JPH03289579A - Multitime window type ultrasonic switch - Google Patents

Abstract

PURPOSE:To clearly display the height of an object by dividing the time required in the detection of the reflected wave of an ultrasonic wave into a predetermined number of time windows and detecting the object in the respective time windows. CONSTITUTION:A worker confirms the lighting state of a display device 3 and sets the display device 3 so as to cancel the receiving signal in a time window W1 with respect to a table 6 by an input apparatus 4. Since a control apparatus 5 neglects the receiving signal in the time window W1, the receiving signal 14 from a wall is not mistaken for an object to be detected. Therefore, the control apparatus 5 confirms that only the receiving signal in a time window W3 is the object to be detected and allows only the light emitting element I3 corresponding to the time window W3 within the display device 3 to light. By this method, the worker can clearly know the height of the object to be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a multi-time window type ultrasonic switch.

[Prior art] In order to detect the presence of customers in unmanned service corners of banks, ultrasonic pulses are emitted from a transmitter at regular intervals, and the ultrasonic pulses are reflected by an object and sent to a receiver. A distance-measuring ultrasonic switch is used that detects the presence or absence of an object by measuring the time it takes for the object to enter the object. An example is shown in FIG.

FIG. 4(a) is a diagram showing the basic operation of a conventional distance measuring type ultrasonic switch, and FIG. 4(b) is a diagram showing a time chart of transmitted and received signals. The ultrasonic switch 30 is installed near the ceiling 31 or a wall, and the ultrasonic pulses 33 transmitted from the wave transmitting section of the ultrasonic switch 30 reach the floor 31.
2 and received by the receiving section of the ultrasonic switch 30 is defined as the required reflection time T8. When the reflected wave from the object to be detected reaches the receiving part further than the required reflection time T,12, if the reflected wave is within the required reflection time T, the reflected wave from the object to be detected reaches the receiving part. It processes the detection object as if it exists, and outputs a signal indicating that the detection object exists.

[Problems to be Solved by the Invention] However, in the conventional method, when there is a wall surface other than the floor surface, the reflected wave from the wall surface is transmitted to the ultrasonic switch 3.
If the reflected wave from the wall surface is received within the required reflection time Ts, there is a problem in that the wall surface is erroneously treated as an object to be detected.

Furthermore, a similar phenomenon occurs when a protrusion is attached to a wall surface, etc., so the ultrasonic switch that simply detects the reflected wave within the required reflection time, as described above, is Currently, attached protrusions and the like are the cause of false alarms.

The presence or absence of obstacles that cause these false alarms is usually investigated after the ultrasonic switch 30 is installed, but it takes a very long time to investigate the presence or absence of obstacles.

The present invention solves the above-mentioned problems, and aims to provide a multi-time window type ultrasonic switch that can clearly define the detection area of a detected object and that does not cause false alarms due to obstacles. It is something to do.

[Means for Solving the Problems] In order to achieve the above object, the multi-time window type ultrasonic switch of the present invention has the following advantages: is divided into a predetermined number of time windows, and objects are detected within each time window.

[Operations] In the present invention, the time required to detect a reflected wave, that is, the time required for reflection, is subdivided into an arbitrary number of time windows,
Since reflected signals are extracted using each time window as a gate, it is possible to clearly display at what height an object exists.

[Example code] Examples will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of a multi-time window type ultrasonic switch according to the present invention, in which 1 is a wave transmitter, 2 is a wave receiver, 3 is a display, and 4 is an input. 5 is a control device, and 6 is a table.

The wave transmitting unit 1 and the wave receiving unit 2 transmit ultrasonic waves/wavelength pulses, respectively.
It performs reception and has the same configuration as the conventional one.

The display device 3 is composed of N light emitting elements corresponding to the maximum set number of time windows.
When the object to be detected is detected in the second time window, the control device 5 lights up the light emitting element I2. Note that a light emitting diode or the like can be used as the light emitting element.

The input device 4 is used to arbitrarily set various data for detecting a detected object in a table 6 within a predetermined range, and is composed of a dip switch or a keyboard and a display section such as a CRT. Ru.

The control device 5 is a microprocessor and RAM.

It is composed of a ROM, etc., and instructs the wave transmitting section 1 to transmit ultrasonic pulses, processes the signals received at the wave receiving section 2, controls the display on the display 3, and transmits the information input through the input device 4. Data is stored in table 6. Note that the signal received by the wave receiving unit 2 is processed digitally or analogously as necessary.

Table 6 shows various data set by the input device 4 for detecting the detected object, specifically, the number of time windows, the time width of each time window, and whether or not the received signal is canceled in any part. , small animal non-detection area,
Alternatively, it stores various data such as a threshold value V for detecting an obstacle. These data are arbitrarily set within the range determined by the input device 4, and their meanings will be described later.

In the configuration shown in Figure 1, there are two methods for not detecting obstacles: one is to cancel the received signal within the time window, and the other is to set a threshold for obstacle detection. be.

First, as a first method, a method of not detecting an obstacle by canceling a received signal within a time window will be described with reference to FIG.

Now, as shown in FIG. 2, the signal 1 received by the wave receiving unit is the signal reflected on the floor after the transmission pulse 10 is transmitted.
The reflected wave 11 from the wall during the reflection time T− up to 3,
Assume that there is a reflected wave 12 from the object to be detected, and table 6
, the time width is T during the required reflection time T
It is assumed that four time windows W+, Wt, Wa, and Wa are set: +, Ta, Ta, and T-.

