JPH02216490A - Malfunction preventing device of object detecting device - Google Patents

Abstract

PURPOSE:To prevent an erroneous detection by constituting a device so that a set condition of a transmission pulse for an original detection is changed by detecting the influence by a reflected wave whose time interval is longer than that of a reflected wave of a detection object body. CONSTITUTION:In order to judge whether a multiple reflected wave exists or not, for instance, in the case of a safety device of an elevator door, a single pulse 2a is transmitted experimentally in the course of opening a door for which a function of the safety device is unnecessary. For instance, after transmitting a single transmission wave 2b transmitted by the single pulse 2a for transmitting the single pulse 2a experimentally in the course of opening a door for which a function of the safety device is unnecessary in the case of the safety device of the elevator door, reception of its transmission wave is confirmed by a multiple reflected wave confirming circuit 10. When a receiving wave exists, an erroneous detection is judged from an overlap of a multiple reflected wave output 2e and a waveform 2f of a gate circuit 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a malfunction prevention device for an object detection device that uses energy waves such as ultrasonic waves.

[Conventional technology]

One example of this type of object detection device is a device that detects the presence or absence of an object by emitting pulsed ultrasonic waves and measuring the time it takes for the pulsed ultrasonic waves to reflect back to the object.
A conventional structure will be explained with reference to FIGS. 4 and 5, taking as an example the elevator door safety device disclosed in Japanese Patent Laid-open No. 73442 and Japanese Patent Application Laid-open No. 53-145249.

In Figure 4, can is the transmitter/receiver of the ultrasonic object detection device, (2) is the ultrasonic pulse emitted from the transmitter/receiver c2D and reflected by the object to be detected (c), and (Foundation) is the elevator door and door. The car with a , the handle is the landing door of the elevator, @ is the landing floor, @ and @ are the walls and ceiling where the landing is located. The safety device for elevator doors is 1. For example, it detects passengers in a non-contact manner so that they do not get caught when the door is closed, and an ultrasonic object detection device Qυ is installed near the ceiling of the car @ on the landing floor. At (5), an ultrasonic pulse (c) is emitted. If a passenger (c) approaches the car door (a), the detection device QD picks up the reflected wave gradient and reverses the door (1) with the closed car door (to). If an elevator user is caught in a crime by opening the door,
This eliminates the problems caused by accidents and ensures safety. If the object to be detected is detected, the reflected wave will not return, so the door will remain closed. However, depending on the structure of the landing, there may be multiple reflected waves that return after being reflected from the floor, walls (2), and ceiling (2), and waves reflected from desks, plants, etc. In addition to reflections from the object to be detected, there are also reflections that are harmful to the original detection.

FIG. 5 shows the configuration of a conventional detection device. (1) is a timing pulse circuit, and (2) is an ultrasonic pulse transmitter.

(3) is a receiver, (4) is a comparator that determines the detection level of the received pulse, (5) is a gate circuit, and (6) is an AN
D circuit, (7) is a double reading circuit to confirm reception,
(81 is a dead area switch, and (9) is an output drive circuit that detects reception and reverses the elevator door to open it.

Figure 6 shows the characteristics of this device. When the timing pulse circuit (1) sends timing pulses with predetermined intervals as shown in (6a) to the transmitter (2), the transmitter (21
Ultrasonic pulses (22a) are emitted from a) as shown in (6b).

If there is an object to be detected (c) such as a person or an object, the reflected wave (2zb) that is reflected after a certain period of time is received by the receiver (21b) and taken into the receiver (3).

Since this received wave (6d) has unnecessary harmful reflected waves such as reflected waves and reflections from walls and floors, a comparator is used to compare the gate waveform (6c) of the gate circuit (5) with the received wave (6d). (4), and the detection output wave (6e) obtained by this is used to determine whether there is a detection target object (c) near the elevator entrance or exit using an AND circuit (6). Therefore, the second reading circuit ()) continues to hold the output detected once as the second reading wave (6f) and uses it for the first detection It is now possible to output Cbgk for the first time. In addition, when the elevator door closes, it will detect the elevator door and malfunction, so a dead area switch +81 is provided, and even if a received wave is detected in this area, when the switch 181 is activated, Output drive circuit (
9), consideration has been given to the possibility of forcing the output fCOF'F.

As described above, people and objects near the elevator entrance are detected without contact while avoiding useless reflections.

An example of this insensitive area is shown in FIG. 6 (6h) and (season).

