JPH04260984A - Device for energyzing scanner - Google Patents

Abstract

PURPOSE: To advance the state of the technique of a scanner, especially a slot scanner and a desk-top work station. CONSTITUTION: These device and method stop the scanner 10 after a prescribed time when no mark is read by the scanner 10 and energize the scanner 10 thereafter. A shadow photosensor 60 operated so as to detect the intensity change of ambient light at the part of a window 18 for scanning and re-energize the scanner 10 by the detection is provided on the part of the window 18 for scanning.

Description

[Detailed description of the invention]

0001

[1. OBJECTS OF THE INVENTION It is a general object of the present invention to advance the state of the art in scanners, particularly slot scanners and desktop workstations. Another object of the invention is to energize the scanner by detecting changes in ambient light intensity at the scanner window.

Another object of the invention is to ensure that the scanner is reenergized each time an object carrying a symbol passes over the window after the scanner has been turned off. Yet another object of the invention is to use a single scanner window for multiple purposes, such as directing laser light through the window to the symbol that is being read, and collecting laser light reflected from the symbol through the same window. It consists in detecting changes in the intensity of ambient light as well as in detecting changes in the intensity of ambient light through the same window.

Another object of the present invention is to seal only a single window of a slot scanner from dust, liquid, and other contaminants. Yet another object of the present invention is to
The objective is to eliminate the need to mechanically turn switches on and off, or start and stop sensors and receivers, to reenergize the scanner.

Yet another object of the present invention is to ensure that waste heat generated by a laser diode during operation is directed to an exposed heat dissipating surface. An additional object of the present invention is to generate an omnidirectional scanning pattern on the symbol while minimizing light intensity and power losses.

[0005]

[2. FEATURES OF THE INVENTION In order to achieve these objects and others that will become apparent below, one feature of the present invention is, briefly, to energize a scanner by sensing changes in the intensity of ambient light. Apparatus and method. The scanner operates to read indicia having portions of different light reflectance, for example barcodes having alternating dark bars separated by light spaces of variable width. The scanner includes a housing and transmitter means disposed within the housing for generating an incident laser beam. The transmitter means preferably includes a laser source, such as a semiconductor laser diode, which generates laser light at a wavelength that is at least marginally visible to the human eye. The transmitter means includes optical means disposed within the housing for optically shaping an incident laser beam and directing it along an optical path to a symbol placed within a working distance relative to the housing. Operates to send an incident laser beam. Laser light is reflected from the symbol. At least a returned portion of the reflected light travels from the symbol toward the housing.

The scanner further includes scanning means for scanning the symbol in an omnidirectional or linear scanning pattern. In a preferred embodiment, the scanning means comprises an electric motor having an output shaft on which the mirrored polygon can rotate about an axis. A plurality of fixed folding mirrors are arranged around this axis. The emitted laser light is incident on one of the mirror sides of the polygon, then reflected on one of the folding mirrors and then reaches the symbol. The reflected laser light is directed to at least one of the folding mirrors, is reflected from one of the mirror sides of the polygon, and is incident on the receiver means. The receiver means may include one or more receiver means operative to, for example, detect the visible light intensity of the reflected laser light over the field of view and generate an electrical signal, usually an analog signal, indicative of the variable light intensity detected. Nohoto diode.

The scanner further includes analog-to-digital signal processing means for processing the analog electrical signal into a digitized electrical signal, and is further operative to decode the digitized electrical signal into a decoded signal indicative of the symbol being read. The decoder means includes decoder means for decoding. A control microprocessor determines when the symbol has been successfully decoded and terminates symbol reading accordingly. A control microprocessor cooperates with a data storage device that stores each decoded signal. The control microprocessor also
The scanner is deenergized at the expiration of a predetermined period when no symbols are read, thereby extending the life of the laser diode as well as the scanning motor. Further details of such scanners are described in the following commonly assigned US patents: US Pat. These U.S. patents include No. 4,251,798 and No. 4,36.
No. 9,361, No. 4,387,297, No. 4
, No. 409,470, No. 4,816,660,
No. 4,896,026, all of which are incorporated herein by reference.

