JP3787193B2 - Symbol reader - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a symbol reader for reading data symbols such as a two-dimensional barcode reader.
[0002]
[Prior art]
Conventionally, a barcode reader used in a POS (Point of Sales) system or the like applies illumination light to a surface including two-dimensional data symbols such as characters and barcodes printed on paper or a container positioned in a reading opening. An apparatus that irradiates and processes the reflected light with an imaging optical system is known. The image information processed by the imaging optical system is binarized, the position of the symbol is confirmed based on the binarized data, the symbol image information is extracted and subjected to predetermined processing such as decoding, The data is transferred to external hardware such as a host computer.
[0003]
Such a two-dimensional data symbol is a two-dimensional arrangement of black and white mosaic patterns. In order to read out with high accuracy, the symbol is completely positioned in the reading aperture, and illumination light is irradiated on the symbol surface for a certain period of time. It is desirable to read by irradiating uniformly. Therefore, the operator must pay attention to the positioning and fixing of the housing when operating the bar code reader.
[0004]
[Problems to be solved by the invention]
However, when a barcode reader is actually used, the symbol reading operation is not necessarily performed by fixing the housing for a certain period of time while the reading opening is in contact with the symbol surface. The reading aperture may not be fixed to the symbol surface. Reading symbols in such situations is likely to fail.
[0005]
An object of the present invention is to solve the above problems, and to stably read a two-dimensional data symbol.
[0006]
In this specification, the “symbol plane” refers to a plane including a symbol positioned at the opening of the symbol reader, and “symbol reading” refers to the imaging processing of the plane positioned at the reading aperture. This refers to the process from extracting and decoding the symbol image information.
[0007]
[Means for Solving the Problems]
A symbol reading apparatus according to the present invention is a symbol reading apparatus that reads a symbol by positioning a symbol surface on which a coded symbol is formed in a reading opening provided on a bottom surface of the casing, and the speed of shaking of the casing. A shake detecting means for detecting the image, an image sensor for photoelectrically converting the optical information on the symbol surface and storing the charge, and a charge readout mode from the image sensor corresponding to the speed of shaking of the housing detected by the shake detecting means. The image pickup control means for selecting is provided.
[0008]
The shake detection means is, for example, an angular velocity sensor.
[0009]
When the shake detection means detects the speed of the first shake, the image pickup control means reads out the electric charge accumulated in the image pickup device, for example, in the field mode.
[0010]
When the shake detection unit detects the speed of the second shake, the imaging control unit reads out the electric charge accumulated in the image sensor in, for example, the frame mode.
[0011]
Preferably, the speed of the first shaking is greater than the speed of the second shaking.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view of a symbol reading apparatus according to an embodiment of the present invention. The housing 10 includes a head portion 10a and a grip portion 10b. A substantially rectangular reading opening 12 is provided on the bottom surface 11 of the head portion 10a. A trigger 15 for starting a reading operation is provided on the side surface of the grip portion 10b. A cable 16 for transmitting the reading result to other hardware is attached to the end of the gripping part 10b opposite to the head part 10a.
[0013]
FIG. 2 is a block diagram of the symbol reading apparatus according to the present embodiment.
A CPU (Central Processing Unit) 20 controls the entire symbol reader. The trigger 15 is connected to the inverter 15a. The inverter 15a outputs a high signal, that is, “1” when the trigger 15 is pressed, and outputs a low signal, that is, “0” when the trigger 15 is not pressed. To do. The output signal of the inverter 15a is input to the port P ₃ of the CPU 20.
[0014]
A CCD drive circuit 32, a light source drive circuit 33, and a signal processing circuit 34 are connected to the CPU 20. A control signal for the CCD drive circuit 32 is output from the port S _3, and a control signal for the light source drive circuit 33 is output from the port S ₄ .
[0015]
In the housing 10, a voltage corresponding to the shaking speed of the housing 10 is output from the angular velocity sensor 40 disposed in the vicinity of the CCD 35 to the housing shaking detection circuit 41. The housing shaking detection circuit 41 uses the angular velocity sensor 40. The analog voltage corresponding to the input value from is output to the comparator 42. As the angular velocity sensor, a conventionally known sensor made of ceramic that generates a voltage corresponding to the vibration velocity when vibrated is used.
