JPS58187886A - Proximity sensor - Google Patents

Abstract

PURPOSE:To detect proximity between two conductive objects by combining a detection probe, a high voltage generation circuit and a corona discharge detecting means. CONSTITUTION:A high voltage is applied to a detection probe 1 with a pointed tip from a high voltage generation circuit 3. As the detection probe 1 approaches an object 2' to be detected made of a conductor at a fixed distance, an intermittent glow corona occurs between both of them. This intermittent glow corona is detected with a search coil 4 and a corona discharge detecting means comprising a peak hold circuit 5. Then, when the output of the peak hold circuit 5 exceeds a fixed level, the detection signal is fed to a Schmitt circuit 6 for actuating a transistor 7. With such an arrangement, the proximity between two conductors can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a proximity sensor that detects the proximity of two electrically conductive objects.

Contact detectors have already been devised for detecting contact between two conductive objects that move relative to each other, such as a tool and a workpiece as shown in FIG. In the 1g1 diagram, (1)
(2) is a tool such as a cutting tool, and (2) is a workpiece called a workpiece. Conventional detectors detect the cutting tool (1) and the workpiece (2).
) forms a loop through which current flows when it comes into contact with the coil, thereby detecting changes in the current flowing through the coil. In this method, in order to prevent scratches when the cutting tool (1) and the workpiece (2) come into contact at normal speed, it is necessary to reduce the speed when the two approach the distance M. Since there is no device that generates an appropriate proximity signal, and for safety reasons the deceleration is started well before K, such as 10 on, there is a drawback that it takes time to detect contact.

By the way, if a high voltage is applied between an object with a sharp tip like the cutting tool (1) and a flat object like the workpiece (2), corona discharge will occur when the two come close to each other. FIG. 2 is a curve diagram showing an example of voltage-tfi characteristics of a needle electrode corona. When the voltage reaches f+jEVg, the current increases rapidly to, for example, 1O to 10AIc, and an intermittent glow-corona occurs. The voltage gradually increases to Vst K
When the current reaches tK, the current becomes a periodic pulse (IJ-ma pulse). When the voltage further increases to reach VoK, the streamer pulse disappears and the discharge becomes a stationary glow corona. Here, the voltage Vg is related to the distance between the 24-electric objects (needle to flat plate), and is always constant if the distance is constant under the same conditions. Therefore, if a constant high voltage is applied between the two objects, intermittent glow corona will occur when the two objects come within a certain distance (for example, 12 meters). The present invention attempts to detect proximity between two conductive objects by utilizing this phenomenon. Hereinafter, the present invention will be specifically explained with reference to the drawings.

FIG. 3 is a block diagram showing a basic first embodiment of the present invention. In the figure, (1') is a detection probe with a pointed tip (t), - (pi).A tool like (1) can be used as the detection probe (1).

(2) is an object to be detected made of a conductor, and the object to be processed (2) can also be used as the object to be detected. (3) is a conventionally known high voltage generation circuit, and the generated high voltage is, for example, 6 to xokV.
shall be. (4) is a detection coil, and (5) is a peak hold circuit, both of which detect the current when the above-mentioned intermittent glow/corona occurs. (6) is a peak hold circuit (
When the output voltage of 5) exceeds a certain level, the transistor (
7) is a Schmidt circuit that operates. The output of transistor (7) can be used for various purposes as a proximity signal. For example, a detection probe (1) and an object to be detected (2)
), it can be used to stop or decelerate the movement at the same time as the proximity signal is generated, or to cut off the high voltage generation circuit at the same time.

Figure 4 is a block diagram showing a second embodiment of the present invention. In the figure, parts corresponding to those in FIG. 3 are designated by the same or similar symbols. In this example, if the proximity signal obtained when the detection probe (1) and the object to be detected (2) approach a certain distance in the example shown in Figure 3 is used for deceleration, the two will get closer and sparks will fly. It was designed to suppress high voltage. In the figure, (5') is a detection circuit, (8
) is a feedback circuit. These circuits include peak hold circuits, waveform shaping circuits, and the like. The output voltage of the feedback circuit (8) is the output voltage of the high voltage generation circuit (3).
In addition to the low voltage 1111 of , its output high voltage is reduced. In this way, the detection probe (1') and the object to be detected (2
), no matter how close they are, sparks will not fly, and therefore no sound will be generated. (6) is a switching circuit that operates when the voltage on the low voltage side of the high voltage generation circuit (3) falls below a certain value, that is, when the detection probe (1) and the object to be detected (2) approach a certain distance. It is. Note that the switching circuit (6) may be operated by the output of the detection circuit (5) or the feedback circuit (8). In addition, the detection probe (1) and the object to be detected (2)
When the high voltage generating circuit (3) comes into contact with the high voltage generating circuit (3), the high voltage generating circuit (3) may be turned off or the output may be set to zero.

As explained above, when a detection probe is used, the proximity sensor of the present invention detects the proximity of the probe and the object to be detected, so the proximity signal can be used for various purposes, as well as When using a tool like this as a detection probe and using a workpiece as the object to be detected, if it is used in conjunction with a contact detector, it is possible to decelerate just before contact, so not only can the af of the detector be increased, Unlike conventional methods, there is no need to program the vehicle to decelerate from a considerable distance, and the time required to detect contact can be significantly shortened.

In addition, in the above, the case where the current is detected when intermittent glow/corona occurs is explained, but in some cases, it may be detected that the current is detected during the occurrence of intermittent glow/corona.
It is also possible to detect the vL flow when corona occurs. In addition, the present invention can be modified in various ways without departing from the gist of the invention as set forth in the claims.

[Brief explanation of the drawings] w, Figure 1 is a diagram showing an example of two conductive objects performing relative motion,
Fig. 2 is a curve diagram showing an example of the voltage-current characteristics of the needle electrode corona, Fig. 3 is a block diagram showing the first embodiment of the present invention, and Fig. 4 is a block diagram showing the second embodiment of the present invention. It is a diagram. (1)...Detection probe, (3)...
High pressure generation circuit, (4,5,5')...Corona discharge detection means, (1)...Tool, (2)...
...Workpiece.

Claims (1)

[Claims] 1. A proximity sensor that includes a detection probe, a high voltage generation circuit, and a corona discharge detection means, and detects the approach of the detection probe and an object to be detected. 2. A proximity sensor comprising a detection probe, a high pressure generation circuit, and a corona discharge detection means, in which a tool is used as the detection probe and a workpiece is the object to be detected.