KR19990061152A - Saturation prevention control circuit of signal transmission and reception system - Google Patents

Abstract

The present invention relates to a saturation prevention control circuit of a signal transmission / reception system. Signal generating means, which enables reliable control of the device, enables the light emitting diode 2 to emit infrared light by the pulse signal generating portion 16 and the light emitting diode driving portion 18, and the signal generating means. A signal transmission and reception circuit comprising a signal circuit having a filter circuit 40 and an amplifying section 42 for receiving light generated by the filter and filtering and amplifying the signal level, wherein the power supply terminal Vcc is connected to a ground terminal. The first capacitor 26 is connected between the first and second resistors 22, 24 connected in series to the second resistor 24, and is reverse biased with respect to the power supply terminal Vcc side between the second resistor 24 and the ground terminal. The photodiode 21 is reversely connected so that the first input terminal (-) is connected between the second resistor 24 and the photodiode 21 via a second capacitor 28. ) Is compared with the input potential supplied from the first input terminal (-) from the reference potential source (34, 36, 38) connected to the second input terminal (+), and the level according to the result value Characterized in that the signal is configured to be generated.

Description

Saturation prevention control circuit of signal transmission and reception 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 and outputs them. 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 the key to determining 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 is composed of a light emitting element and a detection element (for example, photoiode). The detection element has a spontaneous polarization and is polarized to + and-at both ends of the device. Is determined. 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.

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 signal generating means that the light emitting diode can emit infrared light by the pulse signal generating portion and the light emitting diode driving portion, and the light generated by the signal generating means In a signal transmitting and receiving circuit comprising a filter circuit for receiving and filtering and amplifying a voltage level processed by a signal, and a signal receiving means having an amplifier, a first capacitor is provided between a first resistor and a second resistor connected in series between a power supply terminal and a ground terminal. A comparator connected to the light receiving diode so as to be reversely biased between the second resistor and the ground terminal with respect to the power supply side, and a first input terminal of the comparator connected between the second resistor and the light receiving diode terminal via a second capacitor; The reference potential supplied from the reference potential generating source connected to the second input terminal is supplied from the first input terminal. Compared to provide a saturation prevention control circuit of the signal transmitting and receiving system, characterized in that configured so that the level signal corresponding to the results generated.

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.

* Setting of symbols for the main parts of drawings

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

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

22: first resistance, 24: second resistance,

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

30: comparator, 32: third resistance,

34: third capacitor, 36: fourth resistor,

38: fifth 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.

First, FIG. 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 battery power source B + of a vehicle and emits infrared light, the infrared light is emitted. The photodiode 4 is configured such that the temperature of the surface of the element is increased by absorption, thereby changing the magnitude of the spontaneous polarization, and thereby instantaneously changing the charge.

The seventh resistor 10 is configured in parallel with the photodiode 4 to convert the battery voltage applied to the base terminal of the first transistor 6 to a voltage that allows the 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 so that the first transistor can be conducted.

In addition, the second transistor 8 in which the battery power B + of the vehicle is constantly applied to the emitter stage is caused by the conduction of the first transistor 6 in which the photodiode 4 is saturated and conducting to the base stage thereof. The voltage applied from the collector terminal of the transistor 6 is passed through the eighth resistor 12 to be transformed into a voltage at which the second transistor 8 can be conducted and applied to the base terminal of the transistor 8. The voltage is divided by the ninth resistor 14 and input to the control stage of the rear stage.

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 device or circuit for generating a voltage or current pulse of a desired waveform, or a generator. An apparatus for pulse modulating a microwave carrier represents a pulse signal generator.

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 battery power source B + of the vehicle is applied to the light emitting diode 2 to emit infrared light. The sixth resistor 20 for dividing the voltage to a suitable voltage is configured, and the photodiode 21 is configured such that the infrared light emitted from the light emitting diode 2 can be reverse biased when received by the photodiode 21. do.

That is, while the battery power source B + of the vehicle passes through the seventh resistor 22, the sixth resistor is divided by the first capacitor 26 and the sixth resistor 24, respectively, and the first capacitor 26 is charged. Since the photodiode 21 has a reverse bias, the current passed through the 24 has an excessive impedance similar to that of the disconnection state because the photodiode 21 before receiving the infrared light has a saturation state. A current flow is formed only in the capacitor 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 non-inverting terminal (-) of the comparator 30 due to the inflow of the current as described above, 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 inverting terminal (+) of (30), the photodiode 21 is configured such that a normal pulse can be output by differential operation of the comparator 3 only when the infrared light is received.

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 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.

At this time, the comparator 30 is configured inside the saturation prevention circuit 100 so that the voltage generated by the photodiode 21 by the reception of infrared light and the voltage level applied by the reception of the extraneous light can be compared with each other. The level of extraneous light other than the light is saturated so that the output voltage output after comparing with the voltage of the inverting terminal (+) is different from the voltage value of the comparative output when the infrared light is received. It is configured to prevent it from becoming.

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 22, 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 change of the instantaneous charge so that 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 the non-inverting terminal of the comparator 30 ( The voltage flowing into −) is also applied with 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), it is configured to generate and output a reversed pulse. When the photodiode 21 is saturated with extraneous light, the voltage level is different compared to when an infrared light is incident. Normal output voltage is not generated and the signal is filtered by the filter circuit 40 so that the controller (not shown) can be prevented from malfunctioning due to saturation of the photodiode 21 when incident light is incident. do.

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)

Signal generation means by which the light-emitting diode 2 can emit infrared light by the pulse signal generation unit 16 and the light-emitting diode driving unit 18, and a voltage processed by receiving the light generated by the signal generation means. In the signal transmitting and receiving circuit comprising a signal receiving means having a filter circuit 40 and an amplifier 42 for filtering and amplifying a level, A first capacitor 26 is connected between the first and second resistors 22 and 24 connected in series between the power supply terminal Vcc and the ground terminal, and a power supply terminal between the second resistor 24 and the ground terminal. The photodiode 21 is reversely connected so as to be reverse biased with respect to the Vcc side, and the first input terminal (−) is connected between the second resistor 24 and the photodiode 21 via a second capacitor 28. Is connected to a reference potential from the reference potential generators 34, 36 and 38 connected to the second input terminal (+) and the input potential supplied from the first input terminal (-). And a saturation prevention control circuit of a signal transmission / reception system, characterized in that it is configured to generate a level signal in accordance with the result.