JP2017106982A - Projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projector which can enlarge the dynamic range of output light power to a low-power side and can be reduced in size and cost.SOLUTION: A projector 1 includes a laser light source part (laser light sources 11 to 13), a light detection part (photodiode 14) which detects the output light power being the power of laser light outputted from the laser light source part, and a control part 10 which controls the output light power by adjusting a current amount supplied to the laser light source part. The control part 10 feedback-controls the current amount supplied to the laser light source part on the basis of a detection result by the light detection part, when the output light power is controlled with a reference value detected in the light detection part or more and open-loop controls the current amount, when the output light power is controlled with less than the reference value.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a projector using a laser light source.

  Conventionally, a projector that projects an image by scanning a laser beam output from a laser light source is known (see, for example, Patent Document 1). In the projector, it is necessary to adjust the power of the laser beam in order to adjust the brightness of the projected image. In the projector disclosed in Patent Document 1, in order to obtain laser light having a desired power, the power of the laser light is detected by a photodetector, and the laser light source is adjusted so that the detected power becomes constant. .

JP 2009-244797 A

  When a projector is used in a vehicle head-up display (hereinafter referred to as HUD) device, it is necessary to reduce the power of laser light at night so that the user does not feel the projected image dazzling. Specifically, for example, it is necessary to output with a power of about 1/5000 of the maximum output power of the laser light source. However, in the conventional projector, the laser light source is adjusted based on the detection result of the photodetector made of a photodiode, so that it is impossible to obtain laser light having a power less than the detection lower limit of the photodetector. Further, the lower limit of detection can be lowered by using a power meter larger than the photodiode as the photodetector, but the projector cannot be reduced in size when the power meter is used. In addition, since the power meter is generally more expensive than the photodiode, the use of the power meter for the projector increases the cost of the projector.

  Therefore, an object of the present invention is to provide a projector that can expand the dynamic range of output light power to the low power side, and can be reduced in size and cost.

  In order to achieve the above object, a projector according to an aspect of the present invention includes a laser light source unit, a light detection unit that detects output light power that is the power of laser light output from the laser light source unit, and the laser. A control unit that controls the output light power by adjusting an amount of current supplied to the light source unit, and the control unit controls the output light power at a reference value or more detected by the light detection unit. In this case, the current amount is feedback-controlled based on the detection result by the light detection unit, and when the output light power is controlled to be less than the reference value, the current amount is subjected to open loop control.

  As a result, for output light power that cannot be detected by the light detection unit, laser light having a desired output light power can be obtained by open loop control, so that the dynamic range of output light power can be expanded to the low power side. In addition, it is not necessary to use a large photodetection unit such as a power meter that can detect laser light in a low power region, and a small and low-cost photodetection unit such as a photodiode can be used. Can be realized.

  For example, the control unit has a memory that stores a characteristic data set related to the characteristic of the output optical power with respect to the amount of current supplied to the laser light source unit, and opens the current amount based on the characteristic data set. Loop control may be performed.

  As a result, the laser light source unit can be accurately controlled by using the characteristic data set even at a power lower than the detection lower limit of the light detection unit.

  For example, the reference value may be larger than the output light power in the current amount range in which the output light power changes nonlinearly with respect to the current amount.

  Accordingly, since feedback control is not performed in a region where mode competition occurs in the laser light source unit, instability of output light power in feedback control is suppressed.

  The characteristic data set may be a relational expression of the output optical power with respect to the current amount.

  As a result, the capacity used for storing the characteristic data set in the memory can be reduced as compared with the case where each current amount and the table of output optical power corresponding to the current amount are stored as the characteristic data set.

  The relational expression may be a quadratic expression.

  As a result, the output light power of the laser light source unit can be controlled more accurately than when only the relational expression including the linear expression is used.

  The characteristic data set may be a table indicating a relationship between the current amount and the output optical power.

  According to this, since the control unit does not need to calculate the relational expression compared to the case where the relational expression is used, the processing load on the control unit is reduced.

  Further, when the control unit detects a change in a first current amount that is the current amount required to obtain a first power value equal to or higher than the reference value as the output light power, the characteristic data set is detected. May be corrected.

  Thereby, even when the output light power characteristic of the laser light source section changes, laser light having a desired power can be obtained.

  The control unit may correct the characteristic data set by using a ratio of the first current amount after the change to the first current amount before the change.

  According to this, since the laser beam having the first power value equal to or higher than the reference value can be detected by the light detection unit, the relationship between the first power value and the first current amount can be accurately obtained. Therefore, the characteristic data set can be accurately corrected by using the ratio.

  Further, the current amount in the characteristic data set after correction may be a value obtained by multiplying the current amount in the characteristic data set before correction by the ratio.

  Thereby, the characteristic data set can be corrected by a simple calculation. For this reason, the processing load of a control part can be reduced.

  Further, the control unit is configured to continuously change the current amount according to the output light power when the output light power changes from a value less than the reference value to a value equal to or larger than the reference value. The characteristic data set may be corrected.

  Thereby, even when the control unit switches between the feedback control and the open loop control, the output from the laser light source unit can be continuously changed.

