JPS603623B2 - Ultrasonic object detection device - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an ultrasonic object detection device that integrates an ultrasonic transducer and detects an existing object by detecting reflected waves from a detection area of ultrasonic waves transmitted from the transmitter using the receiver. It is. Conventionally, when setting the effective detection area during construction with this type of ultrasonic object detection device, the upper and lower detection distance limits are measured and the detection gate opening/closing time commensurate with each detection distance is set by adjusting a variable resistor. However, this adjustment requires a considerable amount of experience, and the adjustment work is troublesome and time-consuming. Furthermore, in order to prevent false alarms due to environmental changes, after setting the detection area, the detection area is slightly enlarged and the detection area setting confirmation work is performed to check whether the construction is done in a position where there are no reflective objects adjacent to the detection area. However, this setting confirmation work is as troublesome as the detection area setting work. The present invention has been made in view of the above points, and provides an ultrasonic object detection device that has a function of automatically setting a detection area and a function of confirming the setting of the detection area, and is extremely easy to install. The purpose is to The configuration of the present invention will be explained below. FIG. 10 is a block diagram showing the configuration of the present invention, in which the ultrasonic waves transmitted from the transmitter 40a of the integrated ultrasonic transducer 40 and reflected by an object are received by the receiver 40b. The received signal obtained by amplifying the output of the receiver 40b by the amplification part 41 is input to the object detection part 43 via the detection gate 42 which sets a detection area, and detects an object existing within the detection area. In the ultrasonic object detection device configured as above, a wave transmission control section 44 is provided which transmits ultrasonic waves from the transmitter 40a after confirming that no ultrasonic waves are received for a certain period of time after turning on the power, and also includes a wave transmission control section 44 that transmits ultrasonic waves from the transmitter 40a. detection area automatic setting means 45 for setting the opening/closing time of the detection gate 42, which starts reception after the end of the signal and ends reception a predetermined time before the time when the reception signal of the reflected wave from the fixed object is received; A setting confirmation means 46 checks whether an object detection signal can be obtained by increasing the gain of the intensifier 41 by a predetermined amount in a state where the detection area is automatically set, and an object detection signal is obtained by the setting confirmation means 46. An operation control means 47 is provided which operates the detection area automatic setting means 45 again when the object detection signal is not obtained and lowers the gain of the intensifying section 41 to the original state to operate in a predetermined detection state. and
This simplifies construction by making it easier to confirm whether the detection area has been set with sufficient margin, and also ensures that malfunctions caused by reflective objects adjacent to the detection area can be prevented. Examples will be described below using figures. The figure shows one embodiment of the present invention. In the figure, 14 is a microprocessor (hereinafter referred to as CPU) that performs signal processing of a transmitter 30 and a receiver 31, and 16 to 23 are microprocessors in this CPU 14. It represents the constituent blocks, and the functions of each block are as follows. 16 is a ROM in which a program is written, and starts from address 0 after power is turned on. Using this ROM 16, the arithmetic processing circuit 21 performs various calculations and processes. Data from the outside is taken in through inputs 18 and 19, and necessary data resulting from calculations is stored in RAM 17 and taken out as needed. 22 is Y
It is a register, and the address of RAM16 and output latch 2
This specifies an output number of 0. The output latch 20 is an output circuit controlled by the arithmetic processing 21, and serves as a latch circuit. Reference numeral 23 denotes an oscillation circuit, which generates a clock signal for operating the CPU 14 based on the signal from the clock generation circuit 15. Figures 1 and 2 show a block circuit diagram and a specific circuit diagram of an ultrasonic object detection device that uses this CPU 14 to perform signal processing. This is an ultrasonic transducer that converts the ultrasonic waves emitted to and received into electrical signals.This transducer 1 is connected to a transmission/reception switching circuit 2, which has two diodes connected in reverse series. The device 1 can be switched between transmitting and receiving waves. That is, when a large transmission signal is applied from the transmission amplifier circuit 8, the diodes connected in antiparallel are turned on, so a voltage is applied to the ultrasonic transducer 1, but when the transmission signal is turned off, a voltage is applied to the ultrasonic transducer 1. , both diodes are turned off and the output of the ultrasonic transducer 1 is output as a received signal. Therefore, the ultrasonic transducer 1 and the switching circuit 2 transmit the transmitter 4.
