JPH0773262A - Form mark detecting system - Google Patents

Abstract

PURPOSE:To improve the recognizing rate for detection of a form mark and then to improve the mark detecting reliability by automatically control and correct the detecting sensitivity against the fluctuation of the power voltage, the fluctuation of a form medium, the fluctuation of the detecting environment caused by the processing. CONSTITUTION:The stable reference voltage Vo is generated and supplied to the photosensors 13A and 13B against the fluctuation of the power voltage VB. Meanwhile the drive information S1 and S2 are supplied to the bias control units 14-17 from a memory 11 via a control part 10. The bias currents of the photosensors 13A and 13B are automatically controlled at each optimum level in accordance with the attribute of a form bearing a mark. Then the voltage detecting circuits 18 and 19 detect the corresponding bias voltage and digitize these bias voltages to supply them to the part 10. Based on these digitized information, the optimum drive information is selected and supplied to the units 14-17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper mark detection system, and more particularly, to the beginning or end of a paper for a medium (paper) having a page break mark on a form such as a POS device or a portable device. A technique for detecting.

[0002]

2. Description of the Related Art In recent years, POS equipment, portable equipment and the like are required to have high performance and high quality, and highly reliable detection by a plurality of sensors is required. On the other hand, however, there is an increasing demand for reduction in size and weight, and in order to cope with this, a method of detecting a plurality of states using one sensor has been proposed.

However, as will be described below, the paper medium itself used is also diversified, and it has become difficult to perform mark detection over a wide range according to the diversification with high reliability. That is, the paper medium includes thin media, thick media, glossy media, non-glossy media,
Various media such as pre-printed media, plain media, white media, color media, media with marks on the printed surface, media with marks on the back side, media with binding holes, media without binding holes, etc. are included. For example, when a transmissive sensor is used, the detection level changes because the thin medium has high transmissivity and the thick medium has low transmissivity. Therefore, when the user arbitrarily selects the medium, the detection level varies, and there is the inconvenience that the current tone or the like is required. Further, when the reflection type sensor is used, the same problem occurs because the amount of reflected light is different between the medium having gloss and the medium having no gloss. Furthermore, for media with and without binding holes, if the holes overlap the mark detection area, if the holes are disengaged, if there is a hole in the white background, if there is a hole on the mark, etc. Therefore, the mark detection position is displaced. There is also a problem that erroneous detection is performed when dust adheres to the medium surface.
Under such circumstances, there is a demand for a stable detection method for a plurality of media.

Conventionally, various paper mark detection methods have been proposed for the above-mentioned changes in the medium. An example is shown in FIG. The circuit shown in the figure shows the configuration of a photo sensor block in a printer, for example, to which the paper mark detection method is applied. This photo sensor block is
Photodiode D1 and bias variable resistor R1 connected in series between power supply line VB and ground, and phototransistor TR1 and bias variable resistor R connected in series between power supply line VB and ground.
2 and. Although not shown, a sheet having a mark to be detected is interposed between the photodiode D1 and the phototransistor TR1. The presence / absence, position, etc. of this paper mark are indicated by the detection voltage output from the emitter of the phototransistor TR1.

According to the configuration of FIG. 2, the light quantity (that is, the light emission characteristic) of the photodiode D1 can be changed by adjusting the variable resistor R1, and the variable resistor R2 can be changed.
Can be adjusted to change the amplification factor (that is, sensitivity characteristic) of the phototransistor TR1. Therefore,
The amount of reflected light or transmitted light from the paper medium can be adjusted, and the optimum detection voltage level can be set according to the attribute of the paper medium.

FIG. 3 shows another example of the paper mark detection method. In this conventional example, instead of the variable resistors R1, R2 used in the manner of FIG. 2, respectively the photo diode D2 and the phototransistor TR2 a plurality of resistors R ₁₁ to R _1n and R ₂₁ to R _2m They are installed in parallel,
A gate circuit 22 for selectively selecting a bias resistor for the photodiode D2 and the phototransistor TR2, and a means (CP) for controlling the gate circuit.
U) 21.