  Further, the memory stores a plurality of the characteristic data sets, and the control unit is configured such that the output light power detected by the light detection unit is a first power value equal to or greater than the reference value. One of the plurality of characteristic data sets stored in the memory may be selected based on the current amount, and the current amount may be controlled based on the selected characteristic data set.

  Thereby, even when the output light power characteristic of the laser light source section changes, laser light having a desired power can be obtained. Further, according to this configuration, the processing load on the control unit is reduced as compared with the case where the characteristic data set is corrected by calculation.

  Note that the present invention can be realized not only as a projector including such a characteristic processing unit, but also as a control method using steps executed by the characteristic processing unit included in the projector. it can. Further, it can be realized as a program for causing a computer to execute a characteristic step included in a program for causing a computer to function as a characteristic processing unit included in a projector or a control method. Such a program can be distributed via a computer-readable non-transitory recording medium such as a CD-ROM (Compact Disc-Read Only Memory) or a communication network such as the Internet. .

  According to the present invention, it is possible to provide a projector that includes the laser light source unit in which the dynamic range of the output light power is expanded to the low power side and can be reduced in size and cost.

FIG. 1 is a block diagram showing the overall configuration of the projector according to the first embodiment. FIG. 2 is a graph showing an example of the relationship between the input current and output optical power of the laser light source actually measured in the pre-shipment inspection. FIG. 3 is a graph showing an example of the characteristic data set according to the first embodiment. FIG. 4 is a flowchart showing a method for preparing a characteristic data set according to the first embodiment. FIG. 5 is a flowchart showing a method for controlling the output light power of the laser light source in the projector according to the first embodiment. FIG. 6 is a block diagram showing the overall configuration of the projector according to the second embodiment. FIG. 7 is a graph showing an example of the characteristic data set according to the second embodiment. FIG. 8 is a block diagram showing the overall configuration of the projector according to the third embodiment. FIG. 9 is a graph showing an example of the characteristic data set according to the third embodiment. FIG. 10 is a diagram illustrating an installation example of the HUD device according to the fourth embodiment. FIG. 11 is a diagram illustrating an example of a landscape viewed by the user through the windshield. FIG. 12 is a block diagram showing an example of the configuration of the HUD device according to the fourth embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that each of the embodiments described below shows a comprehensive or specific example. Numerical values, shapes, materials, constituent elements, arrangement positions and connection forms of constituent elements, and the like shown in the following embodiments are merely examples, and are not intended to limit the present invention. In addition, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims are described as arbitrary constituent elements.

(Embodiment 1)
[1-1. overall structure]
First, the overall configuration of the projector according to Embodiment 1 will be described with reference to FIG.

  FIG. 1 is a block diagram showing an overall configuration of projector 1 according to the present embodiment.

  As shown in FIG. 1, the projector 1 includes a control unit 10, laser light sources 11 to 13, a photodiode 14, an LD (Laser Diode) driver 15, a memory 16, beam splitters 21 to 24, and a MEMS (Micro Electro Mechanical Systems). A mirror 25 is provided.

  The laser light sources 11 to 13 are a plurality of laser light source units that output laser beams of a plurality of different color components. Specifically, the laser light source 11 is a laser diode that irradiates the MEMS mirror 25 with, for example, blue laser light through the beam splitters 21 to 24. The laser light source 12 is a laser diode that irradiates the MEMS mirror 25 with, for example, green laser light passing through the beam splitters 22 to 24. The laser light source 13 is, for example, a laser diode that irradiates the MEMS mirror 25 with red laser light that passes through the beam splitters 23 and 24. As described above, the laser beams output from the laser light sources 11 to 13 are combined by the beam splitters 21 to 24 and are applied to the MEMS mirror 25.

  The LD driver 15 adjusts the output light power of each of the laser light sources 11 to 13 by supplying current to each of the laser light sources 11 to 13.

  The photodiode 14 is a light detection unit that detects output light power that is the power of laser light output from the laser light source unit. Specifically, the photodiode 14 detects the power of the laser light output from the laser light sources 11 to 13. In the present embodiment, part of the laser light output from each laser light source is separated by the beam splitter 24, and the separated laser light is input to the photodiode 14.

  The MEMS mirror 25 is an optical scanning unit that projects an image by scanning laser light output from a plurality of laser light source units. In the present embodiment, the MEMS mirror 25 scans the horizontal direction at high speed by resonance driving and scans the vertical direction at low speed by DC driving. The driving of the MEMS mirror 25 may be controlled by the control unit 10 or may be controlled by a processing unit different from the control unit 10.

  The control unit 10 is a processing unit that controls the output light power by adjusting the amount of current supplied to the laser light source unit. The control unit 10 includes a memory 16 that stores a characteristic data set relating to the characteristic of the output light power with respect to the amount of current supplied to the laser light source unit. The control unit 10 feeds back the amount of current supplied to the laser light source unit based on the detection result by the light detection unit when the output light power is controlled by a reference value or more that is a power value detected by the light detection unit. Control. On the other hand, when the output light power is controlled below the reference value, the control unit 10 performs open loop control on the amount of current supplied to the laser light source unit. In the present embodiment, the control unit 10 performs open-loop control on the amount of current based on the characteristic data set.