[0008] In slot scanner applications, the housing is incorporated into a generally flat countertop. The housing has a scanner window flush with the countertop. The emitted and reflected laser light passes through this window in opposite directions. Most slots
Scanners normally operate continuously. That is, the laser source and scanning motor are energized as long as power is supplied to the scanner. However, to extend the life of the laser source and motor, some modern slot scanners have a period of inactivity after some predetermined period of time, e.g., 30 minutes, if no symbols are scanned. During operation, the motor and laser source will automatically turn off. Once the laser source and motor are turned off, re-energization is typically accomplished by an operator operating a mechanical push-button switch. Other scanners use a separate light source that sends a beam to a separate photoreceiver, causing the laser source and scanning motor to be repowered when the beam is interrupted by the symbol to be scanned.

According to the invention, an ambient light sensor means, for example a shadow photosensor, is provided at the same window through which the emitted and reflected laser light passes. The shadow photosensor detects changes in ambient light intensity at the window and upon this detection resumes reading the symbol. For example, the photosensor can power or de-energize an electrically operated laser source and/or an electrically operated scanning motor depending on the detected level of ambient light detected at the window. In the preferred embodiment, a pair of peak voltage detectors are connected to the shadow photosensor. Each peak voltage detector charges its respective capacitor to a different voltage when the window is exposed to ambient light in steady state conditions, and the intensity of ambient light at the window drops below the threshold in object detection conditions. When discharging each capacitor at different rates to different voltages. Thus, when an object carrying a symbol passes over the window, the resulting shadow or reduction in illumination at the window is detected by the shadow photosensor, and again
Power is applied to the laser source and/or scanning motor to resume scanning the symbol on the object currently at the window. By using a single window, only one
Only one window needs to be sealed against dust, liquids and other contaminants.

Another feature of the invention is that during operation, the laser
It is designed to remove the waste heat generated by the diode source away from the diode. Laser diodes are sensitive to heat. Therefore, in order to obtain reliable operation, the present invention aims to direct the waste heat directly to a heat-conductive housing made of metal or similar material. The housing has a metal top wall that is flush with the scanning window and countertop. This top wall is exposed to the surrounding environment and dissipates waste heat.

In a preferred embodiment, only three folding mirrors are arranged equiangularly about the axis of the mirrored polygon. Therefore, the emitted and reflected light is reflected off the reflective surface only twice while traveling to and from the symbol to be read. This minimizes power losses and allows the use of low cost optical equipment. In another so-called "smart stand" application, a shadow photosensor is mounted within the base of a countertop-mounted workstation. A head is attached above the base. The aforementioned transmitter means and receiver means are mounted in the head and the ambient light sensor means are mounted in the base adjacent the scanning window through which the symbol-bearing object passes. In a preferred application, the head has a pistol-shaped housing that is removably attached to the base so that it can be used as a handheld scanner when removed from the base, or as a workstation when the base remains attached. be done. Using a shadow photosensor in the base eliminates the need for a separate light transmitter, light receiver to detect an object when it is inside the workstation. Therefore, there is no need to maintain alignment between the optical transmitter and the optical receiver, which was difficult in the past, especially when the head was adjustably attached to the base.

[0012] The novel features considered to be characteristic of the present invention are:
As particularly pointed out in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages, is best understood when read in conjunction with the accompanying drawings, in which: Let's get it.

[0013]

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIG. 1, reference numeral 10 is used herein to designate a slotted countertop 12 incorporated into a generally flat countertop 12 of the type commonly found in supermarket checkout counters.
The scanner is shown in its entirety. The scanner operates to read symbols carried on objects such as food items. As used herein, the term "symbol" refers to an indicia consisting of different parts having different optical reflectances at the wavelength of the light source utilized, eg, a laser. This indicia may be the Universal Product Code (UPC) symbol or any other symbol, such as Code 39, Codabar,
Interleaved 2 of 5, etc. The indicia may be any alphabetic letter and/or number. The term "symbol" also refers to an indicia that, when placed against a background, has a light reflectivity that is different from the background in its entirety or at least in part. In the latter definition, symbol reading is particularly advantageous in the field of robots and object recognition.

