JPH10334176A - Symbol reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably improve the accuracy of reading symbol information by providing a strong directivity illumination means for irradiating the almost end part of the read range of an image pickup means with the light of strong directivity so as to correct the nonuniform distribution of illumination by a weak directivity illumination means. SOLUTION: A linear illumination part is provided with the LEDs 32-1 and 32-2 of weak directivity and the LEDs 32-3 and 32-4 of the strong directivity. The LEDs 32-1 and 32-2 of the weak directivity are provided with the illumination distribution of a smooth chevron shape with an optical axis as a center. Then, they are arranged so as to position the optical axis at the center of the read range relatively. On the other hand, the LEDs 32-3 and 32-4 of the strong directivity are provided with the illumination distribution of a steep chevron shape with the optical axis as the center. They are arranged so as to position the optical axis at the end of the read range relatively and to reinforce the part of small illuminance in the illumination distribution of the LEDs 32-1 and 32-2 of the weak directivity. Thus, a symbol on a printing medium is irradiated with optimum illumination.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises an image sensor comprising a photoelectric conversion element which irradiates a symbol on a print medium with light and outputs an electric quantity corresponding to an amount of light received from the symbol. A symbol reading device.

[0002]

2. Description of the Related Art An LED (light emitting diode) is used as a light source for illumination of a handy type symbol information reader.
Is used. The LED as the light source has directivity, and the illuminance distribution on the symbol printed on the print medium differs depending on the directivity of the LED. The uniformity of the illuminance distribution on the symbol is one of the conditions for accurately reading the symbol information.

[0003] Also, illumination components (
Due to the positional relationship between an LED (for example, an LED) and an image sensor (for example, a CCD = charge coupled device) that receives reflected light from the symbol, as shown in FIG. Lighting area 10 in which light is emitted by the lighting component 103
4 and a reading range 106 imaged by the image sensor 105
The positional relationship with is fixed. The illuminance distribution on the symbol is also determined by the position of the symbol in the reading range 104. In FIG. 25, reference numeral 107 denotes an optical mechanism such as a lens for forming an image of reflected light from the symbol by the image sensor 105, and reference numeral 108 denotes a print medium on which the symbol is printed. Further, since the light intensity of the lighting component is generally constant, the distance between the lighting component and the symbol, the distance between the symbol and the image sensor, the reflectance of the printing surface of the printing medium on which the symbol is printed, or the like. Due to such factors, the amount of reflected light from the symbol varies, and the magnitude of the output signal from the image sensor varies accordingly.

[0004]

In order to accurately read the symbol information, it is necessary to illuminate the symbol with an optimum light amount and with a uniform illuminance distribution. However, as described above, the conventional symbol information reading apparatus has a problem that the LED used as a lighting component has directivity, so that uniform illumination cannot be realized and the accuracy of reading the symbol information is low. there were. The positional relationship between the lighting component and the imaging sensor is fixed, and the distance between the lighting component and the symbol, the distance between the symbol and the imaging sensor, the reflectance of the printing surface of the printing medium on which the symbol is printed, etc. There has been a problem that the magnitude of the output signal of the image sensor greatly differs, and the accuracy of reading the symbol information is unstable.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a symbol information reading apparatus capable of illuminating a symbol on a print medium optimally and stably improving the accuracy of reading symbol information. .

[0006]

The invention corresponding to claim 1 is:
In a symbol reading device provided with an image pickup device constituted by a photoelectric conversion element that irradiates light on a symbol on a print medium and outputs an amount of electricity corresponding to the amount of light received from the symbol, the reading range of the image pickup device A weakly directional illumination means for irradiating a substantially central part of the imaging means with weakly directional light, and a substantially directional light for correcting substantially non-uniform distribution of illumination by the weakly directional illumination means at substantially the end of the reading range of the imaging means And a strongly directional illumination means for irradiation.

According to a second aspect of the present invention, there is provided a symbol reading apparatus including a plurality of image pickup means each including a photoelectric conversion element for outputting an amount of electricity corresponding to an amount of light received from a symbol on a print medium. An image selection means is provided for comparing electrical signals output from the plurality of imaging means and selecting an effective symbol image from the plurality of imaging means.

According to a third aspect of the present invention, there is provided an illuminating means for irradiating a symbol on a print medium with light, and an imaging means comprising a photoelectric conversion element for outputting an electric quantity corresponding to an amount of light received from the symbol. In the symbol reading device having the above, when the electric signal output from the imaging unit may exceed a preset upper limit value, the illumination for reducing the irradiation light amount of the illumination unit based on the electric signal from the imaging unit. An adjusting means is provided.

According to a fourth aspect of the present invention, there is provided an illuminating means for irradiating a symbol on a print medium with light, and an imaging means comprising a photoelectric conversion element for outputting an amount of electricity corresponding to the amount of light received from the symbol. In the symbol reading device having the above, when the electric signal output from the imaging unit may be lower than a preset lower limit, the illumination for increasing the irradiation light amount of the illumination unit based on the electric signal from the imaging unit. An adjusting means is provided.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an overview of two types of handy scanners to which the present invention is applied will be described. FIG. 1 is a perspective view showing a hand-held touch type (contact type) code scanner 1 to which the present invention is applied. An interface cable 3 is connected to the apparatus main body 2. The device main body 2 is connected to an apparatus for processing code data such as a host computer (not shown) by the interface cable 3. In addition to the communication through the interface cable 3, communication means such as wireless communication and infrared communication can be selected and used.

