CN106973462B - For the LED light source direct current Constant-power drive circuit of photoelectric auto-collimator - Google Patents
For the LED light source direct current Constant-power drive circuit of photoelectric auto-collimator Download PDFInfo
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- CN106973462B CN106973462B CN201710328522.8A CN201710328522A CN106973462B CN 106973462 B CN106973462 B CN 106973462B CN 201710328522 A CN201710328522 A CN 201710328522A CN 106973462 B CN106973462 B CN 106973462B
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/10—Controlling the intensity of the light
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Abstract
The present invention relates to a kind of LED light source direct current Constant-power drive circuits for photoelectric auto-collimator, it includes the laser diode as light source, constant-current drive circuit and monitor current sample circuit, the constant voltage values for controlling chip output are changed into constant current to drive light source by the constant-current drive circuit, the monitor current for flowing through light source receiving unit is converted into voltage value by monitor current sample circuit, control chip gathers this voltage value, to obtain the monitor current for flowing through light source receiving unit, the monitor current of the light source receiving unit is flowed through by the way that chip is controlled to gather in real time, obtain the luminous power of current light source；If the luminous power of light source is less than preset value, gradually increase the driving current of light source；Conversely, then it is gradually reduced the driving current of light source.While the present invention can ensure that the luminous power of video collimator LED light source within the full working time is constant, the problem of effectively preventing the ccd image flicker caused by CCD overexposures and PWM pulsewidth modulation type of drive.
Description
Technical field
The present invention relates to LED light source actuation techniques fields, are specifically a kind of LED light source direct current for photoelectric auto-collimator
Constant-power drive circuit.
Background technology
For photoelectric auto-collimator in running hours, the influence of the variation of temperature to light source luminous power (i.e. brightness) is very big,
Light source luminous power significantly reduces with the rise of temperature in the case of driving current constant.It can be seen that the variation of temperature will be straight
Connecing influences the stabilization of CCD detection light intensity, so as to influence measurement accuracy.At present, the domestic light source control proposed for this problem
Method is also immature, there is the light source control method adjusted manually, and also with good grounds picture signal gray scale automatic feedback adjusts pwm pulse
The light source control method of width.
Real-time and high precision it cannot be guaranteed that light source control are adjusted manually.And the mode adjusted according to gradation of image
With limitation, when CCD and reflection line position deviation is larger CCD is caused not receive light source when, can not realize light-source brightness
Control, and the type of drive of pwm pulse modulation can also cause CCD to be imaged the problem of flickering.
The content of the invention
In order to overcome the limitation of influence and the method that using gradation of image adjusts of the temperature to LED light source brightness, this
Invention provides a kind of LED light source direct current Constant-power drive circuit, which can not only realize video collimator in the full working time
Interior LED light source brightness regulation and power limitation control, prevent CCD overexposures, when CCD does not receive light source, remain to realize that light source is bright
Constant control is spent, while solves the problems, such as the flicker of the ccd image caused by PWM pulsewidth modulation type of drive.
According to technical solution provided by the invention, the LED light source direct current invariable power for photoelectric auto-collimator drives
Dynamic circuit, including：As the laser diode of light source, constant-current drive circuit and monitor current sample circuit, two pole of laser
Pipe has LD ends, PD ends and power end；The constant-current drive circuit includes：Resistance R5One end connection laser diode LD end,
Resistance R5Other end connection field-effect tube V2Drain electrode, field-effect tube V2Source electrode connection resistance R16One end, while pass through resistance R23
Ground connection, resistance R16Other end connection amplifier N1Inverting input, while pass through resistance R22Ground connection, amplifier N1In-phase input end
By resistance R3The control signal output of control chip is connected to, while passes through resistance R10It is grounded and passes through capacitance C1It connects
Ground, amplifier N1Output terminal pass through resistance R8It is connected to field-effect tube V2Grid；The monitor current sample circuit includes：Resistance
R7One end connection laser diode PD ends, resistance R7The other end passes through resistance R11Connect amplifier N2In-phase input end, and lead to
Cross resistance R24Ground connection, amplifier N2Output terminal pass through resistance R25It is connected with inverting input, and passes through resistance R25With resistance R21It connects
Ground, amplifier N2Output terminal also pass through resistance R13Connection control chip, exports sampled voltage；Constant-current drive circuit will control chip
The constant voltage values of output are changed into constant current to drive light source, and monitor current sample circuit will flow through light source receiving unit
Monitor current is converted into voltage value, and control chip gathers this voltage value, to obtain the monitor current for flowing through light source receiving unit, profit
With the directly proportional characteristic of the monitor current and light source luminous power that flow through the light source receiving unit, by the way that chip is controlled to gather stream in real time
The monitor current of the light source receiving unit is crossed, obtains the luminous power of current light source；If the luminous power of light source is less than preset value, by
The driving current of cumulative big light source；Conversely, if current luminous power is more than preset value, the driving current of light source is gradually reduced.
