KR20160082085A - Apparatus and method for measuring characteristics of optical filter of laser projector - Google Patents

Abstract

The present invention relates to a device and a method for measuring a property of an optical filter in a laser projector. According to the embodiment of the present invention, the device for measuring a property of an optical filter in a laser projector includes: a temperature adjustment unit for maintaining the temperature of a laser projector at a predetermined temperature; a temperature sensor for detecting the temperature of the laser projector; an optical power measuring unit for measuring radiation intensity output from at least a laser diode in the laser projector; an optical detector output measuring unit for measuring an output current of at least an optical detector in the laser projector; and a control unit controlling a motion of the temperature adjustment unit based on a temperature signal detected by the temperature sensor, controlling the motion of the at least laser diode, and measuring a property of the least an optical filter in the laser projector based on the output current of the optical detector, which is measured by optical detector output measuring unit, and the radiation intensity measured by the optical power measuring unit. The device for measuring a property of an optical filter in a laser projector can measure the property and an error rate of the optical filter in accordance with a change in the temperature and the radiation intensity and can manufacture the laser projector capable of maintaining high image quality against a change in environment as the device for measuring a property of an optical filter in a laser projector can select the optical filter with the low error rate to reduce the change in the optical power due to the temperature.

Description

Technical Field [0001] The present invention relates to an apparatus and a method for measuring an optical filter characteristic of a laser projector,

The present invention relates to an apparatus and a method for measuring optical filter characteristics of a laser projector.

As an information communication medium, the demand of various types of fusion multifunction devices in the modern society is increasing rapidly. In recent years, portable mobile multimedia devices have been widely used. Among them, portable mobile devices having a built-in pico projector having advantages of low output, large screen, and small size are being manufactured.

Among the pico projectors, a laser pico projector using a laser light source includes at least one laser diode (LD) for outputting laser light, a light source for receiving a part of light output from the laser diode and detecting the amount of light output from the laser diode A photodiode (PD) as a detector, and a dichroic optical filter that reflects or transmits light output from the laser diode and outputs the light as projection light and outputs a part of light through a photodiode, Filters, and the like.

The control part of the laser projector constitutes a feedback system that detects light that is transmitted through the optical filter or reflected by the optical filter using a photodiode that is a photodetector and maintains a constant optical output by using the detected amount of light. The output light amount of the laser diode, that is, the light output is changed.

The characteristic of the optical filter of the laser projector changes with the change of the temperature and the amount of light, and when the amount of change of the optical amount of the optical filter according to the temperature is large, the output brightness is changed and the quality of the image is influenced. not.

The patent documents described in the following prior art documents disclose an image display apparatus in which a power reduction of output light is effectively suppressed even when a temperature change or the like occurs, a laser light source apparatus having a high light utilization efficiency and stable output, and an efficiency of utilization are improved.

JP 2008-135689 A

An object of the present invention is to provide an apparatus for measuring the optical filter characteristics of a laser projector capable of measuring the characteristics and the error rate of the optical filter according to changes in temperature and amount of light.

An object of the present invention is to provide a method of measuring the optical filter characteristic of a laser projector capable of measuring the characteristics and error rate of an optical filter according to changes in temperature and light quantity.

According to an aspect of the present invention, there is provided an apparatus for measuring an optical filter characteristic of a laser projector,

A temperature regulator for maintaining the temperature of the laser projector at a predetermined temperature;

A temperature sensor for sensing the temperature of the laser projector;

An optical output measuring unit for measuring an amount of light output from at least one laser diode in the laser projector;

A photodetector output measuring unit for measuring an output current of at least one photodetector in the laser projector; And

And controlling the operation of the temperature adjusting unit based on a temperature signal sensed by the temperature sensor, and controlling the operation of the at least one laser diode. The light amount measured by the light output measuring unit, And a controller for measuring a characteristic of the at least one optical filter in the laser projector based on an output current of the photodetector measured by the photodetector.

In an apparatus for measuring an optical filter characteristic of a laser projector according to an embodiment of the present invention, the characteristic of the optical filter is that, at each temperature within a predetermined temperature range, the optical filter for light output from the at least one laser diode Light reflection and light transmission characteristics of the light emitting device.

In the apparatus for measuring an optical filter characteristic of a laser projector according to an embodiment of the present invention, the control unit may set the minimum current to the maximum current for each of the at least one laser diode at each temperature within a predetermined temperature range To obtain the optical output of the at least one laser diode and the output current of the corresponding photodetector.