The body cases 2a, 2b of the apparatus main body 2
As shown in FIG. 2, the housing is made of a plastic material or the like, and has a hollow structure in which a vertically divided housing is integrally formed by fitting or screwing, and has a dustproof and drip-proof structure. As shown in FIG. 3, a trigger switch 4 for an operator to instruct a reading timing at the time of reading a code is disposed on a side surface of the apparatus main body 2.
On the upper surface of the display, a display device (for example, LED = light emitting) for displaying a status such as reading completion or reading error in a different display method (blinking cycle, lighting time, etc.).
diode) 5 is arranged.

The trigger switch 4 also operates (turns on) when the apparatus main body 2 is turned over or dropped.
To avoid this, the portion of the side surface of the apparatus main body 3 where the trigger switch 4 is disposed is formed in a concave shape and accommodated inside the outer contour of the apparatus main body 3. In the apparatus main body 2, a reading port 6 having an opening for reading is configured by combining two kinds of materials, a hard material and a soft material. That is, as shown in FIG. 4, a hood (cone = cone-shaped member) made of a soft material
7) is attached, and the apparatus main body 2 is composed of the body cases 2a and 2b made of a hard material. This is a structure for absorbing a shock caused by contact with a print medium to be read and preventing damage due to the shock. The shape of the hood 7 is basically conical and has an opening with a small opening area at one end and an opening with a small opening area at the other end. One of the hoods 7 is easily detachably attached to the apparatus main body 2. Have been.

As shown in FIG. 5A, the lens 7a is built in the detachable hood 7, so that the reading magnification and the like can be arbitrarily changed. By making the shape of the opening end of the reading opening 6 that contacts the print medium of the hood 7 the same as the reading range by an image reading sensor described later, the symbols (barcodes and two-dimensional codes) can be smoothly placed within the reading range. Can be accommodated. Also,
As shown in FIG. 5B, by providing a rib 7b for intensity correction at a corresponding position (center position) in the hood 7, the center of the reading range can be easily visually identified. The hood 7 has the above-described function, and realizes an effect of preventing an image from running out. As shown in FIG. 5C, by forming an R-shaped concave portion 7 c at the tip of the hood 7 in contact with the print medium, corresponding to the center of the reading range,
Even when reading a symbol printed on a cylindrical or spherical surface, rolling of a cylindrical or spherical printing medium can be prevented, and stable reading can be realized. In the case where the hood 7 is made translucent, the reading state of the symbol to be read can be directly visually confirmed through the hood 7.
The positioning operation of the touch-type code scanner 1 can be performed so as to fall within the field of view.

A portion of the body cases 2a and 2b opposite to the reading port 6 with respect to the trigger switch 4 is a grip portion for an operator to hold with one hand, so that the vicinity of the trigger switch 4 is narrowed, and the thumb and the index finger are used. To have an appropriate size to hold. Then, the width of the palm increases toward the direction of the little finger in the direction of the little finger, and the shape is such that a smooth projection is formed on the little finger portion.

This allows the trigger switch 4 to be naturally operated with the index finger when the grip portion is gripped by hand.

The angle between the central axis of the grip and the central axis of the reading port 6 is at least greater than 90 °.
It is formed so as to be 0 ° or less. In the positional relationship between the grip portion and the reading port 6 (hood 7), when the grip portion is gripped, the reading port 6 (hood 7) is present on the extension of the arm. By adopting such a shape, the operator can easily bring the reading port 6 into contact with the print medium-shaped symbol at an optimum angle, and the reading operation can be performed by a natural operation. The aim is to improve fatigue and reduce fatigue.

FIG. 6 is a side sectional view showing the structure of a main part of the touch type (contact type) code scanner 1, and FIG. 7 is a side sectional view showing the structure around the reading port 6 of the touch type code scanner 1. It is. The reading port 6 is a place most affected by the external environment as a symbol interface for inputting a symbol image, and is formed of a transparent acrylic resin plate or a glass plate to block an obstacle such as dust. It is covered with a reading port cover 8. The surface of the reading port cover 8 is coated with a reinforcement in order to increase the durability against friction and impact. In particular, in order to prevent the read image from being distorted due to the reading port cover 8,
A glass plate is used as the material, and sapphire coating or diamond coating is used to further enhance the strength and hardness.

In order to illuminate the symbol on the print medium to be read, a plurality of LED illuminators 9-1 are provided inside the reading port 6 (inside the hood 7).
Although not shown, the ED lighting unit 9-1 includes each LED and each LE.
And a diffusion lens formed of a light transmitting material such as a plastic material or a glass material for uniformly diffusing the light from D. There are two types of diffusion lenses, one in which the lens is formed of a material having light diffusion properties, and the other in which a transparent lens and a diffusion plate are combined. As shown in FIG. 8, a diffuse reflection plate 10-1 that reflects and diffuses light emitted from the LED illumination unit 9-1 may be provided on the inner wall of the reading port 6 or the hood 7. Providing the diffusion plate 10-2 on the linear optical path from the LED lighting unit 9-1 to the symbol is also effective for obtaining uniform illumination for the symbol. These LED lighting units 9-1 are turned on (pressed) by the trigger switch 4 for performing a reading operation,
Illumination is performed for a fixed time or until reading is completed.

