TWM582132U - Optical sensor - Google Patents

Abstract

The present invention provides a light sensing device including a sensing circuit, a conversion circuit, a coupling mode selection circuit, and an amplification circuit. The sensing circuit detects the light and generates a corresponding current signal according to the intensity of the light. The conversion circuit converts the current signal into a voltage signal, and the voltage signal includes an AC component and a DC component. The coupled mode selection circuit filters out the DC component of the voltage signal to output an AC component in the voltage signal, or outputs a voltage signal including an AC component and a DC component without filtering the DC component. The amplifying circuit amplifies the voltage signal after filtering the DC component when the coupling mode selection circuit filters out the DC component to generate an output signal, and amplifies the voltage signal including the AC component and the DC component when the coupling mode selection circuit does not filter the DC component. Generate another output signal.

Description

Light sensing device

The present invention relates to a light sensing device, and more particularly to a light sensing device having an AC coupling mode and a DC coupling mode.

A general light sensing device uses a light detecting component to detect ambient light and generate a current to achieve light detection. However, the current generated by the light detecting component is too small, and the current generated by the light detecting component contains too much noise. If the current generated by the light detecting component is directly used for other applications, the light sensing device is likely to be wrong. action.

Furthermore, the circuit design of the light sensing device mostly uses non-integrated passive components. However, the use of excessive non-integrated passive components can result in increased routing and area of the board layout and is susceptible to noise interference. Further, if the light detecting component is damaged and needs to be replaced with a different light detecting component, for example, different types of light detecting components or light detecting components manufactured by different manufacturers, the repairer needs to further adjust other passive components and For the parameter configuration of the relevant circuit, each time the light detecting component is replaced, a set of circuit configurations needs to be adjusted correspondingly, which makes maintenance difficult and lacks flexibility in circuit design.

The present invention provides a light sensing device. The light sensing device includes a sensing circuit, a conversion circuit, a coupling mode selection circuit, and an amplification circuit. The sensing circuit detects a light and generates a corresponding current signal according to the intensity of the light. The conversion circuit converts the current signal into a voltage signal, and the voltage signal includes an AC component and a DC component. The coupling mode selection circuit filters out the DC component of the voltage signal to output an AC component in the voltage signal, or the coupling mode selection circuit does not filter the DC component and outputs a voltage signal including an AC component and a DC component. The amplifying circuit amplifies the voltage signal after filtering the DC component when the coupling mode selection circuit filters out the DC component to generate an output signal, and amplifies the voltage signal including the AC component and the DC component when the coupling mode selection circuit does not filter the DC component. Generate another output signal.

1 and FIG. 2, FIG. 1 is a block diagram of an embodiment of a light sensing device according to the present invention, and FIG. 2 is a circuit diagram of an embodiment of the light sensing device of FIG. The light sensing device 1 includes a sensing circuit 11, a conversion circuit 12, a coupling mode selection circuit 13, and an amplification circuit 14. The conversion circuit 12 is coupled between the sensing circuit 11 and the coupling mode selection circuit 13 , and the coupling mode selection circuit 13 is coupled between the conversion circuit 12 and the amplification circuit 14 .

In an embodiment, the sensing circuit 11 can be implemented as a phototransistor or a photodiode. The sensing circuit 11 detects a light, and the sensing circuit 11 generates a corresponding current signal according to the intensity of the light. For example, the intensity of the light is proportional to the magnitude of the current of the current signal. If the light is stronger, the sensing circuit 11 generates a current signal having a larger current. If the light is weaker, the sensing circuit 11 generates a current. Small current signal.

