JPS58125179A - Method and device for reading of bar code - Google Patents

Abstract

PURPOSE:To extend a video storage time, and to stably convert a variable density bar to a binary-coding signal, by dividing a photoelectric element train of an image sensor into at least 2 groups of equal interval element trains, and scanning them alternately. CONSTITUTION:A video of a bar code is photoelectrically converted by a photodiode train 8a. Odd signal charge obtained by the photodiode train 8a is shifted to a shift register 8c-1 through a transfer gate 8b-1, and even signal charge is shifted to a shift register 8c-2 through a transfer gate 8b-2. Outputs of the shift registers 8c-1, 8c-2 are synthesized at an output gate 8d, and are made a single output.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a barcode control method and apparatus for reading a barcode recorded on a recording medium by scanning the barcode.

When performing high-speed reading processing with a barcode reading device that uses a conventional charge accumulation type image sensor, the accumulation time will be shortened if the signals of all photoelectric elements (all +11# cumulative) of the image sensor are output in the normal usage. A barrier arises where the sensitivity inevitably decreases due to the short length.

Mayu, as a way to increase the output of the image sensor,
Although there are many methods for increasing the brightness of a light source, various problems arise, such as the area covered by the light source, energy consumption, and heat generation.

In the LP, COD image sensor, the odd-numbered pixel column signals and the even-numbered pixel column signals are transferred to separate shift registers and transferred, and the signal electric image is transferred at the output section before entering the electric image detection section. are combined into a single output.

Therefore, the output of the image sensor differs between odd-numbered bits and even-numbered bits due to differences in transfer efficiency of each V-foot register. Therefore, the output repeats alternately and become uneven, and when the output of the image sensor is sampled and held, a waveform is generated as a noise component.The present invention was developed in view of the above problems, and the accumulation time of each pixel of the image sensor is The purpose is to increase the sensitivity by increasing the length and to stabilize the conversion of the monovalued signal corresponding to each density par.

For this purpose, in the first invention of the present application, the odd-numbered first pixel column and the even-numbered sm-th pixel column in the image sensor are scanned separately and alternately, and the electric signal of the first pixel column is extracted and read. After processing, the electric signal of the swR element string is extracted and read processing is performed.

Furthermore, in the eighth invention of the present application, there is provided a scanning means that divides into clock pulses and alternately generates each scanning signal, and adds each scanning signal to the image sensor, and The configuration is such that a driving means for alternately scanning the column and the even-numbered 8th element column is provided.

The present invention is illustrated below! Example J will be explained.

FIG. 1 is an overall configuration diagram of a handy type barcode reading device, and FIG. 2 is a partial perspective view thereof.

1 is pe μ on the barcode, and a barcode 11 is printed on its surface with white bars and black bars as a parallel pattern of light and shade. 2 is the case of the handheld reader,
Reference numeral 8 denotes a light source that irradiates the barcode, and is equipped with a plurality of randes, and the irradiation light is converged and irradiated onto the barcode through a semicylindrical lens. 6 is a reflecting mirror that reflects the reflected light from the barcode in a specific direction (the scanning line direction of the image sensor), and the reflected light passes through the lens 6 and the diaphragm member 7 having a flat slit orthogonal to the reading line. A bar code scanning image is formed on the scanning line of the reading sensor 8 through the bar code. This reading sensor 8 uses a one-dimensional image sensor that converts the scanning barcode image into an electrical signal by linear electronic scanning.

Each dot-by-dot line in FIG. 1 indicates the trajectory of light in the optical system. A scanning clock necessary for driving the 9Vi reading sensor by the driving circuit of the reading sensor is received from the clock generating circuit 18 and applied to the reading sensor. 10 is an analog amplifier that amplifies the electrical signal obtained by the scanning operation of the reading sensor 8. 11 is a waveform shaping circuit that shapes the waveform of the output signal of the analog amplifier H10, and is composed of a sample hold circuit that converts the discrete signal from the amplifier IO into a continuous signal tKf, and a low-pass filter that smooths the output waveform. . 11 is a humparator circuit, which converts the shaped signal from the waveform shaping circuit 11 into high-level and low-level 8-value signals corresponding to black bars and white bars.O18 is an inversion detection circuit,
The rising and falling points of the ii conversion signal are detected, and a latch pulse and a clear pulse slightly delayed from the latch pulse are sent to the latch circuit 16 and the counter 14 each time.