Further, inside the reading port 6, a beam spot LED (target LED) is used as a spot light source.
9-2 is at the center of the two or four reading range at a position that does not interfere with the optical path from the LED illumination unit 9-1 to the symbol on the print medium and the optical path of reflected light from the symbol to the image sensor described later. It is arranged symmetrically with respect to.

Each beam spot LED 9-2 irradiates a focused spot light, and as shown in FIG. 9, each spot light intersects on a predetermined read center axis (for example, the center of the read range). (Overlap). This makes it easy to guide the reading port 6 to the center of the symbol to be read accurately. There is also a method of irradiating the boundary (corner, corner) of the reading range with the spot light without overlapping the spot light at one point in order to clarify the reading range.

Since the target display by the spot light of the beam spot LED 9-2 is not necessary at the time of the actual reading operation, the OFF control is performed in accordance with the trigger timing and turned off at the time of reading.

Symbol image light incident from the reading port 6
(Reflected light from the symbol) is guided to the image sensor 11 housed in the apparatus main body 2 as described later,
An image is formed on the surface of the image sensor 11. A space from the reading port 6 to the image sensor 11 is an optical path of image light, and an optical path is formed by using an optical path changing component 12 including a mirror or a prism depending on the shape of the apparatus main body 2. For image formation, a lens block 13 composed of a lens, a diaphragm, and the like, and a filter block 14 for attenuating and removing unnecessary extraneous light are arranged on the front surface of the image sensor 11 so that image light can be accurately detected. An image is formed on the surface of the image sensor 11. In this embodiment, the lens block 13 and the filter block 14 are formed as one block.

In the lens block 13, one lens or a combination of a plurality of lenses is selected according to the focal length and magnification, and a diaphragm mechanism or a diaphragm component is incorporated according to the amount of reflected light from the object to be read. In. In order to minimize the image distortion caused by the lenses of the lens block 13, it is necessary to correct the image with a plurality of lenses or to employ an aspherical lens. When ghosts due to reflection on the lens surface occur and pose a problem, a lens whose surface is treated with an anti-reflection coating or the like is used.

Since the resolution of the image sensor 11 is fixed, the print size and the fineness (information density) of the symbol
In some cases, the reading process cannot be performed with sufficient accuracy. For this reason, a magnification conversion function is required in order to form an image on the surface of the image sensor 11 in a size suitable for the reading process according to the fineness of the print size of the symbol on the print medium. It is not easy to change (adjust) the magnification of the lens in the lens block 13 disposed inside the apparatus main body 2. Therefore, the reading port 6
The optical path from to the imaging sensor 11 is fixed,
As described above, the magnification conversion function is realized by exchanging the reading port cover 7 to which the lens unit 7-1 for magnification conversion is attached detachably with respect to the apparatus main body 2 as described above. When the configuration and the position of the lens in the lens block 13 can be easily adjusted (exchanged) from the outside of the apparatus main body 2, an arbitrary magnification (angle of view) can be changed by the design. It becomes possible.

The image sensor 11 uses an area sensor, and this one area sensor is used for both reading of a two-dimensional code and reading of a bar code. As the area sensor, a method of arranging image sensors two-dimensionally and reading an image on a surface, and a method of arranging an image sensor one-dimensionally (line
) And read as a scanning type with a line. By using a solid-state image sensor as an image sensor, a smaller device, lower power consumption, and higher reliability can be obtained than an image pickup device such as a camera using an image pickup tube other than the solid-state image sensor. CCD type, MOS type, C type
There are types such as MD type. The MOS type is characterized by low power consumption.

A circuit board 15 on which circuit components of the reader are mounted is housed inside the grip portion. A cable attachment port for drawing out the interface cable 3 is provided at a rear portion inside the grip portion, and an internal circuit board and the interface cable 3 are connected. The center of gravity of the code scanner 1 is positioned at a fulcrum for holding the code scanner 1 which is directly touched by a hand. Gather near points. By arranging in this manner, the operability and the effect of reducing fatigue can be obtained.

As shown in FIG. 10, the electric circuit is roughly divided into an image sensor unit 21, an image memory unit 22, a CPU (central processing unit) unit 2.
3, an I / O unit 24 and a power supply unit 25. Even if each is mounted on an independent board,
Also, a plurality of units may be mixed and mounted on one board. In order to reduce the size of the power supply unit 25 and to make it easier to handle the interface cable 3, in particular, to minimize the number of signal lines included in the interface cable 3 and to ensure its safety, The voltage supplied from the interface cable 3 to the power supply unit 25 is low voltage DC (direct current). The power supply unit 25 converts the supplied low-voltage DC into a plurality of voltages required for circuit operation, and
To 24 required for each circuit. In addition,
Although there is a method of supplying a low voltage AC (alternating current), the interface cable 3 also has a signal line for other data communication, and there is a possibility that induced noise or induced voltage due to a change in the magnetic field of the AC current is generated. Not so desirable.