In the apparatus for measuring an optical filter characteristic of a laser projector according to an embodiment of the present invention,

에 기반하여, 소정의 온도 범위 내의 각 온도에서, 상기 각 레이저 다이오드별, 최소 광출력 내지 최대 광출력에 따른 대응하는 광학 필터의 에러율을 계산하고, 상기에서,

이고,

일 수 있다.

Calculates the error rate of the corresponding optical filter according to the minimum optical power to the maximum optical power for each of the laser diodes at each temperature within a predetermined temperature range,

ego,

Lt; / RTI >

In the apparatus for measuring optical filter characteristics of a laser projector according to an embodiment of the present invention, the optical filter may include a dichroic filter that transmits light of a specific wavelength and reflects light of the remaining wavelengths .

A method of measuring optical filter characteristics of a laser projector according to an embodiment of the present invention includes:

(A) obtaining a light output of the at least one laser diode and an output current of a corresponding photodetector by applying a minimum current to a maximum current, for each of the at least one laser diode, at each temperature within a predetermined temperature range ;

(B) calculating the sensitivity of at least one optical filter in the laser projector based on the optical output of the at least one laser diode and the output current of the corresponding photodetector;

(C) calculating an average sensitivity based on the calculated sensitivity of the optical filter; And

(D) calculating an error rate of the at least one optical filter based on the sensitivity and the average sensitivity.

In a method of measuring optical filter characteristics of a laser projector according to an embodiment of the present invention, the characteristic of the optical filter is that, at each temperature within a predetermined temperature range, the optical filter for light output from the at least one laser diode Light reflection and light transmission characteristics of the light emitting device.

에 의해 계산되고,In the method of measuring optical filter characteristics of a laser projector according to an embodiment of the present invention,

Lt; / RTI >

에 의해 계산되며,The average sensitivity may be expressed as:

Lt; / RTI >

에 의해 계산되고,The error rate of the filter,

Lt; / RTI >

The error rate of the filter may be the error rate of the corresponding optical filter according to the minimum optical power to the maximum optical power for each laser diode at each temperature within a predetermined temperature range.

Further, in the method of measuring optical filter characteristics of a laser projector according to an embodiment of the present invention, the optical filter may include a dichroic filter that transmits light of a specific wavelength and reflects light of the remaining wavelengths .

According to the apparatus and method for measuring optical filter characteristics of a laser projector according to an embodiment of the present invention, it is possible to measure the characteristics and error rate of an optical filter according to temperature and light amount changes, It is possible to manufacture a laser projector capable of maintaining a high-quality image quality even in a change of environment due to a small change in light output.

The features and advantages of the present invention will become more apparent from the following detailed description based on the accompanying drawings.

Prior to this, terms and words used in the present specification and claims should not be construed in a conventional and dictionary sense, and the inventor may appropriately define the concept of a term in order to best describe its invention The present invention should be construed in accordance with the spirit and scope of the present invention.

1 is a block diagram of an optical filter characteristic measuring apparatus of a laser projector according to an embodiment of the present invention;
2 is a flow chart of a method for measuring optical filter characteristics of a laser projector according to an embodiment of the present invention.
3 is a view showing a path of light output from the laser diode and a part of light incident on the photodiode.
FIG. 4 is a graph showing the light output versus current change of a laser diode by temperature. FIG.
5 is a graph showing a photodiode output current with respect to a current change of a laser diode by temperature.
6 is a graph showing an error rate with respect to light output per temperature;

BRIEF DESCRIPTION OF THE DRAWINGS The objectives, specific advantages and novel features of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG.

Prior to that, terms and words used in the present specification and claims should not be construed in a conventional and dictionary sense, and the inventor may properly define the concept of the term in order to best explain its invention Should be construed in accordance with the principles and the meanings and concepts consistent with the technical idea of the present invention.

It should be noted that, in the present specification, the reference numerals are added to the constituent elements of the drawings, and the same constituent elements have the same numerical numbers as much as possible even if they are displayed on different drawings.

Also, "first", "second", "one side". The terms "when" and the like are used to distinguish one element from another, and the element is not limited by the terms.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description of the present invention, detailed description of related arts which may unnecessarily obscure the gist of the present invention will be omitted.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of an optical filter characteristic measuring apparatus of a laser projector according to an embodiment of the present invention.