A transducer 40 is formed in which the transducer 0a and the transducer 40b are integrated. The output of the switching circuit 2 is connected to a pre-receiving amplifier 3 that amplifies weak electrical signals, and the output of the pre-receiving amplifier 3 has a gain whose gain gradually increases from the end of transmission. A time-varying amplifier 4 is connected. The gain of the gain time-varying amplifier 4 is controlled by the output of the voltage time-varying circuit 9, which is reset by the reset signal of the output (2) of the output latch 20 of the CPU 14. An attenuator 5 is connected to the output of the gain time-varying amplifier 9, and here the degree of attenuation is controlled by a signal from the output latch 20 of the CPU 14 (the attenuation becomes smaller when the transistor is turned on). By the tuned amplifier 6 connected to the output of the output 5,
A received signal having the same frequency as the transmitted signal is amplified. This amplified received signal is detected and amplified by the transistor of the waveform shaping circuit 7 and converted into a pulse signal as a digital signal, and the pulse signal is input to the signal switching circuit 11. Here, the delay OFF timer setting signal and the delay OFF timer setting signal are switched by the signal at the output (2) of the output latch 20 of the CPU 14, and the necessary signal is input to the input 19 of the CPU 14. That is, the CPU 14 switches between loading the delay-off time setting value and loading the received signal. The delay O
The FF timer setting signal is generated by the CPU 14 by setting constants using four switches of the setting circuit 10, and is designed to set a desired delay time. 24 is a synchronization circuit, to which the output ■ of the output latch 20 of the CPU 14 and the external synchronization terminal S are connected.
This is a circuit whose output is 0'' only when these two inputs are uo''. This synchronous output is input 1 as a synchronous input signal of the CPU 14.
8 is connected. 12 is an output circuit, and CPU1
The output relay is turned on and off by the signal at output 5 of output latch 4. Reference numeral 13 denotes a display circuit, which is turned on when the automatic setting is not in a good condition. Note that the detection gate 42, the object detection section 43, and the wave transmission control section 4
4. The detection area automatic setting means 45, the setting confirmation means 46, and the operation control means 47 are all realized by logical operation means using the CPU 14. The operation of the embodiment will be explained below. First, the operation of each section other than the CPU 14 will be explained. The transmission signal outputted from the output (2) of the CPU 14 is sent to the transmission amplifier 8, power amplified, and applied to the vibrator 1 via the transmission/reception switching circuit 2. The transducer 1 converts an electrical signal into an ultrasonic signal and transmits it into the air. When the transmission is completed, the transducer 1 acts as a receiving transducer and converts the reflected ultrasonic signal into a weak electrical signal. This signal passes through the transmission/reception switching circuit 2 and is applied to the pre-reception layer amplifier 3. The received signal amplified here is applied to a time-varying gain amplifier 4. The time-varying gain amplifier 4 is an amplifier whose gain increases little by little after the end of wave transmission, and its characteristics are that of a voltage-controlled amplifier as shown in FIG. 9, and the control voltage is generated by the voltage-varying circuit 9. The reset signal for the voltage time varying circuit 9 is sent out from the output (2) of the CPU 14 every time a wave is transmitted, as shown in FIG. The output of the time-varying gain amplifier 4 passes through an attenuator 5 and is then sent to a tuned amplifier 6.