17 is a clock generator that generates clock pulses of a constant frequency. Reference numeral 14 denotes a counter which repeatedly counts clock pulses every time the clear pulse is received and cleared, and the number of hands thereof corresponds to the width of each par of the bar code and indicates a nine value. 1b is a latch circuit, which uses the latch pulse to record the count fl (width of the bar) of the counter 14 immediately before the clear operation. Reference numeral 18 denotes a clock generation circuit, which generates a scanning clock necessary for driving the reading sensor 8 and a timing clock for the sample hold circuit in the waveform shaping circuit 11 from the clock pulse of the clock generator 1f. 16 is a microcomputer, latch circuit 1
Arithmetic processing is executed based on the bar width information obtained in step 6 to decode the barcode. Reference numeral 19 denotes a piezoelectric buzzer. When the reading of the bar code is completed, the microcomputer 16 outputs a signal and the piezoelectric buzzer 19 sounds to notify the operator that the reading has been completed.

Next, FIG. 8 is a configuration diagram showing the detailed configuration of the reading sensor 8, in which a 0 (3D image sensor) is shown as the reading sensor 8'. 8a photoelectrically converts the barcode image to obtain a signal charge. 8b-1 is a transfer gate that transfers the odd-numbered signal charges obtained above to the shift register of 80-1.ab-m transfers the even-numbered signal charges to the shift register of 80-1. 5b-1, 1lb-1 transfer 1 gate) d, 81j transfer 1 gate tarlock φte 01+ φ? It is configured so that G1 can be obtained.

8d is an output gate which combines the outputs of the V atto registers 8e-1, 1 and outputs a single output. 8 is a reset gate whose output is fixed to the drain voltage of COD by a clock pulse of φ18.

In addition, FIG. 1 shows a clock generator 1 for driving the reading sensor 8, a clock generating circuit 18, and a main body 1Ii.
It shows a detailed electrical wiring diagram of 1 circuit 9.

In response to the clock pulses from the clock generator 1), various clock generation circuits 19 perform counting and logic processing, and apply scanning signals for the image sensor 8 to the driver circuit 9.
An electric signal is sent out by the scanning operation of the image sensor 8. In addition, each oscillation generating circuit 19 applies a sample-and-hold control signal to the waveform shaping circuit 11 in synchronization with the scanning signal to control the conversion of a 1m discrete signal into a continuous signal.

Further, FIG. 6 shows an electrical wiring diagram of the detailed configuration of the waveform shaping circuit 11 and comparator 18 in FIG.
Sample hold circuit 11m and low pass filter llb
This converts the discrete signal into a continuous signal and performs waveform shaping to remove high frequency noise, and the comparator 18 converts the signal into a rectangular wave corresponding to the black bar and white bar.

Next, the operation of the above configuration will be explained.

Now, insert the barcode into the reading port of the barcode reader.
A light source 8 irradiates light through a semicylindrical lens. From this K, reflected light is generated whose reflectance differs depending on the white bar and black bar of the barcode Im, and the distribution of light intensity corresponds to the barcode. This reflected light beam passes through the reflecting mirror b, the lens 6°, the diaphragm member 7, and the image sensor 8.
An image for scanning the barcode is displayed on the scanning fM of the barcode. At this time, the diaphragm member 7 is a flat sleeve F that is perpendicular to the reading line, and not only deepens the depth of focus, but also increases the amount of light of the scanning image to the image sensor 8, thereby increasing the reading accuracy. Then, the image for scanning the barcode is formed on the scanning line of the image sensor 8.

The image sensor 8, which has received a necessary loft for driving from the drive circuit 9, is converted into electrical signals having different voltage levels corresponding to the white bar and the black bar of the bar code Ia, respectively, by electronic scanning.

The operation of this image sensor 8 will be explained according to the drive pulses shown in FIG. Figure 6 a) and b) are the transfer 1 gate clock φTG1 for the transfer gate 8b.
The transfer gate clock for transferring odd-numbered signal charges and the transfer gate clock for transferring even-numbered signal charges are applied alternately.

