JPS62248086A - Mark reader - Google Patents

Abstract

PURPOSE:To raise the reading resolution of a quickly moving object and to reduce power consumption by intermittently lighting the 1st light source according to a previously detected synchronizing signal and reading the mark of the 1st light receiving element. CONSTITUTION:The titled device is provided with a photointerrupter 10 having an LED 10A and a phototransistor Tr10B. An LED11, an image sensor 12 and an optical lens 13 are provided the prescribed distance from said photointerrupter 10. The titled device has such a structure that the object 14 with marks such as bar codes moved in the direction of an arrow of the optical path between the LED10A and the Tr10B and that between the LED 11 and the lens 13. As the object 14 moves quickly, the TR10A detects the mark 14A, and therefore the synchronizing signal when the mark enters the visible field of the sensor 12 is obtained beforehand. When the mark 14A moves to enter the visible field of the sensor 12, the LED 11 is intermittently lighted according to the synchronizing signal, and the sensor 12 reads the mark 14A. If the lighting time width is shortened, reading at high resolution can be possible.

Description

Detailed Description of the Invention (Field of Application in Industry-1-) The present invention provides a mark reader for reading marks such as barcodes in which product name and manufacturer information is displayed on a subject according to the thickness and spacing of the bars. It is related to.

(Conventional technology) Conventionally, technology in this field has been published in "Integrated circuit technical data COD image sensor" edited by Toshiba Corporation, 21st Edition (1993).
985-4) There was one described in P. 21. Hereinafter, its configuration will be explained using figures.

FIG. 2 is a schematic diagram of a conventional mark reader.

The mark reader in Fig. 2 is a light emitting diode (hereinafter referred to as LE).
A light source 1 such as a light bulb, a light receiving element 7-2 such as a phototransistor or an image line sensor, and an optical lens 3 for image formation are provided. is a moving structure.

In the following configuration, the light source 1 is lit with direct current, and the subject 4
A mark 14A such as a bar code is imaged by the optical lens 3, and the mark 4A is read by the light receiving element 2.

In this type of mark reader, when an image line sensor is used as the light receiving element 2, the mark t4A of the subject 4 is detected by the image line sensor, so the mark 14A of the subject 4, which is stationary or slowly moving, can be read without decomposition. be able to.

(Problems to be Solved by the Invention) However, in the mark reader having the structure h, since the light source 1 is DC lighting, the sampling time for reading the object 4 is one scan 111 of the image line sensor. Therefore, when the subject 4 moves at high speed, the image becomes blurred, making it impossible to read the mark 14 on the subject 4 with high resolution. Furthermore, since the light source 1 is a DC lighting device, it must be kept on at all times, which also poses a problem in that it consumes a large amount of power.

The present invention provides a mark reader that solves the problems of the prior art, such as low reading resolution for fast moving objects and high power consumption.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a first light source that irradiates a light beam onto a mark on a moving subject, and a first light source that reads the mark from the reflected light of the subject. a second light source and a second light receiving element for detecting in advance a synchronization signal when the moving subject enters the detection area of the first light receiving element; The apparatus further includes a circuit that causes the first light source to turn on intermittently in accordance with a periodic signal and also causes the first light receiving element to perform a mark reading operation.

(Function) According to the present invention, since the mark reader is configured as described above, by shortening the intermittent lighting time of the first light source, the sampling time is shortened, and image blur is reduced even when the subject is moving at high speed. This improves the reading resolution. Furthermore, since the first light source is lit in pulses, power consumption is reduced. Therefore, the above-mentioned problem can be eliminated.

(Example) FIG. 1 is a schematic diagram of a mark reader showing an example of the present invention.