According to the configuration shown in FIG. 3, the biasing resistors R _{11 to} R _1n and the phototransistor T on the side of the photodiode D2 are operated by the cooperation of the CPU 21 and the gate circuit 22.
The bias resistor R ₂₁ to R _2m of R2 side can be variably adjusted. That is, it is possible to programmably change the light amount of the photodiode D2 and the amplification factor of the phototransistor TR2.

FIG. 4 shows still another example of the paper mark detection method. In this conventional example, the variable resistors R1 and R2 in the system of FIG. 2 are replaced with fixed resistors R3 and R4, and further, a comparator 25 for making a comparison judgment of the detection voltage and a reference voltage for giving the comparator. The D / A converter (DAC) 24 and the CPU 23 that controls the D / A converter.

According to the configuration of FIG. 4, the CPU 23 outputs D /
By supplying an appropriate control signal to the A converter 24, the input reference voltage of the comparator 25 can be programmable. That is, it is possible to programmably change the slice level for detecting the voltage indicating the presence / absence, the position, etc. of the paper mark to be detected.

[0010]

In the conventional method shown in FIG. 2, in order to change the detection sensitivity of the photosensor (that is, the light amount of the photodiode D1 and the amplification factor of the phototransistor TR1), the variable resistor R1, R2 needs to be adjusted appropriately. That is, in order to adjust the detection sensitivity of the photosensor, there is a problem that it is necessary to perform optimum adjustment according to the attribute of the paper medium, that is, uniform adjustment for each sensor.

Further, when the voltage of the power supply line VB for supplying power to the photo sensor fluctuates, the detection sensitivity of the photo sensor also fluctuates, and accordingly, appropriate correction is required. In this case, too, there is still the complexity that the optimum adjustment must be performed for each sensor. In the conventional method shown in FIG. 3, the CPU 21 and the gate circuit 22 are used to adjust the bias resistors (R _{11 to} R _1n and R _{21 to} R _2m ) to the optimum values to detect the detection sensitivity of the photosensor. Since the light quantity of the diode D2 and the amplification factor of the phototransistor TR2 are programmable,
Although it is more advantageous than the method shown in FIG. 2 in terms of adjustment work, since a plurality of resistors are provided as bias resistors, the circuit configuration of the sensor part becomes relatively large and complicated. There is. Further, similar to the method of FIG. 2, when the power supply voltage fluctuates, a new adjustment work is required to correct the fluctuation of the detection sensitivity of the photosensor caused by the fluctuation.

In the conventional system shown in FIG. 4, the CPU 23
Since the input reference voltage of the comparator 25 is variably set by using the D / A converter 24 and the D / A converter 24, the slice level for detection can be changed in a programmable manner, which is advantageous in the adjustment work as compared with the method of FIG. However, it does not provide an effective method for the fluctuation of the power supply voltage as in the method shown in FIGS.

The present invention was created in view of the above problems in the prior art, and automatically adjusts detection sensitivity and corrects it for fluctuations in power supply voltage, fluctuations in paper medium, fluctuations in detection environment due to processing, and the like. It is an object of the present invention to provide a paper mark detection method capable of improving the recognition rate of the mark detection and thus improving the detection reliability.

[0014]

In order to solve the above-mentioned problems, a paper mark detecting method according to the present invention includes a reference voltage generating circuit for generating a stable reference voltage against fluctuations in power supply voltage, and the stable reference voltage. And a photosensor unit having a photodiode and a phototransistor, which are arranged with a sheet having a mark interposed therebetween, a control unit for performing control relating to the sheet mark detection, and a control unit for controlling the sheet mark. Memory means connected to store drive information for driving the photo sensor means, range change information, detection information based on paper mark detection, etc. in digital quantity; and memory means for supplying the information through the control section. Bias adjustment for adjusting each bias current of the photodiode and phototransistor based on the drive information. And a voltage detection circuit for detecting the bias voltage of each of the photodiode and the phototransistor based on the bias current adjustment by the bias adjustment unit, digitizing the bias voltage, and supplying the digitized voltage to the control unit. It is characterized in that optimum drive information according to the attribute of the paper is selected from the drive information based on the bias voltage and is supplied to the bias adjustment unit.