[0016]
The comparator 42 is a comparison circuit using an operational amplifier. The casing shake detection circuit 41 is connected to the positive phase input terminal as described above, and the volume Rv, which is a variable resistor, is connected to the negative phase input terminal. . The comparator 42 uses the reference voltage value S ₂ set by the volume Rv as a threshold value, compares this voltage value S ₂ with the output voltage S ₁ of the case shake detection circuit 41, and the output voltage S ₁ is the reference voltage value S _2. If the output voltage S ₁ is lower than the reference voltage value S ₂ , a low signal, that is, “0” is output. The comparator 42 is connected to the CPU 20, and the output value is input to the port P ₁ of the CPU 20.
[0017]
Control signal from the light source drive circuit 33 based on the signal output from the port S ₄ of CPU20 is output, the light source 36 is driven in accordance with the control signal, the illumination light is irradiated to the symbol surface.
[0018]
On the other hand, when the output value of the port S ₃ is determined based on the input values of the ports P ₁ and P ₃ , the CCD drive circuit 32 is controlled based on the signal input from the port S ₃ . As a result, a control signal is output from the CCD drive circuit 32 and the CCD 35 is driven. In the CCD 35, the symbol surface is imaged by photoelectrically converting the reflected light of the illumination light applied to the symbol surface. Image information or all the pixel data of the photoelectric conversion symbol surface is outputted from the CCD35 is a signal processing circuit 34 is subjected to binarization processing and the like are input to the port P _2. Further, the CCD drive circuit 32 outputs a synchronization signal (vertical, horizontal synchronization signal and field index signal FI) used at the time of symbol information extraction and is input to the port P ₄ . The CPU 20 stores all the pixel data input to the port P ₂ in a memory (not shown) based on the synchronization signal input to the port P ₄ .
[0019]
Further, the CPU 20 reads out the imaging information of the symbol plane stored in the memory, and based on the synchronization signal (vertical, horizontal synchronization signal and field index signal FI) input to the port P ₄ , the CPU 20 reads the symbol information from the image information. Information is extracted, and processing such as decoding is performed based on the extracted symbol information. The symbol information that has been successfully decoded is output from the port P ₅ and transmitted to the host computer via the external interface 38.
[0020]
FIG. 3 is a graph showing the relationship between the shaking speed of the housing 10 and the output value S ₁ of the housing shaking detection circuit 41. As the speed of shaking of the housing 10 increases, the output value S ₁ also increases. However, the minimum value and the maximum value of the output value S ₁ are set in advance in the housing shake detection circuit 41. In this embodiment, the minimum value is 2V, the maximum value is 4V, and the reference voltage value S ₂ is, for example, 2 It is set to about 5 V, and corresponds to the shaking speed Vth of the casing. That is, the output value S ₁ is variable in the range of 2V to 4V according to the speed of shaking of the housing 10.
[0021]
FIG. 4 is a truth table showing the relationship between the input values of the ports P ₁ and P _{3 and} the output value of the port S ₃ . In the truth table, as for the output value of the port S ₃ , “0” indicates reading in the field mode, and “1” indicates reading in the frame mode.
In the first row of the truth table, the input value of the port P ₃ is “1”, that is, the trigger 15 is pressed, and the input value of the port P ₁ is “0”, that is, the speed of shaking of the housing 10. The large case is shown. In this case, “0”, that is, a signal instructing reading in the field mode is output from the port S ₃ .
[0022]
In the second row of the truth table, the input value of the port P ₃ is “1”, that is, the trigger 15 is pressed, and the input value of the port P ₁ is “1”, that is, the speed of shaking of the housing 10. The small case is shown. In this case, “1”, that is, a signal instructing reading in the frame mode is output from the port S ₃ .
[0023]
As described above, the value of the port P ₁ is determined using the reference voltage value S ₂ as a threshold, and the read mode is determined according to the value of the port P ₁ . Therefore, if it exceeds the speed Vth of deflection of the housing the rate of deflection of the housing has corresponding to the reference voltage value S ₂ as shown in FIG. 3 becomes reading by field mode, if it does not exceed the Vth Is read out in the frame mode.
[0024]
FIG. 5 is a schematic diagram showing the configuration of a conventionally known CCD used in this embodiment.
In FIG. 5, photodiodes 60 and vertical transfer CCDs 61 corresponding to the respective pixels are alternately arranged. That is, the photodiodes 60 and the vertical transfer CCDs 61 extending in the vertical direction V are alternately arranged in the horizontal direction H. The charges generated in the photodiode 60 are moved to the vertical transfer CCD 61, transferred to the horizontal transfer CCD 62 in the vertical transfer CCD 61, and output from a terminal connected to the horizontal transfer CCD 62.