This mark reader has a second light source, LEDIOA,
and a photoelectric variable sensor-F for detecting the presence or absence of a mark having a phototransistor IOB as a second light-receiving element, for example, a photointerrupter 10;
An LED II which is a first light source for reading marks, an image line sensor 12 which is r- from the first light receiving side, and an optical lens 13 for image formation are provided at a predetermined interval from 0. And between the optical path of these LEDIOA and the phototransistor IOH, and between the LEDII and the optical lens 13
The object 14 having a mark 14A such as a bar code moves across the optical path in the direction of the arrow in the figure.

In the configuration described below, when the subject 14 moves at high speed in the direction of the arrow in the figure, the mark 14A of the subject 14 is detected in advance by the LED IOA and phototransistor IOB.

Based on the detection signal, a synchronization signal is obtained in advance when the position of the moving mark 14A just enters the field of view of the image line sensor 12 through the optical lens 13.The mark 14A moves and after a certain period of time, the image line sensor 12 At that time, the LED 11 is lit intermittently (hereinafter referred to as pulse lighting) in accordance with the synchronization signal obtained earlier, and the image line sensor 12
The mark reading operation is started, and the image line sensor 12 reads the mark 14A.

In this way, the image of the mark 14A of the subject 14 moving at high speed can be read by the image line sensor 12 with good resolution without blurring. That is, when the light source 1 is DC lighting as in the conventional case, the sampling time for capturing the subject 4 is one scanning time of the image line sensor 2.

However, in this embodiment, LE[lLL is lit in pulses in synchronization with the position of mark L4A, so if the pulse lighting time width of LED II is narrowed, the sampling time for capturing the image becomes the lighting time of LED II, and the movement is performed at high speed. Mark 14A can be read with a high resolution of 17 without blurring.

FIG. 3 is a diagram showing an example of the circuit configuration of the mark reader shown in FIG. 1. Note that elements that are the same as those in FIG. 1 are given the same symbols.

This mark reader has a reflective photointerrupter 10, and an image line sensor 12 and an optical lens 13 are provided at a predetermined distance from the photointerrupter 10. The photointerrupter 10 is composed of an LEDIOA, a phototransistor 10B, and a resistor. Further, a delay circuit 20, an LED II pulse lighting circuit 30,
A synchronization circuit 40 with the image line sensor 12, a timing generation circuit 50 for the image line sensor 12, a driver 60 for driving the image line sensor 12, and e)-(
An output control circuit 70 for the interrupter 10 is provided.

The delay circuit 20 receives the output signal 81 of the photointerrupter 10.
One-shot multi-by-break (hereinafter referred to as one-shot multi) F4
! , a resistor R, and a capacitor C. The pulse lighting circuit 30 has a plurality of LEs [111] arranged in an array in pairs with the image line sensor 12, and also has one-show, multi-channel M2, etc., which are operated by the output signal S2 of the delay circuit 2o. , the one-shot multi M
This is a circuit that pulse-lights each LEDll using the output signal s3 of No.2. The synchronizing circuit 4° has a one-shot I/multi M3 which is operated by the output of the pulse lighting circuit 30 and outputs a start pulse signal S4 to the image line sensor 12, and a one-shot I/multi M3 cascaded to this one-shot multi M3. Multi M4. M5 and flip-flop circuit (hereinafter simply referred to as flip-flop) Fl
etc. are right.

The timing generation circuit 50 is a circuit that outputs a plurality of timing signals φT, φ, and φ−9φR based on the start pulse signal S4, and includes a latch circuit LT, a flip-flop F
2. F3, has one shot multi xehg. The driver 60 receives timing signals φT and φ.

It has a plurality of inverters that generate drive pulses S5 from T and φR, and intermittently operates the image line sensor 12 using the drive pulses s5.
This circuit outputs the video signal S6 from the video signal S6. Also,
The output control circuit 70 is a circuit that has a one-shot multi-snorer operated by the output signal S1 of the photointerrupter 10, and supplies the output signal S7 of the one-shot multi-snorer M7 to the delay circuit 20 through an OR gate.