The formed image is converted into an electric signal by the image sensor 11. Here, the image sensor 11 is described as a CCD type. The image sensor unit 21 includes: the image sensor 11; a driver circuit for driving the image sensor 11; an amplifier circuit for amplifying a small output output from the image sensor 11 with a good S / N ratio; It comprises a binarization circuit for quantizing the output analog signal.

As shown in FIG. 11, the output of the image sensor 11 has a shading phenomenon in which the level of the sensor output also drops at both ends of the signal (a signal corresponding to the peripheral portion of the reading range) due to a decrease in optical light amount. Therefore, as shown in FIG. 12, a method of changing the reference value for quantization in the binarization circuit in accordance with the shading phenomenon is used as shading correction. There are other methods for shading correction, and the present invention is not limited to this shading correction method.

The output signal from the image sensor unit 21 is a binary signal obtained by binarizing an image and coordinates for specifying each pixel position are counted and output by a counter. Further, if a configuration is adopted in which the grayscale signal is output simultaneously with the binarized signal, it is effective to use the grayscale signal in the subsequent stage, but the description of the grayscale signal is omitted here for the sake of simplicity. .

The binary video signals “1” and “0” and the address coordinate value from the image sensor unit 21 are stored in a DMA (direct memory access) of the image memory unit 22.
The data is stored in a predetermined position of an image memory which is a main body of the image memory unit 22 through a circuit. Note that the binary video signal and the address coordinate value are not passed through the DMA circuit (not provided).
) May be stored in a predetermined position of the image memory through the CPU unit 23 (CPU bus). When a predetermined number (number of pixels) of data constituting an image is written, a write completion signal is output from the DMA circuit of the image memory unit 22.

When a write completion signal is output from the image memory unit 22, the CPU of the CPU unit 23 is driven based on a code decoding program stored in a program memory (ROM = read only memory). To decode the code value (code data) from the image data stored in the image memory. Said C
A flash ROM is used as the program memory of the PU unit 23. By doing so, it is possible to rewrite a program (for example, a code decoding program) via the interface cable 3 and the communication interface, so that the performance is not determined at the time of manufacture, and the latest By incorporating a program, optimal performance can be improved.

The decoded code value is transferred to an external device such as a host computer through the communication interface of the I / O unit 24. The communication interface is a general-purpose serial port such as RS-232C or C
A CMOS interface for transferring data at a MOS logic level, and a USB port or I
A communication interface that is considered to be the next standard such as EEE1394 is prepared. In addition, an infrared interface that does not use a cable is also practical. The communication protocol for data transfer is performed by the CPU, and the data format and the like can be freely set.

The I / O unit 24 includes an I / O (input / output) port that can be monitored and controlled. The I / O port includes the LED illuminator 9, the trigger switch 4, an external trigger input terminal for receiving an external trigger input, the display device 5, and whether or not the reading process has been performed normally or the result. A sounder (buzzer) that informs the operator audibly is connected.

The read code type can be set by operating the trigger switch 4. That is, FIG. 13 is a diagram showing a flow of a trigger interruption process performed by the CPU unit 23 when the trigger switch 4 is turned on.
(Trigger operation) is a two-dimensional code (matrix code
) Is read (analyzing / decoding processing), and barcode reading processing (analysis / decoding processing) is performed for a long ON operation (continuous operation) that keeps ON for more than a preset time.
I do. The ON / OFF operation of the power supply is linked to the ON operation of the trigger switch 4 for controlling the reading operation. In other words, when the reading operation is in the OFF state, the power is also turned OFF to prevent wasteful power consumption during non-reading.

FIG. 14 is a perspective view showing a gun-type non-contact type code scanner 31, and FIG. 15 is a side sectional view showing a main part of the code scanner 31. This gun-type code scanner 31 is basically the same as the gun-shaped code scanner 31 except that it has two types of image sensors, an area sensor and a linear sensor (line sensor), and has a configuration for non-contact reading. Specifically, since the touch-type code scanner 1 has the same configuration as the above-described touch-type code scanner 1, members having the same functions are denoted by the same reference numerals and description thereof will be omitted.

Inside the reading port 6 of the gun-type non-contact type code scanner 31, a linear illumination section 32 for a linear sensor described later and an area illumination section 33 for an area sensor described later are arranged. . These lighting units 3
Each of the reference numerals 2 and 33 includes an LED and a diffusion lens, similarly to the LED illumination unit 9 of the touch-type code scanner 1. The read code type is set by the operation method of the trigger switch 4, and the drive control of the illumination units 32 and 33 is performed according to the read code type setting. That is, in the short-time ON operation in which the trigger switch 4 is normally turned on and then immediately turned off, the illumination unit 33 for the area sensor is driven to perform illumination, and the long-time ON operation in which the ON is performed for a preset time or more. Then, the linear illumination unit 32 is driven to perform illumination. Each lighting unit 32,
The illumination time 33 is a fixed time or a time from when the trigger switch 4 is turned ON until the reading is completed, similarly to the LED illumination unit 9 described above.