The conversion circuit 12 is coupled to the output of the sensing circuit 11, the conversion circuit 12 receives the current signal generated by the sensing circuit 11, and the conversion circuit 12 converts the current signal into a voltage signal. The coupling mode selection circuit 13 is coupled to the output of the conversion circuit 12, the coupling mode selection circuit 13 receives the voltage signal generated by the conversion circuit 12, and the coupling mode selection circuit 13 selectively filters out the DC component of the voltage signal to output the AC component. That is, the coupling mode selection circuit 13 can switchably filter or not filter the DC component in the voltage signal. In detail, the light sensing device 1 has an AC coupling mode and a DC coupling mode. When the light sensing device 1 is in the AC coupling mode, the coupling mode selection circuit 13 filters out the DC component of the voltage signal and outputs the AC component thereof. The rising slope of the voltage signal and the noise are reduced, and the voltage signal after filtering the DC component is relatively stable, but the voltage level thereof is low; when the light sensing device 1 is in the DC coupling mode, the coupling mode selection circuit 13 does not filter the voltage. The DC component of the signal outputs a voltage signal including an AC component and a DC component, and the voltage signal including the AC component and the DC component has a higher voltage level because it is not attenuated by the coupling mode selection circuit 13.

The amplifying circuit 14 is coupled to the output end of the coupling mode selection circuit 13. When the photo sensing device 1 is in the AC coupling mode, the amplifying circuit 14 receives the voltage signal of the AC component after the coupling mode selection circuit 13 filters out the DC component, and the amplifying circuit 14 Amplifying and filtering the voltage signal after the DC component and generating an output signal (hereinafter referred to as the first output signal), the first output signal is less susceptible to noise interference and has better stability; when the light sensing device 1 is in the DC coupling mode The amplifying circuit 14 receives the voltage signal including the alternating current component and the direct current component, and the amplifying circuit 14 amplifies the voltage signal of the unfiltered DC component and generates an output signal (hereinafter referred to as a second output signal), and the second output signal is compared with the first output. The signal has a higher voltage level. Therefore, according to the AC coupling mode and the DC coupling mode of the light sensing device 1, the light sensing device 1 converts the light into a first output signal that is less susceptible to noise interference after amplification, or converts the light into a voltage level. The second high-output signal, the light sensing device 1 can provide different output signals according to different application products, and the light sensing device 1 has good product compatibility.

In an embodiment, the light sensing device 1 further includes a control circuit 16 coupled to the coupling mode selection circuit 13. The control circuit 16 can control the coupling mode selection circuit 13 to filter the DC component of the voltage signal to output an AC component, or control the coupling. The mode selection circuit 13 does not filter the DC component of the voltage signal to output a DC component and an AC component. Therefore, the designer of the light sensing device 1 can control the coupling mode selection circuit 13 to correspondingly filter or not filter the DC component in the voltage signal according to the application setting control circuit 16 of the light sensing device 1 to generate a corresponding control signal. For example, if the light sensing device 1 is applied in a high noise environment, or the current signal generated by the photoelectric crystal or the photodiode included in the sensing circuit 11 generates more noise, the control circuit 16 can be used. The control device 1 is operated in the AC coupling mode; if the current signal generated by the photoelectric crystal or the photodiode included in the sensing circuit 11 generates a relatively small current signal or the light sensing device 1 is applied to the noise is low In the environment, the light sensing device 1 can be operated in the DC coupling mode by the control of the control circuit 16.

In one embodiment, the conversion circuit 12 includes an operational amplifier 121 and a resistor 122. The operational amplifier 121 includes an output terminal, a positive input terminal, and a negative input terminal. The positive input terminal and the negative input terminal of the operational amplifier 121 are coupled to the sensing circuit 11. The operational amplifier 121 has a negative feedback line. The resistor 122 is coupled between the output of the operational amplifier 121 and the negative input of the operational amplifier 121. That is, the output of the operational amplifier 121 is coupled to the negative input terminal via the resistor 122. The negative feedback line is formed, and the resistance value of the resistor 122 determines the magnification between the input signal and the output signal of the operational amplifier 121. Here, the current signal generated by the sensing circuit 11 flows through the resistor 122. The operational amplifier 121 generates the voltage signal according to the amplification factor determined by the resistor 122 to convert the current signal into a voltage signal, and the output terminal of the operational amplifier 121 outputs a voltage signal.

