CN1037379C - Combined Dual Range Laser Scanner - Google Patents

Abstract

The present invention provides a method for using two laser illuminators with different focal lengths, consisting of a first laser illuminator best suited for close range scanning from close to about 2 feet and a first laser illuminator suitable for long distance scanning from about 2 feet to about 17 feet. It is composed of the second laser illuminating device for scanning. The scanner is equipped with a logic loop network that can select a certain lighting device to work corresponding to various scanning applications. The speed of the laser spot is controlled in order to be able to limit the frequency of the received optical signal to that of the standard signal processing and decoding circuits regardless of which lighting device is selected.

Description

Combined Dual Range Laser Scanner

In general, the present invention relates to combined range laser scanners and methods for electro-optical reading of patterns (such as bar codes) containing areas of differing reflectivity; in more detail, the present invention relates to illumination optics using more than two laser diodes The above combined distance laser scanner and method for focusing at different working distances. The preferred first embodiment of the present invention has two laser illumination optics, a first arrangement optimized for close-up scanning and a second arrangement optimized for long distance scanning. Two laser illumination optics are assembled in a combined range laser scanner.

In order to identify commodities, barcodes have been increasingly adopted especially in the small business world, and various barcode reading devices have thus been developed. Most users of barcode reading devices require portable hand-held scanners that are small in size, light in weight, consume less power, and the like.

Laser-scanning barcode readers can come in a variety of specific form factors, from gun-like housings made of lightweight plastic to portable, hand-held scanning heads. Various parts of the reading device are placed on the frame portion and the handle portion of the gun-shaped housing. That is, in the body of the gun, a small light source, a focusing lens, a small optical device containing a scanning mechanism that enables the light emitted from the light source to scan the barcode in a transverse direction, and a small optical device that can detect the light reflected by the bar code mark during scanning are arranged. light detector.

The small light source can be made of a laser tube (for example a coaxial eg helium-neon laser tube) or a light emitting diode, or a semiconductor laser diode. Since the semiconductor laser diode is smaller and lighter than the laser tube, the size and weight required for the scanning head can be small, and the handling and operation of the scanning head are also easier, so the semiconductor laser diode is ideal. After the light emitted by the light source passes through the optical device, the laser beam is guided to the scanning mechanism arranged on the gun body of the scanning head, and then the barcode mark is cut and scanned horizontally. The scanning mechanism is equipped with at least one stepping motor for scanning, or a resonant rod, or a scanner that enables the laser beam to cut and scan barcodes transversely along the longer direction. If one motor is used, the scanning mechanism can also be composed of two motors. The shaft of the scan motor is fitted with a scan mirror that directs the laser beam passing through the window to the barcode markings.

The light reflected by the barcode marks is detected and processed by a detection circuit. The detection circuit is generally composed of photodetectors such as semiconductor photodiodes. The user determines the position of the handheld reader in order to read the graphic by scanning the barcode markings by cutting them across. In order to recognize the bar code markings, a series of electrical signals generated by the photodetectors are sent to the signal processing circuit. The output signal of the signal processing loop is sent to the barcode graphic decoder loop, where the barcode indicia is decoded.

When the user aligns the reading device with the barcode mark and pulls the trigger, the light beam and detection circuit network are activated and scanning begins. Since the reading device operates in this manner, when the reading device uses a built-in battery, the useful life of the battery can be extended. In a light-weight plastic case, the laser light source, detector, optical device, signal processing circuit, central processing unit CPU and battery are housed. The reading device is designed to aim at the bar code mark from a position away from the bar code mark. That is, the reading device neither snuggles against the indicium nor moves in a cutting manner across the indicia. Generally speaking, this type of handheld bar code reading device is specified for use in the range of several inches. Instead of the scanning manner described above, it is also possible to perform scanning automatically with human reference.

Past photoelectric bar code marking reading laser scanning devices have limited operating ranges as follows: (a) from about 2 feet for the most common density bar code markings, (b) from about 2 feet for lower density bar code markings. 30 inches to 18 feet. Thus, since the past laser scanning device only uses a laser illumination optics device with a single fixed focal length, the depth of focus is small and the working range is narrow.

