CA1269427A - Device for detecting object - Google Patents
Device for detecting objectInfo
- Publication number
- CA1269427A CA1269427A CA000481500A CA481500A CA1269427A CA 1269427 A CA1269427 A CA 1269427A CA 000481500 A CA000481500 A CA 000481500A CA 481500 A CA481500 A CA 481500A CA 1269427 A CA1269427 A CA 1269427A
- Authority
- CA
- Canada
- Prior art keywords
- signal
- detecting
- amplified
- voltage signal
- voltage
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- Geophysics And Detection Of Objects (AREA)
Abstract
TITLE OF INVENTION:
Device for Detecting Object ABSTRACT OF THE DISCLOSURE:
A device for detecting an object comprising a means for converting a variation of a floating capacity be-tween a sensor consisting of an electrode plate and an object to be detected into a variation of a frequency signal and a means for detecting the state of approach of the object in accordance with the rate of change of the frequency signal.
Device for Detecting Object ABSTRACT OF THE DISCLOSURE:
A device for detecting an object comprising a means for converting a variation of a floating capacity be-tween a sensor consisting of an electrode plate and an object to be detected into a variation of a frequency signal and a means for detecting the state of approach of the object in accordance with the rate of change of the frequency signal.
Description
~ 4~ 7 The present invention relates to a device for detecting state of approach of an object such as an obstacle.
Heretofore, a device for detecting an ob;ect which is used, for example, as an obstacle detecting device for detecting an obstacle duri~g running of an automobile comprises a transmit-ter for transmitting an electromagnetic wave or a ultrasonic wave having directivity and a ~eceiver for receiving the wave which has been reflected from the ob;ect, thereby detecting the ob;ect, such as obstacle.
Such a conventional device requires the use of the transmitter and the receiver, so that it ls complicated in construc-tion. Furthermore it employes a wave having directivity, so that it tends to provide an insensible area at close ,range.
The present invention eliminates the disadvantages of the conventional device and provides a device for detecting an approaching ob~ect, such as obstacle, in reliable manner, which has a simple construction.
According to the present invention there is provided a device ~or detecting an ob~ect, comprising: a first means for converting a variation of a floating capacity between a sensor consisting of an electrode plate and an object to be detected into a variation oE a frequerlcy signal; a second means for converting said frequency signal into a voltase signal; a third means including ~irst and second amplifiers arranged so that said voltage signal is supplied to both first and second amplifiers which then produce a first amplified signal and a second ampli-fied signal with a delay, respectively; and a fourth means for comparing said first and second amplified signals and d~tecting the state of approach of the object in accordance with the attenuation of said voltage signal. Thus, the device according to the present inYention provides a superior advantage in that the state of approach of an ob~ect can be detected in reliable ..~ ~, ~ 4~'7 manner by the simple construction. Suitably the device which includes an oscillator for generating a signal having a fixed frequency; two serially connected networks arranged at -the output side of said oscillator; a band-pass filter and amplifier for ef-fecting filtering-off of noise and amplification of the frequency signals fed from said networks; a detector for detecting the amplified frequency signal; and a voltage fluctuation detection circuit for detecting state of approach of the object in accordance with the attenuation of the voltage signal from said detector. Preferably a device in which said voltage fluctuation detection circuit includes: a first amplifier for amplifying an input voltage signal; a second amplifier having the same gain as that of the first amplifier for amplifying the input voltage signal with a fixed delay time; a voltage comparator for comparing the respective amplified outpu-t ~oltages to produce a high level output at the time of lowering of the input voltage signal; and a decision circuit for giving a decision on whether the time width of the high level output of the voltage comparator is wider than a predetermined width or not, thereby detecting the state of approach of the ob~ect to said sensor.
The present invention also provides a method for detecting an ob~ect comprising the steps of: converting a variation of a floating capacity between a sensor consisting of an electrode plate and an ob~ect to be detected into a variation of a frequency signal; converting said frequency signal into a voltage signal; supplying said voltage signal to a first ampli-fier and, after a delay, to a second amplifier which produces a first amplified signal and a second amplified signal with said delay, respectively; and comparing said first and second ampli-fied slgnals to detect the sta-te of approach of the ob;ect in accordance with the attenuation of said voltage signal.