[0015]

According to the above structure, the reference voltage generating circuit generates the reference voltage which is always stable against the fluctuation of the power supply voltage and is supplied to the photodiode and the phototransistor of the photosensor means, respectively. On the other hand, by supplying drive information from the memory means to the bias adjustment unit via the control unit, the bias currents of the photodiode and the phototransistor are automatically adjusted, and the bias current adjustment is performed in the voltage detection circuit. The respective bias voltages of the photodiode and the phototransistor based on it are detected and digitized respectively.
Then, the control unit selects the optimum drive information according to the attribute of the paper medium from the drive information based on the digitized bias voltage, and supplies it to the bias adjustment unit.

As described above, the bias adjusting unit, the voltage detecting circuit, and the control section cooperate to automatically set the bias current (voltage) of each of the photodiode and the phototransistor to an optimum value according to the attribute of the paper medium. Can be adjusted. Therefore, even if there is a change in the sheet medium, a change in the detection environment according to processing, etc., the detection sensitivity of the photo sensor means can be automatically adjusted and corrected, and the recognition rate of mark detection is improved. As a result, detection reliability can be improved.

Further, even when the power supply voltage changes, the reference voltage generating circuit can prevent the change in the detection sensitivity due to the change in the power supply voltage, which has been found in the conventional type, and the complicated adjustment therefor. No work required. For details of other structural features and operations of the present invention,
The embodiments will be described with reference to the accompanying drawings.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a main configuration of a printer to which a paper mark detection system according to the present invention is applied. In the figure, 10 is a microcomputer for controlling the paper mark detection of the present embodiment, 11 is connected to the microcomputer 10, and drive information, range change information, and paper mark detection necessary for paper mark detection processing. An external memory for storing information and the like in a digital amount, 12 is a reference voltage generating circuit for generating a stable reference voltage V _O with respect to a voltage fluctuation of the power supply line (VB), and 13 is supplied with the reference voltage V _O , respectively. Photodiodes (PD) 13A arranged with each other with a sheet having a mark interposed therebetween
And a photo sensor block having a phototransistor (PTR) 13B, and 14 is driving information (first drive information supplied from the external memory 11 via the microcomputer 10).
A bias adjustment circuit for PD that adjusts the bias current of the photodiode 13A based on the adjustment signal S1)
Is also the external memory 11 to the microcomputer 10
Bias adjustment circuit for PTR that adjusts the bias current of the phototransistor 13B based on the drive information (second adjustment signal S2) supplied via the first bias 16 output from the bias adjustment circuit 14 for PD. A constant current bias circuit that performs constant current control of the photodiode 13A based on the adjustment signal S3, and 17 is predetermined by the detection current of the phototransistor 13B based on the second bias adjustment signal S4 output from the PTR bias adjustment circuit 15. A load circuit 18 for generating a voltage (that is, for adjusting the sensitivity of the phototransistor 13B) detects the bias voltage (S5) of the photodiode 13A based on the bias current adjustment by the constant current bias circuit 16 and digitizes it (S7). A voltage detection circuit for supplying to the microcomputer 10, 19 detects a bias voltage (S6) of the phototransistor 13B based on the bias current adjustment by the load circuit 17, digitized (S8) and indicates the voltage detection circuit for supplying to the microcomputer 10.

Bias adjusting circuit 14 for PD and PTR
The bias adjusting circuit 15 converts the first and second adjustment signals S1 and S2 (digital amount drive information) into analog information, and generates first and second bias adjustment signals S3 and S4, respectively. It has a D / A converter (DAC). Further, the voltage detection circuit 18 compares the bias voltage detection signal S5 of the photodiode 13A based on the bias current adjustment by the constant current bias circuit 16 with the threshold adjustment signal S9 supplied from the microcomputer 10 to make digital information S7. It has an A / D conversion unit (ADC) for converting to. Microcomputer 10
Detects and adjusts the light emission characteristic of the photodiode 13A based on the converted digital information.