Returning to FIG. 1, the scanner includes a generally box-shaped housing 14 made of a metallic material and having a top wall 16 that is flush with the generally flat countertop 12. As shown in FIG. A translucent scanning window 18 is also mounted to housing 14 in coplanar relationship with top wall 16 . A plurality of electro-optic components are mounted within the housing 14 below the countertop 12. One of these components includes an operable laser light source, e.g.
A semiconductor laser diode 20 is operative to generate and propagate an incident laser beam that is at least marginally visible to the human eye at about 680 nm from m2. The emitting laser diode beam is highly divergent and diverges differently in different planes both parallel and perpendicular to the longitudinal beam propagation direction. The diode may be of the continuous wave or pulsed type, and the voltage provided by the laser power regulator 22 may be low. For example, 5 volts or 12 volts direct current. A heat sink 24 is in thermal communication with the laser diode and metal housing 14 and is operative to transfer waste heat generated by the diode to the top wall 16 during operation. The top wall 16 is exposed to the surrounding environment and therefore releases waste heat therefrom.

The path of the emitted laser beam includes a focusing lens 26 for optically modifying the emitted laser beam to form a beam spot of a predetermined size on a reference plane located near the scanning window 18. A diaphragm 28 is provided. The window 18 is used to read symbols carried by objects that are in contact with it or at some distance from it. Lens 26 and aperture 28 also direct the emitted laser beam along an optical path 28 through an aperture 32 formed in condenser lens 34. The aperture 28 has a cross-section approximately equal to the cross-section of the emitted laser beam therein, allowing the main portion of the emitted laser beam to pass through the aperture downstream along the optical path 30, and to allow the main portion of the emitted laser beam to pass through the aperture downstream on the way to the symbol. Minimizes power loss. The cross-section of the diaphragm is preferably rectangular or elliptical, in which case the longer dimension of the rectangle or ellipse corresponds to a larger divergence angle of the emitted laser beam and transfers more energy to the symbol.

The emitted laser beam passing through the hole 32 is
A plurality of reflecting mirrors 36 attached around the periphery of the polygonal body 38
enter one of them. The polygonal body 38 is rotated about its axis by an electric scanning motor 40 . A motor power supply 42 is electrically connected to motor 40. A plurality (preferably three) of fixed folding mirrors 42, 44, 46 are arranged equiangularly about the axis of rotation of the polygon. Laser light reflected from one of the polygonal mirrors is directed to one of the fixed folding mirrors and then through the scanning window 18.

The laser beam reflects from the symbol on object 48 in one direction as a reflected component and in many directions as a scattered component. The portion of the scattered laser light that passes through the scanning window 18 in the opposite direction to the emitted laser light, referred to herein as the return portion, reflects the different light reflectances of various portions of the object 48 being scanned, including the symbol. It has variable light intensity. The return portion of the reflected laser light is reflected off at least one of the folding mirrors and one of the mirrors 36 of the polygon 38 before being focused by the lens 34 and sent to a receiver such as a photosensor 50. . Photosensor 50 detects the variable intensity of the focused laser light over a field of view extending along, and preferably beyond, the scanning direction for the symbol. Photosensor 50 generates an electrical analog signal indicative of the variable light intensity detected. This analog signal is sent to an analog-to-digital converter 52
is converted into a digitized video signal by This digitized video signal is decoded by decoder 54 into a decoded signal. A suitable signal processing means for this purpose is disclosed in US Pat. No. 4,251,798. A control microprocessor 56, along with a data storage element 58, processes the decoded signals into data representing symbols according to algorithms contained in the software program. The control microprocessor 56 determines when the symbol has been successfully decoded and stops reading the symbol upon this determination.