Furthermore, the conversion circuit 12 further includes a capacitor 123 coupled between the output terminal of the operational amplifier 121 and the negative input terminal of the operational amplifier 121, and the capacitor 123 is connected in parallel with the resistor 122. The capacitor 123 can filter out high frequency noise. In one embodiment, the resistor 122 is a variable resistor with adjustable resistance. The resistance of the resistor 122 can be controlled by the control circuit 16. The operational amplifier 121 can generate a corresponding voltage signal according to the resistor 122 having different resistance values.

In an embodiment, the coupling mode selection circuit 13 includes an AC coupling capacitor 131 and a changeover switch 132 (hereinafter referred to as a first changeover switch 132). The two ends of the AC coupling capacitor 131 are respectively coupled to the output end of the operational amplifier 121 and the amplifier circuit 14. The AC coupling capacitor 131 is connected in series to the operational amplifier 121 and the amplifier circuit 14. The two ends of the first switch 132 are also coupled to the output of the operational amplifier 121 and the amplifier circuit 14. The first switch 132 is connected in parallel to the AC coupling capacitor 131. The first switch 132 is controlled to be turned on or off by the control circuit 16. The light sensing device 1 is switched to the DC coupling mode or the AC coupling mode by turning on or off the first switching switch 132.

In detail, when the first switch 132 is turned off, the AC coupling capacitor 131 filters out the DC component of the voltage signal, and the amplifier circuit 14 receives the voltage signal including the AC signal after filtering the DC component via the AC coupling capacitor 131 to generate the first When the first switch 132 is turned on, the two ends of the first switch 132 are coupled to the output of the operational amplifier 121 and the amplifier circuit 14 to bypass the AC coupling capacitor 131, and the AC coupling capacitor 131 is not filtered. The DC component of the voltage signal, the amplifying circuit 14 receives the voltage signal including the DC component and the AC component output by the operational amplifier 121 via the first switching switch 132 to generate a second output signal.

In one embodiment, the light sensing device 1 includes input and output ports P1 and P2, and the input and output ports P1 and P2 are respectively located at two ends of the AC coupling capacitor 131, and the input and output ports P1 and P2 are respectively connected to an external capacitor. The AC coupling capacitor 131 is connected in parallel to the external capacitor. The AC coupling capacitor 131 is connected to the external capacitor to generate a larger equivalent capacitance value to further reduce the rising slope and noise of the voltage signal transmitted to the amplifier circuit 14. Therefore, by inputting and outputting 埠P1 and P2, the two ends of the ac coupling capacitor 131 can generate different equivalent capacitance values, and the designer can add an external capacitor to the input/output port P1 according to different application applications of the light sensing device 1. P2 to further improve the product compatibility of the light sensing device 1.

In an embodiment, the coupling mode selection circuit 13 further includes a resistor 133 and switchers 134-137 (hereinafter referred to as a second switch 134, a third switch 135, a fourth switch 136, and a fifth switch 137, respectively). . The one end of the resistor 133 is coupled to the AC coupling capacitor 131 and the first switch 132, and the other end of the resistor 133 is coupled to the switch 134, 135. The second switch 134 is coupled between the resistor 133 and the ground. The third switch 135 is coupled between the resistor 133 and the bias power supply. On the other hand, the amplifier circuit 14 includes an operational amplifier 141 and resistors 142 and 143. The resistors 142 and 143 determine the magnification between the input signal and the output signal of the operational amplifier 141. The operational amplifier 141 includes an output terminal, a positive input terminal, and a negative input terminal. The positive input terminal of the operational amplifier 141 is coupled to the AC coupling capacitor 131, the first switching switch 132 and the resistor 133. The operational amplifier 141 has a negative feedback amplification circuit, and the output of the operational amplifier 141 is coupled to the negative via the resistor 142. The input, that is, the resistor 142 is coupled between the output of the operational amplifier 141 and the input of its operational amplifier 141. The resistor 143, which is coupled to the resistor 142 to determine the aforementioned amplification factor, is coupled between the negative input terminal of the operational amplifier 141 and the fourth switching switch 136. The fifth switching switch 137 is coupled between the resistor 143 and the ground. The resistor 143 is coupled between the negative input terminal of the operational amplifier 141 and the fifth switching switch 137. The fourth switching switch 136 is coupled between the resistor 143 and the bias power supply.

