JPH0896068A - Information reader - Google Patents

Abstract

PURPOSE: To automatically adjust the light receiving amount of a photodetector so as to be an optimum setting level by changing and adjusting the pulse width of a control signal for turning on a light source when read information data is a reading defect. CONSTITUTION: After illuminated light is made to exit with a light intensity which should be proper under the circumstance of a setting condition, etc., from a light projecting part 1 and is reflected on a bar code symbol 101, the light is made incident on a photodetector 2 via an image formation lens 103, etc. In this case, when the lowering of reflection light quantity in the photodetector 2 is confirmed/discriminated by a CPU 5 based on the reading signal to be outputted from a CCD image sensor 21, a proper control signal in which a pulse width to increase lighting time to supplement the lowering of the light receiving amount is longer than a usual pulse width, is outputted from the CPU 5. As a result, because a transistor Tr performs a switching operation by the control signal by the pulse width time and performs power feeding to each power source 11 by the switching time, the lighting time corresponding to the power feeding is increased and optimum light receiving amount can be secured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention projects and irradiates light from a plurality of light sources provided in a light projecting section onto a recording sheet, and the reflected light reflected and returned by the recording sheet is received by a light receiving section. The present invention relates to an information reading device that reads information written on a record slip.

[0002]

2. Description of the Related Art For example, various bar code readers for reading bar codes described in bar code symbols have been proposed and developed. As such a bar code reader, for example, the handy type reader shown in FIG. 3 is known. That is, the barcode reader emits reading light from a light projecting unit 100 having a plurality of light sources to a barcode symbol 101, and reflects light reflected by the barcode symbol 101 and returning to the mirror 102 and the imaging lens 103. Charge coupled image light receiving element 104 (CCD image sensor)
It is designed to receive light.

By the way, such a bar code reader is normally used, for example, when a predetermined amount of illumination light is emitted from the light projecting section for a predetermined bar code symbol to be read, the reflected light amount (reflectance), Alternatively, the amount of light received by the light receiving unit is determined in advance theoretically or from experimental data at the time of trial production, and the optimal luminous intensity (projected amount) of the light source is initialized by this.

[0004]

However, in such a bar code reader, the reflectance of the illumination light is slightly different depending on the type of the bar code symbol in which the bar code is described, and a sufficient amount of reflected light is obtained. In some cases, an accurate information reading operation cannot be obtained without obtaining the information. In addition, the amount of incident light entering the light receiving part may change slightly depending on the environment of the place to be read and the reading time, and also depending on the length of the distance between the barcode reader and the light emitting part or the light receiving part. There is a demand for fine adjustment of the amount of light projected.

In view of the above-mentioned circumstances, therefore, the present invention, even if the brightness of the surroundings changes according to the reflectance fluctuation which varies depending on each recording sheet, the environment of the reading place, the time, etc.
It is an object of the present invention to provide an information reading device capable of adjusting and controlling the light projection amount so that a reading state with an optimum received light amount can always be ensured.

[0006]

That is, according to the present invention, light from a plurality of light sources provided in a light projecting section is projected / irradiated onto a recording sheet, and reflected light reflected by the recording sheet and returned is received by the light receiving section. In the information reading device that receives the light by the device and reads the information written on the recording sheet, when the information data read from the reflected light received by the light receiving unit is a reading failure, the pulse width of the control signal for lighting the light source is changed and adjusted. However, it is provided with a control unit for controlling and adjusting so that the light receiving unit receives the light with the optimum amount of received light.

[0007]

According to the present invention, the control section confirms and detects the level of the amount of light received at that time from the read signal when the reflected light emitted from the light projecting section and reflected by the recording sheet is received by the light receiving section. Then, when the light receiving state is below a predetermined setting level or is significantly higher than the predetermined setting level, the control unit appropriately controls the light source of the light projecting unit, and the light receiving amount at the light receiving unit becomes the optimum setting level. Can be adjusted automatically.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the figure, the same parts as those of the prior art described above are designated by the same reference numerals to avoid redundant description. FIG. 1 shows an information reading device according to the present invention. This information reading device includes an amplifier 3, a signal processing unit 4, and a CPU (control unit) in addition to a light projecting unit 1 and a light receiving unit 2. 5 and, in this embodiment, a handy type which is held by hand is applied.

The light projecting section 1 is provided with a plurality of lamps 11 as a light source, and the lamps 11 are appropriately controlled by the control of the CPU 5.
The lighting time of is controlled. In addition, in order to realize uniform floodlighting of the bar code symbol 101 in an optimal state when the floodlighting unit 1 is used in a normal state, each of the floodlighting units 1 is controlled unless otherwise controlled by the CPU 5. The luminous intensity (light projection amount) of the lamp 11 is initialized to an appropriate value.

