JPH06187479A - Bar code scanner - Google Patents

Abstract

PURPOSE:To improve performance, to reduce manufacture cost, to miniaturize the bar code scanner and to improve the degree of freedom for design by integrating a light emitting element and a light receiving element and making the valid read length equal to or longer than a bar code length. CONSTITUTION:Two LEDs are respectively arranged on both sides of one light receiving element PD. The element area is enlarged rather than that of the LED so as to improve the sensitivity of the light receiving element PD. On the other hand, the length of the light emitting element, and light receiving element are made equal to or longer than the bar code length so that the image of the bar code can be formed on the surfaces of the light receiving element and light emitting element without being magnified. A cylindrical lens 14 is arranged while being faced to an LED/PD array 13 so that the image of a bar code 1 can be formed on the LED/PD array 13. At the back of the array 13, a circuit board 15 provided with a driver, amplifier and binarizing circuit or the like is fitted and further, a circuit board 16 mounting a decoder circuit is fitted to the circuit board 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bar code scanner for reading bar codes used for product management and the like.

[0002]

2. Description of the Related Art FIG. 12 is a perspective view showing a conventional bar code scanner, and FIG. 13 is a block diagram showing the configuration of an electric system.

As shown in FIG. 12, a bar code scanner has a high-intensity LED 2 for illuminating a bar code 1, and a light reflected from a bar code surface illuminated by the high-intensity LED array 2 is reflected in a predetermined direction. A mirror 3,
A lens 4 for receiving the light from the mirror 3, and an image sensor (CCD) arranged at a focus position of the lens 4.
5, each of which is provided with a decoder board 6 for processing the output signal of the image sensor 5.

In FIG. 12, the light emitted from the LED array 2 illuminates the reading section of the bar code 1, and the reflected light at that time is imaged on the image sensor 5 via the mirror 3 and the lens 4, -Electrically converted. The output signal of the image sensor 5 is applied to the decoder board 6 to be decoded.

As shown in FIG. 13, a decoder board 6 connected to the image sensor 5 is an interface for exchanging data with a waveform shaping circuit 7, a microcomputer 8 for fetching an output signal thereof, an external processing device and the like. LE under the control of the circuit 9 and the microcomputer 8.
An illumination control circuit 10 that drives the D array 2, a sensor drive circuit 11 that drives the image sensor 5 under the control of the microcomputer 8, and a power supply circuit 12 that supplies power to each circuit.

[0006]

However, in the above-mentioned prior art, the reduction optical system is used for reading, and therefore the optical path including the reduction lens must be secured. , There is a limit to miniaturization. Further, there is a problem that the lens design becomes complicated and the cost of the lens itself increases.

[0007] Further, conventionally, the LED array has a total number of LEs.
Since D is turned on during the entire reading period, power consumption becomes a problem in a configuration in which a battery is used as a power source. In addition, the light receiving element located farther from the light emitting element is less important in the illumination.

Further, in the LED array, in order to eliminate shading, in designing and manufacturing the LED array, as a measure for reducing the variation in the light amount among the elements, it is necessary to select the elements or to use a diffusion plate. However, a great burden is imposed on the manufacturing, which causes an increase in cost. Further, since shading correction can be performed only on the light receiving side, the degree of freedom in system design is limited.

Further, in the case of the laser type scanner, a plurality of expensive laser light sources, light receiving elements and complicated control mechanism are required for speeding up the operation, which leads to an increase in cost.

An object of the present invention is to provide a bar code scanner capable of improving the performance, reducing the manufacturing cost and downsizing, and increasing the degree of freedom in design.

[0011]

In order to achieve the above object, the present invention provides a bar code reader,
The light emitting element and the light receiving element are integrated, and the effective reading length is made equal to or longer than the bar code length.

Further, the power consumption of the light emitting element is reduced and S /
In order to improve N, the light emitting elements around the light receiving element during the read scanning can be turned on.

Further, in order to reduce the power consumption of the light emitting element, the light amount of the light emitting element can be controlled according to the distance between the light receiving elements.

In order to increase the degree of freedom in design, the light amount of the light emitting element can be controlled according to the characteristics of the light emitting element and the light receiving element.

Further, in order to simplify the control mechanism and reduce the cost, it is possible to divide the light emitting element and the light receiving element into a plurality of groups, and provide a driving means for driving each group independently. .

[0016]

According to the above-described means, the effective reading length is made equal to the bar code length or longer than the bar code length, so that the image of the bar code is united on the light receiving element surface. Therefore, the light emitting element and the light receiving element can be integrated, and the size can be reduced.

