KR100295235B1 - Circuit for controlling saturating the element at signal-transceining system - Google Patents

Abstract

PURPOSE: A control circuit for preventing saturation of a signal transmission and a reception system is provided to prevent a malfunction by restricting saturation of an infrared sensor portion due to an external light. CONSTITUTION: A pulse signal generation portion(16) is used for generating a voltage of or a current pulse of a desired waveform. A light emitting diode drive portion(18) is used for driving a light emitting diode(2). The fourth resistance(20) is used for diving Vcc into predetermined voltages. A photo diode(21) is connected reversely between the sixth resistance(24) and the ground stage. The first capacitor(26) is connected between the fifth resistance(22) and the sixth resistance(24) connected between Vcc and a ground stage. The second capacitor(28) is connected between the sixth resistance(24) and the photo diode(21). The eighth and the ninth resistances(36,38) are connected with the ground stage in order to divide Vcc. A comparator(30) has a non-inverse terminal(+) connected with the eighth and the ninth resistances(36,38). The third capacitor(34) is connected parallel among the eighth and the ninth resistances(36,38) and the non-inverse terminal(+) of the comparator(30).

Description

Saturation prevention control circuit of signal transmission and reception system {CIRCUIT FOR CONTROLLING SATURATING THE ELEMENT AT SIGNAL-TRANSCEINING SYSTEM}

The present invention relates to a saturation prevention control circuit of a signal transmission and reception system, and more particularly, to an saturation prevention control circuit of a signal transmission and reception system that prevents an infrared sensing unit used as a signal transmission and reception system from being saturated with foreign light and malfunctioning. It is about.

As is well known, a sensor is a device that measures physical quantities in various states and converts them into electrical quantities for output. A sensor is a sense organ in human terms, and detects the physical quantity under all conditions of the vehicle quickly and accurately and inputs it to the control computing circuit. Therefore, it is no exaggeration to say that the sensor holds a "key" that determines the good and bad of the control system. Physical quantities required for controlling the vehicle include temperature, pressure, displacement, angular velocity, rotational speed, acceleration, and flow rate. As a sensor, it must operate for a long time under the most difficult conditions such as temperature, shock, vibration, immersion, oil, and noise.

Infrared rays are electromagnetic waves with a longer wavelength than visible light, and their wavelength is in the range of 0.72 to 1000 µm. Infrared sensors are optical sensors that detect light at these wavelengths, and are classified into quantum and thermal types. Recently, high-performance pyroelectric infrared sensors belonging to the thermal type have become available at low cost, and they have been actively used around us. It is used in public markets such as intruder alarm system, automatic door, fire detector, microwave oven, non-contact temperature measurement, film thickness measurement and object control and automation of production process.

The infrared sensor consists of a light emitting element and a detection element (for example, a photodiode). The detection element has a spontaneous polarization and is polarized to + and-at both ends of the device. The magnitude of the polarization is determined depending on the temperature. do. Normally, the charge on the surface of the device is neutralized by ion adsorption and is not apparent. When infrared rays reach the detection element through the window, the temperature of the element surface changes due to absorption of infrared rays. Since the magnitude of the spontaneous polarization changes in response to this change, neutralization of the surface charges due to the adsorption of ions also occurs, but since the change of the spontaneous polarization is faster, the change in charge corresponding to the temperature change can be instantaneously derived.

1 is a diagram illustrating a circuit configuration of a conventional infrared signal transmission / reception system. When the light emitting diode 2 receives power applied from a predetermined power source B + and emits infrared light, the infrared light is converted into a photodiode. 4) is absorbed to increase the temperature of the surface of the device, thereby changing the size of the spontaneous polarization to instantaneously change the charge is derived.

The first resistor 10 is configured in parallel with the photodiode 4 to transform the voltage applied to the base end of the first transistor 6 to a voltage that allows the first transistor 6 to conduct. It is configured in a standby state, so that the voltage generated while receiving infrared light from the photodiode 4 is applied to the emitter end of the first transistor (6) can be conducted to the first transistor (6). Make sure

In addition, the second transistor 8 to which the power source B + is applied to the emitter stage has its transistor (B) due to the conduction of the first transistor 6 to which the photodiode 4 is saturated and conducting at its base end. The voltage applied from the collector stage of 6) is passed through the second resistor 12 to be transformed into a voltage at which the second transistor 8 can be conducted, and is applied to the base terminal of the transistor 8. The voltage is divided by the resistor 14 and input to the control terminal of the rear stage.

However, according to the infrared sensor, even if extraneous light other than infrared is irradiated to the detection device through the window, the temperature of the device surface increases due to absorption of the light, and spontaneous polarization occurs, resulting in a change in the instantaneous charge. There is a lot of problems to cause.

