JPH0134132Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an object detection device suitable for detecting the passage of paper in a copying machine, etc., and particularly includes an ultrasonic transducer or an ultrasonic transmitter and an ultrasonic receiver. The present invention relates to a structure in which at least the analog circuit portions of the wave transmitting circuit and the wave receiving circuit are integrated.

Conventionally, in a copying machine, etc., the entry of copy paper,
Optical or mechanical limit switch types are commonly used to detect passage, but it is not necessarily preferable to use light in a copying machine, and limit switches have disadvantages such as a lack of high-speed response. be. For this reason, the present applicant has previously proposed an object detection device that detects objects such as paper using ultrasonic signals.

By the way, in this type of object detection device that detects objects by transmitting and receiving ultrasonic signals, an ultrasonic transducer using a piezoelectric vibrator or an ultrasonic transmitter and an ultrasonic receiver are used. If the configuration uses an extension cable to connect the set and the transmitting circuit and receiving circuit housed in separate main body cases, interference, induction,
Due to the adverse effects of stray capacitance and the like, when mounted on a copying machine or the like, there are problems such as fluctuations in operating conditions or unstable operation.

In view of the above points, the present invention provides an ultrasonic transducer using a piezoelectric vibrator or a combination of an ultrasonic transmitter and an ultrasonic receiver. The object detection device is installed in a main body case that houses the objects, and elastically supports the external case or piezoelectric vibrator, thereby eliminating the harmful effects of interference, induction, stray capacitance, etc., and stabilizing the operation. This is what we are trying to provide.

Embodiments of the object detection device according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of the invention. In this figure, a main body case 1 houses an analog circuit 2 of a wave transmitting circuit and a wave receiving circuit. Here, the analog circuit 2 includes a pulse drive circuit 3 as a wave transmitting circuit that generates a high frequency pulse signal.
It consists of an amplifier circuit 4 and an amplitude detection circuit 5 of the wave receiving circuit, and a trigger input terminal TG to the pulse drive circuit 3 and a detection output terminal DET are led out to the outside. The amplifier circuit 4 amplifies the high frequency received signal, and the amplitude detection circuit 5 detects the amplitude of the output of the amplifier circuit 4. Further, an ultrasonic transducer TD is attached to the main body case 1 so that the wave transmitting/receiving surface is exposed outside the case. That is, the ultrasonic transducer TD has a built-in piezoelectric vibrator, and its outer case 6 is bonded to the main body case 1 via an elastic support 7, and the ultrasonic transducer TD is connected by a lead wire. It is electrically connected to the pulse drive circuit 3 and the amplifier circuit 4. The ultrasonic transducer
A matching box 8 having a central opening is attached to the wave transmitting/receiving surface side of the TD. This matching box 8 is provided to improve the directivity characteristics of the ultrasonic transducer TD and eliminate the adverse effects of harmful interference waves.

On the other hand, a digital signal processing circuit 9 is provided separately from the main body case 1, which generates a trigger pulse to the pulse drive circuit 3 and performs digital processing after amplitude detection in the wave receiving circuit. This digital signal processing circuit 9 is connected to the analog circuit 2 with a cable or the like, and is connected to the basic synchronization generation circuit 1.
0, an ultrasonic clock circuit 11 that receives a signal from this and generates a trigger pulse, a waveform shaping amplification circuit 12 of the wave receiving circuit, and a flip-flop.
It is equipped with FF.

In the above configuration, if the main body case 1 is arranged so that the wave transmitting/receiving surface of the ultrasonic transducer TD almost faces the paper or other object 20, and the device is operated, a trigger pulse to the trigger input terminal TG is generated. Correspondingly, the ultrasonic transducer TD is activated by the pulse drive circuit 3 included in the analog circuit 2 inside the main body case.
is driven, and an ultrasonic pulse signal is transmitted from this. The reflected signal from the object 20 is received by the ultrasonic transducer TD after a predetermined time delay, and this received signal is amplified and detected by the amplifier circuit 4 and amplitude detection circuit 5 included in the analog circuit 2 inside the main body case, and is sent to the detection output terminal. Output to DET. This output is digitally processed by the waveform shaping amplifier circuit 12 of the digital signal processing circuit 9, and when a reflection with a predetermined time delay is present, the flip-flop FF is activated and an object detection is indicated at its output terminal Q.