The light receiving section 2 is a CCD similar to the conventional one.
A (charge coupled device) 21 is used as an image sensor (hereinafter referred to as CCD image sensor 21) and is connected to the amplifier 3.

The amplifier 3 is configured to increase / enlarge the S / N ratio of the read signal output from the CCD image sensor 21 of the light receiving section 2 to identify / remove noise contained in the read signal. The input is connected to the output of the CCD 21.

The signal processing unit 4 is composed of a binarization circuit for converting an analog signal output from the amplifier 3 into a digital signal. The input is connected to the output of the amplifier 3 and the output is connected to the CPU 5 and It is connected to each input of a signal reading circuit (not shown).

In FIG. 2, when the signal value level of the read signal is much lower than the preset level S (in the case of A) and vice versa, in FIG. The control signal is output to each light source 11 of the light projecting unit 1 so as to detect this and return it to the set value level. The input is connected to the output of the signal processing unit 4 and the output is provided. Is connected to the light projecting unit 1.

Therefore, according to this embodiment, for example, the illumination light is emitted from the light projecting section 1 at an intensity which should be appropriate under the environment of the set conditions, and the bar code symbol 101 is emitted.
After being reflected by the light receiving unit 2 through the imaging lens 103 and the like,
Incident on. As a result, the read signal output from the CCD image sensor 21 of the light receiving unit 2 is output to the signal reading circuit via the amplifier 3 and the signal processing unit 4 and also to the CPU 5.

Therefore, the CPU 5 which has input the signal,
Whether or not the input signal is at a level at which the information recorded on the barcode symbol 101 can be accurately read is instantly identified, and if the reading operation becomes inaccurate or reading failure may occur. If it is detected / determined that there is a large decrease or a large increase in the projected light amount, a control signal for immediately returning it to the optimum level is output to each light source 1 of the light projecting unit 1.
It outputs to 1. For example, in FIG. 2, when the entire bar code symbol 101 is fading or the like and the printed portion is thin (the amount of received light is also reduced), the amount of reflected light reflected back is also reduced. Is brought.

Therefore, the decrease in the amount of reflected light at the light receiving portion 2 is reduced to C
When the CPU 5 confirms / identifies based on the read signal output from the CD image sensor 21, the CPU 5 outputs an appropriate control signal having a longer pulse width for increasing the lighting time in order to supplement the decrease in the received light amount. . As a result, the transistor Tr performs a switching operation for the pulse width time according to the control signal, and power is supplied to each light source 11 for the switching time. Therefore, the lighting time is increased by that amount, and the optimum light receiving amount can be secured. is there. Further, since feedback control is performed in the information reading apparatus of this embodiment, if the set favorable light receiving amount cannot be secured even if the control is further performed by the control signal, the CPU 5 controls again. The signal is output to adjust the lighting time of the light projecting unit 1 again.

In this embodiment, the bar code symbol is used as the recording form, but the recording form is not limited to this. For example, a stamped recording form made of metal having irregularities (the same applicant can Of course, it can be applied to Japanese Patent Application Laid-Open No. 2-71142).

[0018]

As described above, according to the present invention, the CPU detects the light receiving state from the read signal when the reflected light emitted from the light projecting portion and reflected by the recording sheet is received by the light receiving portion. When it is confirmed and detected, and when it is determined that the light receiving state is not a predetermined uniform state, each light source of the light projecting unit is individually controlled by the control signal from the CPU to increase or decrease the light projecting time. Since it is possible to equalize the amount of light received by the portions, it is possible to effectively prevent a reading failure due to the uneven amount of light received.

Further, according to the present invention, when the amount of light received by the light receiving unit is generally reduced, the CP
Since the U can appropriately output a control signal to each light source of the light projecting section to adjust and control the optimum lighting time, there is also an effect that the recording sheet can be always read with the highest sensitivity.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a recording sheet reader according to the present invention.

FIG. 2 is a circuit diagram showing a light projecting section of the device.

FIG. 3 is a schematic configuration diagram showing a conventional example.

[Explanation of symbols]

 1 Light emitting unit 2 Light receiving unit 3 Amplifier unit 4 Signal processing unit 5 CPU

Claims (1)

[Claims] 1. A recording sheet is projected and irradiated with light from a plurality of light sources provided in a light projecting section, and reflected light reflected by the recording sheet and received back is received by a light receiving section and described on the recording sheet. In the information reading device for reading information, when the information data read from the reflected light received by the light receiving unit is a reading failure, the pulse width of the control signal for lighting the light source is changed and adjusted, and the best light receiving amount for the light receiving unit is obtained. An information reading device comprising a control unit that controls and adjusts so that light is incident on the light source.