  In the present embodiment, when the control unit 10 controls the output light power of the laser light source 11, 12, or 13 with a reference value that is equal to or higher than a detection lower limit that can be detected by the photodiode 14, the laser light source 11, The amount of current supplied to 12 or 13 is feedback controlled. That is, the control unit 10 controls the amount of current supplied to the laser light source 11, 12 or 13 so that the detection value by the photodiode 14 becomes a value corresponding to the target power value of the laser light source 11, 12 or 13. . In the case where only the output light power of any one of the laser light sources 11 to 13 is detected by the photodiode 14, the laser light is output from only one of the laser light sources 11 to 13, and the photodiode 14 To detect. For example, in the projector 1, when the laser light is output from each of the laser light sources 11 to 13, an area other than the projection area is irradiated by the MEMS mirror 25. That is, the output light power detection laser beam output for feedback control is output in a region that does not affect the projected image.

  On the other hand, when the output light power of the laser light source 11, 12 or 13 is controlled below the reference value, the control unit 10 performs open-loop control on the amount of current based on the characteristic data set stored in the memory 16.

[1-2. Characteristic data set]
Next, the above-described characteristic data set will be described with reference to FIG.

  FIG. 2 is a graph showing an example of the relationship between the input current and output optical power of the laser light source actually measured in the pre-shipment inspection. It should be noted that a light detector such as a power meter having a detection lower limit power value smaller than that of the photodiode 14 is used in the actual measurement in the pre-shipment inspection. For this reason, the relationship between the input current of the laser light source and the output light power at the output light power less than the detection lower limit power value Pth of the photodiode 14 as shown in FIG. 2 can also be detected. In the following, the relationship between the input current of the laser light source and the output light power may be referred to as output light power characteristics.

  As shown in FIG. 2, the projector 1 cannot detect the output light power of the laser light sources 11 to 13 at a power lower than the detection lower limit power value Pth of the photodiode 14. Therefore, the projector 1 cannot perform feedback control on the output light power of the laser light sources 11 to 13 at power less than the detection lower limit power value Pth.

  Therefore, in the projector 1 according to the present embodiment, the amount of current supplied to the laser light sources 11 to 13 is controlled based on the characteristic data set stored in the memory 16 so as to be less than the detection lower limit power value Pth. Get the output optical power of power. Here, the characteristic data set will be described with reference to FIG.

  FIG. 3 is a graph showing an example of the characteristic data set according to the present embodiment. The solid line shown in FIG. 3 is a graph shown based on the characteristic data set, and the broken line is a graph showing the output optical power characteristic shown in FIG.

  The characteristic data set is calculated based on the output optical power characteristic as shown in FIG. The characteristic data set is calculated at least in a power range equal to or smaller than a reference value Pref, which is a power value equal to or higher than the detection lower limit of the photodiode 14. In other words, the characteristic data set is calculated at least in a current range equal to or less than Iref which is the current amount of the laser light source corresponding to the reference value Pref. The characteristic data set may be calculated even in a range where the power is larger than the reference value Pref.

  The reference value Pref is not particularly limited as long as it is equal to or higher than the detection lower limit of the photodiode 14, but is preferably larger than the output light power in a current amount range in which the output light power changes nonlinearly with respect to the current amount. In this range, mode competition occurs in the laser light sources 11 to 13, so that the output light power becomes unstable over time. For this reason, in order to accurately detect the output light power by the photodiode 14, it is necessary to take a sufficiently long sampling period. Therefore, feedback control in this range is not preferable.

  In the present embodiment, the memory 16 stores a relational expression of the output light power of the laser light sources 11 to 13 with respect to the amount of current supplied to the laser light sources 11 to 13 as a characteristic data set. As shown in FIG. 3, in the present embodiment, the characteristic data set includes three relational expressions f11, f12, and f13. The relational expression f11 is an approximate expression in the range R1 where the current is equal to or less than Ir1. The relational expression f12 is an approximate expression in the range R2 where the current is larger than Ir1 and equal to or less than Ir2 (> Ir1). The relational expression f13 is an approximate expression in the range R3 where the current is larger than Ir2 and equal to or less than Iref (> Ir2). As shown in FIG. 3, in the present embodiment, each relational expression is a linear expression. Note that the range of the current amount in which the output light power changes nonlinearly with respect to the current amount is included in the range R2 and the range R3 illustrated in FIG.

  In the example shown in FIG. 3, the range where the current is 0 or more and Iref or less is divided into three, and the relational expression corresponding to each range is calculated. However, if the number of divisions of the range is 2 or more There is no particular limitation. Further, the relational expression is not limited to a linear expression. The number of divisions and the order of the relational expression are appropriately determined so that the error between the characteristic data set and the actual measurement value is small, and the data amount of the characteristic data set stored in the memory 16 is not excessive. That's fine.

[1-3. Preparation method of characteristic data set]
A method for preparing the characteristic data set described above will be described with reference to FIG.

  FIG. 4 is a flowchart showing a method for preparing a characteristic data set according to the present embodiment.

  In this embodiment, a characteristic data set is prepared for all the laser light sources 11 to 13.