Accordingly, the present invention has been made in view of the above circumstances, and a saturation prevention circuit is formed on the photodiode side to prevent the infrared sensing unit used for transmitting and receiving signals from being saturated by extraneous light. It is an object of the present invention to provide a saturation control circuit of a signal transmission / reception system which prevents a signal from being lost.

According to an embodiment of the present invention for carrying out the above object, the present invention relates to a saturation prevention control circuit of a signal transmission and reception system, wherein a signal generation is made such that a light emitting diode can emit infrared light by a pulse signal generator and a light emitting diode driver. A signal transmitting and receiving circuit comprising a means, a filter circuit for receiving and receiving light generated by the signal generating means and filtering and amplifying a signal processed voltage level, and a signal receiving means having an amplifying portion, between a predetermined power supply terminal Vcc and a ground terminal. The first capacitor 26 is connected between the fifth and sixth resistors 22 and 24 connected in series to each other, so that the reverse bias is applied to the power supply terminal Vcc side between the sixth resistor 24 and the ground terminal. The diode 21 is connected in the reverse direction, and a second capacitor 28 is provided between the sixth resistor 24 and the photodiode 21 terminal to provide predetermined light according to the on operation of the light emitting diode 2. When the light is received, a predetermined voltage level value is applied to the inverting terminal (-), while differentially calculating the voltage level applied to the inverting terminal (-) so as to output a normal pulse to the non-inverting terminal (+). The eighth and ninth resistors 36 and 38 for dividing the applied voltage Vcc to its inverting terminal (-) are connected in series to the ground terminal, and between the eighth and ninth resistors 36 and 38 so as to be applied. A non-inverting terminal (+) provides a saturation control circuit of a signal transmission and reception system at the time of signal transmission and reception comprising a comparator 30 to which the third capacitor 34 is connected in parallel to each other.

According to the present invention having the above-described configuration, a saturation prevention circuit is formed on the photodiode of the infrared sensing unit used for transmitting and receiving a signal so as to prevent saturation and malfunction by the irradiated extraneous light.

1 is a view showing the circuit configuration of a conventional infrared signal transmission and reception system,

2 is a circuit diagram illustrating a configuration of a saturation control circuit of a signal transmission and reception system according to an embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

2: light emitting diode, 16: pulse signal generator,

18: light emitting diode driver, 20: fourth resistor,

22: fifth resistor, 24: sixth resistor,

26: the first capacitor, 28: the second capacitor,

30: comparator, 32: seventh resistance,

34: third capacitor, 36: eighth resistor,

38: ninth resistor, 40: filter circuit,

42: amplification part.

Hereinafter, with reference to the accompanying drawings will be described in detail the configuration of the present invention.

2 is a block diagram showing the configuration of a saturation control circuit of a signal transmission and reception system according to an embodiment of the present invention, and reference numeral 16 denotes a microwave carrier in an apparatus or a circuit or radar for generating a voltage or current pulse having a desired waveform. Denotes a pulse signal generator that is a device for pulse modulation.

In addition, reference numeral 18 denotes a light emitting diode driver having a predetermined driving element for driving the light emitting diode 2, and a predetermined power source Vcc is applied to the light emitting diode 2 to emit infrared light. A fourth resistor 20 for dividing the voltage to a suitable voltage is configured, and the photodiode 21 is configured so that the infrared light emitted from the light emitting diode 2 can be reverse biased when received by the photodiode 21.

That is, a predetermined power supply Vcc passes through the fifth resistor 22 to divide the first capacitor 26 and the sixth resistor 24, respectively, and charge the first capacitor 26 to charge the sixth resistor 24. Since the photodiode 21 has a reverse bias, the photodiode 21 has a large impedance similar to that of the disconnection state because the photodiode 21 before receiving the infrared light has not been saturated. A current flow is formed only at the 28) side, and the current passing through the second capacitor 28 is configured such that only an AC component is detected due to the characteristics of the capacitor.

On the other hand, when the photodiode 21 receives infrared light emitted from the light emitting diode 2, the ions deposited on the photodiode 21 saturate due to the temperature rise of the device and are instantaneously caused by spontaneous polarization. A change in charge is derived to form a passage for current, whereby a current amount flowing into the second capacitor 28 is less than that before the photodiode 21 is saturated.

Since the voltage applied to the inverting terminal (-) of the comparator 30 due to the inflow of the current as described above is applied when the photodiode 21 receives infrared light, less voltage is applied than when it is not received. Compared with the reference voltage induced at the non-inverting terminal (+) of 30), only when the photodiode 21 receives infrared light, the normal pulse can be output by differential operation of the comparator 30.

Here, the third capacitor 34, the eighth resistor 36, and the ninth resistor 38 formed in the comparator 30 divide the applied voltage Vcc, so that the voltage level that can be used as a reference for the comparison is It is configured to be applied to the non-inverting terminal (+) of the comparator 30.

In addition, the voltage signal calculated and output by the comparator 30 passes through the filter circuit 40 and is designed to be amplified through the amplifier 42. For example, the filter circuit 40 Therefore, it is configured to use a cut-on filter or a band pass filter.