The control microprocessor 56 also disables the scanner after a predetermined period of time, eg, 30 minutes, when no indicia have been read by the scanner. This is conveniently done by interrupting the power supply to laser diode 20 and/or motor 40. The decoded signals may be stored locally in storage element 58 or sent to a remote host computer, essentially serving as a large database. Information regarding the decoded signal, such as retail price information, may be obtained from the storage element or the host computer.

According to the invention, an ambient light sensor means, for example a shadow photosensor 60, is provided at the same window 18 as the laser light passes towards or from the symbol. Photosensor 60 is electrically connected to a shadow detector circuit 62, shown in detail in FIG. The shadow detector circuit 62 is electrically connected to both the laser power source 22 and the motor power source 42 to provide power to the diode 20 and motor 40 when it is desired to resume reading after the scanner has stopped. As explained in more detail below, photosensor 60 detects changes in the intensity of ambient light at window 18. When object 48 passes through window 18, the ambient light intensity decreases and casts a shadow thereon.

Referring now to FIG. 2, shadow photosensor 60 and shadow detector circuit 62 are mounted on base 64.
The base 64 is mounted on the counter top 66. The end of the upright bracket 68 is a sleeve-like holder 70, which can be, for example,
It removably receives a barrel 72 of a pistol-shaped scanhead 74 of the type disclosed in U.S. Pat. No. 4,896,026. The contents of this US patent are hereby incorporated by reference. Head 74 may be removed from holder 70 for hand-held operation. In this case, trigger 76 is actuated each time a symbol is to be read. Alternatively, head 74 may remain in holder 70 to create a countertop workstation known as a "smart stand." Object 78 carrying a symbol
is passed through the workstation over scanning window 80. The shadow photosensor 60 faces a scanning window 80 and, in the case of a slot scanner, the surroundings that occur whenever an object is placed above the window 80 and passed across the scanning window, as described above. Detects changes in light intensity.

Referring to FIG. 3, shadow photosensor 6
0 is connected across the input terminals of amplifier 82. The amplified signal is passed through a first peak detector 84 and a second peak detector 8 connected in series with the first peak detector.
6 and sent to. Peak detectors 84, 86 each include diodes D1, D2, resistors R1, R2, and capacitors C1, C2. The first peak detector 84 is
It operates to charge capacitor C1 to a voltage V1 that is proportional to the intensity of ambient light incident on shadow photosensor 60. Second peak detector 86 operates to charge capacitor C2 to a voltage V2 that is proportional to the intensity of ambient light incident on shadow photosensor 60. peak detector 8
The series connection of 4,86 allows the second peak detector to charge only capacitor C2 to a voltage V2 that is lower than voltage V1. This voltage difference is measured by the voltage drop across diode D1 and is typically 0.6v.

The output of the first peak detector 84 is connected to a resistor network R3, R4 which in turn connects the comparator 8
It is connected to the positive input section of No.8. The output of the second peak detector 86 is connected directly to the negative input of a comparator 88. The output of the comparator is connected to the switching transistor T1 via the resistor R5.
The collector of this transistor is connected to a 5V power supply via a resistor R6. Transistor T1
The collector of the second transistor T2 is connected to the base of the second transistor T2, and the collector of the second transistor T2 operates as an output port.

As mentioned above, in steady state conditions, where light is incident on the shadow photosensor 60, V1 is always greater than V2. Comparator 88 detects this voltage difference and provides an output signal to switching transistors T1 and T2. The output of transistor T2 is electrically connected to a power supply controller, such as laser power supply 22 or motor power supply 42;
Laser diode 20 and/or motor 40 are turned off when no indicia are read for a predetermined period of time. When the object passes over the scanning window 18 or 80, the illumination is reduced and this is detected by the shadow photosensor 60 and capacitor C1,
Discharge C2. The time constant of the RC network of peak detectors 84, 86 is such that capacitor C1 is equal to capacitor C2.
Choose one that discharges faster than the current one. Therefore, after a short time, V
1 is smaller than V2. This voltage difference is again sensed by comparator 88, which sequentially detects transistors T1, T2.
generates an output signal that changes the switching state of the The output of transistor T2 thus causes power to be supplied again to laser diode 20 and/or motor 40;
This will cause the scanner to resume reading the symbol on the object currently in the scanning window.

