CN110571645A - Laser power attenuation compensation circuit of image scanning device - Google Patents
Laser power attenuation compensation circuit of image scanning device Download PDFInfo
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- H—ELECTRICITY
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- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
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Abstract
The invention discloses a laser power attenuation compensation circuit of an image scanning device, which ensures that the output power of a laser diode does not change along with the increase of time and the rise of temperature in the image scanning process. A laser power attenuation compensation circuit of an image scanning device comprises: the laser driving module comprises a laser diode LD, a laser driving module and a system function control module; the system also comprises a negative feedback control module, a system compensation module and a reference standard module; the laser driving module and the system function control module are respectively connected with the laser diode LD and are used for providing bias current and modulation current for the laser diode LD; the negative feedback control module is used for detecting the output light power of the laser diode; one input end of the system compensation module is connected with the negative feedback control module, the other input end of the system compensation module is connected with the reference module, and the output end of the system compensation module is connected with the laser driving module so as to provide compensation current for the laser driving module to enable the difference value of the bias current and the threshold current to be stable.
Description
Technical Field
The invention relates to the field of computer X-ray photography imaging, in particular to a laser power attenuation compensation circuit of an image scanning device.
Background
Computed-Radiography (CR) has been widely used in the medical health field, in which X-rays are irradiated onto an image plate containing light-activated fluorescent powder through an object, and a frame of latent image (LatentImage) is generated and stored in the image plate. When laser light with a certain wavelength (600-700 nm) is used for irradiation, the image plate excites fluorescence with a specific wavelength (350-450 nm), the energy distribution characteristic of the fluorescence is completely related to the shape of a latent image, and the fluorescence is collected, converted into an electric signal and digitized, so that the latent image is converted into a two-dimensional digital image which can be stored and transmitted.
Semiconductor lasers have been widely used in image scanning systems due to their small size, good high frequency response, high modulation efficiency, convenience of modulation, etc. In an imaging device based on light-stimulated luminescence (PSL), the stable output laser power is beneficial to improving the uniformity of an image picture.
During the scanning of the information recorded on the image plate with the laser, the following phenomena occur in the laser diode: 1. after the laser diode is used for a period of time, the output power of the laser is attenuated along with the rise of the temperature, so that the image quality of the scanner is influenced; 2. when the temperature of the laser diode is higher, due to overhigh temperature, Ith is very high, so that the output light power of the Laser Diode (LD) is greatly reduced, the current of the laser diode is greatly increased after passing through a feedback circuit, the temperature of the laser diode is further increased, Ith is larger, the Laser Diode (LD) is damaged, and the service life of the laser is influenced; 3. when the laser is turned on and off at high speed in the image scanning device, the phenomenon of laser power overshoot can occur, which causes the instability of output laser power, thereby affecting the imaging quality of the scanning device.
Semiconductor lasers are current-driven light emitting devices. As shown in fig. 1, only when the drive current is at the laser threshold current IthIn the above case, the semiconductor laser can generate and continuously output laser power. When I is>>IthThe power of a semiconductor laser can be expressed as: p = K (I-I)th) And K is the slope of the line in FIG. 1. 1. The semiconductor laser is a temperature sensitive device with threshold current IthAlong with the increase of the temperature and the reduction of the slope delta P/delta I of the P-I curve, the output light power is reduced, and even the laser emission is stopped; 2. as the service time increases, the aging of the device can also cause the threshold current I of the devicethThe output optical power is reduced. The above reasons cause the output power of the semiconductor laser to be attenuated after the semiconductor laser is used for a period of time, thereby affecting the image quality of the scanning device.
The internal structure of a conventional semiconductor laser diode is shown in fig. 2. After light transmitted from a Laser Diode (LD) is detected by a PD, the light power is converted into detection current and is fed back to a control circuit, so that the laser power is monitored. When the temperature is higher, the temperature is too high, resulting in IthThe output light power of the Laser Diode (LD) is greatly reduced, the current of the LD is greatly increased after passing through the feedback circuit, the temperature of the LD is further increased, and I isthAnd more, the Laser Diode (LD) is damaged, thereby affecting the life of the laser.
Common laser driving methods are as follows: when the constant current source is driven, the semiconductor laser generates overshoot laser power during the high-speed turning on and off process, which causes the output laser power to be unstable, thereby affecting the imaging quality of the scanning device, as shown in fig. 3.
