wire 19 Wire 20 Wire

Claims (16)

[Claims] 1. An optical scanning device for reading a code composed of portions having different light reflectances, and having the following structure. a) Optical element. b) When the optical element is attached by first and second wires having a relatively high elastic modulus, and the optical element vibrates due to elastic movement of the first and second wires. , Mounting bracket with relatively low moment of inertia. c) Third and fourth having relatively high elasticity against vibration
Wire is attached to the mountain bracket, and when vibrating due to elastic displacement of the third and fourth wires, the optical element, the mounting bracket, and the first and second wires are A fixed frame that has a relatively high moment of inertia. d) Driving means arranged to vibrate at a relatively high frequency the optical element for the mounting bracket arranged to vibrate at a relatively low frequency with respect to the frame. 2. The mounting bracket is flat,
The optical scanning device according to claim 1, wherein the optical scanning device has a square shape. 3. The optical scanning device according to claim 1, wherein the optical element comprises a flat mirror. 4. The optical scanning device according to claim 1, wherein the driving unit includes an electromagnetic coil that simultaneously drives the first and second frequencies. 5. The optical scanning device has the following configuration. a) Optical element. b) Mounting bracket. The optical element is attached for torsional vibrations with respect to the mounting bracket by first and second wires disposed between the optical element and the mounting bracket,
The optical element has a relatively low moment of inertia when vibrating due to the elastic displacement of the first and second wires. c) The mountain bracket is attached to the mountain bracket by third and fourth wires, which have relatively high elasticity against vibration, and when vibrating due to torsional elastic displacement of the third and fourth wires, A fixed frame in which the optical element, the mounting bracket, and the first and second wires have a relatively high moment of inertia. d) Driving means arranged to simultaneously vibrate the optical element of the mounting bracket arranged to vibrate at a relatively low frequency with respect to the frame at a relatively high frequency. 6. The optical scanning device has the following configuration. a) Light reflection means. b) Means adapted to mount said light reflecting means so as to vibrate about a first axis at a first vibration frequency. c) Means adapted to oscillate the reflecting means about a second axis at a second vibration frequency different from the first vibration frequency and substantially perpendicular to the first axis. d)
Driving means adapted to simultaneously vibrate the reflecting means around both the first and second axes relating to the first and second vibration frequencies. 7. The optical scanning device has the following structure. a) Frame. b) A scanning member having a predetermined moment of inertia. c) A first elongate mounting element adapted to mount the scanning member to the frame to create vibrations about the frame about a first axis extending along the first elongate element. d) The scanning member includes a light reflecting sub-member having a moment of inertia different from a predetermined moment of inertia of the scanning member and a light reflecting member. e) for mounting the light sub-reflecting member for vibrating the scanning member about a second axis that is substantially perpendicular to the first axis and extends along the second elongated element. Second
Slender mounting element. f) Based on the different moments of inertia, the first and second
A common drive unit adapted to couple to the scanning member to simultaneously vibrate the reflective member at first and second frequencies about each of the axes. 8. The reflecting member includes a first mounting bracket having a reflecting member attached thereto, a second mounting bracket, and the first and second mounting brackets along the second axis.
8. An optical scanning device according to claim 7, including a third elongate mounting element extending between the mounting brackets of. 9. The optical scanning device according to claim 8, wherein the first and second mounting brackets are arranged in a common plane. 10. The optical scanning device according to claim 7, wherein the first and second mounting brackets have a substantially rectangular shape. 11. The optical element of claim 8, wherein the third elongated attachment element comprises a linear twisted wire fixed at both ends to the first and second brackets. Scanning device. 12. The scanning device comprises a third plane disposed on a common plane of the first and second mounting brackets.
10. The optical scanning device of claim 9 including the mounting bracket of claim 1. 13. The optical scan of claim 12, wherein the second attachment element is a common linear twist wire that secures the second and third mounting brackets at both ends. apparatus. 14. The optical system of claim 13, wherein the first mounting element comprises a common linear twisted wire adapted to secure the third mounting bracket and the frame at both ends. Scanning device. 15. The optical scanning device as claimed in claim 7, wherein the driving means includes an electromagnetic coil incorporated in the frame and a reciprocating driving element coupled to the scanning member. 16. The first vibration frequency is in the range of 5 to 100 Hertz and the second vibration frequency is in the range of 200 to 80.
8. The optical scanning device according to claim 7, wherein the vibration frequency range is 0 Hz.