According to the configuration of the first embodiment, the analog circuit 2 of the wave transmitting circuit and the wave receiving circuit that processes high frequency signals
is housed in the main body case 1, and the ultrasonic transducer TD is provided in the main body case 1, so that the connection between the ultrasonic transducer TD and the analog circuit 2 can be shortened. , interference, guidance,
It is possible to stabilize the operation by removing the adverse effects caused by stray capacitance and the like. In addition, the ultrasonic transducer TD
By adhering the external case 6 to the main case 1 via the elastic support 7, the ultrasonic transducer
The influence of the vibration of the TD being transmitted to the main body case 1 can be removed.

FIG. 2 shows a second embodiment of the invention. In this figure, an ultrasonic transmitter TD1 and an ultrasonic receiver TD2 are attached to a main body case 1, respectively, so that the wave transmitting surface thereof is exposed outside the case, and the ultrasonic wave receiver TD2 is installed such that the wave receiving surface thereof is exposed outside the case. i.e. ultrasonic transmitter
External case 61 of TD1 and ultrasonic receiver TD2,
62 are respectively bonded to the main body case 1 via the elastic support 7, and the ultrasonic transmitter TD1 is connected to the pulse drive circuit 3 by a lead wire, and the ultrasonic receiver TD1 is connected to the pulse drive circuit 3 by a lead wire.
TD2 is electrically connected to the amplifier circuit 4.
Note that the housing of the analog circuit 2 in the main body case 1, the configuration of the digital signal processing circuit 9, etc. may be the same as in the first embodiment shown in FIG.

FIG. 3 shows a third embodiment of the present invention. In this figure, the outer case 6 of the ultrasonic transducer TD is directly fixed to the main body case 1, and the elastic support is provided inside the ultrasonic transducer TD. That is, the piezoelectric vibrator 32, which has the piezoelectric element 31 attached to the diaphragm 30, is adhered to the outer case 6 via the cylindrical elastic support 7A and the annular elastic support 7B. Note that the provision of the matching box 8 in the external case 6, the housing of the analog circuit in the main body case 1, the configuration of the digital signal processing circuit, etc. may be the same as in the first embodiment shown in FIG.

Note that in addition to the analog circuit, a part of the digital circuit may be provided inside the main body case. Furthermore, the analog circuit may have a hybrid configuration or a chip configuration.

As explained above, according to the present invention, an ultrasonic transducer using a piezoelectric vibrator or a combination of an ultrasonic transducer and an ultrasonic receiver can be configured using at least an analogue of the transmitting circuit and the receiving circuit. By installing the circuit part in the main body case and elastically supporting the external case or piezoelectric vibrator, interference, induction,
It is possible to obtain an object detection device with stable operation by eliminating the adverse effects caused by stray capacitance and the like.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a first embodiment of an object detection device according to the present invention, Fig. 2 is a block diagram showing a second embodiment of the present invention, and Fig. 3 is a block diagram showing a third embodiment of the present invention. FIG. 1... Main body case, 2... Analog circuit, 6,
61, 62... External case, 7, 7A, 7B...
Elastic support, 9...Digital signal processing circuit, 3
2...Piezoelectric vibrator, TD...Ultrasonic transducer,
TD1...Ultrasonic transmitter, TD2...Ultrasonic receiver.

Claims (1)

[Scope of claim for utility model registration] An ultrasonic transducer using a piezoelectric vibrator or a combination of an ultrasonic transmitter and an ultrasonic receiver, including at least the analog circuit portion of the transmitting circuit and the receiving circuit. In an object detection device that is installed in a main body case and detects objects by transmitting and receiving ultrasonic signals, the ultrasonic transducer or the external case of the ultrasonic transmitter and ultrasonic receiver is An object detection device, characterized in that it is attached to the main body case via an elastic support, or the piezoelectric vibrator is attached to the outer case via an elastic support, and the outer case is directly fixed to the main body case. .