In FIG. 3, the subject 14 moves in the direction of the arrow in the figure, and T represents the moving time of the subject 14, the field of view of the image line center 12 through the extraction optical lens 13,
If is the current flowing through the LEDIOA in the photointerrupter lO, Ifp is the current flowing through the LEDIOA in the pulse lighting circuit 30.
11, respectively.

Next, the operation of FIG. 3 will be explained with reference to the timing chart of FIG. 4 and the mark resolution characteristic diagram of FIG. 5.

In addition, in FIG. 4, 14-1 is the first subject;
-2 is the second object, Td is the delay circuit output signal -) S2
Twt is the pulse width of the output signal S3 at the 1,000-shot M2, Tr is the pulse width of the video signal S6, and Tc is the pulse width of the output signal S7 of the output control circuit 70. In Figure 5, the horizontal axis represents the LED lighting pulse width, and the vertical axis represents the relative value of resolved fE (MTF), and the pattern movement speed of mark 14A (for example, barcode) V V = 1000 + s/S V = 860 m5/s It also represents the curve when the storage time (that is, scanning time) of the image line sensor 12 is Tint = 500 islands S.Here, the pattern width W of the barcode represented in black and white, etc. is 0.25 mm, The image line sensor that reads this 12-pixel pixel +P is 13JLm
, the aperture ratio F of the optical lens 13 is 2, and its magnification M is l/
3. Under the condition that the storage time Tint of the image line sensor 12 is 8 ras when 01 o'clock of the barcode is set to 1, the pulse width Tw of the output signal S3 is as follows.

First, in FIG. 3, when the object 14 is inserted into the photointerrupter 10 at a constant speed V, the light emitted from the LEDIOA is reflected by the mark 14A consisting of a black and white pattern on the object 1442, and the reflected light becomes a photointerrupter. Light enters the transistor 10B and a photocurrent IQ flows. As shown in FIG. 4, this light 'high current IQ' flows more to the white pattern than to the black pattern.In the case of the photointerrupter 10, the area of the phototransistor 10B is large and the reflected light is Therefore, even if a fine black and white pattern passes through the photointerrupter 10, it is not possible to clearly distinguish between white and black, and an intermediate output that looks like gray is obtained.The intermediate output is connected in series to the phototransistor 10B. By appropriately selecting the resistance value of the load resistor connected to , the photointerrupter output signal S1 as shown in FIG. At the leading edge of the signal S1 (for example, the point where it changes from a low level ground potential to a high level +5V potential), the one-shot multi M1 is triggered and the output signal -82 is output by a pulse width Td determined by the capacitor C and the resistor R. At that time, the subject 14 has moved to the position 77 hours later in FIG.

C and R of the delay circuit 20 are selected so as to synchronize the time width Tv with the time of the pulse width Td.

Next, at the trailing edge of the output pulse S2, a one-shot multi-function switch in the lighting circuit 30 at the next stage is triggered to generate an output 0 output S3 having a predetermined pulse %Tw. The pulse width Tw at this time varies depending on the moving speed V of the subject 14, but as is clear from FIG. 5, the optimum mode is about 0.2 ms. The pulse width Tw is the pulse lighting circuit 3
The pulse lighting width of the LED11 is 0. The light pulsed by the LED II is reflected by the subject 14, and the reflected light passes through the optical lens 13 and passes through the image line sensor 12.
is illuminated by light.

On the other hand, the image line sensor 12 is connected to the pulse lighting circuit 3.
Scanning is started using the start pulse signal S4 which passes the output S3 of 0 through the synchronization circuit 40. The image line sensor 1
The second scan is performed using timing signals φd, φ, and ゛φ−9φR outputted from the timing generation circuit 50. As a result, the image line sensor 12 outputs a video signal S6 with a pulse width Tr corresponding to the strength of the human-powered light.