is input to. In the attenuator 5, the degree of attenuation is small when the output (2) of the CPU 14 is "H", and the degree of attenuation is large when the output (2) is "L". By doing this, the gain of the entire amplifier system can be varied in two stages using the output signal (2) of the CPU 14. The output of the tuned amplifier 6 is input to a waveform shaping circuit 7, where it is converted into a pulse signal that is high when the received signal exceeds a certain level, and low otherwise. This pulse signal is input to the signal switching circuit 11, and the output of another delay off-timer setting circuit input to this circuit and the pulse signal are switched by the output (■) of the CPU 14 and input to the input 19 of the CPU 14. It has become so. That is, when the output (2) is nH'', the delay off-timer setting signal is input to the input 19 of the CPU 14, and when the output (2) is low, this pulse signal is input to the input 19 of the CPU 14. The output circuit 12 is a relay output, and is turned on and off by the output (2) of the CPU 14. The display circuit 13 is for displaying that setting is not possible, and is controlled by the output (2) of the CPU 14, and displays a flicker on the LED when the following state occurs during automatic setting. (1) When the lower limit detection distance exceeds the preset maximum value when setting the detection area (
0) When the lower limit detection distance becomes larger than the upper limit detection distance when setting the detection area (m) When there is a reflective object within the widened detection area when checking the detection area setting 24 is a synchronous circuit. This is a circuit that determines the timing to start transmitting waves. The output ■ of the CPU 14 is normally high. At this time, the output of the synchronization circuit 24 is also high, and the input 18 of the CPU 14 receives lnH''. In order to start transmitting waves, the output ■ of the CPU 14 is If the current changes to "L", the output of the synchronizing circuit 24 also becomes "L", and the input 18 of the CPU 14 becomes the "L" input. By the way, when there are multiple circuits shown in Figure 1, connect their synchronization terminals to output all CPU 14.
The inputs 18 of all CPUs 14 are configured to become "L" when the signal becomes "L", and the waves are transmitted at the same timing. Next, regarding the operation of the CPU 14, the flowcharts shown in FIGS.
The explanation will be based on the time chart shown in the figure. After installing the ultrasonic object detection device in the specified location, turn on the power supply 2.
5, the CPU 14 starts operating. FIG. 3 shows a flowchart for setting the detection area. When the power is turned on and the program starts, it is confirmed in [1] that no received sound waves are received for a certain period t. This is to check whether received sound waves due to external noise etc. are entering the receiver, and the detailed flowchart can be found in Chapter 6.
As shown in Figure a. First, reset the timer C at [41] to measure the glue gap. Next, in [42], it is determined whether there is a received sound wave, and if there is a received sound wave, the process returns to [41], and if there is no received sound wave, the process proceeds to the time judgment part in [48], and the timer C reaches t. Determine whether or not. Timer C
If it has not reached t, wait until it reaches t while confirming that there is no received sound wave. When the timer C=t., the process proceeds to the wave transmission timing determination section [44]. This step is for synchronizing each detection device when a plurality of ultrasonic object detection devices are operating in the same sound field, and when a single object detection device is operating, the process immediately advances to the next step. If the wave transmission timing is OK, proceed to [2] Wave transmission in FIG. 3. Here, a transmission signal is generated within the CPU 14, and the signal is sent to the transmission amplifier 8 from the output (2) of the output latch. Wave transmission complete (time T)
Then, at [3], timer A for setting the detection gate is started. At [4], timer A waits until 2 seconds have elapsed, and when 2 seconds have elapsed, it is set parallel to timer A [
5] starts the short distance margin time measurement timer B. In [6], check whether there is a received sound wave. The received sound waves referred to here are reverberant signals after transmission or reflected waves from reflective objects near the detector. While these received sound waves are present, counter B is reset at [7], and at [8] it is determined whether timer A has reached the maximum setting time, and if it is less than the maximum value, the timer returns to [5]. Restart B. If it is determined that there is no received sound wave in [6], then [
10] to determine the short distance margin time. If the received sound wave disappears and one second has not passed, return to [6]. On the other hand, if 1 sec has elapsed, the time TN of timer A at this time
is stored in the first memory (RAM 17 in the CPU 14) as the detection gate opening time, that is, the lower limit distance of the detection area. [8] In the timer A maximum value judgment section, if timer A = maximum layer, it means that the settings are not correct.

Press [9] to display the setting not possible, and then press [1].