Disclosure of Invention
In view of the above problems, it is an object of the present invention to provide a laser power attenuation compensation circuit for an image scanning device, which does not change the output power of a laser diode with time and temperature during the image scanning process.
in order to achieve the purpose, the invention adopts the technical scheme that:
a laser power attenuation compensation circuit of an image scanning device comprises: the laser power attenuation compensation circuit comprises a laser diode LD, a laser driving module and a system function control module, and further comprises a negative feedback control module, a system compensation module and a reference module; the laser driving module and the system function control module are respectively connected with the laser diode LD and used for providing bias current and modulation current for the laser diode LD; the negative feedback control module is used for detecting the output optical power of the laser diode; one input end of the system compensation module is connected with the negative feedback control module, the other input end of the system compensation module is connected with the reference module, and the output end of the system compensation module is connected with the laser driving module so as to provide compensation current for the laser driving module to enable the difference value of the bias current and the threshold current to be stable.
Preferably, the system compensation module comprises a comparator U3, a capacitor C1 and a zener diode D3; the inverting input end of the comparator U3 is connected with the negative feedback control module, the non-inverting input end of the comparator U3 is connected with the reference module, and the output end of the comparator U3 is connected with the laser driving module; the capacitor C1 is connected in parallel between the inverting input end and the output end of the comparator U3; the cathode of the voltage stabilizing diode D3 is connected with the output end of the comparator U3, and the anode is connected with 0V.
Preferably, the negative feedback control module comprises a PIN photodiode PD, a resistor R8, a resistor R1, an operational amplifier U1 and a capacitor C2; the PIN photodiode PD is connected with the inverting input end of the operational amplifier U1 after being connected with the resistor R8 in series; the non-inverting input end of the operational amplifier U1 is connected with 0V, and the output end of the operational amplifier U1 is connected with the system compensation module; the resistor R1 is connected in parallel between the inverting input end and the output end of the operational amplifier U1; the capacitor C2 is connected in parallel between the inverting input terminal and the output terminal of the operational amplifier U1.
More preferably, the laser diode LD and the PIN photodiode PD are respectively connected to a power supply VCC.
Preferably, the reference module comprises a resistor R6, a resistor R7, an adjustable resistor VR, and an operational amplifier U4; one end of the resistor R6 is connected with a reference voltage Vref, and the other end is connected with the inverting input end of the operational amplifier U4; the first end of the adjustable resistor VR is connected with a power VCC, the other end of the adjustable resistor VR is connected with 0V, and the adjustable end of the adjustable resistor VR is connected with the non-inverting input end of the operational amplifier U4; the output end of the operational amplifier U4 is connected with the system compensation module; the resistor R7 is connected in parallel between the inverting input terminal and the output terminal of the operational amplifier U4.
Preferably, the laser driving module comprises a resistor R9, a resistor R10, an inductor L1 and a semiconductor transistor Q1; one end of the resistor R9 is connected with the system compensation module, and the other end of the resistor R9 is connected with the base electrode of the semiconductor triode Q1; one end of the resistor R10 is connected with the emitter of the semiconductor triode Q1, and the other end of the resistor R10 is connected with 0V; the inductor L1 is connected between the collector of the transistor Q1 and the laser diode.
Preferably, the system function control module comprises a resistor R5, a resistor R11, a semiconductor triode Q2 and an operational amplifier U5; the inverting input end of the operational amplifier U5 is connected in series with the resistor R5 and the resistor R11 and then is connected with 0V, the non-inverting input end is connected with control voltage, and the output end is connected with the base electrode of the semiconductor triode Q2; and the collector of the semiconductor triode Q2 is connected with the laser diode LD, and the emitter is connected with the resistor R11 in series and then connected with 0V.
preferably, the laser power attenuation compensation circuit further comprises a filter circuit module for providing an impedance for canceling an instantaneous voltage generated by the parasitic inductance.
More preferably, the filter circuit module comprises a resistor R3, a capacitor C3 and a capacitor C4; one end of the resistor R3 is connected with the cathode of the laser diode LD, and the other end of the resistor R3 is connected with the system function control module and the laser driving module; the capacitor C3 and the capacitor C4 are connected in parallel, one end of the capacitor C3 is connected with the negative electrode of the laser diode LD, and the other end of the capacitor C4 is connected with 0V; and the anode of the laser diode LD is connected with a power supply VCC.
