TWI452403B - A light to frequency conversion apparatus and a method thereof - Google Patents

Description

Optical frequency conversion device and method

The invention relates to an optical frequency conversion device and method, in particular to an optical frequency conversion device and method with a correction function, which can improve the linearity of optical frequency conversion, and is suitable for the optical industry and the lighting industry.

The optical frequency conversion device is a device for converting the light intensity in the environment into a digital signal of a frequency. The digital signal that is transferred out is convenient for back-end micro-processing or computer operation, and can be widely used for detecting or controlling the light intensity in the environment. Applications such as the optical industry and the lighting industry. In recent years, due to the rapid development of mobile devices, the demand for backlights for light, durable and low-cost optical devices such as mobile phones, notebooks, PDAs, and the like has been increasing. In addition, small, low-cost sensitization and controllers themselves have important economic benefits. Traditionally, the photoreceptor usually produces an analog signal after detecting light, and an analog digital converter (ADC) is needed to convert the analog signal into a digital signal, so the hardware cost is high.

In order to improve the digital end application of the photosensitive device, the prior art proposes an optical frequency conversion device capable of directly outputting a digital signal with a frequency, without using an analog digital converter, thereby reducing the hardware cost and size; the digital signal can be utilized. Radio, infrared, visible light, ultrasonic and other transmission methods can be widely used in microscopes, color code detection, greenhouse lighting control, LCD screen brightness control and other devices; however, when the number of photoreceptors used in the photosensitive device increases, according to The digital signal generated by the prior art design is not ideal in terms of the frequency and the linearity of the number of photoreceptors used, especially as the number of photoreceptors increases, the output signal The linearity of the frequency also decreases, which affects the accuracy of the use of the back-end digits. To improve this problem, the present invention proposes an optical-frequency conversion device and method with a correction function, which can improve the linearity of the output signal frequency to improve The accuracy of the back-end digital use.

The main object of the present invention is to provide a digital output signal having a frequency converted into a digital output signal, which is converted into a correction voltage, and then the correction voltage is fed back as a voltage applied to the photoreceptor array. An optical frequency conversion device and method for correcting the frequency of the digital output signal and increasing the frequency scaling linearity of the optical frequency conversion output signal.

In order to achieve the above object, the optical frequency conversion device of the present invention comprises a first control unit, a plurality of photosensor arrays, a comparator, a second control unit, a correction unit and a switch. The first control unit is configured to receive a set of encoded signals, and generate a first control signal and a set of second control signals according to the set of encoded signals; the plurality of photoreceptor arrays, wherein each of the photoreceptor arrays Including at least one photoreceptor, and each photoreceptor array includes a different number of photoreceptors for receiving the second set of control signals, and selecting a photoreceptor array according to the set of second control signals for receiving incident light Generating an output current I _ph proportional to the intensity of the incident light; the comparator is configured to receive a reference voltage V _ref and an output current I _{ph of} the photoreceptor array, and generate according to the reference voltage V _ref and the output current I _ph a frequency of the output current I _ph a first signal proportional to the frequency of the output of the comparator and receives the first control signal to control the conduction state of the comparator The second control unit is configured to receive the first frequency output signal and generate a second frequency output signal and a third control signal, wherein a frequency of the second frequency output signal is proportional to a frequency of the first frequency output signal; The correcting unit is configured to receive the second frequency output signal, and generate a correction voltage V _cali according to the second frequency output signal; and the open relationship is respectively connected to the plurality of photoreceptor arrays and the correcting unit, and receive the And a third control signal to control an on state of the switch. When the switch is in an on state, the plurality of photoreceptor arrays are coupled to the correction voltage V _cali .

Thereby, the voltage terminal of the photoreceptor array in the optical frequency conversion device is coupled with the output signal of the optical frequency conversion device to form a feedback circuit, and the applied voltage can be adjusted instantaneously with the frequency output signal, thereby improving The scaled linearity of the frequency output signal.