That is, the comparator 30 compares the voltage level applied to the inverting terminal (-) when the infrared light is received and the reference voltage level applied to the non-inverting terminal (+) by a differential operation. The pulse is configured to be output.

Hereinafter, the operation of the saturation prevention control circuit of the signal transmission and reception system according to the present invention having the above-described configuration will be described in detail.

First, the saturation prevention circuit 100 side is the current by the applied voltage (Vcc) is passed through the seventh resistor 32, the first capacitor 26 and the sixth resistor 24, the first capacitor (26) is charged, and since the photodiode 21 is composed of reverse bias, the impedance of the photodiode 21 side is excessive so that the current flowing through the sixth resistor 24 is mostly the second capacitor. Is applied to (28).

At this time, when the light emitting diode 2 is driven to emit infrared light, the photodiode 21 receives a predetermined pulse signal according to the light emission and the temperature of the internal device increases, thereby polarizing ions deposited on the device. The spontaneous polarization phenomenon is generated to derive the instantaneous change of charge and the photodiode 21 is in a conductive state, so that the current applied to the sixth resistor 24 is transferred to the photodiode 21 side and the comparator ( It is classified into 30) and flows in.

Therefore, since the voltage formed on the second capacitor 28 is smaller than the current flowing before the photodiode 21 is saturated, a low voltage is formed, resulting in an inverting terminal (−) of the comparator 30. ) Is also applied to a lower voltage than before the photodiode 21 is saturated.

At this time, the comparator 30 is a differential inverting comparator and generates a normal pulse signal when the voltage of the inverting terminal (-) configured therein is higher than the voltage level of the non-inverting terminal (+) and generates a low ( LOW) generates and outputs a reversed pulse. When the light emitting diode 2 is not driven and no signal is generated from the light emitting diode 2, the photodiode 21 is supplied via a power supply Vcc. When the saturation circuit prevention unit 100 is reversely biased and physically prevented from saturation, and the infrared light is transmitted to the photodiode 21 according to the on driving of the light emitting diode 2, the photodiode 21 The internal impedance is changed by the photovoltaic effect of) so that the voltage of the first capacitor 26 also changes in conjunction.

In this way, the voltage component changed in synchronization with the light emitting diodes 2 is detected only through the second capacitor 28 and applied to the inverting terminal (-) of the comparator 30, and compared with the applied AC component. When the reference voltage level of interest is applied to the non-inverting terminal (+) of the comparator 30, the comparator 30 generates a normal pulse signal and the filter circuit 40 and the amplifying unit 42 Only desired frequencies are applied sequentially so that they can be selectively amplified.

At this time, even when the external light, for example, sunlight or incandescent light, is irradiated on the photodiode 21, saturation is prevented by the fifth resistor 22 and the sixth resistor 24, so that stable operation is compensated for. It becomes the number.

On the other hand, the saturation prevention control circuit of the signal transmission and reception system according to the present invention described above is a circuit for preventing malfunction due to saturation of the elements generated during signal transmission and reception of the sensing unit employed in various devices without departing from the spirit and spirit of the invention. Applicable to a circuit for preventing saturation due to disturbances such as and noise.

As described above, according to the saturation prevention control circuit of the signal transmission / reception system according to the present invention, a saturation prevention circuit is formed on the photodiode of the infrared sensing unit used for transmitting and receiving signals to prevent saturation and malfunction due to external light irradiated. The advantage is that it enables reliable control of the device.

Claims (1)

A signal generating means which allows the light emitting diode to emit infrared light by the pulse signal generating unit and the light emitting diode driving unit, and a filter circuit and amplifying unit which receive and generate the light generated by the signal generating means to filter and amplify the signal processed voltage level. In a signal transmission and reception circuit composed of a signal reception means having: A first capacitor 26 is connected between the fifth and sixth resistors 22 and 24 connected in series between a predetermined power supply terminal Vcc and the ground terminal, and a power supply terminal between the sixth resistor 24 and the ground terminal. The photodiode 21 is connected in the reverse direction so as to be reverse biased with respect to the (Vcc) side, and the second capacitor 28 is provided between the sixth resistor 24 and the photodiode 21 terminal to connect the light emitting diode 2. When a predetermined light is received according to the ON operation, a predetermined voltage level value is applied to the inverting terminal (-), while differentially calculating the voltage level applied to the inverting terminal (-) so that a normal pulse can be output. Eighth, ninth resistors 36, 38 for dividing the applied voltage Vcc to the inverting terminal (-) are connected in series to the ground terminal so that the reference voltage level is applied to the inverting terminal (+). Comprising a comparator 30 in which the third capacitor 34 is connected in parallel between the resistor (36,38) and the non-inverting terminal (+) Saturation prevention control circuit of the signal transmitting and receiving system according to claim.

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