[0025]
FIG. 6 is an enlarged view showing the configuration of the photodiode 60 and the vertical transfer CCD 61. The vertical transfer CCD 61 of this embodiment is composed of four-phase transfer electrodes of V ₁ , V ₂ , V ₃ , and V ₄ . The photodiodes 60 arranged in the vertical direction V are alternately connected to the electrodes V ₁ and V ₃ . That is, odd-numbered photodiodes (PD ₁ , PD ₃ , PD ₅ ...) Are connected to the electrode V ₁ , and even-numbered photodiodes (PD ₂ , PD ₄ , PD ₆ ...) Are connected to the electrode V _3. It is connected to the. The electric charge accumulated in each photodiode moves to the vertical transfer CCD 61 when a voltage is applied to the connected electrode. Note that the odd-numbered photodiodes correspond to the odd-numbered fields of the image to be read, and the even-numbered photodiodes correspond to the even-numbered fields.
[0026]
FIG. 7 is a cross-sectional view of the image sensor of this embodiment. A p-type silicon substrate 71 is laminated on an n-type silicon substrate 70, and an n-type photodiode 60 is disposed thereon. A vertical transfer CCD 61 is formed in the vicinity of the photodiode 60, and the vertical transfer CCD 61 is shielded by a shielding member 62 made of aluminum. Residual charges of the photodiode 60 are moved to the substrate side by applying a voltage (Vsub) of several tens of volts to the n-type silicon substrate 70, and are removed from the image sensor.
[0027]
FIG. 8 is a timing chart in the case of field reading, and FIG. 9 is a timing chart in the case of frame reading. In the timing chart, FI is a field index signal output from the CCD drive circuit 32. High corresponds to an odd field, and low corresponds to an even field.
In FIG. 8, the substrate voltage is applied at A8, and the residual charge of the photodiode 60 (see FIG. 5) is removed. Thereafter, charges start to be accumulated in the photodiode 60, and when a voltage is simultaneously applied to the electrodes V ₁ and V ₃ (see FIG. 6) of the vertical transfer CCD 61 in B8, the odd-numbered field and even-numbered field accumulated in the photodiode 60 are displayed. The electric charge is transferred to the vertical transfer CCD 61. In the vertical transfer CCD 61, the charges of the odd-numbered photodiodes counted from the horizontal transfer CCD 62 and the adjacent even-numbered photodiodes (PD ₁ and PD ₂ , PD ₃ and PD ₄ ...) Are added to the horizontal transfer. It is transferred to the CCD 62 (see FIG. 5). Charge is output from the horizontal transfer CCD 62 during a period from B8 to D8, and read out as image information of one field.
[0028]
Then, the substrate voltage again is applied at a C8, after the residual charge of the photodiode 60 is removed, the voltage at the same time is applied to the electrodes V _1, V ₃ of the vertical transfer CCD61 in D8, odd accumulated in the photodiode 60 The charges in the field and even field are transferred to the vertical transfer CCD 61. In B8, the vertical transfer CCD 61 adds charges by changing the combination of the odd-numbered photodiode and the even-numbered photodiode (PD ₂ and PD ₃ , PD ₄ and PD ₅ ...), And horizontal transfer. It is transferred to the CCD 62. Similarly, charges are output from the horizontal transfer CCD 62 during the period from D8 to E8, and read out as image information of one field.
[0029]
In FIG. 9, the substrate voltage is applied at A9, and the residual charge of the photodiode 60 is cleared. Initially and subsequently accumulated charges in the photodiode 60, when a voltage to the electrodes V ₁ of the vertical transfer CCD 61 is applied at B9, the charge of the odd field stored in the photodiode 60 are transferred to the vertical transfer CCD 61, charges a vertical The data is transferred from the transfer CCD 61 to the horizontal transfer CCD 62. At the same time, FI switches to a high signal indicating an odd field. A charge is output from the horizontal transfer CCD 62 during a period from B9 to D9, and is read out as image information in an odd field. Meanwhile, the substrate voltage is applied again at C8, and the residual charge of the photodiode 60 is removed. When a voltage is applied to the electrode V ₃ of the vertical transfer CCD 61 at D 9, the even-field charges accumulated in the photodiode 60 are transferred to the vertical transfer CCD 61 and then transferred to the horizontal transfer CCD 62. At the same time, FI switches to a low signal indicating an even field. Charge is output from the horizontal transfer CCD 62 during the period from D9 to F9, and is read out as image information of even fields.
[0030]
Therefore, the read mode is switched, that is, the field mode and the frame mode are switched by controlling the phase of voltage application of V ₁ and V ₃ .