Further, by turning on the light emitting element around the light receiving element during the reading scan, it is possible to reduce the electric power for illumination at an unnecessary portion, prolong the operation time in the battery-driven scanner, downsize the battery, It is possible to reduce the size of the scanner body.

The light amount of the light emitting element is controlled so as to incline depending on the distance between the light receiving elements, and the light emitting elements closer to the light receiving element are more likely to be involved in the illumination, so that the light emitting element is increased. It is possible to reduce power consumption.

When the characteristics of the light emitting element and the light receiving element are non-uniform, by controlling the light amount of the light emitting element in addition to the sensitivity of the light receiving element, it becomes easy to find the optimum point of the system. The degree of freedom in design can be increased.

By dividing the light emitting element and the light receiving element into a plurality of groups and providing a driving means for independently driving each group, each light receiving element and the light emitting element can be driven at the same time, and the reading is completed at a stretch. In addition, the control mechanism can be simplified and the cost can be reduced.

[0021]

1 is a front view showing the structure of an LED / PD array used in a bar code scanner of the present invention.

In this embodiment, one light receiving element PD
Two LEDs on each side (eg photodiode)
It is characterized by the arrangement of. Then, in order to increase the sensitivity of the light receiving element PD, the element area of the light receiving element PD is set to LED.
Bigger than that.

Further, by making the lengths of the light emitting element and the light receiving element equal to or longer than the bar code length, the image of the bar code can be connected to the light receiving element and the light emitting element surface in the same size. it can. As a result, unlike the conventional bar code scanner, it is possible to use a unity magnification lens system and have a structure in which light receiving and emitting elements are integrated, and the scanner can be downsized.

FIG. 2 is a perspective view showing a schematic configuration of the bar code scanner according to the present invention.

A cylindrical lens 14 is provided so as to face the LED / PD array 13 shown in FIG. 1 so that the image of the barcode 1 can be formed on the LED / PD array 13. On the back of the LED / PD array 13,
Circuit board 1 including driver, amplifier, binarization circuit, etc.
5, a circuit board 16 on which a decoder circuit is mounted is further mounted on the circuit board 15.

Although a cylindrical lens is used as the lens in FIG. 2, a cell-hook array lens or the like may be used instead.

In the configuration of FIG. 2, only the necessary LEDs of the LED / PD array 13 are driven, and the contents of the barcode 1 illuminated thereby are received by the LED / PD array 13 via the cylindrical lens 14. Element PD
The light is received by, and photoelectric conversion is performed. The output of the light receiving element PD is amplified and binarized by the circuit board 15, and the barcode is decoded by the circuit board 16.

FIG. 3 is an explanatory view of reading a bar code by the bar code scanner of the present invention.

In FIG. 3, the time elapses from the upper side to the lower side, and the reading is performed from the left to the right. By sequentially operating the light receiving element PD, which is an element for reading, from left to right, it is possible to know black and white of the barcode as a change in the electric signal according to the amount of light incident on the light receiving element PD.

The LED for illumination is lit only in the vicinity of the light receiving element PD that is being read to perform scanning, and the power for illumination of unnecessary portions is reduced. As a result, in a battery-driven scanner whose operation time was limited by the capacity of the battery, it is possible to extend the operation time and reduce the size of the battery, and at the same time, keep the heat generation low,
The scanner body can be downsized.

The reading scan is performed by the element number 3 shown in FIG.
6, 9, 12 and 15 are carried out in this order, and the black and white pattern is taken out as an electric signal from the light receiving element PD from the barcode image of the same size connected on these light receiving elements PD. The resolution is determined by the distance between the light receiving elements PD at this time. In the present embodiment, the distance between the centers of the LED and the light receiving element PD is set to be the same, and 1200 dpi (47 elements / mm)
The light receiving element PD is set to 400d.
pi (16 elements / mm). Then, the light receiving element PD
Since the distance between them is 0.0625 mm, it is possible to read a barcode with a minimum line width of 0.15 mm.

For example, when operating the light receiving element PD having the element number 6 shown in FIG.
The four LEDs of 10 and 11 are turned on, and the four LEDs of the element numbers 4, 5, 7, and 8 are turned off. Similarly, when the light receiving element PD having the element number 9 is operated, by turning off the four LEDs having the element numbers 7, 8, 10, and 11, it is possible to prevent the decrease in S / N due to the wraparound to a minimum. it can.