The spot light emitted from the beam spot LEDs 34 and 35 is, as shown in FIGS.
The irradiation range and direction of each spot light are arranged so as to intersect (overlap) at a predetermined point (for example, the center of the reading range) at a preset focal length on the reading central axis. It is installed so that the irradiation angle of the spot light can be adjusted, and by monitoring the gathering status of the spot light with the image sensor, it is possible to automate the check whether there is a symbol in the reading range. ing. As mentioned above,
In this gun type non-contact type code scanner 31, 2
In order to accurately read two systems of symbols, a dimensional code and a barcode (one-dimensional code), each code is equipped with the optimal illumination, and a target display with spot light is provided to match the symbol to the reading range. . One of the illumination units 32 and 33 is driven by the operation of the trigger switch 4 to perform illumination. However, both can be driven to perform illumination without selection. In such a case, if the light emission wavelengths of the respective imaging sensors described later are made different by an optical filter such as a BPF so that the light emission wavelengths of the respective imaging sensors are different so as not to affect each other's system, The effect can be eliminated.

The image sensor has an area sensor 36 for reading a two-dimensional code and a linear sensor (line sensor) 37 for reading a bar code (one-dimensional code). These image sensors 36 and 37 are constituted by solid-state image sensors like the image sensor 11 described above.
The area sensor 36 is configured by arranging solid-state imaging devices in a matrix, and the linear sensor 37 is configured by arranging solid-state imaging devices in a line (one row). is there. It should be noted that a two-dimensional code can be read by providing an operation mechanism for sequentially operating the linear sensor 37 as well.

In addition, on the front of the area sensor 36,
An area optical mechanism 38 including a lens, an aperture, a filter, and the like for forming an image of reflected light from the symbol by the area sensor 36 is disposed.
7, a linear optical mechanism 39 including a lens, an aperture, a filter, and the like for forming reflected light from a symbol (bar code) by the linear sensor 37 into an image.
Is arranged. A diffusion lens (cylindrical lens) 8a also serving as a shading correction is provided at a position of the reading port cover 8 where the optical axis of the linear illumination section 32 passes.
Is arranged.

FIG. 18 shows a reading range 36A of the area sensor 36 and a reading range 37 of the linear sensor 37.
FIG. Reading range 3 of the area sensor 36
6A is a region which extends in the vertical and horizontal directions so as to take in a two-dimensional code, and the reading range 37A of the linear sensor 37 extends only in one direction (lateral direction) so as to take in a barcode. Area. Generally, the extension (length) of the reading range 37A of the linear sensor 37 in one direction is determined by the reading range 36A of the area sensor 36.
Is larger than the spread in the longitudinal direction.

In the case of a reading device that can read two-dimensional codes and one-dimensional codes simultaneously, there are two methods for installing the image sensor unit. The first method is to use the area sensor 3
This is a method in which only the unit 6 is used and two-dimensional codes and one-dimensional bar codes are read by the same area sensor 36. The second method is to use the area sensor 36.
This is a method of selecting and using a unit made up of a linear sensor 37 and a unit made up of a linear sensor 37 using a two-dimensional code and a one-dimensional bar code to be read.

In the first method, since the area sensor 36 has a smaller number of solid-state imaging devices arranged in one direction (one row or one column) than the linear sensor 37, when the area sensor 36 reads a bar code, , Barcode size and resolution will be limited. The minimum resolution and read size of the bar code that can be read are equivalent to a two-dimensional code. In the second method, a two-dimensional code and a barcode (one-dimensional code) can obtain an independent reading range and reading resolution, respectively, and a large-size barcode currently used in the FA field and the distribution field. Can be read by the linear sensor 37.

For example, 800 × 60
Using a 0 pixel CCD, 4096
Considering the case where a CCD of pixels is used, a resolution of 0.
When reading a code at 25 mm / 4 pixels, the area sensor 36 has a width of 50 mm, and the linear sensor 37 has a width of 25 mm.
It can read symbols up to 6 mm wide. Therefore,
Linear sensor 3 for reading high resolution and wide barcodes
The use of 7 is more advantageous. In general, a two-dimensional code is often printed at a high density and a bar code is printed at a low density. Therefore, the unit including the area sensor 36 and the unit including the linear sensor 37 are independently provided so that the resolution can be individually set. And install it.

FIG. 19 is a block diagram showing the main circuit configuration of the gun-type non-contact code scanner 31. As shown in FIG. In terms of functional configuration, the touch-type code scanner 1 described above is used.
However, the actual circuit configuration of the non-contact type code scanner 31 will be described. The area sensor unit 41 including the area sensor 36 additionally includes a drive circuit 42 (for the area sensor) that drives the area sensor 36, and counts coordinate values based on the drive timing from the drive circuit 42.
A counter 43 (for the area sensor) and an image pickup signal from the area sensor 36 (for the area sensor)
It comprises an amplifying circuit 44 and a binarizing circuit 45 (for an area sensor) which has a shading correction function and converts the image signal amplified by the amplifying circuit 44 into 0 or 1 digital data.

The linear sensor unit 46 including the linear sensor 37 additionally includes the area sensor 37.
A drive circuit 47 (for a linear sensor) that drives
A counter (for a linear sensor) 48 for counting coordinate values based on the drive timing from the drive circuit 47
And amplify the imaging signal from the area sensor 37
An amplifying circuit 49 (for a linear sensor), a binarizing circuit 50 (for a linear sensor) having a shading correction function, and converting an image signal amplified by the amplifying circuit 49 into a digital image signal of 0 or 1; It is composed of

The data selector 51 is connected to the area imaging data line from the binarization circuit 45 of the area sensor unit 41 and the coordinate data line from the counter 43, and to the binarization circuit of the linear sensor unit 46. 5
A linear imaging data line from 0 and a coordinate data line from the counter 48 are connected. This data selector 51
A DMA (direct memory a) based on a selection signal generated by a CPU 52 constituting a control unit main body, based on one of a data line from the area sensor unit 41 and a data line from the linear sensor unit 46.
ccess) 53 to be connected to the output data line.

