JPS6252402A - System for detecting wide-range position of linear mark - Google Patents

Abstract

PURPOSE:To make it possible to always obtain a continuous position detection signal even if a linear mark is separated by any distance from a light receiving element, in an apparatus for detecting the position of the linear mark by two light receivers, by holding the signal difference between two light receiving outputs. CONSTITUTION:Light is projected to a linear mark 9 from a light source 8 and the transmitted or reflected light thereof is detected by two light receiving elements 10, 11. The respective detection signals e1, e2 are compared by an operational amplifier 14 to obtain a difference signal eD which is, in turn, inputted to a hold circuit 17. The detection signals e1, e2 are also inputted to a max. value circuit 15 to detect the max. value and the detection signal eM is compared with a reference value eC by a comparator 16. This reference value eC is set so as to be matched with the max. detection value when the linear mark 9 was moved to one side and output EH=1 is generated when eM>=eC. Output ed is made equal to eD at the time EH=0 and the eD value immediately therebefore is held at the time of EH=1 and outputted.

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-like 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 suddenly deforms into a wave 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, so the position signal cannot be obtained. It has the major drawback that it cannot be obtained.

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 element 1.2 is 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. The characteristics of the output voltage e1 of the light receiving element 1 and the amplifier 5 with respect to the deviation d of the center of the linear mark from the center position of the light receiving elements 1 and 2 are shown in the upper part el of FIG. Similarly, the characteristics of the output voltage e2 of the light receiving element 2 and the amplifier 6 are shown in the upper part e2 of FIG. The difference between the output voltages el and e2 is determined by the operational amplifier 7 to obtain the output e0.

This output voltage e versus excursion. The relationship is shown in the lower part of Figure 5. In this way, the position can be detected using the output voltage eo, which has a sign of 0-, which is proportional to the direction of deviation from the center of the light-receiving element 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 deviation of the linear mark exceeds that range, and as shown in the lower part of FIG.
Or, when it becomes less than dIII-, the output voltage becomes zero,
It has the disadvantage that a position detection signal cannot be obtained and it 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 projects a light beam transmitted or reflected from a linear mark onto two photoelectric elements to determine the position of the linear mark. In the position detection method, a continuous position signal is output by holding a difference signal between two photoelectric elements.

In addition, a continuous position signal is output by holding the difference signal of two photoelectric elements, and the maximum value of the output of the maximum value circuit is held by the maximum value hold circuit using a hold signal generation circuit, and the output is By dividing the pressure using a voltage divider,
By using the comparison voltage of the comparator, the comparison signal can be automatically set.

In addition, by holding the difference signal between the two photoelectric elements, a continuous position signal is output, and by adding a delay circuit, even if the relative position of the linear mark and the light receiving element changes, the operation is delayed. It is configured to compensate and output a highly accurate position signal.

In addition, by holding the difference signal between two photoelectric elements, a continuous position signal is output, and by adding two comparators and a matching circuit, even in the case of discontinuous linear marks, continuous position signals can be output. It is configured to output a position signal.

(Function) The present invention obtains a signal proportional to the position from the difference signal between two light receiving elements, and by combining these signals, even if a linear mark is placed at a position far away from the light receiving element, 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 denotes 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. Photoelectric element 10.1
The output of 1 is amplified by amplifier 12.13 to produce output voltages el and el. These voltages el and el are subjected to the following calculation by the operational amplifier 14 to produce an output eD.
That is, eD=e2-el ゛ The characteristics of the amplifier output el and el with respect to the deviation d between the center of the photoelectric element 10.11 and the center of the linear mark are expressed as the second
FIG. 2(A) shows the relationship between the output e of the operational amplifier 14 and the deviation d in FIG. 2(B).

Next, the output e1 of the amplifier 12.13, the maximum value eH of el
1, that is, FIG. 2 (A) upper = q-o-o-.

-■ is created by the maximum value circuit 15 in FIG. This output eH
and the comparison voltage ec shown in FIG.
Compare by 6.

Here, e = e - Δec1M (Δe(:, <<eH) This output signal EH is shown in Fig. 2 (C). This signal E
1 is a hold signal of the hold circuit 17 that holds the output signal eD of the operational amplifier 14.

Next, the operation shown in FIG. 1 will be explained. Now, in FIG. 2(A), it is assumed that the center position d of the projected image 9 of the linear mark satisfies d2≦d≦d1.

In this case, as shown in FIG. 3C, E■=0, and the hold circuit 17 outputs the input signal e as it is without holding it. That is, e6=eo. In this case, ed has the characteristics indicated by ◎-〇 in FIG. 2(B).

Next, a case where d > d 1 will be explained. In this position range, EH=1 as shown in FIG. 2(C), so the input voltage e of the hold circuit 17 is held by the hold signal El, so the hold circuit 'J! 117
The output ed is (B) - (D
It becomes a constant output value. Further, in the case of d<d2, the output e becomes a constant negative output value of (7) Qf in FIG. 2(B) in the same way as above.

As described above, the value of deviation (difference) d is increased by d+■
In contrast, the output voltage e of the hold circuit 17 becomes [F]-◎-〇-■, as shown in Fig. 2 (B>).As a result, the deviation is small compared to the dimensions of the light receiving element. Even if the position is large, 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. The differences between FIG. 3 and FIG. 1 include a maximum value hold circuit 18, a hold signal generation circuit 181, a voltage divider 19, a delay circuit 20, and comparators 21 and 22.
A matching circuit 23 has also been added.

The maximum value hold circuit 18 holds the maximum value of the output signal e1 or el of the amplifier 12 or 13, that is, the maximum value of the output signal e1 or el of the amplifier 12 or 13, that is, the
>To-6-@-(E) shown above is held and output by the hold signal of the hold signal generating circuit 18'. If this output is eIlI, the output eC of the voltage divider 19 is expressed by the following equation.

ec-kelII=em-△ec (k=dividing voltage ratio, 0<k<1> This signal ec becomes the comparison voltage of the comparator 16, and is shown in FIG.
This is the same signal as the hold signal EFI shown in C).

By adding these maximum value hold circuit 18 and voltage divider 19, even if the illuminance of the light source 8' changes or the characteristics of the light receiving element 10.11 and amplifier 12.13 deteriorate, the comparison voltage eC can be adjusted according to the change. There are effects that can be set automatically.

Next, the delay circuit 20 shown in FIG. 3 will be explained.

Input/output signal e of the hold circuit 17 in the figure. There is a certain value of response delay between and ed. Therefore, when the input signal is in an increasing state, for example, the response time of the output signal is delayed, 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 and 22 and matching circuit 2 in FIG.
3 will be explained. If the linear mark (9) is not continuous but is an intermittent mark, a constant position signal ed cannot be obtained. Therefore, this mark (9) becomes discontinuous,
The outputs e1 and e2 of the amplifiers 12 and 13 are the comparison level e. When the following occurs, outputs are generated in the comparators 21 and 22, and the coincidence circuit 23 detects that these outputs are generated simultaneously, and uses it as a hold signal for the hold circuit 17. Since this holding speed is high, the position signal e during continuous marking is
, is maintained, and ed=e, and even if the linear marks are discontinuous, there is an effect that a continuous, stable and constant position signal ed 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 described in detail 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 with good performance and high accuracy. In addition, even if the edge of a moving object is suddenly deformed into a wave 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 the drawing]

1 and 2 show an embodiment of the present invention,
Figure 1 is a configuration diagram of the present invention, and Figure 2 is an explanatory diagram showing its characteristics. (A) is the photoelectric element output voltage characteristic, (B) is the output voltage difference characteristic, and (C) is the left and right position judgment logic signal. shown respectively. 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... Operational amplifier, 8... Light source, 9... Linear mark, 10.1
1... 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, 2
1/22... Comparator, 23... Matching circuit. Fig. 1ec Fig. 2c custom

Claims (4)

[Claims] (1) In the position detection method, in which the position of the linear mark is detected by projecting the light beam transmitted or reflected from the linear mark onto two photoelectric elements, the difference signal between the two photoelectric elements is held. A wide range position detection method for linear marks, which is characterized by outputting a position signal. (2) In a position detection method that detects the position of a linear mark by projecting the light beam transmitted or reflected from a linear mark onto two photoelectric elements, continuous At the same time, the maximum value of the output of the maximum value circuit (15) is outputted to the hold signal generation circuit (15).
18'), the maximum value is held by the maximum hold circuit (18), and its output is divided by the voltage divider (19), and the comparison of the comparator (16) can be automatically set. Position detection method. (3) In a position detection method that detects the position of a linear mark by projecting the light beam transmitted or reflected from a linear mark onto two photoelectric elements, continuous By adding a delay circuit (20), even if the relative position between the linear mark and the light-receiving element changes, it is possible to compensate for the operation delay and output a highly accurate position signal. Features a wide range position detection method for linear marks. (4) In a position detection method that detects the position of a linear mark by projecting a light beam transmitted or reflected from a linear mark onto two photoelectric elements, continuous By adding two comparators (21, 22) and a matching circuit (23), it is possible to output a continuous position signal even in the case of discontinuous linear marks. A wide range position detection method for linear marks.