~ ~ ~ 9 ~7 Now, the lnvention will be further described with reference to the accompanying drawings, in which:
Fig. 1 is a sircuit diagram showing the principle of the detection of ob~ect according to one embodiment of the present invention;
~;
Fig. 2 iS a block diagram showing an embodiment of the device according to the present invention;
:lu Fig. 3 is a block diagram showing an example of the construction of the voltage fluctuation detecting circuit shown in Fig. 2;
Fig. 4 is a time chart showing the signals in the 1~ voltage fluctuation detecting circuit, shown in Fig. 3; and Fig. 5 is a circuit diagram showing an example of the detailed construction of the voltage fluctuation detecting circuit.
Heretofore, a device for detecting an ob;ect which is used, for example, as an obstacle detecting device for detecting an obstacle duri~g running of an automobile comprises a transmit-ter for transmitting an electromagnetic wave or a ultrasonic wave having directivity and a ~eceiver for receiving the wave which has been reflected from the ob;ect, thereby detecting the ob;ect, such as obstacle.
Such a conventional device requires the use of the transmitter and the receiver, so that it ls complicated in construc-tion. Furthermore it employes a wave having directivity, so that it tends to provide an insensible area at close ,range.
The present invention eliminates the disadvantages of the conventional device and provides a device for detecting an approaching ob~ect, such as obstacle, in reliable manner, which has a simple construction.
According to the present invention there is provided a device ~or detecting an ob~ect, comprising: a first means for converting a variation of a floating capacity between a sensor consisting of an electrode plate and an object to be detected into a variation oE a frequerlcy signal; a second means for converting said frequency signal into a voltase signal; a third means including ~irst and second amplifiers arranged so that said voltage signal is supplied to both first and second amplifiers which then produce a first amplified signal and a second ampli-fied signal with a delay, respectively; and a fourth means for comparing said first and second amplified signals and d~tecting the state of approach of the object in accordance with the attenuation of said voltage signal. Thus, the device according to the present inYention provides a superior advantage in that the state of approach of an ob~ect can be detected in reliable ..~ ~, ~ 4~'7 manner by the simple construction. Suitably the device which includes an oscillator for generating a signal having a fixed frequency; two serially connected networks arranged at -the output side of said oscillator; a band-pass filter and amplifier for ef-fecting filtering-off of noise and amplification of the frequency signals fed from said networks; a detector for detecting the amplified frequency signal; and a voltage fluctuation detection circuit for detecting state of approach of the object in accordance with the attenuation of the voltage signal from said detector. Preferably a device in which said voltage fluctuation detection circuit includes: a first amplifier for amplifying an input voltage signal; a second amplifier having the same gain as that of the first amplifier for amplifying the input voltage signal with a fixed delay time; a voltage comparator for comparing the respective amplified outpu-t ~oltages to produce a high level output at the time of lowering of the input voltage signal; and a decision circuit for giving a decision on whether the time width of the high level output of the voltage comparator is wider than a predetermined width or not, thereby detecting the state of approach of the ob~ect to said sensor.
The present invention also provides a method for detecting an ob~ect comprising the steps of: converting a variation of a floating capacity between a sensor consisting of an electrode plate and an ob~ect to be detected into a variation of a frequency signal; converting said frequency signal into a voltage signal; supplying said voltage signal to a first ampli-fier and, after a delay, to a second amplifier which produces a first amplified signal and a second amplified signal with said delay, respectively; and comparing said first and second ampli-fied slgnals to detect the sta-te of approach of the ob;ect in accordance with the attenuation of said voltage signal.
~ ~ ~ 9 ~7 Now, the lnvention will be further described with reference to the accompanying drawings, in which:
Fig. 1 is a sircuit diagram showing the principle of the detection of ob~ect according to one embodiment of the present invention;
~;
Fig. 2 iS a block diagram showing an embodiment of the device according to the present invention;
:lu Fig. 3 is a block diagram showing an example of the construction of the voltage fluctuation detecting circuit shown in Fig. 2;
Fig. 4 is a time chart showing the signals in the 1~ voltage fluctuation detecting circuit, shown in Fig. 3; and Fig. 5 is a circuit diagram showing an example of the detailed construction of the voltage fluctuation detecting circuit.
2~
3~ -.