Therefore, when the light sensing device 1 is in the AC coupling mode, the control circuit 16 controls the second switching switch 134 to be turned on and controls the third switching switch 135 to be turned off, and the resistor 133 is coupled to the ground via the second switching switch 134 without passing through the first The three-switch 135 is coupled to the bias power supply, and the control circuit 16 controls the fifth switch 137 to be turned on and controls the fourth switch 136 to be turned off. The resistor 143 is coupled to the ground via the fifth switch 137 without passing through the fourth switch 136. Coupled with a bias supply. Therefore, the positive input terminal of the operational amplifier 141 is coupled to the ground through the resistor 133 and the second switch 134, and the negative input terminal of the operational amplifier 141 is coupled to the ground via the resistor 143 and the fifth switch 137. The operational amplifier 141 amplifies the voltage component including the AC component after filtering the DC component by the AC coupling capacitor 131 according to the amplification factor determined by the resistors 142 and 143 to generate a first output signal.

On the other hand, when the light sensing device 1 is in the DC coupling mode, the control circuit 16 controls the second switching switch 134 to be turned off and controls the third switching switch 135 to be turned on, and the resistor 133 is coupled to the bias power supply via the third switching switch 135. The second switch 134 is coupled to the ground, and the control circuit 16 controls the fifth switch 137 to turn off and control the fourth switch 136 to be turned on. The resistor 143 is coupled to the bias power via the fourth switch 136 without the fifth switch. 137 is coupled to the ground. The positive input terminal of the operational amplifier 141 is coupled to the bias power supply via the resistor 133 and the third switch 135. The negative input terminal of the operational amplifier 141 is coupled to the bias power supply via the resistor 143 and the fourth switch 136. The operational amplifier 141 is The amplification factor determined by the resistors 142 and 143 amplifies the voltage signal including the DC component and the AC component transmitted by the first switching switch 132 to generate a second output signal, that is, based on the positive input terminal and the negative input terminal of the operational amplifier 141. The configuration of the bias power supply, the operational amplifier 141 amplifies the current signal generated by the sensing circuit 11 without amplifying the DC signal included in the bias power supply.

In one embodiment, the amplifying circuit 14 further includes a capacitor 144 coupled between the negative input terminal of the operational amplifier 141 and the output terminal of the operational amplifier 141, and the capacitor 144 is connected in parallel with the resistor 142. The capacitor 144 can filter out the high frequency. News. Furthermore, the resistors 142 and 143 are variable resistors whose resistance values can be adjusted, and the resistance values of the resistors 142 and 143 are controlled by the control circuit 16 so that the operational amplifier 141 has an adjustable magnification to generate a corresponding magnification. The first output signal and the second output signal.

In an embodiment, the light sensing device 1 further includes a bias circuit 15 coupled to the sensing circuit 11 . The biasing circuit 15 includes a biasing resistor 151, 152, 153. The biasing resistors 151 and 152 are coupled between the power supply terminal and the grounding terminal, and the biasing resistor 153 is coupled to the connection point between the biasing resistors 151 and 152. Through the bias resistors 151, 152, 153, the bias circuit 15 generates a bias signal to the sensing circuit 11 for the sensing circuit 11 to operate to detect light. Furthermore, the bias circuit 15 includes switches 154, 155. The switch 154 is coupled between the power supply terminal and the bias resistor 151, and the switch 155 is coupled between the bias resistor 153 and the conversion circuit 12 (the switch 155 is coupled to the bias input 153 and the positive input terminal of the operational amplifier 121). between). The switches 154, 155 can be controlled by the control circuit 16 to provide power saving control. When the light sensing device 1 is not required to detect light, the control circuit 16 can control the switches 154, 155 to be turned off to turn off the bias circuit 15. . Further, the bias circuit 15 further comprises a capacitor 156, a capacitor 156 is coupled across the bias resistor 152, the capacitor 156 can be charged to provide regulation of the function, and after the completion of charging capacitor 156, switch 155 to ensure that the operational amplifier 121 and sensing circuit 11 receive a stable bias signal.