The CPU 52 transmits a program memory 55, an image memory 56,
The MA 53 is connected to an I / O (input / output) port 57 and a communication interface 58. A selection signal from the CPU 52 to the data selector 51 is also output to the data selector 51 through the system bus 54. The program memory 55 includes the CPU
52 stores program data and the like for the processing performed by 52.

The image memory 56 has a capacity for storing a plurality of pieces of imaging data.
The imaging data of the unit selected by the data selector 51 is developed as image data in the image memory 56 without passing through the CPU 52 based on the coordinate data. The I / O port 57 includes a target (beam spot LED 34, 35), illumination (illumination unit 32,
33), the trigger switch 4, an external trigger input 59,
A display 60 and a sounder (buzzer) 61 are connected to the assigned input / output ports.

The operation of the two-dimensional reader equipped with the two systems of the area sensor unit 41 and the linear sensor unit 46 is as follows. There are three methods of switching the read code type: an instruction by operating the trigger switch 4, an instruction by a command from the host computer, and automatic switching by analyzing image data.

The determination of the read code type by these methods is performed by using the image data from the sensor unit that reads the determined code type as valid data, by using the data selector 51.
Can be used to control the effective data switching by instructing the connection of the output data from the sensor unit to the DMA, but memory buffers are provided in the area sensor unit 41 and the linear sensor unit 46, respectively.
By temporarily storing the image data before the data selector 51, the image data can be used to determine the order of inputting both image data to the image memory 56. Since the selection signal of the data selector 41 is controlled by the CPU 52, it is possible to automatically set the switching order and the like based on the past tendency by the learning function.

After the trigger input, the linear and area beam spot LEDs 3 indicating the code reading visual field and the reading focal position of the linear sensor 37 and the area sensor 36, respectively.
Lights 4 and 35 are turned off. After the illumination of the spot light is turned off, the imaging input of the linear sensor 37 is performed.
6 is input. FIG. 20 is a diagram showing drive timings of the illumination units 32 and 34 for area and linear, the beam spot LEDs 34 and 35 for area and linear, and the trigger switch 4.

The decoding algorithm realized by the program installed in the CPU 52 performs the feature extraction of the image after the end of the image pickup input by the area sensor 36, for example. This process is a process for checking whether a bar code or a two-dimensional code is present in the image. If its existence is confirmed, decoding processing is performed to determine the success / failure of the reading. If the reading is successful, the result is displayed on the display unit 60, and transmitted and output through the communication interface 58, thus ending the processing. If unsuccessful, the cause of the failure is displayed on the display 60, the reading process is terminated, and the process returns to the trigger input waiting state.

The first embodiment of the present invention will be described with reference to FIGS. FIG. 21 is a diagram illustrating a configuration of the linear illumination unit 32 with respect to the linear sensor 37. The linear illumination unit 32 has a low directivity (not necessarily low light intensity (illuminance)).
1, 32-2, strong directivity (necessary light intensity (illuminance)
Is not large.) LEDs 32-3 and 32-4 are provided.

The LEDs 32-1 and 32-2 having a weak directivity have a gentle mountain-shaped illuminance distribution centered on the optical axis, and are arranged such that the optical axis is relatively located at the center of the reading range. . The LEDs 32-3 and 32-4 having strong directivity have a sharp mountain-shaped (trapezoidal) illuminance distribution around the optical axis, and the optical axis is relatively located at the end of the reading range. The illuminance is small due to the illuminance distribution of the weak LEDs 32-1 and 32-2 (
It is arranged to reinforce the (dark) part.

FIG. 22 (a) shows the area sensor 36 (
14) is a diagram showing a configuration of the area lighting section 33 (9) for the area lighting section 33 (9), and FIG.
It is a figure which shows the illumination range by 3 (9). The area lighting unit 33 includes LEDs 33-1 and 33-2 having low directivity,
LEDs 33-3, 33-4, 33-5, 33-6 with strong directivity
33-7 and 33-8. LED3 with weak directivity
Reference numerals 3-1 and 33-2 are arranged such that their optical axes are relatively positioned at the center of the reading range. LED3 with strong directivity
3-3, 33-4, 33-5, 33-6, 33-7, 33-8, the optical axes of which are relatively located at the ends of the reading range, the LEDs 33-1 having weak directivity, Low illuminance with 33-2 illuminance distribution
(Dark) To reinforce the part,
D33-1 and 33-2 are arranged so as to surround the outer end of the irradiation range. In each LED, the light directly reflected from the symbol of the optical axis deviates from the optical path to the linear sensor 37 or the area sensor 36.