[Problem to be solved by the invention]

Conventional ultrasonic detection devices are configured as described above, and as shown in Figure 4(b), there is a transmission path for multiple reflected waves that reflect several times and enter an object with a high reflectance outside the detection range. If this happens, erroneous detection will occur, and even if objects such as plants or telephone stands are present within the detection range, erroneous detection will occur. That is, if multiple reflected waves enter as shown by the broken line in the received wave (6d) in FIG. 6, the device will make false detections.

For detection purposes, it is possible to move objects such as desks and plants to positions where they do not have a negative impact on harmful entities, but there are limits to this, and multiple reflected waves from structures such as buildings can be moved. When it becomes a problem, it is not easy to deal with it. Furthermore, in order to avoid the effects of harmful reflections, changing the characteristics of the device, such as changing the timing, to suit the situation requires time and effort to make adjustments each time the situation changes, and it may defeat the purpose of use. There has been a problem in that there are many cases in which conventional detection devices cannot be applied after all.

This invention was made to solve the above-mentioned problems, and aims to provide an object detection device using ultrasonic waves or the like that can detect the effects of harmful reflected waves and prevent false detections caused by these waves. .

[Means to solve the problem]

This invention is based on a first
In addition to the 0 pulse generation means and the reflected wave detection means of the 10th pulse, a second pulse generation means and a second reflected wave detection means are provided to detect the reflected wave with a longer time gap than the original reflected wave. Provide detection means.

It is detected that the second reflected wave affects the detection of the tenth reflected wave, and the setting conditions for pulse generation of the tenth pulse generating means are changed.

[Effect]

In object detection using energy waves such as ultrasonic waves in this invention, the time gap is longer than the reflected wave from the object to be detected.
Erroneous signal detection is prevented by detecting the influence of reflected waves and changing the pulse transmission setting conditions for original zero detection.

〔Example〕

An embodiment of this invention is shown in FIGS. 1 to 3.

FIG. 1 shows an example of the configuration of a detection device that uses ultrasonic waves as energy waves, fi, and (2) a transmitter for ultrasonic pulses.

(3) is the receiver of the ultrasonic pulse, (21a) (21
b) is a pair of transceiver elements that transmit and receive ultrasonic pulses; F), (2), C3), (21a), (
21b) constitutes an ultrasonic wave transmitting/receiving means. (1
) is a timing pulse circuit which is the 10th pulse generating means, and (4) is a comparison 6. which compares the signal received by the receiver (3) with a reference value. , +5) is a gate circuit that outputs a gate signal a little later than the timing pulse, (6) is an AN
D circuit, (7) is a circuit that reads the received signal twice, (
41, 15), (61, (71 constitutes the tenth reflected wave detection means. (81 is a dead area switch, and this and the timing pulse circuit (1) constitute the second pulse generation means. (9) is an output drive circuit that controls opening and closing of the elevator door, 0ω is a multiple reflected wave confirmation circuit, (lfl is a false detection discrimination circuit, and (1)
, +5), (81, a., aυ constitute the second reflected wave detection means. a3 is a timing pulse circuit (
This timing pulse correction circuit corrects the pulse generation timing of No. 11, and this and the gate circuit (5) constitute a pulse correction means.

FIG. 2 shows the influence of false detection due to multiple reflected waves as an example of harmful reflected waves, and FIG. 3 is a characteristic diagram illustrating the operation of the present invention.

The operation of an embodiment according to the present invention will be explained with reference to FIGS. 1, 2, and 3.

In order to determine whether multiple reflected waves exist, for example, in the case of a safety device for an elevator, a single pulse (2a) is transmitted on a trial basis while the door is open, when the function of the safety device is unnecessary. Note that although a single pulse is used here, the time interval is as shown in Figure 6 (6a).Multiple pulses may also be used if the time interval is long enough. Using (8), when one door is open, the door opening waveform shown in Figure 6 (6
If the signal is H-+L like 0, 1st door open/door closed waveform 6th
Since the signal becomes L-+H as shown in the figure (6g), it is determined that the door is open because the dead area switch becomes H-+L, and a single pulse (2a) is transmitted. Single pulse (2a
) After transmitting the single transmission wave (2b), the multiple reflected wave confirmation circuit al) confirms the reception of the transmission wave.

In this case, we will introduce the wave, the wave, the reflected wave from the floor, etc. in Figure 6 (6d).
In order to avoid detecting the reflected waves that have already been eliminated and the reflected waves of people and objects that should be detected as multiple reflected waves, confirmation is made by the opening timing of the multiple reflected wave gate waveform (2d). If there is no received wave when the gate circuit (5) generates a gate signal for multiple reflected waves, it is determined that there is no multiple reflected wave and the conventional operation is performed.