According to the above, the first object of the present invention is to provide a combined range laser scanner and method for photoelectrically reading barcodes and other patterns with different reflectivity regions. In order to be suitable for different working distances, combined range laser scanners use two or more laser diode illumination optics that can be optimally adjusted for different distances. The preferred embodiment of the invention is equipped with two laser optics, a first laser illumination optic optimal for scanning from close up to a distance of 2 feet and a second laser optic optimal for scanning from approximately 2 to 17 feet Lighting unit, two laser scanning units are combined in a combined distance laser scanner.

A second object of the present invention is to provide such a combined range laser scanner equipped with a logic loop network capable of selecting the action of a certain laser illumination optics according to the requirements of a specific scanning application. In order to limit the frequency of the received optical signal to the frequency of the standard signal processing decoding loop, depending on which laser illumination optics is selected, the moving speed of the laser spot (for example, by controlling the amplitude of the drive signal of the scanning motor) is controlled. Scanning is achieved by a common vibrating scanning mirror driven by a scanning motor. For the case of the first laser illumination optical device that is most suitable for close or short-distance work, the amplitude of the driving signal applied to the scanning motor is relatively large; In the case of the second laser illumination optics which are most suitable for long-distance scanning operations, the amplitude of the drive signal is relatively small.

In order to solve the above-mentioned problems, the present invention provides a combined distance laser scanner and method having the following features when photoelectrically reading graphics with different reflectivity areas such as barcode marks. A laser scanner consists of: a common scanning mirror for scanning the laser beam from one end of the field of view to the other, a short-range laser illumination optics for short-range scanning operations, and a long-range laser illumination optic for long-distance scanning operations. Laser illumination optics. Concentrating optics are provided in order to collect the light reflected by the scanned field of view and direct it to the detector. A detector detects the reflected laser radiation and generates an electrical signal corresponding to the reflected light.

More specifically, the scanner is also equipped with a selection device for selecting the operation of the short-distance laser illuminating device or the long-distance laser illuminating device in order to enable the scanner to perform short-distance operation or long-distance operation within the field of view. In the case of the first embodiment, the selection device is also equipped with a signal processing circuit capable of analyzing the amplitude and frequency of the reflected light signal when the long-distance laser illumination device is temporarily used and the distance measurement action is activated. If the distance of the barcode is farther when scanning, the frequency of the output signal of the detector is higher and the amplitude is smaller. Conversely, the shorter the distance is when scanning, the frequency of the output signal of the detector is lower and the amplitude is larger. Therefore, the selection of the short-distance illumination optical device or the long-distance illumination optical device can be determined based on the amplitude and frequency of the signal detected by the distance measurement operation. In the case of the second embodiment, a sonar rangefinder is used to detect the distance to an object within the field of view. In the case of the third embodiment, the above-mentioned selection device is a manual selection device operated by the operator, for example, the operator makes a selection by operating a trigger with two gears, the first gear and the second gear.

In the case of the first preferred embodiment, the scanning mirror is a planar scanning mirror driven by a scanning motor. The short-distance laser illumination optical device is a short-distance visible light laser diode assembly arranged in front of the scanning mirror. The long-distance laser illumination optical device is a long-distance visible light laser diode component. Its configuration is that there is a turning mirror placed on the lateral side of the short-distance visible light laser diode component, and the laser radiation is first emitted from the turning mirror, and then by the scanning mirror. reflection.

Furthermore, in a preferred embodiment, the short-distance laser illumination optics and the long-distance laser illumination optics are a combination of integrated laser diodes, both of which are placed in front of the scanning mirror, and the short-distance working motor therein Both motors and long-distance work are designed so that either one can operate.

The ideal working distance for short-range laser illumination optics is from snug to about 2 feet. In contrast, the ideal working distance for long distance laser illumination optics is about 2 to 17 feet from the reading device. The condenser optics each have a common condenser mirror, which is used to concentrate all the laser radiation reflected by the field of view onto a photodetector such as a photodiode.