1, an apparatus for measuring optical filter characteristics of a laser projector according to an embodiment of the present invention includes a temperature sensor 104 for sensing the temperature of the laser projector 100, A temperature control unit 114 for controlling the temperature of the laser projector 100 based on the temperature of the laser projector 100. The laser diodes 300, 302, and 304 included in the laser projector 100, The laser diode control unit 112 for controlling the operation of the laser diode (300, 302, 304 in FIG. 3), and the laser light is reflected or transmitted by the optical filter (306, 308, 310 in FIG. 3) An optical output measuring unit 106 for measuring the amount of light output from the laser projector 100, a photodiode for measuring the output current of the photodiodes (312, 314, and 316 in FIG. 3) Output measuring unit The laser diode control unit 112 and the operation of the temperature control unit 114 and the operation of the laser diode control unit 112 to control the amount of light measured by the optical output measurement unit 106 and the photodiode output measurement unit 108, (FIG. 3, 306, 308, 310) based on the output current of the photodiode measured by the photodiode (not shown).

1, the temperature adjusting unit 102 maintains the temperature of the laser projector 100 constant at a set temperature in accordance with a control signal of the temperature controller 114.

The functions of the temperature control unit 114 and the laser diode control unit 112 may be integrated into the control unit 110. When the functions of the temperature control unit 114 and the laser diode control unit 112 are incorporated in the control unit 110, the control unit 110 controls the temperature of the laser projector 100 based on the temperature of the laser projector 100 sensed by the temperature sensor 104. [ It is possible to control the temperature of the projector 100 and to control the operation of the laser diodes (300, 302, 304 in FIG. 3) included in the laser projector 100.

The characteristics of the optical filters (306, 308, 310 in FIG. 3) are such that, at each temperature within a predetermined temperature range, the corresponding optical filter for light output from each of the laser diodes 300, 302, 306, 308, 310, respectively.

The controller 110 applies a minimum current to a maximum current to each of the laser diodes 300, 302 and 304 at each temperature within a predetermined temperature range, And obtains the output current of each light output and corresponding photodetector.

3 is a view illustrating a path of light output from the laser diodes 300, 302 and 304 and a part of light incident on the photodiodes 312, 314 and 316. Referring to FIG. 3, The light B outputted from the laser diode 300 is reflected by the first optical filter 306 and transmitted through the second optical filter 308 and part of the light B outputted from the B laser diode 300 Is transmitted through the first optical filter 306 and detected by the first photodiode 312, which is a photodetector.

The light R outputted from the R laser diode 302 is reflected by the second optical filter 308 and reflected by the third optical filter 310 and reflected by the R laser diode 302 Is detected by the second photodiode 314, which is a photodetector, through the second optical filter 308.

Some of the light G output from the G laser diode 304 is reflected by the third optical filter 312 and detected by the third photodiode 316 which is the photodetector and the G laser diode 304 G and B transmitted or reflected by the third optical filter 310 are transmitted through the third optical filter 310 and finally emitted from the laser projector 100 .

The operation of the laser diodes 300, 302 and 304 is controlled by the laser diode control unit 112 and the amount of light output from the laser projector 100 is measured by the optical output measuring unit 106, The output currents of the diodes 312, 314, and 316 are measured by the photodiode output measuring unit 108.

The optical filters 306, 308, and 310 may include a dichroic filter that transmits light of a specific wavelength and reflects light of the remaining wavelengths.

The operation of the apparatus and method for measuring optical filter characteristics of a laser projector according to an embodiment of the present invention will be described below with reference to FIGS. 1 to 3. FIG.

In step S200, the control unit 110 sets the initial measurement temperature, and instructs the temperature control unit 114 to hold the laser projector 100 at the set temperature. For example, the initial measured temperature may be set to 10 占 폚, or it may be set to a lower temperature. The temperature controller 114 controls the operation of the temperature controller 102 based on the temperature signal detected by the temperature sensor 104 to maintain the temperature of the laser projector 100 at a predetermined temperature.

In step S202, the control unit 110 selects one of the three laser diodes 300, 302, and 304 in the laser projector 100 to be measured. In this embodiment, the controller 110 selects the R laser diode 308 in step S202, and in step S204, the control unit 110 controls the operation of the laser diode control unit 112 so that the R laser And supplies a minimum current to the diode 302 to turn on the selected R laser diode 302.

The optical output measuring unit 106 measures the amount of light output from the R laser diode 302 and reflected by the optical filters 308 and 310 and outputs the measured amount of light to the control unit 110 in step S206.

In step S208, the photodiode output measuring unit 108 measures the current output from the second photodiode 314, and supplies the measured current to the control unit 110. [

In step S210, the control unit 110 determines whether the maximum setting brightness has been exceeded. That is, the control unit 110 determines whether the maximum current is applied to the R laser diode 302 within an allowable range.