3~
1~~9~7 Fig. 1 is a circuit diagram showing the principle of de-tection of an object according to -the present invention. In the circuit as shown in Fig. 1, when a high frequency signal is applied to a series circuit including an electrode plate 1 and a resistor R, the floating capacity C between -the electrode' plate 1 and the objec-t 2 varies in accordance with the distance -therebetween and the high frequency outpu-t voltage at the potential dividing point varies accordingly. The present invention takes advantage of this phenomenon and -the elec-trode pla-te 1 is u-tilized as a sensor. The state of approach of -the object 2 can be detected by detecting the s-tate of lowering of the output voltage which is caused by the approach of the object 2 to said sensor .
Fig. 2 illus-trates an embodiment of -the device for detecting an object which is constructed on the princi-ple of the present invention as explained above. The device as illustrated in Fig. 2 includes an oscillator 3 for genera-ting a fixed frequency signal, a network ~
consisting of a resis-tance dividing circuit arranged at the output side of said oscillator 3, a sensor 1 consis-ting of an elec-trode plate connected to the dividing point of said network, a band-pass filter and amplifier 6 for effec-ting filtering-off and amplification of the ~ '7 high-frequency output signal produced by said network 4, a detector 6 for effecting detection of the amplified output signal, and a voltage fluctuation detecting circuit 7 for detecting the approach of the ob;ect by detecting the state of lowering of the detected voltage signal and feedin~ an alarm command to a driver 8 of an alarm 9.
In the construction as explained above, when a high-frequency signal having a fi~ed frequency Fo is fed Erom the oscillator 3 to the network 4, a high-frequency output signal which has been attenuated in proportion to the degree of approach u of the object to the sensor 1 is fed to the band-pass filter and amplifier 5, where the noise induced into -the sensor 1 and the like is filtered off and only the high-frequency component having frequency Fo is amplified. The frequency signal which has been amplified to a predetermined level is sub~ected to detection of 1~ the detector 5 and the D.C. voltage signal corresponding to the amplitude of said input frequency signal is fed to the voltage fluctuation detecting circuit 7. This voltage fluctuation detecting circuit 7 serves to detect the state of lowering of the D.C. voltage signal applied thereto and apply an alarm command to 2U the driver 8 ~!~
3U .
~ ~ ~g~'7 Thus, the alarm 9 produces an alarm signal, such as warning sound or warning light.
Fig. 3 illustra-tes an example of construction of the voltage fluctuation detecting circuit 7. This circuit includes a first amplifier 61 for amplifying the output voltage Vo of the detector 6, a second amplifier 62 for amplifying the same output voltage Vo with a predetermined delay, a comparator 63 for comparing the amplified output voltages Vl and V2, and a decision circuit 64 for giving a decision on whether the time width of the comparator output signal S is wider than a predetermined width or not. The amplifiers 61 and 62 have a same gain. The comparator 63 is applied with an offset voltage which is so ad~usted that it produces a low level output when Vl > V2 and a high level output when Vl < V20 l';
In the construction as described above, when the input voltage Vo is lowered during the period T the output voltage Vl of the amplifier 61 is also lowered during the same period, as shown in Fig. 4. The output voltage V2 of the amplifier 62 is lowered, with a flxed delay time Td, with the result that Vl < V2 '' during the 7~
3~
~ 7 period T + Td and consequently the output S of the comparator 63 has a high level. The period of lowering of the input voltage Vo varies, depending on the degree of approach of the object 2 to said sensor 1, and consequently the decision circuit 64 gives an alarm command when the time width of the output S of the comparator becomes wider than a predetermined value.
~;
In this regard it is to be noted that Vl = v2 when the lnput voltage Vo has become fixed, without variation of the position of the ob~ect 2 rela-tive to the sensor 1, while Vl > V2 when the ob-Ject 2 moves away from the sensor 1, and in each of these cases the output of the comparator 63 becomes of low level, so that no alarm command is produced thereby.
Fig. 5 illustrates an example of the detailed 1~ construction in which the each portion of the amplifiers 61 and 62 consists of an operational amplifier. The operational amplifier OP2 includes a delay element Cd connected in parallel with a feedback resistor. In this circuit construction, an offset voltage of the voltage comparator 63 is omitted by 2U properly selecting the offset voltages of the respective operational amplifiers OPl and OP2.