On the other hand, the voltage detection circuit 19 includes the load circuit 17
Phototransistor 1 based on bias current adjustment by
3B bias voltage detection signal S6 is set to threshold adjustment signal S
A / D for comparing and judging with 9 and converting to digital information S8
It has a converter (ADC). The microcomputer 10 detects and adjusts the sensitivity characteristic of the phototransistor 13B based on the converted digital information.

In the above-mentioned structure, the microcomputer 10 receives the adjustment command and the like from the main body of the printer device (not shown), and in response thereto, reads the drive information from the external memory 11 and supplies it to the bias adjustment circuits 14 and 15. The bias currents of the photodiode 13A and the phototransistor 13B are adjusted by the constant current bias circuit 16 and the load circuit 17, respectively, and the fluctuation rate of the detection voltage output through the voltage detection circuits 18 and 19 is calculated to calculate Existence (presence / absence) is judged for the first time. When it is determined that there is a sheet, the stepping motor is driven to feed the sheet, and the primary mark detection adjustment is performed based on the variation rate of the detected voltage in the state of being applied to the mark.

Next, the microcomputer 10 adjusts the biases of the photodiode 13A and the phototransistor 13B in the detected mark portion,
The ratio of the amount of emitted light and the amount of received light is determined, and the maximum value, the minimum value, the average value, etc. of the ratio of the amount of emitted light and the amount of received light are calculated. Further, the microcomputer 10 biases the threshold voltage of each ADC in the voltage detection circuits 18 and 19 based on the difference between the calculated minimum value of the ratio of the amount of emitted light and the amount of received light and the level when there is no paper. The output of each DAC in the adjustment circuits 14 and 15 is automatically corrected to optimize the detection range.

The detection information, the range change information, etc. are stored in the external memory 11 and are retained even when the power (VB) is off. Then, it is stored and held until it is updated again, or the above-mentioned automatic correction is performed at the same time when the power is turned on. If a round hole is made in the mark portion of the paper, for example, a light reflection plate is provided at a predetermined position behind the hole (that is, the back surface of the paper on which the paper is traveling) to correspond to an intermediate level of the normal detection level. The automatic correction is performed by detecting the hole portion with the detection voltage. If the size of the hole is smaller than the size of the mark portion, automatic correction is performed according to the detection position.

As described above, according to the detection method of this embodiment,
Compared with the conventional method (see FIGS. 2 to 4), the light amount of the photodiode 13A and the amplification factor (sensitivity) of the phototransistor 13B with respect to reflected light or transmitted light can be automatically set for each paper medium. , Threshold adjustment signal S9
By automatically determining the transmittance or reflectance of the paper medium to be detected by using the result and holding the result in the external memory 11,
The detection sensitivity can be automatically adjusted.

It is also possible to adjust the amplification factor by the difference between the black level and the white level. Furthermore, by determining the level of transmittance or reflectance for each paper medium, it is possible to automatically recognize the paper mark when the paper medium is changed.
By analyzing dust, holes, marks, and other printing on the medium, the recognition rate of mark detection can be increased. This contributes to improvement in detection reliability.

Further, even if the power supply voltage changes, the reference voltage generating circuit 12 can eliminate the inconvenience (the change in the detection sensitivity due to the change in the power supply voltage) which has been found in the conventional type. Therefore, a complicated adjustment work for correction is unnecessary.