Further, the impedance value ZAB (jw) of the filter circuit block is as follows:
ZAB(jw)= R+R3+jwL-j/(w(C3+C4))
A, B represents the positive terminal and the negative terminal of the laser diode LD, R represents the circuit internal resistance, R3 represents the resistance value of the resistor R3, L represents the parasitic inductance, j represents the imaginary unit, w represents the circuit angular frequency, and C3 and C4 represent the capacitance values of the capacitor C3 and the capacitor C4, respectively.
By adopting the technical scheme, compared with the prior art, the invention has the following advantages:
at higher temperature, the traditional control method can cause that the laser diode can not work normally due to over-driving, and the laser power attenuation compensation circuit can solve the problems of laser diode feedback and system compensation when the temperature is too high, so that the laser diode can output power normally and stably at higher temperature. In the laser power attenuation compensation circuit, the laser diode outputs laser power more stably and accurately, and the output power of the laser diode is not changed along with the increase of time and the rise of temperature in the image scanning process, so that the aim of improving the imaging quality of an imaging device is fulfilled.
Drawings
in order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
FIG. 1 is a schematic diagram of a P-I curve of a semiconductor laser LD;
FIG. 2 is a schematic diagram of a semiconductor laser structure;
FIG. 3 is a laser power curve diagram of a conventional laser driving method;
FIG. 4 is a schematic diagram of a laser power attenuation compensation circuit according to an embodiment of the present invention;
FIG. 5 is a flow chart of laser power attenuation compensation according to an embodiment of the present invention;
Fig. 6 is an equivalent circuit diagram of a filter circuit block according to an embodiment of the present invention;
FIG. 7 is a graph of laser power after passing through a filter circuit module;
FIG. 8 is an image of a case where the laser power is unstable;
Fig. 9 is a video image when the laser power is stably output.
in the above-described figures of the drawings,
101. A system function control module; 102. a laser driving module; 103. a system compensation module; 104. a negative feedback control module; 105. a reference benchmark module; 106. and a filter circuit module.
Detailed Description
Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings so that the advantages and features of the invention may be more readily understood by those skilled in the art. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The present embodiment provides a laser power attenuation compensation circuit of an image scanning device. Referring to fig. 4 and 5, the laser power attenuation compensation circuit mainly comprises a laser diode LD, a system function control module 101, a laser driving module 102, a system compensation module 103, a negative feedback control module 104, a reference module 105, and a filter circuit module 106.
the laser diode LD is used as a laser light source of the image scanning device, and is used to emit a laser beam, and the emitted laser beam forms a laser spot for scanning the image plate. The anode of the laser diode LD is connected to a power source VCC, and the cathode of the laser diode LD is connected to the system function control module 101 and the laser driving module 102, respectively, after passing through the filter circuit module 106.
The system function control module 101, which is a constant current source control circuit, provides a suitable bias current for the laser diode LD to turn on and off the laser output of the laser diode LD. The system function control module 101 specifically includes a resistor R5, a resistor R11, a transistor Q2, and an operational amplifier U5. The inverting input end of the operational amplifier U5 is connected with a resistor R5 and a resistor R11 in series and then connected with 0V, the non-inverting input end is connected with control voltage, and the output end is connected with the base electrode of a semiconductor triode Q2; the collector of the semiconductor triode Q2 is connected with the cathode of the laser diode LD, and the emitter is connected with the 0V after being connected with the resistor R11 in series.
The laser driving module 102 is an LD driving circuit for providing a proper bias current and modulation current to the semiconductor laser diode LD. The bias current is constant, which enables the semiconductor laser to work in a linear region above the threshold current all the time, and the modulation current is changed, which makes corresponding switch switching action according to the voltage signal provided by the system compensation module 103. The laser driving module 102 includes a resistor R9, a resistor R10, an inductor L1, and a semiconductor transistor Q1; one end of the resistor R9 is connected with the system compensation module 103, and the other end is connected with the base electrode of the semiconductor triode Q1; one end of the resistor R10 is connected with the emitter of the semiconductor triode Q1, and the other end is connected with 0V; the inductor L1 is connected between the collector of the transistor Q1 and the laser diode. The inductor L1 is used to prevent the ac signal from affecting the modulation current, but not the dc signal. Because the cathode of the laser diode keeps certain impedance, the load of the high-speed output circuit to the signal of the frequency can be kept stable, and if the load of the output end is unstable, the output laser signal can generate emission and ringing phenomena.
