JPH0748041B2 - Potentiometer device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention is used in the field of position detection circuits.

The present invention relates to a potentiometer device, and more particularly, to a potentiometer position detection circuit attached to a drive system such as an X-ray fluoroscopic imaging table, and more particularly to an additional abnormality detection circuit thereof.

(B) Conventional technology A limit switch and a segment or a mercury switch or the like has been conventionally used as a position detecting means, and each of these switches needs to be adjusted by moving the position or segment of the switch so as to operate at each position. There is.

(C) Problem to be Solved by the Invention In the position detecting means described above, since it is necessary to move the limit member one by one to adjust the position, it takes time and effort, and switches, sections, etc. are provided by the number of points of the detected position. Cost is high because there is.

Further, it is not easy to limit the operation because the position room is small.

Therefore, a potentiometer has come to be used as a position detecting means, and the stop or limit position can be easily adjusted by changing the comparison voltage in the comparison circuit with a trimmer or a variable resistor.

Further, by securing the range of the comparison voltage to some extent, the limitation due to the size of the installation chamber can be performed only by adjusting the trimmer.

However, in the conventional potentiometer detection circuit, if the wiring to each terminal of the potentiometer is broken, there is a problem due to looseness of the potentiometer installation. Etc. cannot be detected.

It is an object of the present invention to provide a potentiometer detection circuit which performs not only the original position detection of a potentiometer but also wire disconnection, loose mounting, and drive system abnormality detection.

(D) Means for Solving the Problems The above-mentioned object is a potentiometer device for detecting the position of a driving body, and a circuit for detecting disconnection by a comparator in which a comparison voltage that can be predicted and detected when the wiring of the potentiometer is disconnected is set. And the potentiometer detection voltage is 2
Each sample and hold circuit that holds in two different clock units, a detection circuit that detects a change state between the output voltages of both hold circuits, a drive signal of the driver and the output of the detection circuit are logically determined, and It is achieved by including a circuit for detecting an abnormality or a mounting failure of the potentiometer.

(E) Action Using a potentiometer for position detection, input the detected voltage to a comparison circuit or comparator, and within that circuit,
Compared with the voltage corresponding to each limit switch, when the detected voltage becomes larger or smaller than the comparison voltage,
It is determined that the predetermined position has been reached, and an output signal to that effect is detected.

In this case, the limit or stop position can be easily adjusted by changing the comparison voltage in the comparison circuit with a trimmer (variable resistor). Further, by securing the range of the comparison voltage to some extent, the limitation due to the size of the installation chamber can be performed only by adjusting the trimmer.

The above is the general operation of the conventional potentiometer detection circuit.

In the present invention, in addition to the general operation, the potentiometer detection voltage is temporally managed, and at the same time, the drive signal (ON, OFF) for the drive system is taken in, and the drive signal is ON even though it is ON. If the detected voltage of the potentiometer does not change, it is judged that the potentiometer has come off due to looseness, etc.
However, if the detected voltage is changing, it is determined that the drive unit is operating due to the welding of the relay on the drive unit, etc., and each abnormality is detected.
When the potentiometer is broken, set a predictive detection voltage that swings to + or-voltage to detect breaking of the potentiometer wiring.

(F) Embodiment A preferred embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing the first embodiment.

Connect the detection potentiometer 1 attached to the detection section to the circuit, connect terminal X to + 15V and terminal Z to -15V, and connect the common terminal Y to detect voltage (changes in the range of about + 10V to -10V).
To get The output of the common terminal Y is input to the comparators 6, 7, 9 and the sample hold circuits 10, 11 as the voltage V through the noise filter 2.

First, the output circuit of the limit position will be described.

The detection voltage V is input to the comparator A (6) and the trimmer A
Compared with the voltage A set in (4), when the detected voltage V is larger than the set voltage A, a signal reaching the position A is output from the comparison circuit A, and this output is the trimmer A (4).
Changes the set voltage, and this voltage A changes to the detection voltage V
The position of position A can be adjusted by moving up and down.

The same applies to the position B. If the detected voltage V and the set voltage B are input to the comparator C (7) and the former is large, the position B
The arrival signal is output.

Next, a circuit configuration for detecting three abnormal modes will be described.

First, in order to detect the abnormality A, that is, the disconnection of the potentiometer wiring, the predictive detection voltage C when each line of the potentiometer 1 is disconnected is set to the comparison voltage, and this voltage and the detection voltage V are set to the comparator C (9). Then, the abnormality is detected by making a comparison with each other and obtaining an output signal when the respective voltages are substantially equal.

In the illustrated example, the predictive detection voltage C is -15V for the wiring of the terminals X and Y and + 15V for the wiring of the terminal Z.
In particular, since the wiring of the terminal Y is connected to −15V by the high resistance 3 of mega ohm, for example, even if the Y line is disconnected, it can be detected.

Next, abnormality mode B (drive system failure, etc.), abnormality mode C
The detection of (such as looseness of potentiometer attachment) will be described.

The detection voltage V is applied to the sample and hold circuits A (10) and B (1
The voltage V is held alternately at different times (CLOCK A, B) determined by 1). Then, the voltages a and b held by the comparator D (12) are compared with each other, an output signal of a ≠ b or a = b is obtained, and this output signal and the drive signal fetched from the drive system control unit are obtained. ON or non-driving signal OFF is input to the logic circuits 14 and 13 to determine whether there is an abnormality.

If the AND circuit 13 ANDs the voltage a ≠ b during stop and determines that the output of the potentiometer is changing even though the drive signal is OFF, it is determined that there is welding of the relay related to the drive unit, and the abnormal output signal Is obtained.

Further, in the AND circuit 14, when the drive unit is operating and the hold voltage a
≒ b (this is when the amount of change in voltage V that changes between CLOCK A and B is small) is ANDed, and if it is determined that the output of the potentiometer does not change even though the drive signal is ON, the potentiometer is loose. As a result, a signal indicating an abnormality is output.

(G) Effect According to the present invention, adjustment of the limit position can be easily performed only by moving the trimmer, and abnormality detection such as welding of the relay applied to the drive unit and disconnection of the potentiometer wiring can be performed.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing one embodiment of the present invention. 1 is a potentiometer, 4 and 5 are trimmers or variable resistors, 6 and 7 and 9 and 12 are comparators, 10 and 11 are sample and hold circuits, and 13 and 14 are AND circuits.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01C 10/00 Z

Claims (1)

[Claims] 1. A potentiometer device for detecting the position of a driving body, wherein a circuit for detecting disconnection by a comparator in which a comparative voltage capable of detecting and detecting when the wiring of the potentiometer is disconnected is set, and a potentiometer detection voltage for two different clocks. Each of the sample and hold circuits held in units, a detection circuit for detecting a change state between the output voltages of the both hold circuits, a drive signal of the driver and the output of the detection circuit are logically judged, and an abnormality in the drive system or a potentiometer And a circuit for detecting a mounting failure of the potentiometer device.