As shown in FIG. 3, when the light-receiving element PD having the element number 6 is used for reading, the four LEDs having the element numbers 1, 2, 10 and 11 are turned on, but the light amount of the LEDs 1 and 11 is increased. Is controlled to about half of the light amount of the LEDs 2 and 10. This makes it possible to reduce unnecessary power consumption.

Further, depending on the characteristics of the light receiving element PD, 1
The light intensity of each LED may not provide sufficient illuminance on the barcode surface. For this reason, a plurality of LEDs are driven, but the closer the LED is to the light receiving element PD, the greater the contribution to illumination. However, as described above, since S / N is deteriorated, there is a trade-off relationship, and L is changed according to the distance from the light receiving element PD.
It is necessary to give an inclination to the light quantity of the ED. Further, although the LED located far from the light receiving element PD has a low rate of contributing to illumination, it needs to be turned on to some extent in order to reduce uneven illuminance around the light receiving element during operation. On the other hand, by lighting the LED as in the present invention, the above-mentioned problem can be solved.

Further, according to the present invention, a phenomenon called shading in which the illuminance at the scanner end portion is lower than that at the central portion can be eliminated. Since shading was conspicuously shown in the conventional LED arrangement, shading correction was essential, but the present invention does not require a shading correction mechanism, which enables cost reduction.

However, even in the present invention, the characteristics of the light receiving element and the light emitting element may be non-uniform due to manufacturing problems. Therefore, as a countermeasure against this, in the present invention, a solution is achieved by determining the sensitivity of the light receiving element PD and the light amount of the LED based on a test chart in which a standard barcode image is written in advance and storing them in the control unit. ing. In addition,
Similar to the conventional shading correction mechanism, it is possible to calibrate based on the standard white plate immediately before the operation is started, and it is possible to change the light amount of the LED in addition to the sensitivity of the light receiving element PD. It is easy to find the optimum point of
The degree of freedom in design can be increased. Incidentally, since the conventional shading correction depends only on the sensitivity of the light receiving element PD, the degree of freedom in design has been poor.

FIG. 4 is an explanatory view showing grouping of light receiving elements.

Here, the light receiving element PD is divided into four groups A to D, and each group is configured to perform a parallel operation, that is, each group can independently perform a simultaneous reading operation. In such a configuration, when the groups A to D exceed the board size and cannot be mounted on the same board, the groups can be connected by mounting them. Even if the ends of the adjacent groups overlap, it is possible to treat them as if they are electrically continuous by the circuit board 16.

Incidentally, in the conventional bar code scanner, since the image sensor is used for receiving light, the reading is performed serially, and the number of divisions is limited. However, in the present invention, the division is easy, and in an extreme case, the reading can be completed at once by driving the respective elements at the same time.

FIG. 5 is a perspective view showing a mounting example of the bar code scanner shown in FIG.

In this embodiment, the effective reading width is 65 m.
m, and the semiconductor substrate 17 is attached in close contact with the cylindrical lens 14. This semiconductor substrate 17
Mounts the LED / PD array 13 and a part of the circuit board 15 (driver in this case) on the same board. An insulating layer 18 is formed on the semiconductor substrate 17, and a heat sink (not shown) for radiating heat from the semiconductor circuit is embedded in the insulating layer 18. Further, on the insulating layer 18, a substrate 19 on which a binarization circuit and a decoder circuit are mounted is attached.

In this embodiment, as shown in FIG.
Since D and PD are arranged in a line, the total number of elements is 3,
It will be 070. Therefore, it is inevitable that the sensitivity of the light receiving element PD varies and the brightness of the LED varies. In the past, the cost was increased because it was handled by selection.

To solve this problem, the present invention is directed to the light receiving element PD.
The problem is solved by controlling the illumination by the LED so that the sensitivity of is apparently constant. Specifically, there are a method of controlling the number of LEDs to be turned on and a method of controlling a current passed through the LEDs. In this embodiment, a method is used in which four LEDs are lit and two outer currents are controlled.

FIG. 6 is a block diagram showing a control circuit for controlling the light emitting element group and the light receiving element group.

The PD array 20 has a switch (SR) 2
1 is connected, an amplifier 22 for amplifying the output signal of the PD array 20 is connected to the switch 21, and an A / D converter 23 for converting the amplified output into a digital signal is connected to the amplifier 22. Has been done.

The LED array 24 has switches (SR) 25, 26 for selecting the LEDs to be turned on.
Are sequentially connected, and the switches 25 (SW1) and 26 are connected.
(SW2) and the switch 21 are the clock generator 2
Controlled by 7. Further, the switch 25 is connected to a light emission control unit 28 for controlling the energization current.

