JPH0410964B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention uses a light source and two The present invention relates to an improvement of a position detection system constructed by combining light receiving elements of the above, and is used in the field of manufacturing technology industry for position detectors of this type.

(Prior art) Conventionally, as a position detection means for a strip-shaped object such as a running film or paper, the reflected light or transmitted light at the end of the strip is usually projected onto a light-receiving element, and an output voltage proportional to the amount of light received is used. A method for detecting the position of an object is known. However, according to this method, if the edge of the strip material is deformed into a wavy shape, it may become impossible to obtain a normal position signal, and the change in the amount of light at the edge of a transparent object is extremely small, making it difficult to obtain a position signal. The major drawback is that it cannot be used.

In order to eliminate the above-mentioned drawbacks, a photoelectric position detection method for linear marks using light receiving elements 1 and 2 as shown in FIG. 4 has been proposed. The light receiving elements 1 and 2 are a type of semiconductor such as a photodiode or a solar cell, and the amount of light received changes depending on the projection of the linear mark 3 by the light source 4. Naturally, a lens system may be used for this projection. Light receiving element 1
and the deviation d of the center of the linear mark from the center position of 2
Output voltage e ₁ of photodetector 1 and amplifier 5 for
The characteristics are shown in Fig. 5, upper part _e1 . Similarly, light receiving element 2
And the characteristics of the output voltage e ₂ of amplifier 6 are shown in the upper part of Figure 5.
Shown in e ₂ . The difference between the output voltages e ₁ and e ₂ is determined by the operational amplifier 7 to obtain the output e ₀ . The relationship of this output voltage e ₀ to the deviation is shown in the lower part of FIG. In this way, the position can be detected using the output voltage e ₀ of sign +- which is proportional to the direction of deviation +- from the center of the light-receiving element with respect to the center position of the linear mark.

However, according to this detection method, the detection signal remains within the range where the light-receiving element exists, and the linear mark deviation exceeds that range and exceeds d _n + or d _n - as shown in the lower part of FIG. Below this, the output voltage becomes zero, a position detection signal cannot be obtained, and the position cannot be distinguished from the center position.

(Problems to be Solved by the Invention) The present invention is capable of positioning the strip of material by always generating a position signal with continuous directionality, no matter how far the linear mark position on the strip of material is from the light-receiving element. The object of the present invention is to provide a linear mark position detection method that can detect a wide range of marks.

(Means for solving the problems) In order to solve the above-mentioned problems, the present invention has the following features:
In a position detection method in which the position of a linear mark is detected by projecting a light beam transmitted or reflected from a linear mark onto two photoelectric elements, the voltage of one of the two photoelectric elements becomes higher than the comparison voltage. The device is configured to output a continuous position signal by holding the difference signal between the two photoelectric elements while the sensor is moving.

Also, while the voltage of either of the two photoelectric elements is higher than the comparison voltage, a continuous position signal is output by holding the difference signal between the two photoelectric elements, and the two photoelectric elements When the signal decreases from the maximum value, the hold signal generation circuit holds the maximum voltage of the two photoelectric elements using the maximum value hold circuit using the negation signal of the comparator output, and this voltage is divided by the voltage divider. By using this as the comparison voltage of the comparator, the comparison signal can be automatically set.

Also, while the voltage of either of the two photoelectric elements is higher than the comparison voltage, by holding the difference signal between the two photoelectric elements, a continuous position signal is output, and the output of the comparator is By adding a delay circuit and using its output as the hold signal of the hold circuit, even if the relative position of the linear mark and the light receiving element changes, the operation delay is compensated for and a highly accurate position signal is output. It is composed of

Also, while the voltage of either of the two photoelectric elements is higher than the comparison voltage, a continuous position signal is output by holding the difference signal between the two photoelectric elements, and the two photoelectric elements The signals of these two photoelectric elements are input to two comparators, and when the signals of these two photoelectric elements become equal to or less than the comparison voltage at the same time,
By detecting it with a coincidence circuit connected to the comparator output and using it as a hold signal of the hold circuit, a continuous position signal is output even in the case of discontinuous linear marks.