By reading the following detailed description of several preferred embodiments with reference to the accompanying drawings, the above-mentioned purpose and advantages of the combined distance metering and scanning device of the present invention will be easily understood. In all figures, the same parts are indicated by the same reference numerals.

A brief description of the attached drawings:

Fig. 1 is a diagram showing the range of scanning and decoding areas of various barcode resolutions 4 by the combined dual-distance laser scanner of the present invention.

FIG. 2 is a block diagram of the main functions and components of the first embodiment of the combined dual-range laser scanner of the present invention.

3 is a block diagram of the main functions and components of a second embodiment of the combined dual-range laser scanner of the present invention.

Fig. 4 is a schematic diagram of a typical configuration of the optical device of the combined dual-range laser scanner of the present invention.

Fig. 5 is a side view of a typical optical arrangement of the combined dual-range laser scanner of the present invention.

FIG. 6 is a front view of the exemplary optical device of FIG. 5 .

Fig. 7 is a sectional view showing the structure and main parts of the laser diode module of the present invention.

Figure 8 is a schematic diagram of a gun-type bar code reading device that may be used in connection with the combined dual-range laser scanner of the present invention.

Figure 1 shows the range of scanning and decoding areas of the combined dual (long and short) range scanner of the present invention for various barcode resolutions in the case of high quality barcode indicia. It can be considered that the short-distance code area is read from the bar code pattern close to about 2 feet, while the long-distance decoding area is the bar code pattern read from about 2 feet to 17 feet. As shown in Figure 1, the resolution possible at the bar code graphic ranges from 0.005 inch bar width for very close range bar code graphic to 0.05 inch bar width for long distance bar code graphic. There is overlap between the short range decoding area and the long range decoding area, in fact the short range decoding area is about 4 x 1/2 feet wide and the long range decoding area is from about 10 inches to about 12 feet wide. However, it is not optimal to perform decoding work outside a range narrower than the above-mentioned area.

Figure 2 is a block diagram of the main functions and components of the first embodiment of the combined dual (long and short) range scanner of the present invention. The combined dual-range scanner scans, analyzes and transmits barcode data in fractions of a second. Aiming the combined dual range scanner at the bar code mark and pulling the trigger 12 initiates the following sequence of actions.

The distance measurer 14 in the scanning module detects the distance of the barcode mark. In the case of the first preferred embodiment, the structure of the distance measurer 14 can be to temporarily activate the long-distance scanning mechanism to realize the distance measurement action, and use the signal processing circuit to analyze the amplitude and frequency of the reflected light signal. If the barcode is placed farther away when scanning, the frequency component of the generated detector output signal will be higher, and the amplitude will be higher. On the contrary, if the scanning distance is closer, the frequency component of the generated detector output signal will be lower. The greater the amplitude. Therefore, it can be determined whether to select a short-distance lighting device or a long-distance lighting device based on the signal amplitude and frequency detected from the distance measurement operation. In a second embodiment, the distance finder 14 can be formed by a commercially available distance finder in the form of a Polaroid sonar for cameras. According to the output of the distance measuring device, the switching circuit network 16 decides whether to select the short-distance visible light laser diode 18 or the long-distance visible light laser diode 20 .

In the case of the first preferred embodiment, the short-distance laser illumination optical device and the long-distance laser illumination optical device are arranged in the near front of the scanning mirror, and are designed to work either in a short-distance working mode or in a long-distance working mode, They form a single integral laser diode assembly. In addition, in other preferred embodiments, as shown in Fig. 4, Fig. 5 and Fig. 6, the optical device for short-distance laser illumination and the optical device for long-distance laser illumination are separated.