Further, by adjusting current-limiting resistance R in constant-current drive circuit5And R23The mode of resistance value limits the driving of light source
Current maxima.
Further, by the way that the software in chip is controlled to preset the value of luminous power, the driving current of light source is automatically adjusted
Mode overcomes the influence of temperature, controls light source light power invariability.
It is an advantage of the invention that：
(1) effectively overcome influence of the temperature change to light source luminous power, realized within the photoelectric auto-collimator full working time
LED light source brightness regulation and power limitation control.
(2) effectively prevention is due to the excessively high caused CCD overexposure problems of light-source brightness.
(3) when CCD does not receive light source, remain to realize the control that light-source brightness is constant.
(4) substitute PWM pulsewidth type of drive using the mode of constant current driving, solve due to PWM pulsewidths type of drive and
The problem of caused ccd image flicker.
Description of the drawings
Fig. 1 is laser diode pin definitions and bottom package schematic diagram in the embodiment of the present invention.
Fig. 2 is constant-current drive circuit figure.
Fig. 3 is monitor current sample circuit figure.
Fig. 4 is circuit diagram of the present invention.
Specific embodiment
The invention will be further described with reference to the accompanying drawings and examples.
The present invention selects a kind of laser diode (abbreviation LED) of band receiving unit (i.e. PD) as photoelectric auto-collimator
Light source, and devise constant-current drive circuit and monitor current sample circuit.
Constant-current drive circuit is exactly using voltage-electric current conversion regime, will control the constant electricity of chip D/A modules output
Pressure value is changed into constant current to drive light source.Monitor current sample circuit will be flowed through using the mode of electric current-voltage conversion
The monitor current of light source receiving unit is converted into voltage value.Control chip gathers this voltage value by A/D modules, is flowed through to obtain
The monitor current of light source receiving unit.
Using the directly proportional characteristic of the monitor current and light source luminous power that flow through the light source receiving unit, by controlling chip
The monitor current of the light source receiving unit is flowed through in acquisition in real time, obtains the luminous power of current light source.If due to temperature rise etc. because
Element causes the luminous power of light source to be less than preset value, then gradually increases the driving current of light source；Conversely, if current luminous power is more than in advance
If value is then gradually reduced the driving current of light source.Overcome temperature by way of the driving current that software automatically adjusts light source
It influences, realizes the power limitation control of photoelectric auto-collimator LED light source.
In addition, constant-current drive circuit can limit the driving current of LED light source by way of adjusting current-limiting resistance resistance value
Scope can effectively avoid the problem that due to software the factors such as improper being set to cause LED light source luminous power, CCD overexposures.
Fig. 1 is laser diode pin definitions in embodiment, and 1 foot is LD ends as shown in the figure, and 2 feet are power end (+5V), 3
Foot is receiving unit end (PD).
Fig. 2 is constant-current drive circuit figure.Since the output of control chip D/A modules is without buffering, therefore amplifier is used to be imitated with field
Should pipe composition common source amplifying circuit, amplifier N1For field-effect tube V2Stable grid voltage is provided, field-effect tube is made to be operated in constant current
Area.Wherein amplifier has cushioning effect to output.The constant-current drive circuit includes：Resistance R5One end connection laser diode LD
End, resistance R5Other end connection field-effect tube V2Drain electrode, field-effect tube V2Source electrode connection resistance R16One end, while pass through resistance
R23Ground connection, resistance R16The inverting input of other end connection amplifier N1, while pass through resistance R22Ground connection, amplifier N1It is same mutually defeated
Enter end by resistance R3The control signal output DAC of control chip is connected to, while passes through resistance R10It is grounded and passes through electricity
Hold C1Ground connection, amplifier N1Output terminal pass through resistance R8It is connected to field-effect tube V2Grid.