  As shown in FIG. 4, first, in the pre-shipment inspection, the output light power characteristics of each laser light source are actually measured (S10). Here, a characteristic at a power equal to or lower than the reference value Pref is detected using a photodetector that can detect low-power laser light such as a power meter.

  Subsequently, a characteristic data set is created based on the actually measured characteristic of the output light power (S20). In the present embodiment, the range of the output light power equal to or smaller than the current amount Iref that becomes the reference value Pref is divided into a plurality of regions, and a relational expression is calculated for each region. Although the calculation method of the relational expression is not particularly limited, for example, linear approximation may be used.

  Subsequently, the created characteristic data set is stored (S30). In the present embodiment, a relational expression including a linear expression is stored in the memory 16 as a characteristic data set.

  By repeating the above steps for each laser light source, a characteristic data set can be prepared.

[1-4. Control method of output light power of laser light source]
Next, a method for controlling the output light power of the laser light sources 11 to 13 in the projector 1 according to the present embodiment will be described with reference to FIG.

  FIG. 5 is a flowchart showing a method of controlling the output light power of laser light sources 11 to 13 in projector 1 according to the present embodiment.

  As shown in FIG. 5, first, a characteristic data set of each laser light source is prepared (S100). The preparation method of the characteristic data set is as described above.

  Subsequently, an output light power characteristic at a power equal to or higher than the reference value Pref of each laser light source is acquired (S110). In the present embodiment, a current having a current amount equal to or greater than Iref is sequentially supplied to each laser light source, and the output light power of each laser light source is detected by the photodiode 14. Thereby, the output light power characteristics of the laser light sources 11 to 13 are acquired. In order to obtain the output light power characteristics, at least two different current amounts may be supplied to each laser light source and the corresponding output light power may be detected. As a result, the output light power characteristic can be approximated to a first order.

  As the reference value Pref, by using a power value larger than the output light power in the current amount range in which the output light power of the laser light source changes nonlinearly with respect to the current amount, the output light power at the power equal to or higher than the reference value Pref. The characteristics are almost linear. For this reason, when the output light power characteristic is first-order approximated, the error between the actual characteristic and the first-order approximation is small enough to be ignored. Note that the output light power characteristic at a power equal to or higher than the reference value Pref of each laser light source may not necessarily be acquired as a first-order approximation characteristic. For example, the output light power characteristic may be acquired as a table indicating the relationship between the amount of current and the output light power.

  Then, the target value of each output light power of each laser light source is determined (S120). For example, each target value is determined based on a signal input from the outside to the control unit 10 of the projector 1.

  Subsequently, it is determined whether each target value is less than a reference value Pref (S130). In the present embodiment, the control unit 10 compares the target value with the reference value Pref to determine whether the target value is less than the reference value Pref.

  If the target value is less than the reference value Pref (Yes in S130), the amount of current supplied to each laser light source is determined based on the characteristic data set prepared in Step S100 (S150).

  On the other hand, when the target value is equal to or greater than the reference value Pref (No in S130), the amount of current supplied to each laser light source is determined based on the output light power characteristic acquired in Step S110 (S140).

  Subsequently, a laser beam is output by supplying each laser light source with an amount of current determined for each laser light source (S160).

  Subsequently, the output light power characteristic at the power equal to or higher than the reference value Pref of each laser light source is updated (S170). Here, the output optical power characteristic is acquired and the output optical power characteristic is updated as in step S110.

  As described above, in the projector 1 according to the present embodiment, laser light having a desired power is output from each laser light source regardless of the power value equal to or higher than the detection lower limit of the photodiode 14 and the power value lower than the detection lower limit. be able to.

[1-5. effect]
As described above, in projector 1 according to the present embodiment, control unit 10 opens the amount of current supplied to each laser light source at a power less than reference value Pref, which is a power value detected by photodiode 14. Loop control. For this reason, a laser beam having a desired power can be obtained even at a power lower than the detection lower limit of the photodiode 14.

  As a result, for output light power that cannot be detected by the photodiode 14, laser light having a desired output light power can be obtained by open loop control, so that the dynamic range of the output light power can be expanded to the low power side. In addition, it is not necessary to use a large-sized photodetection unit such as a power meter that can detect laser light in a low power region, and a small and low-cost photodetection unit such as the photodiode 14 can be used. The projector 1 capable of reducing the cost can be realized.

  In the projector 1 according to the present embodiment, the control unit 10 includes a memory that stores a characteristic data set relating to the characteristic of the output light power with respect to the amount of current supplied to each laser light source. Further, when the output optical power is controlled to be less than the reference value Pref, the current amount is subjected to open loop control based on the characteristic data set.

  Thereby, even when the power is less than the detection lower limit of the photodiode 14, each laser light source can be accurately controlled by using the characteristic data set.

  In the projector 1 according to the present embodiment, the reference value Pref may be larger than the output light power in the current amount range in which the output light power changes nonlinearly with respect to the current amount.

  Thereby, since feedback control is not performed in a region where mode competition occurs in the laser light sources 11 to 13, instability of output light power in feedback control is suppressed.

  In the projector 1 according to the present embodiment, the memory 16 may store a relational expression of the output light power with respect to the current amount as the characteristic data set.