As described above, according to the first embodiment, the LEDs 32-1, 32-2, 33-1 and 33 having weak directivity are used.
-2, the parts with low illuminance in the illuminance distribution of the illumination by the LED-2-3, 32-4, 33-3, 33-4, 33-
By locally reinforcing 5, 33-6, 33-7, and 33-8, symbols have a minimum illumination range with respect to the reading range, and there is little or no illuminance, and symbols are illuminated almost uniformly. be able to. Therefore, the reading accuracy of the symbol information can be stably improved.

The present invention is not limited to the first embodiment. The light source may have a directivity other than the LED, and three or more types having different directivities may be used. The number of light sources may be other than two or four, and various arrangements of the light sources and various illumination shapes are also applicable.

A second embodiment of the present invention will be described with reference to FIG. In the second embodiment, a plurality of linear sensors 37 are provided, and the best signal is selected from the output signals of the plurality of linear sensors 37 and used for reading symbol information. FIG. 23 is a block diagram showing a circuit configuration for processing output signals of a plurality (N) of linear sensors 37-1 to 37-N.

Although not shown, the N linear sensors 37-1 to 37-N are arranged so that the reading positions are shifted in accordance with the illuminance distribution of the illumination. These linear sensors 37-1 to
The output signal from 37-N is input to the selector 72 and also to the signal comparison circuit 73. The signal comparison circuit 73 compares the input output signals from the linear sensors 37-1 to 37-N, and uses the comparison result as a select signal to select the selector 7.
Output to 2.

Although the internal configuration of the signal comparison circuit 73 is not clearly shown, as a first example, the peak value of the input signal is compared to detect the signal having the maximum peak value, and the maximum value is detected. There is a type that generates a select signal for selecting a signal having a peak value of and outputs it to the selector 72. Further, as a second example, an average value of input signals is obtained, and a signal having a value closest to the average value is detected.
In some cases, a select signal for selecting a signal closest to the average value is generated and output to the selector 72.

As described above, according to the second embodiment, by selecting and using the best signal among the output signals of the plurality of linear sensors 37-1 to 37-N, the linear illumination is achieved. Even if the illuminance distribution on the symbol by the unit 32 is not uniform, the imaging signal at the best illumination position can be selected and used for code analysis, so that the accuracy of reading the symbol information can be stably improved. it can. In this embodiment, a linear sensor and a method of obtaining a peak maximum value or an average value by comparing signals have been described. However, the present invention is not limited to this. It is also applied to those that are mixed with sensors,
Further, a value other than the peak maximum value or the average value in the signal comparison, for example, the (N / 3) th value from the top may be used.

A third embodiment of the present invention will be described with reference to FIG. In the third embodiment, when an output signal from an imaging sensor such as the imaging sensor 11, the linear sensor 37, and the area sensor 36 exceeds a preset upper limit value or falls below a lower limit value. sometimes,
The light intensity of the illumination units 32 and 33 is adjusted. FIG.
4 is a block diagram showing a circuit configuration for processing output signals from image sensors such as the image sensor 11, the linear sensor 37, and the area sensor 36. Imaging sensor 1
The output signal from 1 (36, 37) is output to an amplifier circuit (not shown) or a binarization circuit (not shown) as described above, and is also output to a signal level check circuit 74.

The signal level check circuit 74 checks a signal input from the image sensor 11 (36, 37) based on the upper limit value or the lower limit value set by the reference value setting circuit 75, and checks that the input signal is When the value exceeds the upper limit value or falls below the lower limit value, the illumination unit 9-1 (32, 33).
) Is output to the illuminance adjustment circuit 76 for adjusting the light intensity (illuminance). Upon receiving the adjustment control signal, the illuminance adjustment circuit 76 adjusts the light intensity of the illumination unit 9-1 (32, 33) according to the adjustment control signal.

That is, if the upper limit is set by the reference value setting circuit 75 in order to prevent the illumination on the symbol from being too bright, the output signal from the image sensor 11 (36, 37) is set to the upper limit. If it exceeds the value, the illuminance adjustment circuit 7
6, the adjustment control is performed so as to lower the light intensity of the illumination unit 9-1 (32, 33). As a result, it is possible to prevent the illuminance on the symbol from decreasing and the illumination from being too bright. When the lower limit is set by the reference value setting circuit 75 to prevent the illumination on the symbol from being too dark,
When the output signal from the image sensor 11 (36, 37) falls below the lower limit, the illumination unit 9-1 (
Adjustment control is performed to increase the light intensity of (32, 33). Thereby, the illuminance on the symbol is increased, and the illumination is prevented from being too dark.

As described above, according to the third embodiment, the output signal from the image sensor 11 (36, 37) is
When the value exceeds the upper limit set by the reference value setting circuit 75 or falls below the lower limit, the illuminance adjustment circuit 76 causes the illumination unit 9-1 to operate.
By reducing or increasing the light intensity of (32, 33), the illuminance on the symbol is stabilized at an optimum value without being affected by the brightness of the reading environment or the surface condition of the print medium (light reflectance). Can be done. Therefore, the reading accuracy of the symbol information can be stably improved.

In the first to third embodiments, the effect of stably improving the accuracy of reading the above-described symbol information can be obtained by using each of them alone.
They may be implemented in combination.

[0068]

As described in detail above, according to the present invention,
It is possible to provide a symbol information reading device that can irradiate optimal illumination to a symbol on a print medium and can stably improve the accuracy of reading symbol information.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a handy type touch type code scanner common to the embodiments of the present invention.