[0027]

As described above, according to the present invention, a stable voltage that is not affected by fluctuations in the power supply voltage is supplied to the photosensor, and the bias amount of the photosensor is optimized according to the attributes of the paper medium. By automatically adjusting to the value,
Even if there is a change in the power supply voltage, a change in the paper medium, a change in the detection environment due to processing, etc., the detection sensitivity of the photosensor can be automatically adjusted and corrected. This contributes to an improvement in the recognition rate of mark detection, and in turn to an improvement in detection reliability.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main configuration of a printer device to which a paper mark detection method according to the present invention is applied.

FIG. 2 is a circuit configuration diagram for explaining an example of a paper mark detection method in the related art.

FIG. 3 is a circuit configuration diagram for explaining another example of the paper mark detection method in the related art.

FIG. 4 is a circuit configuration diagram for explaining still another example of the paper mark detection method in the related art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Control part (microcomputer) 11 ... Memory means (external memory) 12 ... Reference voltage generation circuit 13 ... Photosensor means (block) 13A ... Photodiode (PD) 13B ... Phototransistor (PTR) 14 ... 1st bias Adjusting circuit (bias adjusting circuit for PD) 15 ... Second bias adjusting circuit (bias adjusting circuit for PTR) 16 ... Constant current bias circuit 17 ... Load circuit 18, 19 ... Voltage detection circuit S1, S2 ... Driving for bias adjustment Information S3, S4 ... PD and PTR bias adjustment signals S5, S6 ... Bias voltage (detection signal) S7, S8 ... Digitized bias voltage (detection signal) S9 ... (for bias voltage comparison judgment) threshold value Adjustment signal VB ... Power supply voltage V _O ... Stable reference voltage

Claims (5)

[Claims] 1. A reference voltage generation circuit (12) for generating a stable reference voltage (V _O ) against fluctuations in a power supply voltage (VB).
And, while receiving the supply of the stable reference voltage respectively,
A photosensor means (13) having a photodiode (13A) and a phototransistor (13B) which are arranged with a sheet having a mark interposed therebetween, and a control section (10) for performing control relating to sheet mark detection. Memory means (11) connected to the control unit for storing drive information for driving the photo sensor means, range change information, detection information based on paper mark detection, etc. in a digital amount; A bias adjusting unit (14 to 17) for adjusting each bias current of the photodiode and the phototransistor based on the drive information (S1, S2) supplied through the control unit, and a bias current by the bias adjusting unit. Each bias voltage of the photodiode and phototransistor based on the adjustment ( S5, S6) are detected, each is digitized and supplied to the control section (18,
19), and selecting optimum drive information according to the attribute of the sheet of paper from the drive information based on the digitized bias voltage (S7, S8) and supplying it to the bias adjustment unit. Paper mark detection method characterized by. 2. The bias adjustment unit includes a first bias adjustment signal (S3) for the photodiode and a second bias transistor for the phototransistor based on the drive information.
First and second bias adjustment circuits (14, 15) for respectively generating the bias adjustment signal (S4), and a constant current bias circuit for performing constant current control of the photodiode based on the first bias adjustment signal. The sheet mark according to claim 1, further comprising: (16); and a load circuit (17) that generates a predetermined voltage by a detection current of the phototransistor based on the second bias adjustment signal. Detection method. 3. The first and second bias adjustment circuits,
3. The paper mark detection method according to claim 2, further comprising a D / A converter that converts the digital amount of drive information into analog information and generates the first and second bias adjustment signals, respectively. 4. The voltage detection circuit compares the bias voltage detection signal of the photodiode based on the bias current adjustment by the constant current bias circuit with a threshold adjustment signal (S9) supplied from the controller. 3. The paper mark detection method according to claim 2, further comprising: an A / D conversion unit for converting into digital information, and detecting and adjusting a light emission characteristic of the photodiode based on the converted digital information. . 5. The voltage detection circuit compares the bias voltage detection signal of the phototransistor based on the bias current adjustment by the load circuit with a threshold adjustment signal (S9) supplied from the control unit to perform digital determination. 3. The paper mark detection method according to claim 2, further comprising an A / D conversion unit for converting the information into information, and detecting and adjusting the sensitivity characteristic of the phototransistor based on the converted digital information.