When implemented, the photoreceptor is a photodiode.

In implementation, each photoreceptor array further includes a switching element.

In implementation, the switch further includes at least one switching element.

In implementation, the switch further includes a plurality of switching elements, the number of which is the same as the number of photoreceptor arrays.

In implementation, the switching element of the photoreceptor array or the switching element of the switch is a field effect transistor.

In implementation, the second control unit further includes a trigger circuit and a digital scaling circuit, wherein the trigger circuit is configured to generate the third control signal, including a clock signal, a first D-type positive and negative Flip-flop, the data end (D) is for receiving the first frequency output signal, the clock end inputs the clock signal, and the output end outputs a first delay signal, and a second D type is positive In the inverter, the data terminal (D) inputs the first delay signal, the clock terminal inputs the clock signal, and the output terminal outputs a second delay signal and a NAND gate for Receive this a first delay signal and the second delay signal, and generating the third control signal according to the first delay signal and the second delay signal; and the digital scaling circuit is configured to generate the second frequency output And a signal for receiving the second delayed signal and scaling the frequency of the second delayed signal to generate the second frequency output signal.

In implementation, the correction unit further includes a microprocessor and a digital to analog converter (DAC) circuit, and after receiving the second frequency output signal, the microprocessor generates a set of digital code, and then the digital The analog analog circuit converts the set of digital bit codes into a correction voltage V _cali .

An optical frequency conversion method according to the present invention includes the following steps: a. receiving a set of encoded signals by a first control unit, and generating a first control signal and a set of second control signals according to the set of encoded signals; Receiving the second set of control signals by a plurality of photoreceptor arrays, wherein each photoreceptor array comprises at least one photoreceptor, and each photoreceptor array comprises a different number of photoreceptors, and a photosensitive light is selected according to the set of second control signals An array for receiving incident light and generating an output current I _ph proportional to the intensity of the incident light; c. receiving a reference voltage V _ref and an output current I _{ph of the} photoreceptor array by a comparator, and according to the reference voltage V _ref and the output current I _ph generate a first frequency output signal having a frequency proportional to the output current I _ph , the comparator receiving the first control signal to control the on state of the comparator; d. The second control unit receives the first frequency output signal and generates a second frequency output signal and a third control signal, wherein the frequency of the second frequency output signal is proportional to First frequency output signals; E receiving the output signal at a second frequency correction unit and generating a correction voltage V _cali according to the second output signal frequency;. F with a plurality of switches are connected to the photoreceptor array. And the correcting unit, and receiving the third control signal to control an on state of the switch, and when the switch is in an on state, the plurality of photoreceptor arrays are connected to the correction voltage V _cali .

In order to have a better understanding of the features and functions of the present invention, the embodiments are described in detail with the drawings:

1 is a circuit block diagram of an embodiment of an optical frequency conversion device of the present invention, which includes a first control unit 110, a plurality of photosensor arrays 120, a comparator 140, and a second control. The unit 150, a correction unit 160 and a switch 130.