the negative feedback control module 104 includes a PIN photodiode PD, a resistor R8, a resistor R1, an operational amplifier U1, and a capacitor C2. One end of the PIN photodiode PD is connected with a power supply VCC, and the other end of the PIN photodiode PD is connected with the inverting input end of the operational amplifier U1 after being connected with a resistor R8 in series; the non-inverting input end of the operational amplifier U1 is connected with 0V, and the output end is connected with the system compensation module 103; the resistor R1 is connected in parallel between the inverting input end and the output end of the operational amplifier U1; the capacitor C2 is connected in parallel between the inverting input terminal and the output terminal of the operational amplifier U1. The PIN photodiode PD is a light detection device, specifically, a PD terminal of a semiconductor laser. The output light power of the laser diode LD is detected by the PIN photodiode PD, and then fed back to the system compensation module 103 through the operational amplifier U1.
The reference module 105 includes a resistor R6, a resistor R7, an adjustable resistor VR, and an operational amplifier U4. One end of the resistor R6 is connected with a reference voltage Vref, and the other end is connected with the inverting input end of the operational amplifier U4; the first end of the adjustable resistor VR is connected with a power VCC, the other end of the adjustable resistor VR is connected with 0V, and the adjustable end of the adjustable resistor VR is connected with the non-inverting input end of an operational amplifier U4; the output end of the operational amplifier U4 is connected with the system compensation module 103; the resistor R7 is connected in parallel between the inverting input terminal and the output terminal of the operational amplifier U4. The reference module 105 is used to provide a proper voltage to make the laser diode LD obtain a required driving current; when the input channel has no signal, the reference module 105 can make the laser driving module 102 not to operate, so as to avoid the occurrence of false operation.
a system compensation module 103 for providing a suitable compensation current to make the difference I between the bias current and the threshold currentBIAS -IthRelatively stable, thereby stabilizing the laser output power, and has a function of preventing the laser diode from being damaged by over-driving at a high temperature. The system compensation module 103 comprises a comparator U3, a capacitor C1, and a zener diode D3; the inverting input end of the comparator U3 is connected to the negative feedback control module 104 (specifically, the output end of the operational amplifier U1), the non-inverting input end is connected to the reference module 105 (specifically, the output end of the operational amplifier U4), and the output end is connected to the laser driving module 102; the capacitor C1 is connected in parallel between the inverting input end and the output end of the comparator U3; the cathode of the voltage stabilizing diode D3 is connected with the output end of the comparator U3, and the anode is connected with 0V. The output light power of the laser diode LD is detected by the PIN photodiode PD, fed back to the inverting input terminal of the comparator U3 through the operational amplifier U1, and the reference voltage Vref is fed back to the non-inverting input terminal of the comparator U3 through the operational amplifier U4, and then output voltage after passing through the comparator U3, so as to drive the semiconductor triode Q1 of the laser driving module 102 to work, and the working flow is as follows: LD output optical power ↓ → PD output current ↓ → U1 output voltage ↓ → VR ↓ → U3 output voltage ↓ → Q1 base current ↓ → Q1 collector current (i.e. I ↓ → Q1 currentB) ↓ → LD outputs optical power ↓.
In the laser driving circuit in the prior art, due to overhigh temperature, Ith is very large, so that the output light power of a laser diode is greatly reduced, and I is obtained after the operation and amplification effectsBThe increase is so large that the die temperature of the laser diode is further increased, which makes Ith larger, and the vicious circle can burn out the laser diode. The voltage stabilizing diode D3 in the circuit provided by the invention can clamp the voltage output by the operational amplifier U3 in a safe range after the voltage is larger than a certain value, so that the semiconductor laser is prevented from being damaged by over-driving, and the laser diode LD can safely and stably work under the condition of high temperature。
And the filter circuit module 106 is used for effectively eliminating the phenomenon of laser power overshoot of the semiconductor laser in the high-speed opening and closing process. The filter circuit module 106 includes a resistor R3, a capacitor C3, and a capacitor C4; one end of the resistor R3 is connected to the negative electrode of the laser diode LD, and the other end is connected to the system function control module 101 (specifically, the inductor L1) and the laser driving module 102 (specifically, the collector of the semiconductor triode); the capacitor C3 and the capacitor C4 are connected in parallel, one end of the capacitor C3 is connected to the cathode of the laser diode LD (specifically, connected between the cathode of the laser diode LD and the resistor R3), and the other end is connected to 0V.