The laser beam generated by the selected solid-state laser diode is sent to the plane scanning mirror by means of the focusing optical device in the laser diode assembly, and the barcode mark is cut and scanned horizontally by means of the vibrating scanning mirror. Scanning is performed by means of a common vibrating flat scanning mirror driven by a scanning motor. For the case of the first laser illuminating device that is most suitable for close work or short-distance work, due to the short distance to the short-distance barcode target, the amplitude driven by the scanning motor is relatively large; on the contrary, for the second laser lighting device that is most suitable for long-distance scanning In the case of a laser lighting device, the amplitude of the scanning motor drive signal is relatively small due to the long distance to the long-distance barcode target. The various scan speeds allow the frequency of the received optical signal to be limited to that of standard signal processing and decoding circuits. A vibrating scan mirror reflects the laser beam and directs it through the exit window onto the bar code mark. Typically, the laser beam cuts and scans across the barcode indicia back and forth at a rate of about 36 times per second. A photodetector detects the laser light reflected from the bar code indicia and converts the light signal into an analog electrical signal. The analog signal is processed by an analog loop network 22 using known techniques. The form of this analog signal expresses the information contained in the barcode indicia.

A signal conditioning circuit in digitizing circuit 24 converts the analog signal to a digitized bar graph signal using known techniques. The graphic signal is sent to the interface control module in the control block 26 and decoded.

3 is a block diagram of the main functions and components of a second embodiment of the combined dual-range laser scanner of the present invention. In the case of this embodiment, the operator operates the trigger 12 with the first gear and the second gear, and selects one of the short-range or long-range laser diodes to work. The working process is described below. Under the situation of working with the distance, at first the trigger plate is placed on the first gear position, and the logical switchover loop network 32 in the combined double-range scanner will select the long-distance laser diode to work, and select the laser diode to work under the aiming mode. Properly aimed scan amplitude for the scan motor. As we all know, in the aiming mode, initially the flat scanning mirror works and vibrates at a low speed to form the horizontal scanning line of the visible laser beam. Using this visible scan line, the operator can aim the scanner at a distance of up to 18 feet.

Then, pull the trigger into second gear. Since the original trigger was in the first gear for a long time, the long-distance laser beam and long-distance scanning amplitude were selected. After pulling the trigger to the second gear, the flat scanning mirror vibrates with the conventional long-distance scanning frequency and amplitude, and the detection circuit is activated. The light reflected by the curved surface condenser is concentrated to the photodetector, and the output signal of the photodetector is digitized after being amplified, and then becomes a digital signal, which is then processed by the decoder. Scanning is accomplished by means of a common vibrating plane mirror driven by a scanning motor. Then, for the first laser illumination optics best suited for close-up or short-distance work, the amplitude of the scan motor drive signal is large, and for the second laser illumination optics with long-distance scanning such that the amplitude of the scan motor drive signal is smaller. The various scan speeds limit the frequency of the received optical signal to that of standard signal processing loops and standard decoding loops. Thereafter, work is performed according to the technique explained in the first embodiment.

In short-range work situations, the operator aims the scanner at the barcode at short distances (from snug to 24 inches). Then put the trigger switch directly in the second gear. Since the trigger has the shortest dwell time in first gear, the logic loop network 32 will select the short range laser diode 20 and short range scan amplitude. Firstly, the scanning motor vibrates at a low speed to generate a visible horizontal scanning line, the operator can aim the scanner according to the visible scanning line, and the scanning mirror operates in an aiming mode. The scanning mirror then vibrates at a regular short-range scanning frequency and amplitude and activates the detection loop. The return light reflected on the condenser is collected on the photodetector, and the output signal of the photodetector is amplified and digitized into a digital signal, which is processed by the bar code decoding circuit.

Fig. 4 is a schematic diagram of a typical configuration of the optical device of the combined dual-range laser scanner of the present invention. A short-distance visible laser diode assembly 40 and a long-distance visible laser diode assembly 42 are arranged on both sides of a photodetector 44 that detects laser radiation collected by a condenser lens 40 . In other embodiments, components 40, 42, and 44 may be arranged in different geometric positions.