The first control unit 110 is configured to receive a set of encoded signals 113, and generate a first control signal 111 and a set of second control signals 112 according to the set of encoded signals 113; each of the plurality of photoreceptor arrays is photosensitive The array includes at least one photoreceptor 121, wherein each photoreceptor array has a different number of photoreceptors; the photoreceptor array is configured to receive the set of second control signals 112, and select a photoreceptor according to the set of second control signals An array for receiving incident light and generating an output current I _ph 124 proportional to the intensity of the incident light; the photoreceptor can be any photosensitive element capable of generating an output signal proportional to the intensity of the incident light, such as a photodiode ( Each photoreceptor array may further include a switching element 122, which is typically a field effect transistor, wherein a metal oxide semiconductor field effect transistor (MOSFET) is preferred; the comparator 140 is used for Receiving the output current I _ph 124 and a reference voltage V _ref 141, and generating a first frequency output signal 142 having a frequency proportional to the output current I _ph , the comparator 140 receiving The first control signal 111 is used to control the on state of the comparator; the second control unit 150 is configured to receive the first frequency output signal 142 and generate a second frequency output signal 152 and a third control signal 151, wherein The frequency of the second frequency output signal 152 is proportional to the frequency of the first frequency output signal 142; the correction unit 160 is configured to receive the second frequency output signal 152 and generate a correction based on the second frequency output signal 152 The voltage V _cali 162; and the switch 130 is connected to the plurality of photoreceptor arrays 120 and the correction unit 160 respectively, and receives the third control signal 151 to control the conduction state of the switch. When the switch 130 is in the on state, the switch 130 A plurality of photoreceptor arrays 120 are coupled to the correction voltage V _cali 162; the switch 130 may further include a switching element, which is typically a field effect transistor, wherein a metal oxide semiconductor field effect transistor (MOSFET) is preferred; The switch 130 may further include a plurality of switching elements, preferably in the same number as the number of photoreceptor arrays.

The relationship between the output signal frequency of the optical frequency converter and the incident light intensity can be obtained by the following calculation:

First, since the photoreceptors used in the photoreceptor array 120 are all the same, the photocurrent I _ph induced by each photoreceptor under the same light intensity is also the same; after the light is incident on the photoreceptor, the induced photocurrent I _ph photoreceptor so that discharge starts, and thus reduces the input voltage V _j 140 of the comparator; if V _j is reduced to below the reference voltage V _ref of the comparator, the comparator output voltage is converted to a high potential (logic high) Therefore, the third control signal generated by the second control unit 150 is output as logic true to turn on the switch 130; if the switch 130 is connected to an applied voltage V _i , when the switch 130 is turned on, the negative input terminal of the comparator is connected The applied voltage V _{i is} applied while the photoreceptor in the photoreceptor array 120 begins to charge. The frequency f of the output signal produced by the comparator 140 can be obtained by: f = I _ph / C _total (V _i - V _ref ) (1)

Where C _total is the total capacitance of the comparator's negative input. According to the formula (1), the relationship between the frequency of the output signal generated by the comparator and the photocurrent I _ph is proportional. Taking a photodiode as an example, the photocurrent I _ph can be obtained by: I _ph =PA _j λ η _c /hc (2)

Where P is the incident light power, A _j is the contact area, λ is the incident light wavelength, η _c is the external quantum efficiency, h is the Planck constant, and c is the speed of light. According to the formula (2), the output current I _ph is proportional to the incident light power. Combining equations (1) and (2), we can get f=PA _j λ η _c /hc C _total (V _i -V _ref ) (3)

The total capacitance C _total can be obtained by: C _total = Σ ₁ ⁿ C _jn + C _comp + C _line (4)

Where C _jn is the equivalent capacitance of each photodiode, C _comp is the capacitance of the comparator, and C _line is the capacitance of the transmission line. Combining equations (3) and (4), we can get f=PA _j λ η _c /hc(V _i -V _ref )*(Σ ₁ ⁿ C _jn +C _comp +C _line ) (5)

It can be concluded from equation (5) that since the total capacitance varies with the number of photodiodes used, the linear relationship between the frequency and the incident light intensity is also affected.

The invention proposes to convert the output signal into a correction voltage, and then the correction voltage is fed back to the photodiode plus voltage V _i terminal, and at this time, V _i in the formula (5) will be equal to V _cali , then the first ( 5) The formula becomes f=PA _j λ η _c /hc(V _cali -V _ref )*(Σ ₁ ⁿ C _jn +C _comp +C _line ) (6)

Therefore, the nonlinear term from the capacitance can be compensated by the (V _cali -V _ref ) term, and the linearity of the output frequency and the incident light intensity is improved.