In an embodiment, the light sensing device 1 further includes an input port P3, and the input port P3 is located between the bias resistors 151 and 152 of the bias circuit 15. The designer of the photo sensing device 1 can An external component is added as needed to connect the bias circuit 15 to the input port P3. Furthermore, as shown in FIG. 3, the optical sensing device 1 further includes an analog-to-digital conversion circuit (ADC) 17, which can be coupled to the output of the operational amplifier 121, and the analog digital conversion circuit 17 can operate The voltage signal generated by the amplifier 121 is converted into a digital signal for use in other circuits inside the light sensing device 1 or other circuits outside the light sensing device 1; or the analog digital conversion circuit 17 may be coupled to the operational amplifier 141. The analog output circuit 17 converts the first output signal and the second output signal generated by the operational amplifier 141 into digital signals for use in other circuits inside the light sensing device 1 or outside the light sensing device 1 Other circuits are applied.

In an embodiment, the light sensing device 1 can be applied to a fire protection system, and the light sensing device 1 is a smoke sensor, that is, the sensing circuit 11 can further include other light emitting units to generate an infrared light. When the smoke enters the light sensing device 1, the smoke particles cause the light beam of the infrared light to scatter, so that the photoelectric crystal or the photodiode of the sensing circuit 11 receives the scattered light. When the amount of smoke is more, the more light is received by the photoelectric crystal or the photodiode, the stronger the light is, and the larger the reverse current generated by the photoelectric crystal or the photodiode is. Figures 4 and 5 illustrate the larger reverse current generated by the optoelectronic crystal or photodiode as the intensity of the light increases. Therefore, when the amount of smoke in the environment is larger, the reverse current generated by the photoelectric crystal or the photodiode is larger, the sensing circuit 11 can generate a corresponding current signal, and according to the photoelectric crystal or photodiode produced by different manufacturers, the sense The current value of the current signal generated by the measuring circuit 11 is in the range of 100 pA to 1 uA.

In summary, according to one embodiment of the light sensing device of the present invention, the light sensing device is internally provided with a plurality of sets of switchable circuits, and the light sensing device can be set to a DC coupled mode or an AC coupled mode, and the operational amplifier The magnifications are all adjustable, and the light sensing device further has a built-in input and output port for external use, and the light sensing device can adjust and add on the circuit according to the characteristics of the photodiodes of different photoelectric crystals on the market. Components that greatly enhance the flexibility of their design and maintenance to meet most of the photoelectric smoke detection applications on the market. Moreover, in this case, the passive components, the filter circuit and the operational amplifier are integrated, thereby reducing the number of passive components to reduce the routing and area of the circuit board layout.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention. Any person having ordinary knowledge in the technical field can make some changes and refinements without departing from the spirit and scope of the present case. This is subject to the definition of the scope of the patent application.

1‧‧‧Light sensing device  11‧‧‧Sensor circuit  12‧‧‧Transition circuit  121‧‧‧Operational Amplifier  122‧‧‧resistance  123‧‧‧ Capacitance  13‧‧‧Coupling mode selection circuit  131‧‧‧AC coupling capacitor  132‧‧‧First switch  133‧‧‧resistance  134‧‧‧Second switch  135‧‧‧third switch  136‧‧‧fourth switch  137‧‧‧ fifth switch  14‧‧‧Amplification circuit  141‧‧‧Operational Amplifier  142‧‧‧resistance  143‧‧‧resistance  144‧‧‧ Capacitance  15‧‧‧Bias circuit  151-153‧‧‧ Bias resistance  154-155‧‧‧ switch  156‧‧‧ Capacitance  16‧‧‧Control circuit  17‧‧‧ analog digital conversion circuit  P1‧‧‧Import  P2‧‧‧Import  P3‧‧‧Import  

FIG. 1 is a block diagram showing an embodiment of a light sensing device according to the present invention.  FIG. 2 is a circuit diagram showing an embodiment of the light sensing device of FIG. 1. FIG.  FIG. 3 is a circuit diagram of another embodiment of the light sensing device of FIG. 1. FIG.  FIG. 4 is a circuit diagram of an embodiment of a photo-crystal or photodiode included in the sensing circuit of FIG. 1. FIG.  [Fig. 5] is a graph showing the current versus bias voltage of the photoelectric crystal or photodiode of Fig. 4.  