If there is a received wave, it is determined that it is a multiple reflected wave, and the false detection discrimination circuit I outputs the multiple reflected wave output (2e) and the gate circuit (
If it overlaps with the waveform (2f) in 5), it is determined that it is a false detection.

As a result, if it is determined that there is no erroneous detection, the conventional operation is performed, and if erroneous detection is confirmed as in the erroneous detection output (2g), the timing pulse interval is corrected by the timing pulse correction circuit az. In order to prevent the gate waveform (2f) and the multiple reflected wave (2e) from overlapping, it is sufficient to delay the return time until the transmitted wave is received. For example, as shown in FIG. A modified timing pulse (3a) is generated by adding the double time to the timing pulse interval for transmitting a transmission wave, and a dead area switch (81) is generated.
Transmission while the door is closed is performed at the corrected timing/<rus (3a).

Also, because the timing pulse interval has widened.

The gate/curse of the gate circuit (5) that is synchronized with this is also modified, and the modified gate pulse (3C) is used to detect people and objects, and the gate is opened even if multiple reflected waves are received. Since the timing does not overlap, false detection will not occur.

If multiple reflected waves are detected as described above, change the transmission timing pulse interval.

The received wave due to multiple reflected waves no longer overlaps with the gate pulse, making it possible to prevent false detection.

It is recommended that the detection of multiple reflected waves using a single pulse (23) be carried out in situations where customers are most comfortable (such as when the building is closed) so that the true reflected waves from the detected object are not mistaken for multiple reflected waves. is necessary.

In addition, all of the above has explained multiple reflected waves as harmful reflected waves, but as shown in FIG. 2 (2c), it is sufficient if the 10th reflected wave detection means also captures reflected waves with a long propagation time delay. Harmful substances can be detected by means other than multiple reflected waves.

As a method to prevent false detection due to harmful reflected waves such as multiple reflected waves, we have explained an example in which the timing pulse interval of the transmitted wave is widened by adding twice the gate pulse width to the timing pulse interval. Prepare several cases in which the correction width pattern is changed instead of just doubling, and repeat single pulse detection to gradually widen the timing pulse interval to obtain a range that does not overlap with the gate pulse and prevent false detection. is also possible.

Although some of the first and second pulse generating means and reflected wave detecting means are common to the equipment, different configurations may be used.
In addition, the method has been described in which the time period during which the first and second pulse generation operations are performed is automatically switched for each operation using, for example, a dead area switch (8).

It is also possible to switch automatically and manually at regular intervals, and even in the same time period, the same effect can be obtained by operating them together by changing the pulse width conditions, etc.

In addition, the setting conditions can be changed not only by the time interval of the pulses but also by changing the pulse width, etc. to achieve the same effect.

Furthermore, although the above explanation has been given using an example in which ultrasonic waves are used as an elevator safety device, it is clear from the embodiments that ultrasonic flaw detection or an alarm device that uses energy waves such as radio waves may also be used.

〔Effect of the invention〕

As described above, according to the present invention, the configuration is configured to detect the influence of reflected waves with long time intervals (in addition to the reflected waves of the original object to be detected), and to change the setting conditions of the emitted pulses for the original detection. Therefore, it is possible to obtain a malfunction prevention device for an object detection device that can prevent erroneous object detection due to energy waves.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of this invention, Figs. 2 and 3 are characteristic diagrams of an embodiment of this invention, Figs. 4 and 5 are block diagrams of a conventional embodiment, and Figs. FIG. 6 is a characteristic diagram of a conventional embodiment. In the figure, +1+ is a timing pulse circuit, (2) is a transmitter, (3) is a receiver, (4) is a comparator, and (5) is a gate circuit. αG is a multiple reflected wave confirmation circuit, and U is a false detection discrimination circuit. (13 is a timing pulse correction circuit. In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] (1) An object detection device that emits an energy wave in a predetermined direction and detects an object using the reflected wave, which (a) emits an energy wave for detecting an object in a predetermined direction, and (b) a tenth wave transmitter/receiver for generating a signal for causing the wave transmitter/receiver to emit an energy wave at predetermined time intervals;
(c) first reflected wave detection means that operates after a predetermined time delay each time the energy wave is emitted and detects the presence or absence of the reflected wave; (d) whether the reflected wave is a legitimate reflected wave; (e) a second signal generating means for controlling an energy wave emitting operation to testly emit an energy wave for detecting a different harmful reflected wave; (f) a second reflected wave detection means for detecting the reflection of the energy wave for a period longer than the interval; and (f) the second reflected wave detection means detects the reflection of the test energy wave during the long period. An object detection device comprising: a correction means for identifying the detected object and changing a condition for setting the predetermined time interval of the first signal generation means based on the identification signal. Malfunction prevention device.