JPS5913072B2 - optical code reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an apparatus that optically scans a recording medium to read codes thereof.

To give a little more detail, regarding barcode reading devices installed in portable input devices used in supermarkets etc., especially for this type of portable input devices, light weight and miniaturization are required. However, the present invention is intended to provide a reading device that solves the problem that it is difficult to reduce the weight and size of the device because the design is inevitably constrained by this requirement in relation to power consumption. O Recently, in supermarkets, etc., product cards with the product code corresponding to the displayed product are pasted on the product display shelves, and the person in charge of ordering at the store looks at the number of products remaining on the display shelf and determines the order quantity. After making the decision, input the product code 5 and order quantity of Vc and C on the input devices you carried with you on the spot, and send the collected order data via telephone line to the computer center, where the orders collected from each store are sent to the computer center. A system is adopted that processes orders all at once based on data.

No. 0 Input devices used for such purposes are equipped with barcode reading devices to read and process barcodes printed on product cards in order to shorten input time and reduce input errors. I came.

25 Input devices used for the above purposes are particularly required to be (c) lightweight and compact; (2) to be able to be used for a long time.

30 Nickel-cadmium batteries, which are rechargeable batteries, are usually used to power this input device.
Due to the size, weight, etc. of devices that are intended to be lightweight and compact, it is not possible to use large-capacity batteries, and this type of devices has been subject to significant restrictions in terms of power consumption.

On the other hand, the majority of barcode reading devices included in these input devices scan and read barcodes with a light pen.

This light pen for reading barcodes usually emits light from a light source such as a light emitting diode or lamp from the tip of the pen through a lens or glass fiber, and absorbs the light reflected from the recording paper surface on which the barcode is printed. The presence or absence of light is detected by a light receiving element such as a phototransistor or photodiode and converted into an electrical signal, but since the light source consumes a large amount of power, it is necessary to use a large capacity battery to operate such a light pen on batteries. It could not be put to practical use without the use of. For this reason, this type of input device is lightweight as described above. There is a strong demand for compactness,
Devices equipped with such optical reading devices are limited in their ability to be lightweight and compact due to their power consumption. It was difficult to plan for miniaturization. In order to solve the above-mentioned problems, the present invention has been devised to reduce the power consumption of the light source that performs optical scanning in an optical code reading device, thereby making it possible to operate the device with a small capacity battery. lightweight. This allows for compactness.

The present invention will be explained below with reference to an embodiment shown in the drawings. 1st
3 and 2 are circuit diagrams showing the configuration of the present invention.
The figure is a timing chart.

In Figure 1, the block LP indicated by a dotted line is a part configured in the light bench, where the LED is a light emitting diode that serves as a light source, and the PT is a light receiving element that converts the reflected light from the recording paper surface on which the barcode is printed into an electrical signal. , AMl is a DC amplifier that amplifies the electric signal from the light receiving element PT, and when the bar code shown by A in Fig. 3 is scanned with the light pen, an electric signal Sig shown by Sig in Fig. 3 is output from the light pen. Output. The current flowing through the light emitting diode LED is fixed by a resistor R, and is switched on and off by a transistor T.

Transistor T1 is controlled by a read control signal LON (see signal LOn in FIG. 3). When reading a barcode with the light pen mentioned above, the pen tip is brought into contact with the white part in front of the barcode, that is, the part A of the recording medium shown in Figure 4, and then the barcode is scanned and read. .

In this case, when the tip of the pen is away from the recording medium, the light receiving element PT does not substantially receive the reflected light from the surface of the recording medium due to the light emitted from the light emitting diode LED, so the output signal Sig is at a low level. . Then, with the tip of the pen in contact with the white part A of the recording medium,
The light receiving element PT receives the light reflected from the recording medium surface by the light emitted from the light emitting diode LED, and outputs an output signal Si.
g becomes high level. Therefore, it is possible to detect whether the pen tip has contacted the label surface based on the state of the output signal Sig. Output signal Si in FIG.
g is input to a DC amplifier AM2 as shown in FIG. 2, and the output of this DC amplifier AM2 is sent to a voltage comparator COP and a demodulation circuit M, respectively.

In this figure 2, 0SC is a pulse oscillator and the third
As shown by 0SC in the figure, a pulse with a constant pulse width TOn is generated at a constant period Tp, and normally (when the tip of the pen is away from the surface of the recording medium), this pulse is used to generate the read control signal LOn. The light emitting diode LED is pulse driven.

The period Tp of this pulse is determined from the movement of the human hand,
In other words, since the pen is scanned by a person, a certain amount of time is required from the time the pen comes into contact with the white part A of the recording medium until the pen starts scanning, and enough pulses are generated within this certain period of time. The cycle is set.

Experimentally, it is considered that the certain period of time is about 20 msec without any problem, and therefore, it is sufficient to set the period Tp to 10 msec. On the other hand, the pulse width TOn transistor T1 and the light receiving element PTl DC amplifier AM, . It can be determined by the response characteristics of AM2 and voltage comparator COP.
If this pulse width TOn is, for example, 0.2 msec, then
The current flowing through the light emitting diode LED is 0.2-XlOO
(%) Duty pulse current.