At this time, the control device 5 detects the reflected wave and detects the received signal 14 corresponding to the reflected wave 11 from the wall and the detected object, as shown in FIG. Received signal 15 corresponding to reflected wave 12 and reflected wave 1 from the floor surface
3 is received. Since the received signal 16 is outside the range of the required reflection time Te, the control device 5 does not recognize it, but simply setting the time window will result in the time windows W+, We, Ws, W-
By gating the received signal at , not only the received signal 15 from the real detected object but also the received signal 14 from the wall is mistakenly recognized as the received signal from the detected object, and the time window W, It is determined that the object to be detected is present at W3, and the light emitting elements lllll3 corresponding to these time windows are turned on. Therefore, the operator checks the lighting state of the display 3, and in the case of FIG. 2, uses the input device 4 to set the table 6 to cancel the received signal within the time window W. As a result, the control device 5 ignores the received signal within the time window W+, so that the received signal 14 from the wall will not be mistaken for the detected object. Therefore, the control device 5 recognizes only the received signal 15 within the time window W3 as the detected object,
Only the light emitting element In corresponding to the time window Ws in the display 3 is turned on. This allows the operator to easily and clearly know at what height the object to be detected is present.

As described above, when the received signal within the time window is canceled, even if there is a received signal from the real detected object within the time window, it will not be recognized, so the time width of the time window to be canceled It is clear that the number of time windows needs to be set to a minimum, and for this reason, the number of time windows and their duration can be arbitrarily set within a predetermined range by the input device 4.

According to this first method, a small animal non-detection area can be secured to prevent small animals such as rats and cats moving on the floor from being mistakenly detected as objects to be detected. In other words, when using an ultrasonic switch as a security sensor, it is important to clearly distinguish between humans and small animals, but according to the first method above, an arbitrary Since the received signal within the time window can be canceled, by setting the time window up to a height of about 30 cm from the floor and canceling the received signal within the time window, you can create an area where small animals are not detected. can be ensured.

Next, as a second method, a method of not detecting an obstacle by setting a threshold value for detecting the obstacle will be described with reference to FIG. In FIG. 3, four time windows W+, W2, Wa, and W4 with time widths T+, Ta, T3, and T4 are set in table 6 during the required reflection time T@, and Furthermore, a threshold value V L h is set in the time window W2, and during the time window W2, the reflected wave 2 from the wall
It is assumed that there are 2. In addition, in the figure, 20 indicates a transmitted wave, and 21 indicates a reflected wave from the floor surface.

The threshold value V th is set to a level that somewhat exceeds the level of the received signal 24 corresponding to the reflected wave 22 from the wall.

At this time, the control device 5 compares the level of the received signal with the threshold value V th during the time window W2, and if the received signal level is lower than the threshold value V, the received signal The signal is determined to be the received signal 24 from the wall and ignored, and if the received signal level is equal to or higher than the threshold value V i h, the received signal is the received signal 25 from the real detected object. It is determined that this is the case, and the light emitting element I2 corresponding to the time window W2 in the display 3 is turned on.

According to the first method described above, all received signals within the time window are canceled, so even if the real object to be detected is at the same height as an obstacle such as a wall, the received signals are ignored. However, according to the second method, if the object to be detected is at the same height as the obstacle, the level of the received signal will be higher than when only the obstacle is present. Therefore, it is possible to easily determine whether or not the object to be detected exists at the same height as the obstacle.

Either one of the first method and the second method described above may be employed, or both may be used in combination.

In the above explanation, when setting the time width of the time window, setting the cancellation, or setting the threshold value Vi-, first set the time window appropriately, and then determine the height of the obstacle depending on the lighting state of the display 3. This can be done by checking whether an object exists.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible. For example, in the embodiments described above, the control device 5 is composed of a microprocessor or the like, but it can also be composed of a normal logic circuit. In addition, although the display device 3 is made up of a light emitting element, it can also be made up of a CRT, a liquid crystal display device, etc. In that case, the display section of the input device 4 and the display device 3 can also be used. be able to.

[Effects of the Invention] As is clear from the above description, according to the present invention, the following effects can be obtained.

■Since the number of time windows and their duration can be set arbitrarily, the height of the reflection can be clearly seen on the display. Further, it is possible to easily check whether there is any reflection from other than the floor surface after installing the multi-time window type ultrasonic switch according to the present invention.

■Since any received signal within the set time window can be canceled, even if there are obstacles such as walls, eaves, lighting equipment, etc. within the required reflection time, these obstacles will not be mistaken as the detected object. Never.

■The time width of the time window can be set arbitrarily, so
The time width of the time window to be canceled can be minimized.

■By setting a time window to the time width near the floor surface of the required time for reflection and canceling the received signal within the time window, it is possible to secure a small animal non-detection area where small animals are not detected.

- By setting a threshold value for not detecting an obstacle in the time window in which the obstacle exists, it is possible to detect an object at the same height as the obstacle without causing false alarms due to the obstacle.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an embodiment of a multi-time window type ultrasonic switch according to the present invention, and FIG. 2 is a diagram showing a method of not detecting obstacles by canceling received signals within a time window. Fig. 3 is a diagram for explaining a method of not detecting an obstacle by setting a threshold value for detecting an obstacle, and Fig. 4 is a diagram showing an example of a conventional distance measuring type ultrasonic switch. . 1... Wave transmitter, 2... Wave receiver, 3... Display, 4
... input device, 5 ... control device, 6 ... table. Applicant Atsumi Electric Co., Ltd.

Claims (2)

[Claims] (1) Multi-time, which is characterized by dividing the time required to detect reflected waves of ultrasonic waves to detect the presence or absence of an object to be detected into a predetermined number of time windows, and detecting the object within each time window. Window type ultrasonic switch. (2) The multi-time window type ultrasonic switch according to claim 1, wherein the time width of the time window is adjustable, and any part of the received signal can be ignored if necessary.