If it is determined in step S210 that the maximum current is not applied to the R laser diode 302 in step S210, the control unit 110 controls the operation of the laser diode control unit 112 in step S212, 302) by a predetermined amount to increase the brightness, and the process proceeds to step S206 again.

The control unit 110 controls the operation of the laser diode control unit 112 to apply the minimum current to the maximum current to the laser diode 302, The optical output of the laser diode 302 measured by the optical output measuring unit 106 and the output current of the photodiode measured by the photodiode output measuring unit 108 are measured.

The photodiode measurement unit 108 measures the optical output measured by the optical output measurement unit 106 and the second photodiode 108 measured by the photodiode output measurement unit 108. [ The control unit 110 controls the operation of the laser diode control unit 112 to turn off the R laser diode in step S214.

In step S216, the control unit 110 determines whether the measurement for all the laser diodes is completed. If the measurement for all the laser diodes is not completed, the control unit 110 determines whether or not the measurement is completed for the laser diodes 300 and G, which are the unmeasured laser diodes, in step S208, Step S208, step S210 and step S212 are performed to apply the minimum current to the maximum current to the laser diode at the set temperature for the unmeasured laser diode, and the optical output of the laser diode corresponding thereto is output to the optical output measuring unit 106 , And the output current of the photodiodes 312 and 316 is measured through the photodiode output measuring unit 108. [

In step S216, if the measurement for all the laser diodes is completed for the set temperature, it is determined in step S220 whether the measurement for all the temperature ranges is completed.

If it is determined in step S220 that the measurement for all the temperature ranges, for example, 10 DEG C to 60 DEG C, has not been completed, the process returns to step S200 to set the set temperature to the temperature of the next step, and steps S202 to S216 Is repeatedly performed to perform measurement on all the laser diodes in a predetermined temperature range.

The optical output of the temperature-dependent laser diode (LD) as shown in Fig. 4 is measured by the above steps S200 to S220, and the current change of the temperature-dependent laser diode as shown in Fig. 5 The photodiode output current is measured. FIGS. 4 and 5 are graphs showing measurement results for any one of the laser diodes as an example.

As described above, when all the measurements are completed for the predetermined temperature range, in step S222, the controller 110 calculates the sensitivity of the optical filter according to the equation (1) based on the measured results.

The optical output is an amount of light that is output from each of the laser diodes 300, 302, 304 of the laser projector 100 and is reflected by the corresponding optical filter 306, 308, 310 or transmitted through the optical filter, And the amount of light measured by the output measuring unit 106. [

The output current of the photodetector (photodiode) is output from each of the laser diodes 300, 302 and 304 of the laser projector 100 and transmitted through the corresponding optical filters 306, 308 and 310, 314, and 316 when light reflected by the photodiodes 312, 314, and 316 is detected by the corresponding photodiodes 312, 314, and 316, respectively.

In addition, the controller 110 calculates the average sensitivity according to Equation (2).

Further, the control unit 110 calculates the error rate of the optical filter for each temperature and each optical output according to Equation (3), based on the calculated sensitivity and the average sensitivity.

As shown in Fig. 6, an error rate for the light output per temperature is obtained. 6 is a graph for any one of the laser diodes.

Table 1 illustrates the measurement results and error rates for the R laser diode 302, illustratively at 25 占 폚.

Light output 1.205 10.52 20.53 30.32 40.49 50.38 60.34 PD output current 18.3105 155.389 303.435 450.301 603.294 747.812 896.072 Sensitivity 15.19544 14.77082 14.78008 14.85162 14.89983 14.84343 14.85038 Average sensitivity 14.8845143 Error rate (%) 2.08892 -0.76384 -0.70163 -0.22100 0.10290 -0.27602 -0.22933

In Table 1, since the output currents of the photodiodes 314 corresponding to the seven light outputs of the R laser diode 302 were measured, the number measured in the equation (2) was seven. Based on the photodiode output current according to each optical output, the sensitivity of the filter is calculated by Equation (1), the average sensitivity is calculated by Equation (2), and finally the optical filter 308 ) Is calculated.

Although Table 1 shows the photodiode output current and error rate for seven optical outputs, it is also possible to calculate the error rates by measuring the photodiode output current for a greater number of optical outputs, from the lowest light output to the maximum light output.

Table 1 also shows the measurement results and error rates for the R laser diode 302, the corresponding photodiode 314, and the corresponding optical filter 308, at illustratively 25 ° C, Range, for example, at 0 캜 to 60 캜, the measurement results as shown in Table 1 above can be obtained.

In the entire measurement temperature range, the error rates shown in Table 1 indicate that the light reflection and the light transmission characteristics of the corresponding optical filter 308 for the light output from the R laser diode 302 are within a predetermined range based on the average sensitivity Represents sensitivity variation.