[0031]
When reading in the field mode, the pixel information in the even field and the pixel information in the odd field are added and processed. Therefore, the amount of image information is reduced by half compared to the reading in the frame mode, but the imaging time (from the charge accumulation time) is reduced. This is an effective reading mode when there is a high possibility that the casing is shaken because the time required for reading out all pixel data is about half that of the frame mode.
[0032]
On the other hand, when image information is read in the frame mode, the amount of image information is large and the decoding accuracy is improved, but the charge accumulation time and the time required for reading are twice as long as the field mode. Therefore, when reading in the frame mode, it is necessary to position the reading opening on the symbol surface for a long time, and it is vulnerable to disturbance due to the hand shake of the operator.
[0033]
FIG. 10 is a processing flow from the imaging process of the symbol surface to the transmission of symbol data. At the start of the processing flow, the power source of the symbol reading apparatus main body is turned on, the CPU 20 is in an operating state, and each drive circuit, CCD 35, and light source 36 are in a driveable state. In step 100, it is determined whether or not the trigger 15 is pressed. If the trigger 15 is pressed, the process proceeds to step 101. If the trigger 15 is not pressed, no new process is performed. That is, the trigger 15 is pressed and the symbol reading process is started.
[0034]
In step 101, the value of the port P ₁ is confirmed. If “1”, that is, the speed of shaking of the housing 10 is large, the process proceeds to step 102, where the image information on the symbol plane is read in the field mode. On the other hand, if the value of the port P ₁ is “0”, that is, the speed of shaking of the housing 10 is small, the process proceeds to step 103 and the image information on the symbol plane is read in the frame mode. The read image information is subjected to binarization processing and predetermined image processing, and then stored in the memory.
[0035]
In step 104, image information on the symbol plane is read from the memory, and only pixel data corresponding to the data symbol is extracted from the image information, that is, a symbol extraction process is performed. Decoding processing is performed in step 105 based on the extracted pixel data. If the decoding process is successful in step 105, symbol information is transmitted to an external host computer in step 106 as a successful symbol reading. If the decoding process fails, transmission to the host computer is not performed. The symbol reading result is notified to the operator by a buzzer or a display lamp (not shown) provided on the housing.
[0036]
As described above, according to the present embodiment, the imaging mode is set according to the speed of shaking of the casing detected by the angular velocity sensor. For this reason, the reliability of the imaging information on the symbol plane is increased, the possibility of failure in extracting and decoding symbol information from the imaging information on the symbol plane is reduced, and the probability of successful symbol reading is increased.
[0037]
【The invention's effect】
As described above, according to the present invention, it is possible to stably read a two-dimensional symbol in accordance with the fixed state of the housing.
[Brief description of the drawings]
FIG. 1 is a perspective view of a symbol reading apparatus according to an embodiment of the present invention.
FIG. 2 is a block diagram of a symbol reading apparatus according to the present embodiment.
FIG. 3 is a graph showing a relationship between a case shake amount and an output value of a case shake detection circuit;
FIG. 4 is a truth table of arithmetic processing in a CPU built in the symbol reading device.
FIG. 5 is a schematic diagram of a CCD used in the symbol reading device of the present embodiment.
FIG. 6 is an enlarged view showing the configuration of a CCD photodiode and a vertical transfer CCD.
FIG. 7 is a cross-sectional view showing a layer structure of a CCD.
FIG. 8 is a timing chart for reading image information in a field mode.
FIG. 9 is a timing chart for reading image information in a frame mode.
FIG. 10 is a processing flow of symbol reading in the present embodiment.
[Explanation of symbols]
10 Housing 12 Reading opening 15 Trigger 20 CPU
60 Photodiode 61 Vertical transfer CCD
62 Horizontal transfer CCD

Claims (3)

  A symbol reading device for reading the symbol by positioning a symbol surface on which a coded symbol is formed in a reading opening provided on a bottom surface of the housing, and a shake detecting means for detecting a speed of shaking of the housing; An image pickup device that photoelectrically converts the optical information on the symbol surface to store charges, and an image pickup that selects a readout mode of charges from the image pickup device corresponding to the shaking speed of the casing detected by the shake detection means And a symbol reading device.   2. The symbol reading apparatus according to claim 1, wherein the shake detecting means is an angular velocity sensor. If the shake detecting means detects the speed of the first swing, the charges said imaging control means is accumulated in the imaging element is read out in the field mode, the speed of the swing detecting means said first shaking when detecting the speed of the small second swing than is the symbol reading device according to claim 1, wherein the imaging control means and said reading by tying the charge accumulated in the imaging element in a frame mode.

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