(Function) The present invention obtains a signal proportional to the position from the difference signal of two light receiving elements, and by combining these signals, a linear mark is placed at a position far away from the light receiving element. Also, by obtaining constant and continuous position and direction signals, it is possible to obtain position signals of linear marks drawn on a wide range of strip material.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which 8 is a light source. Reference numeral 9 represents an image of a linear mark drawn on a strip of a moving body such as paper or film projected onto photoelectric elements 10 and 11 either directly or through a lens system. The outputs of the photoelectric elements 10 and 11 are outputted by an amplifier 12,
13 to produce output voltages e ₁ and e ₂ . These voltages e ₁ and e ₂ are subjected to the following calculation by the operational amplifier 14 to produce an output e _D. That is, e _D = e ₂ - _{e 1} The characteristics of the amplifier outputs e ₁ and e ₂ with respect to the deviation d between the center of the photoelectric elements 10 and 11 and the center of the linear mark are shown in FIG. 2A, and the calculation for the deviation d is Amplifier 14
The relationship between the output e and _D is shown in Figure 2B.

Next, the maximum value of the outputs e ₁ and e ₂ of amplifiers 12 and 13
e _M , that is, ---- on FIG. 2A is created by the maximum value circuit 15 in FIG. This output e _M and
A comparator 16 compares it with the comparison voltage e _C shown in FIG. 2A.

Here, e _C =e _M -Δe _C (Δe _C <<e _M ) This output signal E _H is shown in FIG. 2C. this signal
E _H becomes a hold signal of the hold circuit 17 that holds the output signal e _D of the operational amplifier 14 .

Next, the operation shown in FIG. 1 will be explained. now,
In FIG. 2A, it is assumed that the center position d of the projected image 9 of the linear mark satisfies d ₂ ≦d≦d ₁ . In this case, E _H =0 from C in the figure, and the hold circuit 17 outputs the input signal e _D as it is without holding it. That is, e _d = e _D. in this case,
e _d becomes the - characteristic in FIG. 2B.

Next, the case of d>d ₁ will be explained. _{In this} position range, E _H = ₁ as shown in FIG. As shown in Figure 2 B-
It becomes a constant output value. Further, in the case of d<d ₂ , the output e _D becomes a constant negative output value of - shown in FIG. 2B in the same manner as above.

As described above, the value of deviation (difference) d is -∞<
For d<+∞, the output voltage of the hold circuit 17
e _D becomes --- as shown in Figure 2B. As a result, no matter how large the deviation is compared to the dimensions of the light receiving element, continuous position detection signals in the positive and negative directions can be obtained, and the operating range can be expanded to any extent.

Next, FIG. 3 will be explained. Figure 3 is the first
The difference from the figure is that a maximum value hold circuit 18, a hold signal generation circuit 18', a voltage divider 19, a delay circuit 20, comparators 21 and 22, and a coincidence circuit 23 are added.

The maximum value hold circuit 18 holds and outputs the maximum value of the output signal e ₁ or e ₂ of the amplifier 12 or 13, ie, the hold signal of the hold signal generating circuit 18' shown in FIG. 2A. If this output is e _n , the output of the voltage divider 19 is
e _C becomes the following formula.

e _C = ke _n = e _n -△e _C (k = voltage division ratio, 0 < k < 1) This signal e _C becomes the comparison voltage of the comparator 16, and is the same as the hold signal E _H shown in Figure 2 C. This is the signal.

These maximum value hold circuit 18 and voltage divider 1
By adding 9, the illuminance of the light source 8 or the light receiving elements 10, 11 and the amplifiers 12, 13 can be changed.
This has the advantage that even if the characteristics of EC deteriorate, the comparison voltage e _C can be automatically set according to the change.

Next, the delay circuit 20 shown in FIG. 3 will be explained. The input/output signal eD of the hold circuit 17 in the same figure
There is a certain value of response delay between e and _d . Therefore, when the input signal is in an increasing state, for example, the output signal is delayed in response time, so when a hold signal is applied, the input value is held, causing an error in the output signal. Therefore, a delay circuit 20 is added in order to delay the hold point by the response time and to operate the hold circuit 17 when the output signal _ed has established an accurate value.

This has the effect that even if there is an operation delay in the hold circuit 17, this can be compensated for and an output signal _ed with high temporal accuracy can be obtained.

Note that the comparators 21, 22 and matching circuit 23 in FIG. 3 will be explained next. If the linear mark 9 is not continuous but an intermittent mark, a constant position signal
e _d will no longer be obtained. Therefore, when this mark 9 becomes discontinuous and the outputs e ₁ and e ₂ of the amplifiers 12 and 13 become lower than the comparison level e _C , outputs are generated in the comparators 21 and 22, indicating that these outputs have occurred at the same time. It is detected by the coincidence circuit 23 and used as a hold signal for the hold circuit 17. Since this holding speed is high, the position signal e _D at the time of continuous marks is held, and e _d = e _D. Even when the linear marks are discontinuous, a continuous and stable constant position signal e _d is obtained. There is an effect that can be obtained.