5 and 6 are side and front views, respectively, of a typical optical arrangement of the combined dual-range scanner of the present invention. The short-distance visible laser diode assembly 50 is arranged in front of the flat scanning mirror 54 driven by the scanning motor 56 and the driving mechanism 58 , and is located near the front end of the casing 52 . Long range visible laser diode assembly 60 disposed adjacent to short range visible laser diode assembly 50 is illuminated by long range visible light laser diode assembly 62 with heat sink 64 disposed adjacent to flat scan mirror 54 at the rear of housing 52 . The laser radiation emitted from the laser diode 62 to the turning mirror 60 is reflected by the turning mirror 60 to the vibrating scanning mirror 54, and then reflected to the vibrating scanning mirror 54, and then exits the scanner through the exit window.

The laser radiation reflected by the barcode pattern is received by the curved condenser lens 66 , reflected by it and then collected on the photodiode photodetector 68 . As shown in FIG. 6, the planar scan mirror 54 and curved condenser mirror 66 are preferably constructed as a single combined mirror driven by a scan motor 56 using known techniques.

Fig. 7 is a sectional view showing the structure and main parts of a typical laser diode module. A typical laser diode assembly 70 includes a visible light laser diode 74 and a focus lens 78 that are urged toward opposite ends of a housing 72 by springs 76, respectively. The laser beam focused at an appropriate distance by the focus lens 78 passes through the opening located at the center of the other end of the housing, and then exits as a laser beam. In the case of a short-distance laser diode assembly, lens 78 focuses the laser beam at a focal point suitable for short-distance scanning operations, while in the case of a long-distance laser diode combination, lens 78 focuses the laser beam at a focal point suitable for long-distance scanning operations. focus.

In the first preferred embodiment, both the short-distance laser illumination optical device and the long-distance laser illumination optical device are arranged in front of the scanning mirror (for example, the position of the short-distance laser diode assembly 60 in Fig. 5 and Fig. 6 ), they Laser diode assemblies that can be designed to operate in either long-range or short-range modes as a single unit. In this embodiment, two laser openings 80' and 80' adjacent to each other are arranged on both sides of the center line of the assembly shown by the dotted line 82 in Fig. 7(B). The curvature of the lens surface (one side is used to focus the near focus, the other is used to focus the far focus), the focus lens is made as a compound lens, it has two parts separated by the center line shown by the dotted line in Fig. 7(B). lens surfaces with different focal points. In the laser diode block 74, two different laser diodes are disposed immediately behind the two laser openings 80' and 80'. Since the two laser diodes in the laser diode block 74 are easily arranged laterally side by side, it is easy to understand that the laser diodes themselves are extremely small.

8 is a schematic diagram of a gun-type barcode reading device that can be used in conjunction with the combined dual-range laser scanner of the present invention. The reading device 10 can be specifically implemented as a hand-held scanner as shown in the figure, or can be implemented as a desktop workstation, that is, a fixed scanner. In the case of a preferred embodiment, the combined dual-distance laser scanning mechanism is specifically placed in a housing 155 with an exit window 156 . The laser beam passes through the exit window 156 and shoots to the barcode mark outside the casing for scanning.

Typically, the exit beam 151 is generated internally by a laser diode-like device within the reading device 100 and directed toward the bar code indicia on the target a few inches from the front of the device. The outgoing light beam 151 is scanned according to the scanning pattern. The user determines the position of the hand-held device so that the scan pattern can cut across the barcode symbol to be read. Light 152 reflected from the indicia is detected by a light detector 158 within the reading device. A series of electrical signals generated by photodetector 158 are processed and decoded in order to reproduce the data represented by the bar code.

In a preferred embodiment, the reading device 100 is a gun-type reading device with a handle portion 153 similar to the handle of a pistol. The user pulls the trigger 154 after aiming at the bar code mark to be read, and the light beam 151 and the loop network of the detector act. If the device has a built-in battery, the effective life of the battery is extended. In the housing 155 made of light-weight plastic, in addition to the battery 162, a laser light source, a photodetector 158, an optical device and a signal processing circuit network, and a central processing unit CPU 140 are housed. The light-transmitting window 156 at the front end of the housing 155 not only allows the light beam 151 to exit, but also allows reflected light to enter. The reading device 100 is designed so that the user can aim at the bar code indicium from the device away from it. That is, the device 100 should neither engage the marking nor move laterally across the cut. Typically, this type of handheld bar code reading device is specified for use in the range of several inches.