If DAC ends output voltage is UDAC, amplifier N1Positive input voltage is U+, negative sense input voltage is U-, according to amplifier
The short characteristic of empty short void,
U-=U+=UDAC×R3/(R3+R10) (1)
If V2Source voltage is Us,
Then US=(V-/R22)*(R16+R22) (2)
If field-effect tube V2Drain-Source electric current (i.e. the driving current of LED) be IDS, flow through R16Electric current for I ',
Flow through R16Electric current be IS：
IDS=I’+IS (3)
Work as R16+R22It is far longer than R23When, I ' is negligible, IDS≈IS
IDS=IS=Us/R23 (4)
(1) (2) formula is brought into, is obtained
IDS=UDAC×R3/(R3+R10)×(R16+R22)/R22/R23 (5)
(5) formula shows to work as R3、R10、R16、R22、R23One timing of resistance value, the driving current of LED can set DAC by software
End exports to adjust.
If field-effect tube V2Drain-source voltage is UDS, the operating pressure drop of laser diode is ULED, the power supply of laser diode
For U, then
ULED+UDS+IDS×R5+ Us=U (6)
By (4) Shi Ke get, Us=IDS×R23 (7)
(7) formula is brought into and can obtained, Uled+UDS+IDS×R5+IDS×R23=U (8)
Again because UDS>0,
Then ULED+IDS×(R5+R23)<U (9)
Thus,
IDS<(U-ULED)/(R5+R23) (10)
Due to the operating pressure drop U of laser diodeLED, field-effect tube V2Conducting voltage is UDSWith the power supply U of laser diode
It is definite value, the maximum of the driving current of LED is by resistance R5And R23It codetermines.
Fig. 3 is monitor current sample circuit figure, and circuit includes：Resistance R7One end connection laser diode PD ends, resistance R7
The other end passes through resistance R11Connect amplifier N2In-phase input end, and pass through resistance R24Ground connection, amplifier N2Output terminal pass through
Resistance R25It is connected with inverting input, and passes through resistance R25With resistance R21Ground connection, amplifier N2Output terminal also pass through resistance R13Even
The ADC ends of control chip are connect, export sampled voltage.
The PD ends of laser diode and resistance R7、R24Series connection, if sampled voltage is UADC, the electric current of PD output terminals is IM, can
Obtain relational expression：
UADC=IM×R24×(R25/R21) (11)
Again due to the electric current I of PD output terminalsMWith the luminous power P of laser diode0It is directly proportional, if proportionality coefficient is K, then IM
=K × P0, so
UADC=K × P0×R24×(R25/R21) (12)
Due to K, R24、R25、R21It is fixed value, so, the power P of laser diode0With sampled voltage UADCIt is directly proportional.
Control chip can be by sampling UADCTo obtain luminous power P at this time0.Software is by presetting P0Value, obtain UADCExpection
Value.If the U that actual samples arriveADCLess than UADCDesired value, then increase the output at DAC ends, if the U that actual samples arriveADCIt is more than
UADCDesired value, then reduce the output at DAC ends, thus control LED light source luminous power it is constant.
The circuit diagram of the present invention is as shown in Figure 4.
The present embodiment comes specific so that SANYO company models shown in FIG. 1 is the red laser diodes of QL65F7SA as an example
Illustrate embodiments of the present invention, it can be seen that light output 650nm, rated power 10mW.Amplifier selects AD8052, field effect in circuit
Should pipe selection IRF7811A, N-channel Metal-Oxide Semiconductor field-effect tube.
In the present embodiment Fig. 2, R3For 470 ohm, R10For 1k ohm, R22For 15k ohm, R16For 1.5k ohm, R5For 51
Ohm, R23For 20 ohm by (5) Shi Ke get,
IDS=UDAC× 470/ (470+1000) × (1500+15000)/15000/20=UDAC× 0.0176 (ampere).
The operating pressure drop U of the present embodiment laser diodeLED=2.3V, the power supply U of laser diode is 5V.If selection, by
(10) Shi Ke get, the operating current I of the LED light source of settingDS<(U-ULED)/(R5+R23Thus)=38mA is prevented due to LED works
Make electric current it is excessive caused by ccd image overexposure problem.
In the present embodiment Fig. 3, due to UADC(unit V), it is 0.0004 (unit that laser diode, which sets proportionality coefficient as K,
MV/mW), P0Unit is mW, UADCUnit is V.Set luminous power P0For maximum 10mW when, UADCFor maximum 3V,
It is obtained by (12) formula, 3=0.0049 × 10/1000 × R24×(R25/R21)
Then R24×(R25/R21)=61224,
Because select R25=8.2k, R21=2k, R24=15k, R7=1k, R11=470 ohm, R13=470 ohm.