The device for detecting an ob~ect according to the ~;
3~
9~7 present invention has a simple construction, as a whole, so that it provides little trouble. It has no insensible area at close range, as in the conventional device, and provides better detecting state as ob;ect approaches to the device. It can detect the approaching object only and produce an optimum alarm.
Accordingly it is advantageous to detect an object when an automobile is moving backward, for example.
:l.u 1';
2~) ~;
3U .
3~
1~~9~7 Fig. 1 is a circuit diagram showing the principle of de-tection of an object according to -the present invention. In the circuit as shown in Fig. 1, when a high frequency signal is applied to a series circuit including an electrode plate 1 and a resistor R, the floating capacity C between -the electrode' plate 1 and the objec-t 2 varies in accordance with the distance -therebetween and the high frequency outpu-t voltage at the potential dividing point varies accordingly. The present invention takes advantage of this phenomenon and -the elec-trode pla-te 1 is u-tilized as a sensor. The state of approach of -the object 2 can be detected by detecting the s-tate of lowering of the output voltage which is caused by the approach of the object 2 to said sensor .
Fig. 2 illus-trates an embodiment of -the device for detecting an object which is constructed on the princi-ple of the present invention as explained above. The device as illustrated in Fig. 2 includes an oscillator 3 for genera-ting a fixed frequency signal, a network ~
consisting of a resis-tance dividing circuit arranged at the output side of said oscillator 3, a sensor 1 consis-ting of an elec-trode plate connected to the dividing point of said network, a band-pass filter and amplifier 6 for effec-ting filtering-off and amplification of the ~ '7 high-frequency output signal produced by said network 4, a detector 6 for effecting detection of the amplified output signal, and a voltage fluctuation detecting circuit 7 for detecting the approach of the ob;ect by detecting the state of lowering of the detected voltage signal and feedin~ an alarm command to a driver 8 of an alarm 9.
In the construction as explained above, when a high-frequency signal having a fi~ed frequency Fo is fed Erom the oscillator 3 to the network 4, a high-frequency output signal which has been attenuated in proportion to the degree of approach u of the object to the sensor 1 is fed to the band-pass filter and amplifier 5, where the noise induced into -the sensor 1 and the like is filtered off and only the high-frequency component having frequency Fo is amplified. The frequency signal which has been amplified to a predetermined level is sub~ected to detection of 1~ the detector 5 and the D.C. voltage signal corresponding to the amplitude of said input frequency signal is fed to the voltage fluctuation detecting circuit 7. This voltage fluctuation detecting circuit 7 serves to detect the state of lowering of the D.C. voltage signal applied thereto and apply an alarm command to 2U the driver 8 ~!~
3U .
~ ~ ~g~'7 Thus, the alarm 9 produces an alarm signal, such as warning sound or warning light.
Fig. 3 illustra-tes an example of construction of the voltage fluctuation detecting circuit 7. This circuit includes a first amplifier 61 for amplifying the output voltage Vo of the detector 6, a second amplifier 62 for amplifying the same output voltage Vo with a predetermined delay, a comparator 63 for comparing the amplified output voltages Vl and V2, and a decision circuit 64 for giving a decision on whether the time width of the comparator output signal S is wider than a predetermined width or not. The amplifiers 61 and 62 have a same gain. The comparator 63 is applied with an offset voltage which is so ad~usted that it produces a low level output when Vl > V2 and a high level output when Vl < V20 l';
In the construction as described above, when the input voltage Vo is lowered during the period T the output voltage Vl of the amplifier 61 is also lowered during the same period, as shown in Fig. 4. The output voltage V2 of the amplifier 62 is lowered, with a flxed delay time Td, with the result that Vl < V2 '' during the 7~
3~
~ 7 period T + Td and consequently the output S of the comparator 63 has a high level. The period of lowering of the input voltage Vo varies, depending on the degree of approach of the object 2 to said sensor 1, and consequently the decision circuit 64 gives an alarm command when the time width of the output S of the comparator becomes wider than a predetermined value.
~;
In this regard it is to be noted that Vl = v2 when the lnput voltage Vo has become fixed, without variation of the position of the ob~ect 2 rela-tive to the sensor 1, while Vl > V2 when the ob-Ject 2 moves away from the sensor 1, and in each of these cases the output of the comparator 63 becomes of low level, so that no alarm command is produced thereby.