FIG. 2 is a block diagram showing another embodiment of the optical frequency conversion device of the present invention. In this embodiment, the plurality of photoreceptor arrays 120 are three photoreceptor arrays, respectively comprising 1, 5, and 25 photodiodes, and the first control unit 110 receives a set of encoded signals (S ₀ , S ₁ ), generating a first control signal 111 and a set of second control signals 112 according to the set of coded signals, respectively corresponding to the switch control of the three photoreceptor arrays, encoding the signals (S ₀ , S ₁ ) and the first The corresponding relationship between the control signal and the selected photoreceptor array is as shown in Table 1; the switch 130 includes three field effect transistors respectively connected to the photoreceptor array, wherein the field effect transistor is a metal oxide semiconductor field effect transistor (MOSFET) is preferred.

The second control unit 150 includes a trigger circuit 170 and a digital scaling circuit 180. The trigger circuit 170 includes a clock signal (CLK) 176 and a first D-type flip-flop (Flip-flop). 171, the data terminal (D) is configured to receive the first output signal 142 of the comparator, the clock terminal inputs the clock signal, and the output terminal outputs a first delay signal 172; a second D-type positive The counter 173, the data terminal (D) inputs the first delay signal 172, the clock terminal inputs the clock signal, and the output terminal outputs a second delay signal 174; and a NAND gate 175. The first delay signal 172 and the second delay signal 174 are used to generate the third control signal 151. The digital scaling circuit is used to receive the second delay signal 174. And generating the second frequency output signal 152 by scaling the frequency digits of the second delayed signal 174 to different frequencies according to a set of encoded signals (S ₂ , S ₃ ); Table 2 is the set of encoded signals in the embodiment. Correspondence between (S ₂ , S ₃ ) and scaling factor; the correction unit 1 60 includes a microprocessor 163 and a digital to analog converter (DAC) circuit 164. After receiving the second frequency output signal, the microprocessor generates a set of digital code 161 by calculation processing. The set of digital code 161 The digital conversion analog circuit 164 is further converted into a correction voltage V _cali 162; the set of digital code is usually a set of binary code, and the number of bits can be increased or decreased according to requirements; finally, the correction voltage V _cali 162 is fed back to This switch acts as an applied voltage to the photoreceptor array.

3A and 3B are graphs showing the simulation result of the output signal frequency versus the output current I _{ph in} the embodiment, wherein the abscissa is the photocurrent I _ph , the ordinate is the output signal frequency, and the 3A diagram shows the five photodiodes. In the simulation results using the correction circuit (triangle) and without the correction circuit (square), Figure 3B shows the simulation results of the 25 photodiodes using the correction circuit (triangle) and not using the correction circuit (square), and Comparison of simulation results when using one photodiode (diamond). The figure shows that when using the correction circuit, the linearity of the output frequency is better than the correction circuit. The simulation results show that when using the correction circuit, 5 photodiodes and 25 photodiodes are used and 1 is used. The frequency ratio of the photodiode is 4.27 and 11.97, respectively. After using the correction circuit, the ratio rises to 4.96 and 24.85, respectively, close to the theoretical values of 5.0 and 25.0. The simulation results show that the correction circuit can greatly increase the output frequency. Linearity.

Figure 4 is a flow chart of an embodiment of the optical frequency conversion method of the present invention, comprising the steps of: a. receiving a set of encoded signals 113 by a first control unit 110, and generating a first according to the set of encoded signals 113. Control signal 111 and a set of second control signals 112; b. receiving the set of second control signals 112 in a plurality of photoreceptor arrays 120, wherein each photoreceptor array includes at least one photoreceptor 121, and each photoreceptor array Depending on the number of photoreceptors, a photoreceptor array is selected according to the second control signal 112 for receiving incident light and generating an output current I _ph 124 proportional to the incident light intensity; c. receiving a comparator 140 The reference voltage V _ref 141 and the output current I _ph 124 of the photoreceptor array, and according to the reference voltage V _ref and the output current I _{ph ,} generate a first frequency output signal 142 whose frequency is proportional to the output current I _ph , the comparison The receiver 140 receives the first control signal 111 to control the on state of the comparator; d. receives the first frequency output signal 142 by a second control unit 150, and generates a second frequency output signal 15 2 and a third control signal 151, wherein the frequency of the second frequency output signal 152 is proportional to the frequency of the first frequency output signal 142; e. receiving the second frequency output signal 152 by a correction unit 160, and according to the second frequency The output signal 152 generates a correction voltage V _cali 162; f. is connected to the plurality of photoreceptor arrays 120 and the correction unit 160 by a switch 130, and receives the third control signal 151 to control the conduction state of the switch, when the switch is turned on. In the state, the plurality of photoreceptor arrays are connected to the correction voltage V _cali .