The laser generates a lead inductance (parasitic inductance) in the high-speed current switching process, and the modulation current flowing through the lead inductance generates an instantaneous voltage which is the same as the change of the modulation current, and the instantaneous voltage causes the fluctuation of the laser power. The filter circuit module 106 can provide proper impedance for the laser diode circuit at this time, and can counteract the influence of instantaneous voltage generated by parasitic inductance, thereby avoiding the occurrence of laser power overshoot phenomenon and providing a stable laser light source for the image scanning device.
The laser diode LD is regarded as a load regardless of the parasitic capacitance of the laser diode, and its frequency equivalent circuit diagram is shown in fig. 6. The impedance value Z of the filter circuit module 106AB(jw) is represented by the following formula:
ZAB(jw)= R+R3+jwL-j/(w(C3+C4))
A, B respectively represents the positive terminal and the negative terminal of the laser diode LD, R represents the circuit internal resistance, R3 represents the resistance value of a resistor R3, L represents the parasitic inductance, j represents the imaginary unit, w represents the circuit angular frequency, and C3 and C4 respectively represent the capacitance values of a capacitor C3 and a capacitor C4.
The formula shows that: when w 2L (C3+ C4)<<Impedance value Z of 1 hourAB(jw) = R + R3. The laser power curve after passing through the filter circuit module 106 is shown in fig. 7, and it can be seen that the occurrence of the laser power overshoot phenomenon is avoided by using the filter circuit module 106, and a stable laser light source is provided for the image scanning device.
In the laser power attenuation compensation circuit of this embodiment, when the output optical power of the laser diode LD is reduced, the output current of the PIN photodiode is reduced, the voltage output by the operational amplifier U1 is reduced, and at this time, the resistance of the adjustable resistor VR is reduced, so that the voltage output by the comparator U3 is increased, the base current of the semiconductor triode Q1 is increased, the collector current of the semiconductor triode Q1 is increased, and a suitable current is provided for the laser diode LD, thereby increasing the output optical power of the laser diode LD.
the laser power attenuation compensation circuit of the embodiment prevents the output power of the laser diode from changing along with the increase of time and the increase of temperature in the image scanning process. At a higher temperature, the conventional control method may cause that the laser diode cannot normally work due to over-driving, and the laser power attenuation compensation circuit of the embodiment can solve the problems of laser diode feedback and system compensation when the temperature is too high, so that the laser diode can normally and stably output power at the higher temperature. The laser driving method in the prior art is as follows: the constant current source is used for driving, and a power overshoot phenomenon can occur in the high-speed opening and closing process of the laser diode, so that the imaging quality of the scanning device is influenced; the filter circuit adopted by the laser power attenuation compensation circuit of the embodiment can effectively reduce the laser power overshoot phenomenon, thereby improving the imaging quality of the image device. In this embodiment, the laser diode is controlled by combining the constant current source and the constant power source, the constant current source is used for rough adjustment, and the constant power source (APC) is used for fine adjustment, so that the laser diode outputs more stable and accurate laser power, thereby achieving the purpose of improving the imaging quality of the imaging device, as shown in fig. 8 and 9.
The above embodiments are merely illustrative of the technical ideas and features of the present invention, and are preferred embodiments, which are intended to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.
Claims (10)
1. A laser power attenuation compensation circuit of an image scanning device comprises: the laser power attenuation compensation circuit comprises a laser diode LD, a laser driving module and a system function control module, and is characterized by further comprising a negative feedback control module, a system compensation module and a reference module; the laser driving module and the system function control module are respectively connected with the laser diode LD and used for providing bias current and modulation current for the laser diode LD; the negative feedback control module is used for detecting the output optical power of the laser diode; one input end of the system compensation module is connected with the negative feedback control module, the other input end of the system compensation module is connected with the reference module, and the output end of the system compensation module is connected with the laser driving module so as to provide compensation current for the laser driving module to enable the difference value of the bias current and the threshold current to be stable.
2. the laser power attenuation compensation circuit of claim 1, wherein the system compensation module comprises a comparator U3, a capacitor C1 and a zener diode D3; the inverting input end of the comparator U3 is connected with the negative feedback control module, the non-inverting input end of the comparator U3 is connected with the reference module, and the output end of the comparator U3 is connected with the laser driving module; the capacitor C1 is connected in parallel between the inverting input end and the output end of the comparator U3; the cathode of the voltage stabilizing diode D3 is connected with the output end of the comparator U3, and the anode is connected with 0V.