The main operations in FIG. 3 are explained above. Next, the operation of the output control circuit 70 will be explained. This output control circuit 70 is
In order to better use the mark reader, the subject 14
Only the presence or absence of the mark 14A is outputted as an output signal S7, and once the output signal Sl is input to the delay circuit 20, the next input is given a constant pulse width of 〒c time in the output signal S7. This is to prevent it from entering. the result,·
The pulse lighting of the image line sensor 12 is
It will light up only once for every 4. In FIG. 4, a later first subject 14-1 and an earlier second subject 14-
Since there is no reflective object between photo interrupter 1 and
The output signal Sl of 0 is a signal equivalent to black.

Furthermore, the one-shot multi-M4.
M5. and flip flow 2 F1 are circuits for resetting each pixel in the image line sensor 12 after reading a predetermined bit of the video signal S6 which is the output of the image line sensor 12. , the subject 14 can enter the camera at any time.

The advantages of this embodiment can be summarized as follows. Since the mark 14A is read by the image line sensor 12, it can be read with high resolution. In particular, by narrowing the pulse lighting time of the LEI) 11 in synchronization with the mark 14A position i of the subject 14, the sampling time is shortened, and even the subject 14 moving at high speed can be read with less image blur and high resolution. Moreover, since the LED II is lit in pulses, power consumption can be reduced.

The invention is not limited to the illustrated embodiment, but is susceptible to various modifications. Examples of variations include the following.

(i) By adding one more set of LEDIOA and phototransistor 10B, even if the moving speed of the subject 14 is not known, the moving speed of the subject 14 can be determined from the added LE[) and the detection signal of the phototransistor -. This makes it possible to detect marks with high resolution even for the subject 14 whose moving speed is unknown.

(ii) LEDI constituting the photointerrupter 10
OA may be another light source such as '+(i)J, a laser diode, etc., and the phototransistor IOB may also be another light receiving element such as a photodiode or a photothyristor. Similarly, the array of LED II in the pulse lighting circuit 30 may be any other light source, and even the image line sensor I.
2 may be configured with other light receiving elements.

(iii) The mark reader circuit may be configured with a circuit other than that shown in FIG.

(Effects of the Invention) As described in detail in 1-1, according to the present invention, the marks on the subject are confirmed in advance using the second light source and the second light receiving element, and the first light source is turned on after a certain period of time. Since the mark is read by the first light-receiving element by lighting pulses, it is possible to read the mark of a subject moving at high speed with high resolution without blurring. Furthermore, by pulse lighting of the first light source, the effect of reducing the amount of mental energy consumed can be expected.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a mark reader showing an embodiment of the present invention, FIG. 2 is a schematic configuration diagram of a conventional mark reader, FIG. 3 is a diagram showing an example of the circuit configuration of FIG. 1, and FIG. FIG. 3 is a timing chart, and FIG. 5 is a mark resolution characteristic diagram in FIG. lO...Photo interrupter, IOA...LED
(second light source), IOB... phototransistor (second light receiving element/-), 11... LED (first light source), 12... image line sensor (first light receiving element), 13...Optical lens, 14.14-1.14
-2...Subject, 14A ・? -ri, 20-...d
Detour, 30... Pulse lighting circuit, 4o... Same 1/1 circuit, 50... Timing generation circuit, 6o... Driver, 7o... Output control circuit. Applicant's representative: Kyo Kakinoki Seiatana The mark reader of the present invention (Fig. 1) and the conventional mark reader (Fig. 2/10). Phototransistor 12, Imagery>Se) 13° Optics-Sens 14 Subject-14A: Mark, /2;

Claims (1)

[Scope of Claims] A mark reader comprising a first light source that irradiates a light beam onto a mark on a moving subject, and a first light receiving element that reads the mark from reflected light from the subject, wherein the moving subject is a second light source and a second light receiving element for detecting in advance a synchronizing signal when entering the detection area of the first light receiving element; and intermittent lighting of the first light source in accordance with the synchronizing signal, and A mark reader comprising: a circuit that causes a first light-receiving element to perform a mark reading operation.