As described above, the detection method according to the present invention can be effectively applied to continuous or discontinuous marks of various widths drawn on all strip materials.

(Effects of the Invention) As detailed above, according to the present invention, the center positions of linear marks of various widths drawn on a strip material can be continuously detected over an extremely wide range with good linearity. This has the effect of providing this type of position detection method that is efficient and highly accurate. In addition, even if the edge of a moving object is suddenly deformed into a wave-like shape, its position and direction can be detected reliably.Furthermore, the position can be detected even if the edge of a moving object is stationary or moving. be. Further, even if the light source changes, the detection level of the linear portion of the characteristic can be automatically adjusted, and the delay in operation of the hold circuit can be compensated for. In addition, even if the linear marks are drawn intermittently rather than continuously, the mark positions in the continuous state are memorized and continue to be output, so continuous position signals can be obtained, which is extremely excellent in detection and practical use. It has a certain effect.

[Brief explanation of drawings]

1 and 2 show embodiments of the present invention, FIG. 1 is a configuration diagram of the present invention, and FIG. 2 is an explanatory diagram showing its characteristics. A shows the photoelectric element output voltage characteristics;
B indicates the output voltage difference characteristic, and C indicates the left/right position determination logic signal. FIG. 3 is a block diagram showing another embodiment of the present invention. FIG. 4 is a block diagram of a conventional linear mark photoelectric deflection detector, and FIG. 5 is a schematic diagram showing its deflection-electrical characteristics. 1, 2... Light receiving element, 3... Linear mark, 4...
...Light source, 5, 6...Amplifier, 7...Operation amplifier,
8... Light source, 9... Linear mark, 10, 11...
Light receiving element, 12, 13...Amplifier, 14...Operation amplifier, 15...Maximum value circuit, 16...Comparator,
17...Hold circuit, 18...Maximum value hold circuit, 18'...Hold signal generation circuit, 19...
... Voltage divider, 20... Delay circuit, 21, 22... Comparator, 23... Matching circuit.

Claims (1)

[Claims] 1. A light beam transmitted or reflected by a linear mark,
In a position detection method that detects the position of a linear mark by projecting it onto two photoelectric elements, while the voltage of one of the two photoelectric elements is higher than the comparison voltage, the difference between the two photoelectric elements is detected. A wide range position detection method for linear marks, which is characterized by outputting continuous position signals by holding the signal. 2. The light beam transmitted or reflected by the linear mark,
In a position detection method that detects the position of a linear mark by projecting it onto two photoelectric elements, while the voltage of one of the two photoelectric elements is higher than the comparison voltage, the difference between the two photoelectric elements is detected. By holding the signal, a continuous position signal is output, and when the signals of the two photoelectric elements decrease below the maximum value, the hold signal generating circuit 18' uses the negation signal of the comparator output to output the two photoelectric elements. The maximum voltage of the photoelectric element is held by the maximum value hold circuit 18, and this voltage is divided by the voltage divider 19 to obtain the comparison voltage of the comparator 16.
A wide range position detection method for linear marks, characterized in that a comparison signal e _c can be automatically set by setting e _c . 3. The light beam transmitted or reflected by the linear mark,
In a position detection method that detects the position of a linear mark by projecting it onto two photoelectric elements, while the voltage of one of the two photoelectric elements is higher than the comparison voltage, the difference between the two photoelectric elements is detected. By holding the signal, a continuous position signal is output, and by adding a delay circuit 20 to the output of the comparator 16 and using the output as the hold signal of the hold circuit 17, the relative position between the linear mark and the light receiving element is determined. A wide range position detection method for linear marks, which is characterized by compensating for operational delays and outputting highly accurate position signals even when the position changes. 4 The light beam transmitted or reflected by the linear mark,
In a position detection method that detects the position of a linear mark by projecting it onto two photoelectric elements, while the voltage of one of the two photoelectric elements is higher than the comparison voltage, the difference between the two photoelectric elements is detected. By holding the signal, a continuous position signal is output, and the signals of the two photoelectric elements are transmitted to two comparators 21 and 2, respectively.
2 and detects by the coincidence circuit 23 connected to the comparator output that the signals of these two photoelectric elements become equal to or less than the comparison voltage at the same time, and uses this as a hold signal for the hold circuit 17. A wide range position detection method for linear marks characterized by being able to output continuous position signals even in the case of discontinuous linear marks.