The error rates of the corresponding optical filters 306 and 310 for the light output from the remaining B laser diodes 300 to G laser diodes 304 can also be calculated based on the measured results The error rate of all the optical filters 306, 308 and 310 is measured to determine whether the light reflection and light transmission characteristics of the optical filters 306, 308 and 310 are within a predetermined range based on the average sensitivity in the entire measurement temperature range .

By measuring the error rates associated with the optical filter for each laser diode in the entire measurement temperature range as described above, the amount of change in optical output can be predicted, and by comparing the obtained error rates with the error rate of the tolerance range, Can be selected.

Therefore, by using the selected optical filter, it is possible to manufacture a laser projector capable of maintaining a high-quality image quality even in a change in environment due to a small change in light output according to temperature.

According to the apparatus and method for measuring optical filter characteristics of a laser projector according to an embodiment of the present invention, since the characteristics and the error rate of the optical filter can be measured according to the temperature and the amount of light change, So that a high-quality projector can be manufactured.

The apparatus and methods discussed herein may be implemented using various means, depending on the application. For example, these methods may be implemented in the form of hardware, firmware, software, or any combination thereof. In an implementation involving hardware, the control circuitry or control portion may comprise one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), field programmable gate arrays (FPGAs), processors, , Microprocessors, electronic devices, other electronic units designed to perform the functions discussed herein, or a combination thereof.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It is clear that the present invention can be modified or improved.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims.

100: laser projector 102: temperature adjuster
104: temperature sensor 106: optical output measuring unit
108: photodiode output measuring unit 110:
112: laser diode control unit 114: temperature control unit
300: B laser diode 302: R laser diode
304: G laser diode 306: first optical filter
308: second optical filter 310: third optical filter
312: first photodiode 314: second photodiode
316: Third photodiode

Claims (9)

A temperature regulator for maintaining the temperature of the laser projector at a predetermined temperature;
A temperature sensor for sensing the temperature of the laser projector;
An optical output measuring unit for measuring an amount of light output from at least one laser diode in the laser projector;
A photodetector output measuring unit for measuring an output current of at least one photodetector in the laser projector; And
And controlling the operation of the temperature adjusting unit based on a temperature signal sensed by the temperature sensor, and controlling the operation of the at least one laser diode. The light amount measured by the light output measuring unit, And a controller for measuring a characteristic of the at least one optical filter in the laser projector based on an output current of the optical detector measured by the optical detector. The method according to claim 1,
The characteristics of the optical filter include,
And optical reflection characteristics and light transmission characteristics of the optical filter with respect to light output from the at least one laser diode at each temperature within a predetermined temperature range. The method of claim 2,
Wherein,
For each of said at least one laser diode, at a temperature within a predetermined temperature range, a minimum current to a maximum current to obtain an optical output of said at least one laser diode and an output current of a corresponding photodetector Optical filter characteristic measuring device. The method of claim 3,
Wherein,

Calculates the error rate of the corresponding optical filter according to the minimum optical power to the maximum optical power for each of the laser diodes at each temperature within a predetermined temperature range,

ego,

The optical filter characteristic measurement device of the laser projector. The method according to claim 1,
Wherein the optical filter includes a dichroic filter that transmits light of a specific wavelength and reflects light of the remaining wavelengths. (A) obtaining a light output of the at least one laser diode and an output current of a corresponding photodetector by applying a minimum current to a maximum current, for each of the at least one laser diode, at each temperature within a predetermined temperature range ;
(B) calculating the sensitivity of at least one optical filter in the laser projector based on the optical output of the at least one laser diode and the output current of the corresponding photodetector;
(C) calculating an average sensitivity based on the calculated sensitivity of the optical filter; And
(D) calculating an error rate of the at least one optical filter based on the sensitivity and the average sensitivity. The method of claim 6,
The characteristics of the optical filter include,
And at each temperature within a predetermined temperature range, optical reflection and light transmission characteristics of the optical filter with respect to light output from the at least one laser diode. The method of claim 7,
The sensitivity,

Lt; / RTI >
The average sensitivity may be expressed as:

Lt; / RTI >
The error rate of the filter,

Lt; / RTI >
Wherein the error rate of the filter is an error rate of a corresponding optical filter according to a minimum optical output or a maximum optical output for each of the laser diodes at each temperature within a predetermined temperature range. The method of claim 6,
Wherein the optical filter includes a dichroic filter that transmits light of a specific wavelength and reflects light of the remaining wavelengths.

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