  As a result, the capacity used for storing the characteristic data set in the memory 16 can be reduced as compared with the case where each current amount and the corresponding table of output optical power are stored as the characteristic data set. .

(Embodiment 2)
Next, a projector according to Embodiment 2 will be described. In the projector 1 according to the first embodiment, the characteristic data set calculated based on the actual measurement in the pre-shipment inspection is used, but the output light power characteristic in the laser light source composed of a laser diode or the like is not necessarily constant. For example, the output optical power characteristic changes with a change in environmental temperature. Therefore, in the present embodiment, a projector capable of obtaining laser light having a desired power even when the output light power characteristic changes will be described focusing on differences from the projector 1 according to the first embodiment. .

[2-1. overall structure]
First, the overall configuration of the projector according to the present embodiment will be described with reference to FIG.

  FIG. 6 is a block diagram showing an overall configuration of projector 1a according to the present embodiment.

  As shown in FIG. 6, in the projector 1a according to the present embodiment, the constituent elements are the same as those of the projector 1 according to the first embodiment, but the configuration of the control unit 10a and the memory 16a is related to the first embodiment. Different from the projector 1. In the present embodiment, when the control unit 10a detects a change in the first current amount that is a current amount required to obtain the first power value equal to or greater than the reference value Pref as the output optical power, the characteristic data Correct the set. Then, the control unit 10a stores the corrected characteristic data set in the memory 16a, and performs open loop control on the amount of current supplied to each laser light source based on the corrected characteristic data set. As a result, in the present embodiment, even when the error between the characteristic data set and the actual output light power characteristic becomes large due to a change in environmental temperature or the like, it is possible to obtain laser light having a desired power. it can.

[2-2. Correction method of characteristic data set]
Next, a method for correcting the characteristic data set in the projector 1a according to the present embodiment will be described with reference to FIG.

  FIG. 7 is a graph showing an example of the characteristic data set according to the present embodiment. FIG. 7 shows relational expressions f11, f12, and f13 representing characteristic data sets before correction, and relational expressions f21, f22, and f23 representing characteristic data sets after correction.

  The output light power characteristic of each laser light source at room temperature (for example, 25 ° C.) is as shown by a broken line in FIG. As described in the first embodiment, the relational expressions f11, f12, and f13 are calculated as a characteristic data set based on the output optical power characteristic.

  However, the output light power characteristic when each laser light source is used varies depending on the environmental temperature or the like. For example, when the environmental temperature is about 60 ° C., the output light power characteristic is as shown by a two-dot chain line in FIG.

  Here, a case where the reference value Pref is used as an example of the first power value will be described. The current amount (first current amount) necessary to obtain the power of the reference value Pref (first power value) is Iref when the environmental temperature is normal temperature, but when the environmental temperature is 60 ° C. Is Iref1 shown in FIG.

In the present embodiment, the curve indicating the output light power characteristic has a characteristic of expanding and contracting in the current axis direction according to the environmental temperature, as shown in FIG. Therefore, the relational expression f1n (n = 1, 2, 3) when the environmental temperature is normal temperature is
y = a _1n x + b _1n (n = 1, 2, 3) (1)
When the environmental temperature is 60 ° C., the relational expression f2n (n = 1, 2, 3) is
y = a _2n x + b _2n (n = 1, 2, 3) (2)
a _2n = a _1n × Iref / Iref1 (3)
b _2n = b _1n (4)
Can be determined. In the above formulas (1) to (4), the variable x is a variable corresponding to the amount of current, and the variable y is a variable corresponding to the output optical power. Further, a _1n and a _2n (n = 1, 2, 3) are constants representing the slopes of the respective relational expressions, and b _1n and b _2n (n = 1, 2, 3) are intercepts of the respective relational expressions. Is a constant representing That is, in the present embodiment, the current amount in the corrected characteristic data set is a value obtained by multiplying the current amount in the characteristic data set before correction by the ratio Iref1 / Iref. Further, when the output light power changes from a value less than the reference value Pref to a value greater than or equal to the reference value Pref by the above correction method, the characteristics are set so that the amount of current continuously changes according to the output light power. The data set can be corrected. Thereby, also in the case where feedback control and open loop control are switched in the control part 10a, the output from each laser light source can be changed continuously.

  By using the above formulas (1) to (4), it is possible to correct the relational expression when the output light power characteristic changes due to a change in environmental temperature or the like. That is, the relational expression can be corrected as follows. First, when the environmental temperature is room temperature (for example, at the time of inspection before shipment), the current amount Iref when the output light power from each laser light source becomes the reference value Pref is obtained. When the projector 1a according to the present embodiment is actually used, the current amount Iref1 when the output light power detected by the photodiode 14 becomes the reference value Pref is detected at a predetermined timing. Using the ratio between the detected current amount Iref and the current amount Iref1, the corrected relational expressions f21, f22, and f23 can be obtained from the above formulas (2) to (4). The corrected relational expression may be stored in the memory 16a.

  In the present embodiment, the example in which the reference value Pref is used as the first power value equal to or higher than the reference value Pref is shown, but the first power value is not limited to the reference value Pref. The first power value may be any power value that is equal to or greater than the reference value Pref.