As mentioned above, when the tip of the light pen is in contact with the white area A on the surface of the recording medium, when a pulse signal is generated from the pulse oscillator 0SC, it is outputted as the read control signal LOn via the OR gate 0R, which causes the transistor T
, becomes 0N, the light emitting diode LED emits light, and the light receiving element PT receives the reflected light from the surface of the recording medium.As a result, the output signal Sig from the light pen becomes high level and the voltage is increased via the DC amplifier AM2. The signals are input to a comparator COP and a demodulation circuit M, respectively. The voltage comparator COP compares the input signal with a reference voltage r and derives a high level output signal when the input level becomes high (see COP in FIG. 3).

The output of this voltage comparator COP is sent to the edge detection circuit ED, which detects the rising and falling edges of the input signal and outputs an output signal χ shown by ED in FIG. The one-shot multi-pipe radar V that can be triggered is triggered by this. As shown by V in FIG. 3, the output time Tm of the one-shot multi-pipe radar is set based on the relationship between the length up to the first bar in the white area A of the recording medium and the scanning time of the pen, that is, the range of the time Tm. An edge detection output is output inside the sensor, and therefore, during scanning, the output is held at a high level by being triggered by the edge detection signal. Then, the output of the one-shot multi-pipe radar is output as a read control signal LOn through the OR gate 0R, thereby maintaining the transistor T1 in the ON state, and thereafter causing DC current to flow through the light emitting diode LED for demodulation.

After that, when the scanning of the bar code is finished and the tip of the light pen leaves the surface of the recording medium and the output period Tm of the multi-pipe radar V has passed, the transistor T1 again generates the read control signal LOn based on the pattern signal of the pulse oscillator 0SC. It is driven by LP in FIG. 3 indicates the state of the light pen; on the H side, the tip of the pen is in contact with the recording medium, and on the L side, it is separated from the recording medium. In this reading device, when the light pen is away from the recording medium, the light emitting diode LED is pulse-driven based on the pulse of the pulse oscillator 0SC, and when scanning a bar code, the tip of the light pen is moved to the starting position of the recording medium. (Part A) When Vc is brought into contact, the light emitting diode LED is automatically switched to DC drive by the operation of the one-shot multi-pipe radar, barcode scanning is performed by this DC drive, and this scanning is completed. When the tip of the light pen leaves the surface of the recording medium, the light emitting diode LED is again driven by pulse 1 based on the pulse oscillator 0SCifC. Pulse 1 from this DC, drive
Since a stop code is attached to the end of the bar code, switching to drive can also be made in response to detection of this stop code. When performing a reading operation with a light pen in this way, if you compare the time it takes to actually scan and read a barcode with the time the pen separates from the recording medium and does not read, This latter time is spent most of the time when reading is not performed, and power consumption during this time is extremely large.

Therefore, by driving the light source in pulses as described above during the time when reading is not actually being performed, unnecessary power consumption is eliminated, and most of the time during the reading operation is driven by pulses, and the light source is driven in pulses. The power consumption of the device can be significantly reduced, which means that even if the battery capacity is small, the device can withstand long-term use. In addition, since the light source is automatically switched from pulse drive to DC drive or from DC 1 drive to pulse drive, it does not place any burden on the operator, and there is no inconvenience caused by the operator forgetting to change the switch, ensuring power consumption savings. I can contribute. As described above, the present invention includes a light source that irradiates a recording medium, a light receiving means that receives reflected light from the recording medium irradiated by the light source, and a code for the recording medium based on an output signal of the light receiving means. Starting with an optical code reading device comprising means for reading, during the reading operation of said device,
Pulse 1 is applied to the light source in order to pulse drive the light source at a constant cycle.
A pulse oscillator for supplying a driving signal, and supply means for supplying a direct current and a driving signal to a light source whose drive is controlled based on an output signal from the light receiving means, and when the light source is pulsed by the oscillator, The light source is switched from pulse 1 drive to DC drive by operating the supply means in response to an output signal from the light receiver obtained by the light receiver receiving reflected light from the recording medium. Yes, the light source can be driven in pulses during most of the time when the code on the recording medium is not actually being read during the reading operation, which can greatly reduce power consumption in the light source and eliminate the need for large-capacity batteries. As a result, it is lightweight for this type of input device. In response to the demand for compactness, there are no power constraints like conventional models, so it is lightweight.
It has the feature of being able to be made compact.

[Brief explanation of drawings]

1 and 2 are circuit diagrams showing the configuration of the apparatus of the present invention, FIG. 3 is a timing chart related to barcode reading, and FIG. 4 is a diagram showing a recording medium on which a barcode is printed. LED: Light emitting diode, PT: Light receiving element, AMI and AM2: DC amplifier, T1: Transistor, M: Demodulation circuit, COP: Voltage comparator, 0SC: Pulse oscillator,
ED: Edge detection circuit, V: One-shot multi-pipulator, LOn: Reading control signal, Sig: Output signal from the light pen.

Claims (1)

[Claims] 1. An optical system consisting of a light beam that irradiates a recording medium, a light receiving means that receives the reflected light from the recording medium irradiated by the light source, and a means that reads the code of the recording medium based on the output signal of the light receiving means. In the code reading device, a pulse oscillator supplies a pulse drive signal to the light source in order to pulse drive the light source at a constant cycle during a reading operation of the device;
supply means for supplying a DC drive signal to a light source whose drive is controlled based on an output signal from the light receiving means, and when the light source is pulse-driven by the oscillator, the light receiving means receives reflected light from the recording medium. In response to an output signal from the light receiving means obtained by receiving light, the supply means is operated to switch the light source from pulse drive to DC drive, and pulse drive the light source until the recording medium is detected. An optical code reading device characterized in that a light source is driven by direct current through detection.