[0024] Here, each or two of the above components
It is to be understood that combinations of two or more may find useful application in other types of configurations different from those described above. Although the present invention has been described as incorporating an ambient light-based sensing structure into a scanner, it is not intended that the invention be so limited. This is because various modifications and changes can be made without departing from the spirit of the invention.

[0025] Without further analysis, the above description
The advantage of the invention is that, by applying current knowledge, it can be applied to a variety of applications without omitting features which, from the point of view of the prior art, clearly constitute essential features of the general or particular aspects of the invention. are fully covered and, accordingly, such applications should and are intended to be included within the meaning and range of equivalents of the claims.

[Brief explanation of the drawing]

FIG. 1 is a partial schematic diagram, partially in section, of a slot scanner powered by an ambient light-based sensing device according to the present invention.

FIG. 2 is a partially cross-sectional, partial schematic illustration of a countertop workstation powered by an ambient light-based sensing device according to the present invention.

FIG. 3 is an electrical diagram of a shadow photosensor and associated circuitry for sensing ambient light level changes in accordance with the present invention.

[Explanation of symbols]

10 Slot scanner 12 Counter top 14 Housing 16 Top wall 18 Scanning window 20 Laser diode 22 Laser power regulator 24 Heat sink 26 Focusing lens 28 Aperture 30 Optical path 32 Hole 34 Condensing lens 36 Folding mirror 38 Polygon 40 Scanning Electric motor 42 Motor power supply 48 Target object 50 Photo sensor 52 Analog-digital converter 54
Decoder 56 Control microprocessor 58 Data storage element 60 Shadow photosensor 62 Shadow detector circuit 64 Base 66 Countertop 68 Upright bracket 70 Holder 72 Body 74 Pistol scan head 76 Trigger 78 Object 80 Scan window 82 Amplifier 84 1 peak detector 86 2nd peak detector 88 Comparator

Claims (27)