It is obtained by (12) formula, UADC=0.0049 × P0/ 1000 × 15000 × (8200/2000)=0.3 × P0
Optical power value at this time is set as P by software, and reads U in real timeADCValue, if UADCIt is then gradual less than 0.3 × P
Increase UDACIf UADCLess than 0.3 × P, then U is gradually reducedDACValue.So as to fulfill LED light source steady operation setting light work(
Rate value.
It is 12 to be selected in the present embodiment and control chip DAC, and output area is 0~3V, then UDACLeast regulating amount be
3/4096=0.00073V.
It is understood through above-mentioned analysis, the present invention can ensure that the luminous power of video collimator LED light source within the full working time is permanent
While determining, the problem of effectively preventing the ccd image flicker caused by CCD overexposures and PWM pulsewidth modulation type of drive.
Claims (3)
1. for the LED light source direct current Constant-power drive circuit of photoelectric auto-collimator, it is characterized in that, including the laser as light source
Diode, constant-current drive circuit and monitor current sample circuit, the laser diode have LD ends, PD ends and power end；Institute
Stating constant-current drive circuit includes：Resistance R5One end connection laser diode LD end, resistance R5Other end connection field-effect tube V2Leakage
Pole, field-effect tube V2Source electrode connection resistance R16One end, while pass through resistance R23Ground connection, resistance R16Other end connection amplifier N1's
Inverting input, while pass through resistance R22Ground connection, amplifier N1In-phase input end pass through resistance R3It is connected to the control of control chip
Signal output part processed, while pass through resistance R10It is grounded and passes through capacitance C1Ground connection, amplifier N1Output terminal by resistance R8 connect
It is connected to field-effect tube V2 grids；The monitor current sample circuit includes：Resistance R7One end connection laser diode PD ends, electricity
Hinder R7The other end passes through resistance R11Connect amplifier N2In-phase input end, and pass through resistance R24Ground connection, amplifier N2Output terminal
Pass through resistance R25It is connected with inverting input, and passes through resistance R25With resistance R21Ground connection, amplifier N2Output terminal also pass through resistance
R13Connection control chip, exports sampled voltage；The constant voltage values for controlling chip output are changed into constant by constant-current drive circuit
Electric current drives light source, and the monitor current for flowing through light source receiving unit is converted into voltage value by monitor current sample circuit, control
Chip gathers this voltage value, to obtain the monitor current for flowing through light source receiving unit, utilizes the prison for flowing through the light source receiving unit
Electric current and the directly proportional characteristic of light source luminous power are controlled, flows through the monitoring electricity of the light source receiving unit by the way that chip is controlled to gather in real time
Stream obtains the luminous power of current light source；If the luminous power of light source is less than preset value, gradually increase the driving current of light source；Instead
It, if current luminous power is more than preset value, is gradually reduced the driving current of light source.
2. the LED light source direct current Constant-power drive circuit of photoelectric auto-collimator is used for as described in claim 1, it is characterized in that,
By adjusting current-limiting resistance R in constant-current drive circuit5And R23The mode of resistance value limits the driving current maximum of light source.
3. the LED light source direct current Constant-power drive circuit of photoelectric auto-collimator is used for as described in claim 1, it is characterized in that,
By the way that the software in chip is controlled to preset the value of luminous power, the mode for automatically adjusting the driving current of light source overcomes the shadow of temperature
It rings, controls light source light power invariability.
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| CN201710328522.8A CN106973462B (en) | 2017-05-10 | 2017-05-10 | For the LED light source direct current Constant-power drive circuit of photoelectric auto-collimator |
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| CN201710328522.8A CN106973462B (en) | 2017-05-10 | 2017-05-10 | For the LED light source direct current Constant-power drive circuit of photoelectric auto-collimator |
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| JP7414738B2 (en) * | 2018-06-04 | 2024-01-16 | メルク パテント ゲゼルシャフト ミット ベシュレンクテル ハフツング | Calibration devices for optical detectors and setting devices for setting calibration points for calibration devices |
| CN112033901A (en) * | 2020-08-10 | 2020-12-04 | 珠海格力电器股份有限公司 | Light source zero compensation device, sensor and light source zero compensation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPH08172236A (en) * | 1994-12-15 | 1996-07-02 | Nec Corp | Apc circuit |
| JP2005169785A (en) * | 2003-12-10 | 2005-06-30 | Canon Inc | Constant voltage generator and image forming apparatus |
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