FIG. 2 is a front sectional view showing a body case of the handy type touch code scanner.

FIG. 3 is a top view showing the handy type touch code scanner.

FIG. 4 is a perspective view showing the handy type touch code scanner main body and the hood.

FIG. 5 is a perspective view showing various hoods that can be attached to the handy type touch code scanner main body.

FIG. 6 is a side cross-sectional view showing a main configuration of the handy type touch code scanner.

FIG. 7 is a side sectional view showing a configuration around a reading port of the handy type touch code scanner.

FIG. 8 is a diagram showing a diffuse reflection plate and a diffusion plate of the handy type touch code scanner.

FIG. 9 is a perspective view showing an irradiation state of a spot light on a symbol printed on a print medium of the handy type touch code scanner.

FIG. 10 is a block diagram showing a functional configuration of a main part of the handy type touch code scanner.

FIG. 11 is a view showing a shading phenomenon of the handy type touch type code scanner.

FIG. 12 is a view showing shading correction of the handy type touch code scanner.

FIG. 13 is a view showing the flow of a trigger interruption process performed by the handy type touch code scanner.

FIG. 14 is a perspective view showing a gun-type non-contact code scanner common to the embodiments of the present invention.

FIG. 15 is a side cross-sectional view showing a main part configuration of the non-contact code scanner of the gun type.

FIG. 16 is a perspective view showing an irradiation state of spot light on a symbol printed on a print medium of the non-contact type code scanner of the same gun type.

FIG. 17 is a view for explaining the focal length of spot light of the non-contact type code scanner of the same gun type.

FIG. 18 shows a non-contact code scanner 2 of the same gun type.
The figure which shows the reading range corresponding to the kind of sensor.

FIG. 19 is a block diagram showing a main circuit configuration of the non-contact code scanner of the gun type.

FIG. 20 is a diagram showing drive timings of an area and linear illumination unit, area and linear beam spot LEDs, and a trigger switch of the non-contact type code scanner of the same gun type.

FIG. 21 is a diagram showing a configuration of a linear illumination unit for the linear sensor in the code scanner according to the first embodiment of the present invention.

FIG. 22 is a diagram showing a configuration of an area illuminating unit for an area sensor in the code scanner of the embodiment and an illumination range thereof.

FIG. 23 is a block diagram showing a circuit configuration for processing output signals of a plurality of linear sensors in the code scanner according to the second embodiment of the present invention.

FIG. 24 is a block diagram showing a circuit configuration for processing an output signal from an image sensor in the code scanner according to the third embodiment of the present invention.

FIG. 25 is a diagram showing an optical axis of illumination, an optical axis of reflected light, an illumination range, and a reading range in a conventional code scanner.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Touch-type code scanner, 4 ... Trigger switch, 6 ... Reading port, 7 ... Hood, 9-1 ... LED illumination part, 9-2, 34, 35 ... Beam spot LED, 11 ... Image sensor, 23 ... CPU unit 31, a gun-type non-contact code scanner, 32, a linear lighting unit, 33, an area lighting unit, 32-1, 32-2, 33-1 and 33-2 ... LE with weak directivity
D, 32-3, 32-4, 33-3, 33-4, 33-5, 33-6, 3
3-7, 33-8: LED with strong directivity, 36: Area sensor, 37 (37-1 to 37-N): Linear sensor, 51: Data selector, 52: CPU, 72: Selector, 73: Signal comparison Circuit 74: Signal level check circuit 75: Reference value setting circuit 76: Illuminance adjustment circuit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Makoto Sugiyama 6-78, Minamicho, Mishima-shi, Shizuoka Pref.

Claims (4)

[Claims] 1. A symbol reading apparatus comprising: an imaging unit configured to irradiate a symbol on a print medium with light and output an electric quantity corresponding to an amount of light received from the symbol, and Weakly directional lighting means for irradiating a substantially central part of the reading range of the imaging means with light having weak directivity, and correcting an uneven distribution of illumination by the weakly directional lighting means at substantially the end of the reading range of the imaging means. And a strong directional illumination means for irradiating with strong directional light. 2. A symbol reading apparatus comprising a plurality of image pickup means comprising photoelectric conversion elements for outputting an electric quantity corresponding to an amount of light received from a symbol on a print medium, the plurality of image pickup means being provided. A symbol reading device for comparing an electric signal output from the image pickup device and selecting an effective symbol picked-up image from the plurality of image pick-up devices. 3. A symbol comprising: illuminating means for irradiating a symbol on a print medium with light; and imaging means comprising a photoelectric conversion element for outputting an amount of electricity corresponding to the amount of light received from the symbol. In the reading device, when there is a case where the electric signal output from the imaging unit exceeds a preset upper limit value, an illumination adjustment unit that reduces an irradiation light amount of the illumination unit based on the electric signal from the imaging unit. A symbol reading device comprising: 4. A symbol comprising: illuminating means for irradiating a symbol on a print medium with light; and imaging means comprising a photoelectric conversion element for outputting an amount of electricity corresponding to the amount of light received from the symbol. In the reading device, when there is a case where the electric signal output from the imaging unit is lower than a preset lower limit, an illumination adjustment unit that increases an irradiation light amount of the illumination unit based on the electric signal from the imaging unit. A symbol reading device comprising: