JPS6252802B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a detection device for generating a positioning signal when an object is to be positioned to a certain degree, and particularly relates to obtaining continuous position signals in a servo control device or the like.

2. Description of the Related Art Conventionally, it has been common practice to know the position of an object by combining a light emitting device and a light receiving device. A conventional method is shown in FIG. Figure 1a shows the configuration of the detection unit, Figures 1b and c are its output waveform diagrams, where 1 is a light emitting device, 2 is a light receiving device, 3 is an object to be detected, 4 is a power supply that supplies current to the light emitting device, 5 is an amplifier for amplifying the detection signal from the light receiving device, and 6 is a waveform shaping circuit.

When the detected object 3 moves in the x direction of the arrow 9 and enters between the opposing optical paths of the light emitting device 1 and the light receiving device 2, the electrical signal detected by the light receiving device is outputted from the amplifier 5 by the output section 7 as shown in Figure b. It is obtained in the form shown.
This signal is level-sliced by a waveform shaping circuit 6 and passed through a Schmitt circuit as a rectangular output 8 as shown in Fig. c, at which point the end position of the object is detected. With this type of detection method, it is possible to determine whether or not there is an object to be detected, but it is difficult to know its exact position.

Another method for performing this position detection more accurately is to use two light receiving devices as shown in FIG. 2, and obtain a difference output between the two light receiving devices and use it as a position detection signal. In FIG. 2a, 10a and 10b are light receiving devices, 11b is an aperture or slit provided in the object to be detected 11, 12 is a light emitting device, 13 is a differential amplifier, and 14 is a power source that supplies current to the light emitting device. . If the object now moves in the x direction of arrow 15, as the slit 11b moves together with the object, an output waveform as shown in FIG. 2b appears at the output of the differential amplifier 13. From this, for example, the object can be positioned at a point B where the detection signal waveform crosses zero.

However, with the detection method device shown in Figure 2, the magnitude of the position value that can be detected by the position signal is not only limited by the width of the slit, but also by the length of the part where the slit is provided. If the length is not long enough for the distance the object moves, there is a risk that multiple position signals for positioning will be detected, such as the signals described below. That is, the third
Detection signals at both ends 11a and 11c of the object 11 provided with the slit shown in FIG. , 18 can be regarded as zero-crossing points of the position detection signals corresponding to 11a, 11b, and 11c, respectively.
Therefore, with this type of detection method device, the detection signal is insufficient for use in servo control.

The present invention aims to solve the above-mentioned problems and provide a moving object position detection device capable of detecting a signal suitable for servo control, thereby enabling accurate positioning of the object. For this reason, the present invention provides a position detection device for detecting the position of an object to be detected passing through and moving between opposing optical paths of a light emitting device and a light receiving device. A light emitting device and a light receiving device are respectively disposed at the end of the object to be detected and at the position of the aperture, and the position is detected by output signals from the respective light receiving devices. Furthermore, a plurality of pairs of detectors each consisting of a light emitting device and a light receiving device facing each other on the optical path are arranged adjacent to each other on the moving path of the object to be detected so that at least one of the optical paths is blocked by the object. The detector is arranged vertically, and the position is detected using the output signal of the detector. Furthermore, by making the facing pair of the light emitting device and the light receiving device movable to a predetermined position, the position of the moving object can be detected optically and with high precision without contact, and the servo control system can be controlled. can be done accurately.

Embodiments of the present invention will be described below with reference to the drawings. Note that the same functional parts as in FIGS. 1 to 3 are designated by the same reference numerals.

FIG. 4 shows an embodiment of the present invention, with a schematic configuration a, a plan view b of main parts, and diagrams c to f showing signal waveforms of each part.

In the figure, 12 is a light emitting device (first light emitting device), 10a and 10b are light receiving devices arranged on opposing optical paths, 11 is an object provided with a slit 11b, and 13 is a differential amplifier circuit (second voltage (generation circuit), 14 is a power source for supplying current to the light emitting device 12. 12' is another light emitting device (second
14' is a power source for supplying power to 12', 16a, 16b, 16c are light receiving devices arranged on the optical path facing the light emitting device, and 17 is a power source for supplying power from 16a, 16b, 16c. 18 is a voltage generator (first voltage generation circuit) operated by 17; 19 is operated by 17 and outputs from the voltage generator 18 and the differential amplifier circuit 13; This is an adder (addition circuit) that adds. At this time, the predetermined distance A from the center of the slit 11b to the end 11a of the member and the distance between the two groups of detection devices 12, 12'A' and the center position of 10a, 10b to the center position of 16a, 16b, 16c. The distances A'' are set to be equal.Also, the light receiving devices 16a, 16b, 16c are connected to the end surface 1 of the member 11 provided in the slit 11b, as shown in figure b.
They are arranged diagonally with respect to 1a and 11c, and are equally spaced from each other by T.

Next, the functional operation of the position detection device having the above configuration will be explained. When the slit member 11 moves in the x direction indicated by the arrow 15, each optical path is interrupted, and detection signals from each light receiving device are obtained over time on the x axis as shown in Figure c. That is, the light receiving device 16c is first shielded, then 16b and 16a are shielded in this order to obtain signals such as A, B, and C. At this time, since the light receiving device 16b and the light receiving devices 10a and 10b located at the slit 11b are set at the same distance, they work synchronously, so when the light receiving device 16b operates, two As shown in , the differential output between 10a and 10b becomes almost zero. 1
The output signals of 6a to 16c are amplified and waveform shaped at 17, and then binarized. These binarized signals are shown as binary level signals A to C in Figure d, corresponding to A to C in Figure C, respectively. That is, A is 16c', B is 16b', and C is 16a'. The voltage generator 18 operated by the above-mentioned 16b' generates the + voltage 23 shown in Fig. B' when 16b' is at 1 level, and the - voltage 24 when it is at 0 level, as shown in Fig. e.
is starting to occur. Also, 17 is 16
From c'a and 16a'c, the signal 20 in figure d is obtained.

As a result of the above, the position signal for servo control is 20 above.
From the signal 10a-10b, the signal 10a-10b is used between 21 and 22 (d figure) of the signal 20, the signal 23 is used before 21, and the signal 24 is used ahead of 22. As shown in the figure, continuous position detection signals can be easily obtained.

In other words, since the waveform signal always has signals 23 or 24 added to the portion other than the zero cross point, points 16, 17, and 18 of the signal waveform as explained using FIG. 3b are used as position detection signals. It cannot be regarded as a zero cross point. The above signal waveform (f
10a-10b) in the figure can be easily achieved by suitably changing the amplification ratio in each part in the well-known waveform shaping cycle. As described above, a signal indicating an accurate fixed position can be obtained without generating a plurality of zero cross points as in the case of FIG.

The detection resolution of the position detection described above is determined by the slit and the light receiving devices 10a and 10b, but the detection accuracy can be increased by using a light receiving device having a shape in which one light receiving surface is divided into two. FIG. 5 shows an embodiment of such a light receiving device. This light receiving device has two light receiving surfaces 25 and 26 formed by a dividing line 27. According to current semiconductor technology, this dividing line 27 can be
It is possible to provide accurately on the order of m,
By placing this between 10a and 10b mentioned above, the differential output from the light receiving device can be made into a value corresponding to the moving distance in μm, and is sufficiently practical as a signal for high-precision servo control. It is.

Another embodiment of the invention is shown in FIG. If this embodiment is applied to the case where the length of the member with the slits to be used must be increased depending on the distance the object to be detected moves, the length of the member with the slits can be changed to the length of the member with the slits. It can be determined as appropriate regardless of the length.

In the figure, 28-1 to 28-n are detectors that are newly installed combinations of a light emitting device and a light receiving device, and the distance between them is shorter than the length L of the member 11 with a slit, so that one of them is always shielded. It is set up and installed to be in a given situation. For example, if either the detector 28-1 or 28-2 is shielded, it is known that the object to be detected is located on the left side of the detector sensor 16b, and
If any one of 8-3 to 28-n is shielded, it can be seen that the object to be detected is located on the right side. Therefore, with the detection signals of these 28-1 to 28-n, it is possible to quickly move to the position of the signal detection device sensor 16b, and by combining these detectors, the detector 16b and the detector 16b can be moved to the exact same position as in FIG. 4f. I can get a signal. According to this method, it is possible to shorten the length of the member with the slit. Note that such a detector can also be manufactured as a single block. By installing a single detector or a combination of multiple detectors integrated in this way on the moving path of the movable body, the position to be determined can be easily changed, and the time required for setting and adjustment can be greatly reduced.

As explained above, according to the present invention, the position of a moving object can be optically detected in a non-contact manner and with high precision. Since the detection signal can also be clearly identified, it exhibits an extremely excellent effect when used in a servo control system.

[Brief explanation of the drawing]

In FIGS. 1 and 2, the configuration a and the output signal of a conventional position detection device are shown in b. Figure 3 shows the conventional configuration a
and its output signal b, FIG. 4 is a configuration a of an embodiment of the position detection device according to the present invention, a plan view b of main parts, and signals c to f, FIG. 5 is an embodiment of the light receiving device, and
The figure shows the configuration of another embodiment of the device of the present invention. In the figure, 10a and 10b are light receiving devices, 11
are objects to be detected, 11a and 11c are ends, 11b is a slit, 12 and 12' are light emitting devices, 13 is a differential amplifier, 14 and 14' are power supplies, 15 is a moving direction,
16a, 16b, 16c are light receiving devices, 17 is an amplifier and waveform shaping circuit, 18 is a voltage generator, 19 is an adder, 25, 26 are light receiving surfaces, 27 is a dividing line, 2
8-1 to 28n are detectors.

Claims (1)

[Scope of Claims] 1. In a position detection device that detects the position of an object to be detected passing through a moving path between opposing optical paths of a light emitting device and a light receiving device, a position detecting device that faces a first light emitting device across the moving path. a pair of light receiving devices are disposed in order along the moving direction, and three light receiving devices are disposed at a predetermined distance from the pair of light receiving devices across the moving path and facing the second light emitting device. A first voltage generating circuit in which the devices are arranged in order along the moving direction and whose output level changes according to the output level of the central light receiving device among the three light receiving devices; a second voltage generating circuit that generates a voltage corresponding to the difference in the outputs of the light receiving devices; After that, the second voltage generating circuit generates an output during the period until it is detected by the last light receiving device, and during the other periods, the first voltage generating circuit generates an output.
A position detection device characterized by comprising an adder circuit that generates an output of a voltage generating circuit. 2. Claim 1, characterized in that the first light emitting device, the second light emitting device, the pair of light receiving devices, and the opposing pairs of three light receiving devices are respectively movable to predetermined positions. The position detection device described.