) and redo the settings. After the opening time of the detection gate is set in this way, the presence or absence of a received sound wave is determined in [12] in order to set the closing time of the detection gate. If there is no received sound wave, it is determined in [13] whether the timer A has reached the set maximum time, and if it is within the set maximum time, the process returns to [12]. If there is a received sound wave in [12] or if timer A reaches the set maximum time in [13], then the time T when there is a received sound wave in [14] or from the maximum time set in timer A is determined in [14]. The time TF obtained by subtracting a certain long-distance margin time tc2 is set as the detection gate closing time in the second memory (RAM of CPU14).
17). It is determined in [15] whether the detection gate opening/closing times TN and TF obtained in this way are set correctly. If the closing time TF of the detection gate is larger than the opening time TN, the setting is correct, but if TN≧TF,
Since the detection gate opening/closing times TN and TF are not set correctly, turn on the setting not possible display and return to [1] to redo the settings. When TN<TF is established in [15], it means that the setting of the detection area is completed, and in [16], the setting impossible display is turned off and the process proceeds to the next step. When the detection area setting is completed, the detection area setting confirmation work is carried out as shown in FIG. This is to check whether there are any reflective objects near the detection area that could cause malfunctions. [17] is to confirm that the received sound wave does not exist for a certain period of time (t.), and the details are as explained in the explanation of the detection area setting above. If the received sound wave does not exist for a period t, then [18
] to set a gain up signal, and attenuator 5 increases the gain of the receiver higher than usual to slightly expand the detection area. Then, in [19], a transmission signal is created and sent to the transmission amplifier 8 from the output latch output (■). When the wave transmission is completed, timer A is reset and started at [20]. Then, it waits at [21] until the time on the timer A reaches the time TN stored in the first memory. When the time of timer A reaches TN, the timer A starts to judge whether or not there is a received sound wave at [22].
waits until the time TF becomes the time TF stored in the second memory. If timer A time < TF and there is a received sound wave, it means that there is a reflective object within the widened detection area, which means that there is a possibility of malfunction due to environmental changes, and the mounting position of the detection device is not appropriate. Therefore, in step [24], a display indicating that settings are not possible is made, and the process returns to step [1] in FIG. 2 again to set the detection area again. If the value of timer A = TF in [25], the set opening/closing time of the detection gate has been set correctly, and the setting disabled display is turned off in [26], and in [27]
The gain up signal is reset to return the gain of the receiver to the original value, and the process proceeds to the check number determination section [28]. In [28], find out how many cycles the above confirmation work was repeated,
If it is not the set number of times, return to [17] and start confirmation work. If the test passes the set number of consecutive tests, it means that the detection area setting confirmation work has been completed and the process moves on to the next step. Once the detection area setting confirmation work is completed, normal detection operation begins. This will be explained using the flowchart shown in FIG. [29] confirms that the received sound wave does not exist for time t. This is so that when the reflected wave of the sound wave transmitted in the previous period is received or noise is received, the timer C is reset.The detailed flowchart is shown in Figure 5a. is as described above. If the received sound wave does not exist for a certain period of time, a delayed off test is performed in [30]. When an output relay that has been turned on is turned off, the relay is turned off after a certain time delay after the received sound disappears while the detection gate is open.A detailed flowchart is shown in FIG. 5b. First, in [45], it is determined whether the detection signal is set. If it is set, the delay time measurement counter D is set to 0" in [49] and the delay off test is completed. If the detection signal has been reset in [45], proceed to [46] and counter ○ is compared with the delay time setting value, and if counter ○<setting value, count up counter D by one at [47].If counter D=setting value, go to [48]
At step [49], the output relay of the output circuit 12 is outputted with an off signal from the output latch, and at step [49], the counter D is reset to ``○'' to complete the delayed off test.In this way, when the delayed off test is completed, , [31] creates a transmission signal and sends it from the output latch output ■ to the transmission amplifier 8. When the transmission is completed, timer A is reset and started at [32].Then, the timer A is started at [33]. A waits until time TN, which is stored in the first memory, is reached. When the time of timer A reaches TN, the process proceeds to [34] and [35] and checks whether there is a received sound wave in [34]. If there is no received sound wave, it is checked in [35] whether the timer A has reached the time TF stored in the second memory.Here, the received sound wave continues until the timer A reaches time TF. If not, the detection signal is reset to move to the next cycle [2