  As described above, even when the output light power characteristic of each laser light source changes by performing open loop control of each laser light source using the corrected relational expression, the desired power The laser beam can be obtained.

  In this embodiment, an example in which the characteristic data set is a relational expression including a linear expression has been described. However, the characteristic data set may not necessarily be a relational expression including a linear expression. For example, the characteristic data set may be a table showing the relationship between the amount of current and the output optical power. In this case, in the table, for example, the characteristic data set can be corrected by multiplying the current amount by Iref1 / Iref.

  In this embodiment, a configuration for correcting the characteristic data set when the output optical power characteristic changes is used. However, the configuration for changing the characteristic data set in accordance with the change of the output optical power characteristic is used. It is not limited to. For example, a plurality of characteristic data sets may be stored in the memory 16a, and a characteristic data set having characteristics close to the changed output optical power characteristics may be selected. This eliminates the need for calculation in the correction of the characteristic data set, thereby reducing the processing load on the control unit 10a.

[2-3. effect]
As described above, in projector 1a according to the present embodiment, control unit 10a has a first current amount that is a current amount required to obtain a first power value equal to or higher than reference value Pref as output light power. When a change is detected, the characteristic data set is corrected.

  Thereby, even when the output light power characteristic of each laser light source changes, laser light having a desired power can be obtained.

  In projector 1a according to the present embodiment, control unit 10a corrects the characteristic data set using the ratio of the first current amount after the change to the first current amount before the change.

  According to this, since the laser beam having the first power value equal to or greater than the reference value Pref can be detected by the photodiode 14, the relationship between the first power value and the first current amount can be accurately obtained. Therefore, the characteristic data set can be accurately corrected by using the ratio.

  In projector 1a according to the present embodiment, the current amount in the corrected characteristic data set is a value obtained by multiplying the current amount in the characteristic data set before correction by the ratio.

  Thereby, the characteristic data set can be corrected by a simple calculation. For this reason, the processing load of the control part 10a can be reduced.

  In the projector 1a according to the present embodiment, the control unit 10a determines that the amount of current depends on the output light power when the output light power changes from a value less than the reference value Pref to a value greater than or equal to the reference value Pref. The characteristic data set is corrected so as to change continuously.

  Thereby, also in the case where feedback control and open loop control are switched in the control part 10a, the output from each laser light source can be changed continuously.

  In the projector 1a according to the present embodiment, the memory 16a may store a plurality of different characteristic data sets. In this case, the control unit 10a uses a plurality of characteristic data sets stored in the memory 16a based on the amount of current when the output light power detected by the photodiode 14 is the first power value equal to or greater than the reference value Pref. Select one of them. Then, the control unit 10a performs open loop control of the current amount based on the selected characteristic data set.

  Thereby, even when the output light power characteristic of each laser light source changes, laser light having a desired power can be obtained. Further, according to this configuration, the processing load of the control unit 10a is reduced as compared with the case where the characteristic data set is corrected by calculation.

(Embodiment 3)
Next, a projector according to Embodiment 3 will be described. In the first embodiment and the second embodiment, an example in which a relational expression including a primary expression is used as the characteristic data set is shown. However, in this embodiment, a relational expression including a primary expression and a relational expression including a quadratic expression are used. The example which combines is shown. Hereinafter, the projector according to the present embodiment will be described focusing on differences from the projector 1 according to the first embodiment.

[3-1. overall structure]
First, the overall configuration of the projector according to the present embodiment will be described with reference to FIG.

  FIG. 8 is a block diagram showing an overall configuration of projector 1b according to the present embodiment.

  As shown in FIG. 8, in the projector 1b according to the present embodiment, the constituent elements are the same as those of the projector 1 according to the first embodiment. Different from the projector 1. In the present embodiment, the memory 16b of the control unit 10b stores a relational expression including a quadratic expression as a characteristic data set in a current amount range in which the output light power changes nonlinearly with respect to the current amount. The output light power characteristic in the current amount range in which the output light power of each laser light source changes nonlinearly with respect to the current amount can be approximated with a quadratic expression with high accuracy. For this reason, in this Embodiment, the output light power of each laser light source can be controlled accurately.

[3-2. Characteristic data set]
Subsequently, a characteristic data set of the projector 1b according to the present embodiment will be described with reference to FIG.

  FIG. 9 is a graph showing an example of the characteristic data set according to the present embodiment.

  As shown in FIG. 9, in the present embodiment, the characteristic data set includes relational expressions f31 and f32. The relational expression f31 is an approximate expression including a linear expression in the current amount range R11 in which the output light power changes substantially linearly with respect to the current amount. The relational expression f32 is an approximate expression including a quadratic expression in the current amount range R12 in which the output light power changes nonlinearly with respect to the current amount.

  As described above, by using the relational expression f32 including the quadratic expression as the characteristic data set in the current amount range R12 in which the output optical power changes nonlinearly with respect to the current amount, the characteristic data set and the output based on the actual measurement are used. An error from the optical power characteristic can be reduced. Therefore, in the present embodiment, it is possible to control the output light power of each laser light source with higher accuracy than when only a relational expression including a linear expression is used.