Claims (11)

A light sensing device comprising:  a sensing circuit for detecting a light and generating a corresponding current signal according to the intensity of the light;  a conversion circuit for converting the current signal to a voltage signal, the voltage signal comprising an alternating current component and a direct current component;  a coupling mode selection circuit for filtering the DC component of the voltage signal to output the AC component, or outputting the DC component and outputting the voltage signal including the AC component and the DC component;  An amplifying circuit for amplifying the filtered voltage signal to generate an output signal when the coupling mode selection circuit filters out the DC component, and amplifying the AC when the coupling mode selection circuit does not filter the DC component The voltage signal of the component and the DC component to generate another output signal.   The light sensing device of claim 1, further comprising a bias circuit coupled to the sensing circuit and the conversion circuit, the bias circuit generating a bias signal, the sensing circuit is based on the bias voltage The signal operates to detect the light, and the bias circuit includes:  Two bias resistors coupled between the power supply terminal and the ground terminal; and  A switch is coupled between one of the bias resistors and the power terminal.   The light sensing device of claim 2 further comprising an input port located at a connection point between the two bias resistors. The light sensing device of claim 1, further comprising a bias circuit coupled to the sensing circuit and the conversion circuit, the bias circuit generating a bias signal, the sensing circuit is based on the bias voltage The signal operates to detect the light, and the bias circuit includes:  a first bias resistor coupled to the power terminal;  a second bias resistor coupled to the first bias resistor and the ground and coupled to the first bias resistor between the power terminal and the ground terminal;  a capacitor connected in parallel to the second bias resistor;  a third bias resistor coupled to the connection point between the first bias resistor and the second bias resistor and coupled to one end of the capacitor;  A switch is coupled between the third bias resistor and the conversion circuit.   The light sensing device of claim 1, wherein the coupling mode selection circuit comprises:  An AC coupling capacitor is coupled in series with the conversion circuit and coupled between the conversion circuit and the amplification circuit to filter out the DC component of the voltage signal to output the AC component;  A first switching switch is connected in parallel to the AC coupling capacitor.   The optical sensing device of claim 5, wherein the amplifying circuit comprises an operational amplifier, the operational amplifier having a negative feedback circuit, wherein the coupling mode selection circuit further comprises:  a second switching switch coupled to the AC coupling capacitor and the first switching switch, and coupled between the positive input end and the ground end of the operational amplifier;  a third switching switch coupled to the AC coupling capacitor and the first switching switch, and coupled between the positive input end of the operational amplifier and the bias power supply;  a fourth switching switch coupled between the negative input terminal of the operational amplifier and the bias power supply; and  A fifth switching switch is coupled between the negative input terminal and the ground terminal of the operational amplifier.   The light sensing device of claim 5 further includes two input and output ports respectively located at two ends of the AC coupling capacitor. The light sensing device of claim 6, wherein the two input and output ports are connected to an external capacitor. The optical sensing device of claim 1, further comprising a control circuit for controlling the coupling mode selection circuit to filter the DC component of the voltage signal to output the AC component, or to control the coupling mode selection circuit The DC component of the voltage signal is filtered to output the voltage signal including the AC component and the DC component. The optical sensing device of claim 1, wherein the amplifying circuit comprises an operational amplifier and a plurality of variable resistors, the operational amplifier having a negative feedback circuit, the variable resistors being located on the negative feedback circuit. The optical sensing device of claim 1, wherein the conversion circuit comprises an operational amplifier and a variable resistor, the operational amplifier having a negative feedback line, the variable resistance being located on the negative feedback line.