3. The laser power attenuation compensation circuit of claim 1, wherein the negative feedback control module comprises a PIN photodiode PD, a resistor R8, a resistor R1, an operational amplifier U1 and a capacitor C2; the PIN photodiode PD is connected with the inverting input end of the operational amplifier U1 after being connected with the resistor R8 in series; the non-inverting input end of the operational amplifier U1 is connected with 0V, and the output end of the operational amplifier U1 is connected with the system compensation module; the resistor R1 is connected in parallel between the inverting input end and the output end of the operational amplifier U1; the capacitor C2 is connected in parallel between the inverting input terminal and the output terminal of the operational amplifier U1.
4. The laser power attenuation compensation circuit of claim 3, wherein the laser diode LD and the PIN photodiode PD are respectively connected to a power supply VCC.
5. The laser power attenuation compensation circuit of claim 1, wherein the reference module comprises a resistor R6, a resistor R7, an adjustable resistor VR, and an operational amplifier U4; one end of the resistor R6 is connected with a reference voltage Vref, and the other end is connected with the inverting input end of the operational amplifier U4; the first end of the adjustable resistor VR is connected with a power VCC, the other end of the adjustable resistor VR is connected with 0V, and the adjustable end of the adjustable resistor VR is connected with the non-inverting input end of the operational amplifier U4; the output end of the operational amplifier U4 is connected with the system compensation module; the resistor R7 is connected in parallel between the inverting input terminal and the output terminal of the operational amplifier U4.
6. The laser power attenuation compensation circuit of claim 1, wherein the laser driving module comprises a resistor R9, a resistor R10, an inductor L1, and a semiconductor transistor Q1; one end of the resistor R9 is connected with the system compensation module, and the other end of the resistor R9 is connected with the base electrode of the semiconductor triode Q1; one end of the resistor R10 is connected with the emitter of the semiconductor triode Q1, and the other end of the resistor R10 is connected with 0V; the inductor L1 is connected between the collector of the transistor Q1 and the laser diode.
7. The laser power attenuation compensation circuit of claim 1, wherein the system function control module comprises a resistor R5, a resistor R11, a semiconductor transistor Q2, and an operational amplifier U5; the inverting input end of the operational amplifier U5 is connected in series with the resistor R5 and the resistor R11 and then is connected with 0V, the non-inverting input end is connected with control voltage, and the output end is connected with the base electrode of the semiconductor triode Q2; and the collector of the semiconductor triode Q2 is connected with the laser diode LD, and the emitter is connected with the resistor R11 in series and then connected with 0V.
8. The laser power attenuation compensation circuit of claim 1, further comprising a filter circuit module for providing an impedance that cancels a transient voltage generated by parasitic inductance.
9. the laser power attenuation compensation circuit of claim 8, wherein the filter circuit module comprises a resistor R3, a capacitor C3, and a capacitor C4; one end of the resistor R3 is connected with the cathode of the laser diode LD, and the other end of the resistor R3 is connected with the system function control module and the laser driving module; the capacitor C3 and the capacitor C4 are connected in parallel, one end of the capacitor C3 is connected with the negative electrode of the laser diode LD, and the other end of the capacitor C4 is connected with 0V; and the anode of the laser diode LD is connected with a power supply VCC.
10. The laser power attenuation compensation circuit of claim 9, wherein the impedance value Z of the filter circuit moduleAB(jw) is represented by the following formula:
ZAB(jw)= R+R3+jwL-j/(w(C3+C4))
A, B represents the positive terminal and the negative terminal of the laser diode LD, R represents the circuit internal resistance, R3 represents the resistance value of the resistor R3, L represents the parasitic inductance, j represents the imaginary unit, w represents the circuit angular frequency, and C3 and C4 represent the capacitance values of the capacitor C3 and the capacitor C4, respectively.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
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| CN113892961A (en) * | 2021-10-26 | 2022-01-07 | 桂林市啄木鸟医疗器械有限公司 | A laser scanning control device and image scanning system |
| CN117895325A (en) * | 2024-01-05 | 2024-04-16 | 瀚湄信息科技(上海)有限公司 | Constant power driving circuit of semiconductor laser |
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| CN113892961A (en) * | 2021-10-26 | 2022-01-07 | 桂林市啄木鸟医疗器械有限公司 | A laser scanning control device and image scanning system |
| CN117895325A (en) * | 2024-01-05 | 2024-04-16 | 瀚湄信息科技(上海)有限公司 | Constant power driving circuit of semiconductor laser |
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