Odd-numbered signal charges and even-numbered signal charges can be taken out.・e) and d) are for V resistors! /7
Treasure clock φ1・9. φ■, and each signal charge is sequentially transferred to the output gate l by this clock. e) is a reset pulse φ1g for the reset gate, and this reset pulse turns on the reset gate.
, 0FII and collect the output. Therefore, when a lock is applied to the image sensor 8 as shown in FIG. 6, the transfer 1 gate clock of the transfer gate 5b-iKa) is applied, the transfer gate 8b-1 is opened, and the odd-numbered signal charges are shifted all at once. It is moved to register 8e-1. and b), e) shift register clock, d
) is applied, the odd-numbered signal charges are sequentially transferred to the output (g)8d and output.

At this point, since the gate of the transformer 71 of 8a is closed, even-numbered signal charges are still stored in the capacitors in the photodiode array 8a. Therefore f)
As shown in period T, only Kfr signal charges are sequentially taken out. Next, a transfer 1 gate clock is applied to the transfer gate 8b-s, and the transfer gate Hb-s is opened, and the even-numbered double fv/l loads are transferred all at once to the shift registers 8e-11c.

Then, in the same manner as described above, only even numbered signal charges are sequentially output. This output waveform is shown in period T1 of f). Continuous scanning is performed by repeating the above-mentioned start and check operations. (Note that x=Ti) Therefore, the accumulation time of the signal charge in the photodiode array is the time interval between one gate clock of each transfer, and thus becomes T1 time in this case. Further, the barcode decoding cycle time is Tz (=Ts) time.

As a result of the above, it is possible to obtain an accumulation time that is 8 times the bar code decoding cycle time, and compared to the case where all the signal charges of the photodiode array are output at once, when the bar code decoding cycle is the same, the accumulation time is 8 times longer than the bar code decoding cycle time. The time is doubled and the sensitivity is doubled. Electrical signal f of the output of this image sensor 8
) is amplified by an analog amplifier lO, and then applied to the waveform shaping circuit 11.

The operation of this waveform shaping circuit will be explained with reference to the detailed electrical connection diagram of the main parts in FIG. The sample hold circuit 11m, which receives sampling pulses synchronized with scanning signals from various clock generation circuits 18, uses the sampling pulses to
The electrical signal output from the image sensor 8 is sampled and held, and the discrete signal synchronized with the clock pulse is converted into a continuous signal. It is an inverting amplifier for inverting the 1m signal output from the Fi% image sensor 8. This inverted rancid electrical signal.

The diode 11d and the capacitor Ile hold each peak value, and the analog switch 11f, which is closed by the sampling pulse and passes the peak value of the video signal, sets the capacitor 11g to each peak value voltage. can be conveyed. The peak value voltage transmitted to this capacitor 11gK is held until the next sampling point.

llh is a transistor, which transmits the peak value voltage stored in the capacitor ll@ to the capacitor l1gK, and when the analog switch llf is opened, it is discharged in synchronization with the sampling pulse, and in preparation for holding the next peak value. There is. FIG. 7 shows the timing of sampling pulses. C) K in order to pass the peak value of the Ifi video signal through the capacitor l1gK.

A-J-1: This is a sampling pulse that closes 1l-f by X inches. d) is a sampling pulse that discharges the voltage of the capacitor 116.

llb is a low-pass filter that removes high-frequency noise from the sample hole and the waveform of output i and extracts low-frequency components; The frequency is set lower than the continuous signal frequency. This low bass fi~
1lbK) Noise components and the like are removed from the video signal to make it a smooth signal. The waveform at this time is shown in g) of FIG. Waveform shaping is performed by this sample hold circuit 1xa and low pass filter llb.

1m is a comparator circuit that converts the above output waveform into high-level and low-level 2G signals corresponding to the black bar and white bar, ls Hatake, lsb are diodes connected in antiparallel,
1lio is condansu rtj.

The reference signal is obtained by reducing the amplitude of the signal by a predetermined potential difference equal to the diode forward voltage drop and shifting the phase by using the diodes connected in antiparallel. 1ild is a comparator that compares the reference signal with the output signal from the low-pass filter to obtain a binary signal. The width of each high level and each low level of the s-value signal corresponding to the black bar and white bar is measured by a counter and a clock generator that generates a clock pulse of a constant frequency, and the length of the bar code is obtained. The data is imported into the microcomputer 16 as a. Based on this captured bar length information, arithmetic processing is performed according to a predetermined arithmetic program to perform a reading operation.