In step f, the applied voltage of the photoreceptor array will change with the feedback correction voltage V _cali , so the frequency of the output signal can be adjusted.

Therefore, the present invention has the following advantages: the present invention converts incident light intensity into a digital signal of a frequency, converts the frequency output signal into a correction voltage by calculation processing, and returns the correction voltage as a photodiode. Reverse bias to correct the output signal frequency, thus improving the scalable linearity of the frequency-converted output signal frequency, further improving the accuracy of the back-end digital application.

In summary, the present invention can achieve the intended purpose, and provides an optical frequency conversion device and method with a signal correction function and an improved linearity of the optical frequency conversion output signal. It does have the value of industrial use, and patent applications are filed according to law.

The above description and drawings are merely illustrative of the embodiments of the present invention, and those of ordinary skill in the art can

110‧‧‧First Control Unit

111‧‧‧First control signal

112‧‧‧second control signal

113‧‧‧ Coded signal

120‧‧‧Photoreceptor array

121‧‧‧Photoreceptor

122‧‧‧Switching elements

124‧‧‧Output current I _ph

130‧‧‧ switch

140‧‧‧ Comparator

141‧‧‧reference voltage V _ref

142‧‧‧First frequency output signal

150‧‧‧Second Control Unit

151‧‧‧ Third control signal

152‧‧‧Second frequency output signal

160‧‧‧Correction unit

161‧‧‧digit code

162‧‧‧Correct voltage V _cali

163‧‧‧Microprocessor

164‧‧‧Digital to analog circuit

170‧‧‧ trigger circuit

171‧‧‧First D-type flip-flop

172‧‧‧First delayed signal

173‧‧‧Second D-type flip-flop

174‧‧‧second delayed signal

175‧‧‧Anti-gate

176‧‧‧ clock signal (CLK)

1 is a block diagram showing a circuit of an embodiment of an optical frequency conversion device of the present invention.

Fig. 2 is a circuit block diagram showing another embodiment of the optical frequency conversion device of the present invention.

3A and 3B are diagrams showing the simulation result of the output signal frequency versus the output current in the present embodiment.

Fig. 4 is a flow chart showing an embodiment of an optical frequency conversion method of the present invention.

110‧‧‧First Control Unit

111‧‧‧First control signal

112‧‧‧second control signal

113‧‧‧ Coded signal

120‧‧‧Photoreceptor array

121‧‧‧Photoreceptor

122‧‧‧Switching elements

124‧‧‧Output current I _ph

130‧‧‧ switch

140‧‧‧ Comparator

141‧‧‧ the reference voltage V _ref

142‧‧‧First frequency output signal

150‧‧‧Second Control Unit

151‧‧‧ Third control signal

152‧‧‧Second frequency output signal

160‧‧‧Correction unit

162‧‧‧Correct voltage V _cali

Claims (10)