[Claims] Claim 1: A device for energizing a scanner, comprising:
a) reading means for electro-optically reading an indicia having portions of different light reflectance passing over a window exposed to ambient light; and (b) reading means at the expiration of a predetermined period during which the indicia could not be read. (c) an ambient light sensor located at the window for detecting changes in the intensity of ambient light at the window and reenergizing the reading means in response to this detection; An apparatus characterized in that it includes means. 2. The apparatus of claim 1, wherein the reading means comprises transmitter means for sending a laser beam to the indicia through the window and detecting reflections therefrom, and receiver means for collecting light reflected from the indicia through the window. and wherein the transmitter means, receiver means and sensor means are all located on the same side of the window. 3. The apparatus of claim 2, wherein the scanner is a slot scanner mounted on a substantially flat countertop, and the window is flush with the countertop. 4. The apparatus of claim 3, wherein the transmitter means includes a laser diode and optically modifies the laser beam to focus it as a beam spot of a predetermined size on a reference plane located near the window. and an optical assembly for causing. 5. The apparatus of claim 4, wherein the reading means further includes means for scanning the beam spot in an omnidirectional scanning pattern over the indicia. 6. The apparatus according to claim 5, wherein the scanning means includes a mirror rotatable about an axis, means for rotating the polygon about the axis, and a plurality of folding mirrors arranged about the axis. A device characterized in that: 7. The apparatus of claim 4, wherein the laser diode generates waste heat during operation and is mounted within a housing of heat transfer material to remove heat from the diode. , wherein the housing has a wall surface that is flush with the countertop and is adapted to radiate waste heat to the surroundings. 8. Apparatus according to claim 1, characterized in that the sensor means includes means for supplying power to the reading means upon said detection. 9. The apparatus of claim 8, wherein the reading means includes an electrically actuated laser source and an electrically actuated scanning element, and upon said detection, power is applied to one of said laser source and scanning element. A device characterized in that it is supplied to at least one side. 10. The apparatus of claim 1, wherein the reading means generates a laser beam directed at the indicia;
comprising transmitter means for reflecting light therefrom and receiver means for collecting light reflected from the indicia, the transmitter means and receiver means being located on one side of the window and the sensor means being located on the opposite side of the window. A device characterized by: 11. The apparatus of claim 10, wherein the scanner is a countertop workstation, the countertop workstation having a base mounted on the countertop and mounted at a height above the base. 1. A device comprising: a head; wherein the reading means is mounted within the head; and the sensor means is mounted within the base. 12. Apparatus according to claim 11, characterized in that the head is pistol-shaped and is removably mounted on the base. 13. The apparatus of claim 1, wherein the sensor means includes a pair of peak voltage detectors, each peak voltage detector detecting a voltage when the window is steadily exposed to ambient light. It operates to charge each capacitor for different voltages and at different rates for different voltages when the ambient light intensity at the window drops below the threshold in the object detection condition. A device characterized in that it discharges a capacitor. 14. Apparatus according to claim 1, characterized in that the indicia are passed in a predetermined direction across the window. 15. A method of energizing a scanner, comprising:
(a) electro-optically reading an indicia passing over a window exposed to ambient light having portions of different light reflectance; and (b) ceasing the reading at the expiration of a predetermined period during which the indicia was not read. (c) detecting the intensity of ambient light at the window and resuming reading in response to this detection. 16. The method of claim 15, wherein the step of reading includes the steps of transmitting a laser beam to and reflecting from the indicia through the window and collecting the light reflected from the indicia through the window. A method characterized by: 17. The method of claim 15, wherein the scanner is a slot scanner incorporated into a generally flat countertop, further comprising the step of mounting a window flush with the countertop. Method. 18. The method of claim 17, wherein the step of reading comprises using a laser diode and optically modifying the laser beam to focus it as a beam spot of a predetermined size on a reference plane located near the window. and an optical assembly for causing. 19. The method of claim 18, wherein the step of reading further comprises the step of scanning the beam spot in an omnidirectional scanning pattern over the indicia. 20. The method of claim 19, wherein the scanning step is carried out by rotating the mirrored polygon about an axis and placing a plurality of folding mirrors about the axis. . 21. The method of claim 18, wherein the laser diode generates waste heat when operated, and further comprising removing heat from the diode by mounting the diode within a housing of heat transfer material exposed to the surroundings. A method characterized in that it includes a step of leaving. 22. The method of claim 15, wherein the reading step is performed by electrically actuated components and the sensing step includes powering these components upon detection. . 23. The method of claim 22, wherein the reading step is performed by an electrically actuated laser source and an electrically actuated scanning element, and at least one of these components is powered at the time of said detection. A method characterized by being supplied. 24. The method of claim 16, wherein the scanner is a countertop workstation;
The countertop workstation has a base mounted on the countertop and a head mounted at a height above the base, the reading step comprising:
A method carried out by a component mounted in the head, characterized in that the detection step is carried out by a component mounted in the base. 25. The method of claim 24, further comprising the step of removably mounting the head on the base. 26. The method of claim 15, wherein the detecting step is performed by a pair of peak voltage detectors;
Each peak voltage detector charges a respective capacitor to a different voltage when the window is exposed to steady ambient light, and the intensity of ambient light at the window reaches a threshold in the object detection condition. A method characterized in that it operates to discharge each capacitor at different rates for different voltages when the voltage drops further. 27. The method of claim 15, wherein the step of reading includes passing the indicia in a predetermined direction across the window.