  In the present embodiment, a relational expression consisting of a quadratic expression is used only in the range R12, but a relational expression consisting of a quadratic expression may also be used in the range R11. Furthermore, the range R12 may be divided into a plurality of ranges, and a relational expression including a plurality of quadratic expressions may be used.

[3-3. effect]
As described above, in the projector 1b according to the present embodiment, the memory 16b uses a quadratic relational expression as a characteristic data set in the current amount range in which the output light power changes nonlinearly with respect to the current amount. I remember it.

  Thereby, in this Embodiment, the output light power of each laser light source can be controlled with a sufficient precision rather than the case where only the relational expression which consists of a primary expression is used.

(Embodiment 4)
Next, a projector according to Embodiment 4 will be described. In this embodiment, an example of a projector according to Embodiment 1 and a HUD device using the projector will be described with reference to FIGS.

  FIG. 10 is a diagram illustrating an installation example of the HUD device 2 according to the present embodiment.

  As shown in FIG. 10, the HUD device 2 includes a projector 100 and a combiner 60 (which constitutes a transparent display board). A detailed configuration of the projector 100 will be described later.

  The projector 100 is installed in a transportation device such as the automobile 200, and is installed on a dashboard of the automobile 200, for example. The combiner 60 is a display surface installed on a part of the windshield 210 of the automobile 200. The projector 100 projects an image on the combiner 60 by irradiating the combiner 60 with light. Since the combiner 60 is composed of a polarizing element, a wavelength selection element, a half mirror, and the like, the image projected by the projector 100 is superimposed and displayed on the scenery outside the vehicle. Note that the windshield 210 itself may have the function of the combiner 60 in some cases.

  FIG. 11 is a diagram illustrating an example of a landscape viewed by the user 300 through the windshield 210.

  As described above, the combiner 60 is installed on the windshield 210. The image projected from the projector 100 is displayed on the combiner 60. As shown in FIG. 11, the projector 100 has a function of displaying information related to car navigation (for example, route information to a destination), information related to a car (for example, fuel consumption information), and the like on the combiner 60. For example, the projector 100 includes route information 61 to the destination (“Osaka”, “Kobe” and “arrows” indicating the corresponding routes), and distance information 62 to the destination (“1.0 km”). Is displayed on the combiner 60 (an example of a content image). As shown in FIG. 11, since the image projected from the projector 100 is displayed in the front landscape, the user 300 can acquire information useful for driving without diverting the line of sight while driving the automobile 200. it can.

  FIG. 12 is a block diagram showing an example of the configuration of the HUD device 2 according to the present embodiment.

  The HUD device 2 includes the projector 100 and the combiner 60 as described above.

  The projector 100 displays an image by irradiating a laser beam. In the present embodiment, projector 100 includes main CPU 120, operation unit 130, and display control unit 110 in addition to the components of projector 1 according to the first embodiment.

  The main CPU 120 controls each part of the projector 100.

  The operation unit 130 receives operations by the user 300 such as an operation of turning on the power of the HUD device 2 (projector 100), an operation of changing the projection angle of the image, and an operation of changing the color tone or brightness of the image. The operation unit 130 may be configured with, for example, a hardware button or a software button, or may be configured with a remote controller and a receiver that receives radio waves transmitted from the remote controller.

  The display control unit 110 includes a video processing unit 111, a mirror control unit 112, and a mirror driver 113.

  The video processing unit 111 performs control for projecting an image on the combiner 60 based on a video signal input from the outside. Specifically, the video processing unit 111 controls the driving of the MEMS mirror 25 via the mirror control unit 112 based on the video signal, and lasers from the laser light sources 11 to 13 via the control unit 10. Control light irradiation.

  The mirror control unit 112 controls the mirror driver 113 based on the control by the video processing unit 111 to control the driving of the MEMS mirror 25. That is, the mirror control unit 112 scans the laser light emitted from the laser light sources 11 to 13 on the combiner 60 by controlling the tilt of the MEMS mirror 25. Thereby, the mirror control unit 112 projects an image on the combiner 60. That is, an image indicating the route information 61 and the distance information 62 projected on the combiner 60 is formed by the laser light sources 11 to 13 for image formation.

  As described above, in the projector 100 and the HUD device 2 according to the present embodiment, by using the configuration of the projector 1 according to the first embodiment, a laser having a desired power at a power less than the detection lower limit of the photodiode 14. Light can be obtained. As a result, when the projector 100 and the HUD device 2 are used at night, an image can be formed on the combiner 60 with laser light having a sufficiently small power. For this reason, it is suppressed that the user 300 feels the said image dazzling.

(Variations, etc.)
Although the projector according to each embodiment of the present invention has been described above, the present invention is not limited to these embodiments.

  For example, in each of the above embodiments, the configuration in which each memory or the like stores a relational expression as a characteristic data set is shown. However, the memory is a table indicating the relationship between the amount of current and the output optical power as the characteristic data set. May be stored. According to this, since the control unit does not need to calculate the relational expression, the processing load on the control unit is reduced.

  In each of the above embodiments, each projector includes a plurality of laser light sources, but the projector may include one laser light source.