An optical frequency conversion device comprising: a first control unit for receiving a set of encoded signals, and generating a first control signal and a set of second control signals according to the set of encoded signals; a plurality of photoreceptor arrays, wherein Each photoreceptor array includes at least one photoreceptor, and each photoreceptor array includes a different number of photoreceptors for receiving the set of second control signals, and selecting a photoreceptor array according to the set of second control signals, Receiving incident light and generating an output current I _ph proportional to the intensity of the incident light; a comparator for receiving a reference voltage V _ref and an output current I _{ph of} the photoreceptor array, and according to the reference voltage V _ref And the output current I _ph generates a first frequency output signal having a frequency proportional to the output current I _ph , the comparator receiving the first control signal to control the conduction state of the comparator; a second control unit, It is configured to receive the first frequency output signal and generate a second frequency output signal and a third control signal, wherein the frequency of the second frequency output signal is proportional to a frequency of the first frequency output signal; a correction unit for receiving the second frequency output signal, and generating a correction voltage V _cali according to the second frequency output signal; and a switch connecting the plurality of switches respectively The photoreceptor array and the correction unit receive the third control signal to control an on state of the switch, and the plurality of photoreceptor arrays can be coupled to the correction voltage V _cali when the switch is in an on state. The optical frequency conversion device of claim 1, wherein the photoreceptor is a photodiode. The optical frequency conversion device of claim 1, wherein each of the photoreceptor arrays further comprises a switching element. The optical frequency conversion device of claim 1, wherein the switch further comprises at least one switching element. The optical frequency conversion device of claim 4, wherein the switch further comprises a plurality of switching elements, the number of which is the same as the number of the photoreceptor arrays. The optical frequency conversion device of claim 3, 4 or 5, wherein the switching element is a field effect transistor. The optical frequency conversion device of claim 6, wherein the field effect transistor system is a metal oxide semiconductor field effect transistor (MOSFET). The optical frequency conversion device of claim 1, wherein the second control unit further comprises: a trigger circuit for generating the third control signal, comprising a clock signal (CLK), a first A D-type flip-flop (Flip-flop), the data end (D) is for receiving the first frequency output signal, the clock terminal inputs the clock signal, and the output end outputs a first delay signal, In the two-D type flip-flop, the data terminal (D) inputs the first delayed signal, the clock terminal inputs the clock signal, and the output terminal outputs a second delayed signal, and a reverse gate (NAND gate) And receiving the first delayed signal and the second delayed signal, and generating the third control signal according to the first delayed signal and the second delayed signal; a digital scaling circuit for generating the second frequency output signal for receiving the second delayed signal and scaling the frequency of the second delayed signal to generate the second frequency output signal. The optical frequency conversion device of claim 1, wherein the correction unit further comprises a microprocessor for receiving the second frequency output signal, and generating a set of digital code according to the second frequency output signal; And a digital to analog converter (DAC) circuit for generating the correction voltage V _cali , receiving the set of digital code, and generating the correction voltage V _cali according to the set of digital codes. An optical frequency conversion method includes the following steps: a. receiving a set of encoded signals by a first control unit, and generating a first control signal and a set of second control signals according to the set of encoded signals; b. The array of sensors receives the second set of control signals, wherein each photoreceptor array includes at least one photoreceptor, and each photoreceptor array has a different number of photoreceptors, and a photoreceptor array is selected according to the set of second control signals for Receiving incident light and generating an output current I _ph proportional to the intensity of the incident light; c. receiving a reference voltage V _ref and an output current I _{ph of the} photoreceptor array by a comparator, and according to the reference voltage V _ref and the output The current I _ph generates a first frequency output signal having a frequency proportional to the output current I _ph , the comparator receiving the first control signal to control the conduction state of the comparator; d. receiving by a second control unit The first frequency outputs a signal, and generates a second frequency output signal and a third control signal, wherein the frequency of the second frequency output signal is proportional to the first frequency input Frequency signals; E receiving the output signal at a second frequency correction unit and generating a correction voltage V _cali according to the second output signal frequency;.. F to a plurality of switches are connected to the photoreceptor array and a correction unit And receiving the third control signal to control the conduction state of the switch, and when the switch is in an on state, the plurality of photoreceptor arrays can be connected to the correction voltage V _cali .