In the configuration of FIG. 8, the clock generator 27 determines the scanning speed for reading, and generates a clock signal of, for example, 1 MHz, and thereby the reading speed can be set to about 300 scans / second. it can. The switches 21 and 2 are synchronized with this clock signal.
5, 26 operate, the light receiving element PD in the PD array 20 and the LED in the LED array 24 operate, and reading is performed.

FIG. 7 is a timing chart showing the operation of the circuit of FIG. In the figure, A to D on the right side show the passage of time.

Here, in the state of A, reading is performed, but at this time, it is indicated by active low that the light receiving element PD having the element number 6 is in operation. The switch 21 of FIG. 6 produces this signal, and its configuration is based on the shift register.

This shift register controls the PD array 20 so as to operate in the order of element numbers 3, 6, 9, 12, and 15 by using a signal obtained by dividing the signal from the clock generator 27 by 3 as a control signal.

At the timing of time C shown in FIG. 7, the reading operation is not performed. Therefore, it is necessary to stop the operation of the light emitting element, which is realized by controlling the output of the shift register by the 1/3 counter shown in FIG.

FIG. 8 is a block diagram showing details of the light emission control section 28.

The clock generator 27 has 1/30
70 counter 28a and 1/3 counter 28b are connected, and the output of each is applied to shift register 28c.

Further, the 1/3070 counter 28a has R
The OM 28d is connected, and the D / A converter 28e is connected to the ROM 28d. The output of the D / A converter 28e becomes a first signal for driving the switch 26,
The output of the shift register 28c becomes the second signal for driving the switch 26.

FIG. 9 is a circuit diagram showing a detailed structure of the switches 25 and 26. Here, only an example of a circuit that drives one LED is shown, and the other LEDs have the same configuration, so the description thereof will be omitted. In addition, the illustration of the entire circuit is omitted because it overlaps.

An LED is connected to the power supply line V _CC, and the collector of a transistor 30 _A is connected to this LED via a resistor 29 _A. The output of the clock generator 27 is connected to the base of the transistor 30 _A , and the emitter is grounded. The collectors of the transistors 30 _A are connected to the collectors of the transistors 31 _A and 32 _A , and the emitters thereof are both grounded.

Transistors 30 ₁ to 30 _A , 30 _{A + 1} to
The base of each of the 30 _N transistors is individually connected to the output of the shift register without switch 21,
Similarly, the transistors 31 _{1 to} 31 _A , 31 _{A + 1 to} 31 _N
The bases of each of the N transistors are individually connected to the output of shift register 28c. The bases of the N transistors of the transistors 32 _{1 to} 32 _A and 32 _{A + 1 to} 32 _N are commonly connected and are connected to the output of the D / A converter 28e.

In FIG. 8 and FIG. 9, the switch 25 completely lights up the LED (lighting without current control), whereas the switch 26 has different light emission amounts at the timings A and D. This light emission amount is stored in the ROM 28d as a correction value, and the switch 26 is controlled based on this stored value. By such control, it is possible to deal with the unevenness of illumination due to the variation between the elements and the design of the optical path.

In FIG. 8, the output of the shift register is controlled by the 1/3 counter 28b, and the position information of each element is generated by the 1/3070 counter 28a. ROM by the output of the 1/3070 counter 28a
The address of 28d is given, and the correction value is output to the data side. After passing this through the D / A converter 28e,
It is given as a base signal to the transistors 32 _{1 to} 32 _{A to} 32 _N, and the current control of each LED is performed.

SW2 (SR) shown in FIG. 7 is equal to SW2 (D /
A) is a signal indicating whether the signal is valid or invalid. This signal does not become LOW at the timings of B and C described above, and the transistor transistors 31 and 32 do not operate as apparent from FIG. The converted output of the D / A converter 28e is input to the transistor 32 group, and SW2 (D / A) shown in FIG.
Thus, the illuminance on the bar code surface is maintained at an appropriate value by controlling the current of the light emitting element.

FIG. 10 is a block diagram showing another embodiment of the present invention.

In this embodiment, in addition to the light receiving element and the light emitting element, the driving circuit and the amplifier are integrated into a module, and the decoder 37 is connected to each of the modules 33, 34, 35 and 36. Both ends (excluding the modules at both ends) of the light receiving element and the light emitting element are overlapped as shown in FIG. The reason for this is that a large substrate could not be used due to a problem in device manufacturing, and each module had to be connected and used. By doing so, it is possible to relax the accuracy of mechanical bonding that keeps the distance between each element of the connection part constant. The processing of the overlapped portion is performed by the decoder 3
Since the counter on 7 can find out which is the corresponding part, it is possible to avoid double decoding during the decoding process.