  In the projector 100 according to the fourth embodiment, the control unit 10, the main CPU 120, the video processing unit 111, and the mirror control unit 112 are specifically a microprocessor, a ROM, a RAM, a hard disk drive, a display unit, and a keyboard. It may be configured as a computer system including a mouse or the like. A computer program is stored in the RAM or hard disk drive. These processing units achieve their functions by the microprocessor operating according to the computer program. Here, the computer program is configured by combining a plurality of instruction codes indicating instructions for the computer in order to achieve a predetermined function.

  Furthermore, some or all of the constituent elements constituting each of the above-described devices may be configured by one system LSI (Large Scale Integration). The system LSI is a super multifunctional LSI manufactured by integrating a plurality of components on one chip, and includes, for example, a computer system including a microprocessor, ROM, RAM, and the like. In this case, a computer program is stored in the ROM. The system LSI achieves its functions by the microprocessor operating according to the computer program.

  Furthermore, some or all of the constituent elements constituting each of the above-described devices may be configured from an IC card that can be attached to and detached from each device or a single module. The IC card or module is a computer system that includes a microprocessor, ROM, RAM, and the like. The IC card or the module may include the super multifunctional LSI described above. The IC card or the module achieves its function by the microprocessor operating according to the computer program. This IC card or this module may have tamper resistance.

  Further, the present invention may be the method described above. Further, the present invention may be a computer program that realizes these methods by a computer, or may be a digital signal composed of the computer program.

  Furthermore, the present invention relates to a non-transitory recording medium that can read the computer program or the digital signal, such as a flexible disk, a hard disk, a CD-ROM, an MO, a DVD, a DVD-ROM, a DVD-RAM, a BD ( It may be recorded on a Blu-ray (registered trademark) Disc), a semiconductor memory, or the like. Further, the digital signal may be recorded on these non-temporary recording media.

  Further, the present invention may transmit the computer program or the digital signal via an electric communication line, a wireless or wired communication line, a network represented by the Internet, a data broadcast, or the like.

  The present invention may be a computer system including a microprocessor and a memory, wherein the memory stores the computer program, and the microprocessor operates according to the computer program.

  Further, by recording the program or the digital signal on the non-temporary recording medium and transferring it, or transferring the program or the digital signal via the network or the like, another independent computer It may be implemented by the system.

  Furthermore, the above embodiment and the above modification examples may be combined. For example, in the projector according to the fourth embodiment, the configuration of the projector 1a according to the second embodiment or the projector 1b according to the third embodiment may be used.

  The present invention can be applied as a projector to, for example, a head-up display device mounted on an automobile.

1, 1a, 1b, 100 Projector 2 HUD device 10, 10a, 10b Control unit 11, 12, 13 Laser light source (laser light source unit)
14 Photodiode (light detector)
15 LD driver 16, 16a, 16b Memory 21, 22, 23, 24 Beam splitter 25 MEMS mirror 60 Combiner 61 Path information 62 Distance information 110 Display control unit 111 Video processing unit 112 Mirror control unit 113 Mirror driver 120 Main CPU
130 operation unit 200 automobile 210 windshield 300 user

Claims (11)

A laser light source unit;
A light detection unit that detects output light power that is the power of laser light output from the laser light source unit;
A control unit that controls the output light power by adjusting the amount of current supplied to the laser light source unit;
The controller is
When the output light power is controlled to be equal to or higher than the reference value detected by the light detection unit, the current amount is feedback controlled based on the detection result by the light detection unit, and the output light power is less than the reference value. When controlling with a projector, the current amount is controlled in an open loop. The controller is
A memory storing a characteristic data set relating to the characteristic of the output light power with respect to the amount of current supplied to the laser light source unit;
The projector according to claim 1, wherein the current amount is open-loop controlled based on the characteristic data set. The projector according to claim 2, wherein the reference value is larger than the output light power in the current amount range in which the output light power changes nonlinearly with respect to the current amount. The projector according to claim 2, wherein the characteristic data set is a relational expression of the output light power with respect to the current amount. The projector according to claim 4, wherein the relational expression is a quadratic expression. The projector according to claim 2, wherein the characteristic data set is a table indicating a relationship between the amount of current and the output light power. The control unit corrects the characteristic data set when detecting a change in a first current amount that is the current amount required to obtain a first power value equal to or higher than the reference value as the output light power. The projector according to any one of claims 2 to 6. The projector according to claim 7, wherein the control unit corrects the characteristic data set using a ratio of the first current amount after change to the first current amount before change. The projector according to claim 8, wherein the current amount in the characteristic data set after correction is a value obtained by multiplying the current amount in the characteristic data set before correction by the ratio. When the output light power changes from a value less than the reference value to a value greater than or equal to the reference value, the control unit is configured so that the amount of current continuously changes according to the output light power. The projector according to claim 7, wherein the characteristic data set is corrected. The memory stores a plurality of the characteristic data sets,
The control unit includes a plurality of the characteristic data sets stored in the memory based on the current amount when the output optical power detected by the light detection unit is a first power value equal to or greater than the reference value. The projector according to claim 2, wherein the current amount is controlled based on the selected characteristic data set.

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