Return to 9]. If the received sound wave is present when the timer A < TF, it means that the received sound wave was present during the period when the detection gate was open, and the process proceeds to [37]. Here, it is checked whether or not the received sound waves were present within the detection gate for N consecutive periods. When it exists for N consecutive periods, [3
Turn on the output relay at step 9], set the detection signal at step 40, and move on to the next cycle. If N cycles are not continuous in [37], then in [38] the number of cycles in which the received sound wave was present in the detection gate is memorized, and in order to move on to the next cycle,
29]. To summarize the above operations, when the power is turned on, the flowchart shown in Figure 2 checks to see if there are reflective objects near the detection area that could cause malfunctions caused by environmental changes. If an object exists, a setting is disabled display is displayed and the setting is performed again, and if a reflective object does not exist, the process proceeds to the flowchart of FIG. 5 and normal object detection operation is performed. In addition, in the example, timers A to ○, detection gate,
Although the memory is formed by the CPU 14, it goes without saying that it may be formed by individual circuits having the same functions. The present invention is configured as described above, and includes a wave transmission control section that transmits ultrasonic waves from a transmitter after confirming that no ultrasonic waves are received for a certain period of time after turning on the power, and
Detection area automatic setting means for setting an opening/closing time of a detection gate that starts receiving the reception signal after the end of the reverberation signal and ends the reception a predetermined time before the time when the reception signal of the reflected wave from the fixed object is received. and a setting confirmation means for checking whether an object detection signal is obtained by increasing the gain of the intensifier by a predetermined amount in a state where the detection area is automatically set, and when an object detection signal is obtained by the setting confirmation means. In addition to operating the detection area automatic setting means again, when an object detection signal is not obtained, the operation control means is provided to lower the gain of the multiplication part to its original state and operate it in a predetermined detection state. It will automatically check whether there are any reflective objects adjacent to the detection area, making it easier to check whether the detection area has been set with sufficient margin, and making installation extremely simple. With,
This has the effect of reliably preventing malfunctions caused by reflective objects adjacent to the detection area.

[Brief explanation of the drawing]

Fig. 1 is a block circuit diagram of an embodiment of the present invention, Fig. 2 is a specific circuit diagram of the above, Figs. 3 to 6 are flow charts of the above, Fig. 7 is a time chart of the above, Figs. FIG. 9 is a block circuit diagram showing the main part of the same as above, and FIG. 10 is a block circuit diagram showing the implementation of the present invention. 14 is a CPU forming a timer, a detection gate, a memory, a subtraction section and a judgment section, 30' is a transmitter, and 31 is a receiver. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10

Claims (1)

[Claims] 1 The receiver receives the reflected waves of the ultrasonic waves transmitted from the transmitter of the integrated ultrasonic transducer by the object, and the receiver output is amplified by the amplification section. In an ultrasonic object detection device that inputs a wave signal to an object detection unit via a detection gate that sets a detection area and detects an object existing within the detection area, the ultrasonic wave signal is input for a certain period of time after the power is turned on. A transmitting control unit is provided to transmit the ultrasonic wave from the transmitter after confirming that the ultrasonic wave is not received, and to start receiving the received signal after the reverberation signal ends, and to detect the received signal of the reflected wave from the fixed object. detection area automatic setting means sets the opening/closing time of the detection gate to finish reception a predetermined time before the time when the detection area is automatically set; A setting confirmation means for checking whether a detection signal is obtained; and a setting confirmation means for reactivating the detection area automatic setting means when an object detection signal is obtained by the setting confirmation means, and increasing the width when an object detection signal is not obtained. 1. An ultrasonic object detection device comprising: operation control means for lowering the gain of the section to its original state to operate in a predetermined detection state.