As described above, by separately and alternately outputting the odd-numbered and even-numbered electrical signals of the pixel rows of the image sensor as a single output, it is possible to have an accumulation time eight times longer than the decoding cycle time. When the time is the same, compared to when all the signals of the pixel rows of the image sensor are output to the palace, f and the accumulation time of each pixel row Vi are doubled, and the sensitivity can be increased eight times, which is an excellent effect.

This means that the 8/N ratio df of the output of the image sensor
It is now possible to accurately convert to an 8-value signal that corresponds to the white and black parts of the barcode, and is stable. You will be able to perform nine reading operations.

Further, in order to normally perform stable reading, the reading is completed when the results of several readings match. Therefore.

Since the decoding cycle can be shortened, reading can be completed quickly.

According to the above embodiment, the pixel row of the image sensor is divided into three, odd numbered and even numbered, and the output is taken out. However, if there is no interval IJi in the resolution of It is also possible to divide the pixel rows into a structure in which each signal electric image is output separately and alternately, and to process each output of the image sensor.

Moreover, according to the above embodiment, it becomes a one-dimensional image sensor!
Although a January image is shown, the same can be applied to an eight-dimensional image sensor.

As described above, according to the present invention, the light 1 of the image sensor is divided into at least 8 groups of equally spaced element arrays, and the odd-numbered first element array and the even-numbered second array Because the columns are scanned separately and alternately, and the electrical signal reading operation for each scan is performed separately, the characteristics of each odd-numbered and even-numbered column of the internal structure of the image sensor where the barcode image is formed are It is possible to eliminate the influence on the reading operation due to signal fluctuations due to dispersion, and by increasing the image storage time of each element by alternating operation, increasing the sensitivity, it is possible to convert to an 8-value signal corresponding to each bar of 1m light. It has an excellent stabilizing effect.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram showing an original embodiment of the present invention, FIG. 2 is a partial perspective view thereof, FIG. 8 is a detailed configuration diagram of an image sensor, and FIG. 4 is a detailed electrical connection diagram of the main parts. The isb diagram is a partially detailed electrical wiring diagram, Figure 6 (→~(
The stirrup is a signal waveform diagram of each part to explain the operation, Figure 7 (&) ~
(The mountains are signal waveform diagrams used to explain the operation. ■... Barcode label/1/l la... Barcode, g... Hand reader case, 8... Light source,
4... Kamaboko-shaped lens, 5... Reflective mirror, 6...
Lens, 7...Aperture member, s...Image sensor, 9...Drive circuit, 1G...Analog amplification ill,
11... Waveform shaping circuit, ljl... Comparator,
18... Reversal detection 11.14... Counter, 15.
・Latch circuit, 16-・Microcomputer, 17
... Clock generator, 18... Various clock generation circuits, 19... Piezoelectric buzzer, Sa... Photodiode array, 8b.
Shift register, 8d...output gate F, $...reset gate. Takashi Okabe, Daibajin Masukyoshi

Claims (2)

[Claims] (1) Equipped with an image sensor that converts an image of reflected light from a barcode based on an array of light and dark bars recorded on a recording medium into an electrical signal, and converts the electrical signal into nine dew values corresponding to each density of the bar code. In the barcode reading method for converting into a signal, the photoelectric element array of the image sensor is divided into at least two groups of equally spaced element arrays, and the odd numbered first element array and the even numbered second element array are separately and alternately arranged. Let it scan. The electrical signal from the first element row is extracted, and then the electrical signal from the second element row is extracted as a single output. A barcode reading method characterized by reading each element array for each complete signal. (2) An image sensor that converts an image of reflected light from a barcode based on an array of light and dark bars recorded on a recording medium into an electrical signal, and the electrical signal corresponds to each light and dark bar of the barcode! A barcode reading device comprising: a processing means for converting a skinned signal Kl'; and a clock generator for generating clock pulses of a constant frequency. scanning means for dividing the clock pulse into at least three odd-numbered and even-numbered groups of the image sensor and alternately generating each scanning signal; and applying each scanning signal to the image sensor. A bar code provided with a driving means that scans the odd-numbered first element row of the photoelectric element row to extract the electrical signal, and then scans the even-numbered g-th element row and extracts the electrical signal. Reading both eyes.