In addition, a keyboard 148 and a display 1490 are also provided in order to make the reader 100 function as a portable computer terminal.

Continuing with the description of FIG. 8, in order to focus the scanning beam on the bar code indicia located on the appropriate datum, an appropriate lens 157 (or multi-lens arrangement) may be used. In addition, a light source 146 such as a semiconductor laser is positioned to direct a beam of light onto the optical axis of lens 157 . The laser beam passes through the semi-transparent mirror 147 and other lenses or beam forming mechanisms if necessary, is reflected by the vibrating scanning mirror 759 mounted on the scanning motor 160 activated by the trigger 154, and exits through the window 156. If the light emitted by the light source 146 is visible light, the aiming light may not be included in the optics. Since the aiming light creates a visible spot (which can be scanned like a laser beam or can be stationary), the user can use this visible light to aim the reading device at the bar code indicia before pulling the trigger 154 if desired.

Above, several embodiments of the combined dual-distance laser scanner of the present invention and their variants have been described in detail, so that one can understand the content and principles disclosed by the present invention, as well as multiple alternatives shown to experts in the field. Use structure.

Code Description

12 trigger

14 distance measurer

16 transfer switch circuit network

18 Short distance visible light laser diode

20 long distance visible light laser diode

22 Analog loop network

24 digital loop

26 control cabinet

32 transfer switch circuit network

40 short distance visible light laser diode components

42 Long distance visible light laser diode components

44 photodiodes

46 Condenser

50 Short distance visible light laser diode components

52 shell

54 plane scanning mirror

56 scanning motor

58 drive mechanism

60 long-distance planar folding mirror

62 Long distance visible light laser diode components

64 Radiator

66 Curved Condenser

68 photodiode detectors

70 typical laser diode components

72 component housing

74 Visible laser diode blocks

76 spring

78 focus lens

80 central opening

80’ two openings

82 Centerline

100 barcode reading device

140 Central Processing Unit CPU

146 light sources

147 Translucent mirror

148 keyboard

149 monitors

151 outgoing beam

152 incident reflected light

153 handle part

154 trigger

155 shell

156 light-transmitting window

157 lens

158 photodetectors

159 vibrating scanning mirror

160 scanning motor

162 battery

170 barcode tokens

Claims (4)

1. A combined dual-range laser scanner for photoelectrically reading marks with areas of different reflectivity, comprising: a laser scanning mechanism with a scanning mirror for scanning the laser beam within the field of view; for A concentrating optical device that collects light reflected by the scanned field of view; a light detector that detects the reflected light collected by the concentrating optical device and generates an electrical signal corresponding to the reflected light; it is characterized by comprising: short-range laser illumination optics for short-range scanning work, Long-distance laser illumination optics for long-distance scanning work, and The operation of the short-distance laser illumination optical device for short-distance work in the field of view can be selected, and the selection device for the operation of the long-distance laser illumination optical device for long-distance work in the field of view can also be selected. 2. A scanner according to claim 1, wherein said selection means comprises a range finder capable of detecting the distance to objects within the field of view. 3. A scanner according to claim 1, wherein said selection means comprises a manual switch for manually selecting either said short distance laser illumination optics or said long distance laser illumination optics. 4. The combined distance laser scanning method of laser beam scanning, which includes the steps of scanning the laser beam from one end of the field of view to the other end with a scanning mirror, and irradiating the scanning mirror with a short-distance laser illumination optical device during short-distance scanning work. Step, is characterized in that, it comprises the following steps: The step of illuminating the scanning mirror with long-range laser illumination optics when working with long-range scanning that is longer than short-range, the step of collecting laser radiation reflected by the scanned field of view with concentrating optics, and The step of detecting laser radiation directed by concentrating optics to a photodetector.

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