[0063]

Since the present invention is configured as described above, it has the following effects.

In the bar code scanner of the first aspect, in the bar code reading device, the light emitting element and the light receiving element are integrated, and the effective reading length is made equal to or longer than the bar code length. Therefore, the light emitting element and the light receiving element can be integrated, and the size can be reduced.

In the bar code scanner according to the second aspect, since the light emitting element around the light receiving element is turned on during the reading scan, the operation time is extended, the battery is downsized, and the heat is generated in the battery-driven scanner. It is possible to reduce the size and downsize the scanner body.

In the bar code scanner according to the third aspect of the invention, since the light emitting elements in the periphery except for the vicinity of the light receiving element during the scanning for reading are turned on, the S / of the light receiving element is turned on.
N can be improved and stable reading becomes possible.

In the bar code scanner of the fourth aspect, since the light amount of the light emitting element is controlled according to the distance between the light receiving elements, the power consumption of the light emitting element can be reduced.

In the bar code scanner of the fifth aspect, since the light amount of the light emitting element is controlled according to the characteristics of the light emitting element and the light receiving element, the degree of freedom in design can be increased.

In the bar code scanner according to the sixth aspect, the light emitting element and the light receiving element are divided into a plurality of groups, and the driving means for independently driving each group is provided at the same time. The light emitting element can be driven, the reading can be completed at a stretch, and the control mechanism can be simplified to reduce the cost.

[Brief description of drawings]

FIG. 1 is an LE used in the barcode scanner of the present invention.
It is a front view which shows the structure of a D / PD array.

FIG. 2 is a perspective view showing a schematic configuration of a barcode scanner of the present invention using the LED / PD array shown in FIG.

FIG. 3 is an explanatory diagram of reading a barcode by the barcode scanner of the present invention.

FIG. 4 is an explanatory diagram showing grouping of light receiving elements.

5 is a perspective view showing an implementation example of the barcode scanner shown in FIG. 2. FIG.

FIG. 6 is a block diagram showing a control circuit for controlling a light emitting element group and a light receiving element group.

7 is a timing chart showing the operation of the circuit of FIG.

FIG. 8 is a block diagram showing details of a light emission control unit according to the present invention.

FIG. 9 is a circuit diagram showing a detailed configuration of switches SW1 and SW2 according to the present invention.

FIG. 10 is a block diagram showing another embodiment of the present invention.

11 is an explanatory diagram showing a module arrangement of the embodiment of FIG.

FIG. 12 is a perspective view showing a conventional barcode scanner.

FIG. 13 is a block diagram showing a configuration of an electric system of a conventional barcode scanner.

[Explanation of symbols]

 1 Bar Code 13 LED / PD Array 14 Cylindrical Lens 15 Circuit Board 16 Circuit Board 17 Semiconductor Substrate 18 Insulating Layer 19 Substrate 20 PD Array 21 Switch 22 Amplifier 23 A / D Converter 24 LED Array 25 Switch 26 Switch 27 Clock Generator 28 Light Emission Control unit 28a 1/3070 counter 28b 1/3 counter 28c shift register 28d ROM 28e D / A converter 29 resistor 30 transistor 31 transistor 32 transistor 33, 34, 35, 36 module 37 decoder

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[Procedure amendment]

[Submission date] December 22, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 12

[Correction method] Change

[Correction content]

[Fig. 12]

Claims (6)

[Claims] 1. A bar code scanner in which a light emitting element and a light receiving element are integrated in a bar code reading device, and the effective reading length is set to be equal to or longer than the bar code length. 2. The bar code scanner according to claim 1, wherein the light emitting element around the light receiving element is turned on during reading scanning. 3. The bar code scanner according to claim 1, wherein the light emitting elements in the periphery of the light receiving element except for the vicinity of the light receiving element during the reading scan are turned on. 4. The bar code scanner according to claim 1, wherein the light amount of the light emitting element is controlled according to the distance between the light receiving elements. 5. The bar code scanner according to claim 1, wherein the light amount of the light emitting element is controlled according to the characteristics of the light emitting element and the light receiving element. 6. The bar code scanner according to claim 1, wherein the light emitting element and the light receiving element are divided into a plurality of groups, and driving means for independently driving each group is provided.