Fig. 5 illustrates an example of the detailed 1~ construction in which the each portion of the amplifiers 61 and 62 consists of an operational amplifier. The operational amplifier OP2 includes a delay element Cd connected in parallel with a feedback resistor. In this circuit construction, an offset voltage of the voltage comparator 63 is omitted by 2U properly selecting the offset voltages of the respective operational amplifiers OPl and OP2.
The device for detecting an ob~ect according to the ~;
3~
9~7 present invention has a simple construction, as a whole, so that it provides little trouble. It has no insensible area at close range, as in the conventional device, and provides better detecting state as ob;ect approaches to the device. It can detect the approaching object only and produce an optimum alarm.
Accordingly it is advantageous to detect an object when an automobile is moving backward, for example.
:l.u 1';
2~) ~;
3U .
Claims (4)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A device for detecting an object, comprising: a first means for converting a variation of a floating capacity between a sensor consisting of an electrode plate and an object to be detected into a variation of a frequency signal; a second means for converting said frequency signal into a voltage signal;
a third means including first and second amplifiers arranged so that said voltage signal is supplied to both first and second amplifiers which then produce a first amplified signal and a second amplified signal with a delay, respectively; and a fourth means for comparing said first and second amplified signals and detecting the state of approach of the object in accordance with the attenuation of said voltage signal.
a third means including first and second amplifiers arranged so that said voltage signal is supplied to both first and second amplifiers which then produce a first amplified signal and a second amplified signal with a delay, respectively; and a fourth means for comparing said first and second amplified signals and detecting the state of approach of the object in accordance with the attenuation of said voltage signal.
2. A device for detecting an object according to Claim 1, in which the device includes an oscillator for generating a signal having a fixed frequency; two serially connected networks arranged at the output side of said oscillator; a band-pass filter and amplifier for effecting filtering-off of noise and amplification of the frequency signals fed from said networks; a detector for detecting the amplified frequency signal; and a voltage fluctuation detection circuit for detecting state of approach of the object in accordance with the attenuation of the voltage signal from said detector.
3. A device for detecting an object according to Claim 2, in which said voltage fluctuation detection circuit includes:
a first amplifier for amplifying an input voltage signal; a second amplifier having the same gain as that of the first ampli-fier for amplifying the input voltage signal with a fixed delay time; a voltage comparator for comparing the respective amplified output voltages to produce a high level output at the time of lowering of the input voltage signal; and a decision circuit for giving a decision on whether the time width of the high level output of the voltage comparator is wider than a predetermined width or not, thereby detecting the state of approach of the object to said sensor.
a first amplifier for amplifying an input voltage signal; a second amplifier having the same gain as that of the first ampli-fier for amplifying the input voltage signal with a fixed delay time; a voltage comparator for comparing the respective amplified output voltages to produce a high level output at the time of lowering of the input voltage signal; and a decision circuit for giving a decision on whether the time width of the high level output of the voltage comparator is wider than a predetermined width or not, thereby detecting the state of approach of the object to said sensor.
4. A method for detecting an object comprising the steps of: converting a variation of a floating capacity between a sensor consisting of an electrode plate and an object to be detected into a variation of a frequency signal; converting said frequency signal into a voltage signal; supplying said voltage signal to a first amplifier and, after a delay, to a second amplifier which produces a first amplified signal and a second amplified signal with said delay, respectively; and comparing said first and second amplified signals to detect the state of approach of the object in accordance with the attenuation of said voltage signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000481500A CA1269427A (en) | 1985-05-14 | 1985-05-14 | Device for detecting object |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000481500A CA1269427A (en) | 1985-05-14 | 1985-05-14 | Device for detecting object |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1269427A true CA1269427A (en) | 1990-05-22 |
Family
ID=4130489
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000481500A Expired - Lifetime CA1269427A (en) | 1985-05-14 | 1985-05-14 | Device for detecting object |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1269427A (en) |
-
1985
- 1985-05-14 CA CA000481500A patent/CA1269427A/en not_active Expired - Lifetime
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed | ||
| MKEC | Expiry (correction) |
Effective date: 20121205 |