JP2012080286A - Optical device and image display device - Google Patents

Abstract

An optical device and an image display device capable of detecting the lifetime of a light source are provided.
A threshold current setting unit for setting a threshold current value from a temperature of a light source detected by a temperature detection unit, and an estimation for calculating an estimated lifetime of the light source based on the temperature of the light source and the value of the threshold current. A life calculation unit, a drive current control unit that controls the drive current so that the drive current converges within a predetermined control range, and a convergence that determines whether the drive current has converged within the control range within a predetermined time A determination unit, a life determination unit that compares the cumulative use time of the light source with the estimated life and determines whether the cumulative use time has reached the life of the light source, and a direction in which the value of the drive current decreases in the control range A convergence range adjustment unit capable of performing adjustment to shift in a predetermined amount stepwise, and a drive stop unit that stops driving the light source.
[Selection] Figure 2

Description

  The present invention relates to an optical device and an image display device, and more particularly to an optical scanning type optical device and an image display device that display an image by two-dimensionally scanning light for image formation emitted from a light source. is there.

  2. Description of the Related Art Conventionally, an optical scanning optical device and an image display device that display an image by two-dimensionally scanning image forming light generated based on an image signal are known.

  As such an optical device and an image display device, a light source unit having a light source that emits light having an intensity corresponding to a supplied current, and an optical scanning unit that two-dimensionally scans the light emitted from the light source of the light source unit There is known a drive control unit that sequentially supplies a current corresponding to an image signal to a light source when the scanning position of the optical scanning unit is within an effective scanning range.

  For example, when a semiconductor laser diode or the like is used as the light source of the light source unit, light is hardly emitted below the threshold current value. Therefore, a DC bias current having a threshold current value is passed through the semiconductor laser element that is a light source, and a current obtained by superimposing a current having an intensity corresponding to the image signal on the DC bias current is caused to cause the semiconductor laser element to emit light. ing.

  As a technique for detecting the lifetime of such a semiconductor laser, the following Patent Document 1 calculates a semiconductor laser lighting time and based on the calculated lighting time and a preset reference lighting time. A technique for determining whether or not a product has reached the end of its life has been disclosed.

Japanese Unexamined Patent Publication No. 2000-180764

  However, the threshold current value of the light source changes due to heat generated when the semiconductor laser emits light, changes in the outside air temperature, and the like. Therefore, there arises a problem that the state of the light source cannot be accurately grasped.

  The present invention has been made in view of such circumstances, and provides an optical device and an image display device capable of detecting the lifetime of a light source.

  In order to achieve the above object, the invention according to claim 1 is directed to a light source unit having a light source, temperature detecting means for detecting the temperature of the light source, driving current input to the light source, and controlling the temperature. A control unit that determines a lifetime of the light source based on a detection result by the detection unit, and the control unit stores the temperature based on a relationship between a temperature of the light source and a threshold current for the light source stored in advance. A threshold current setting unit configured to set a value of the threshold current from the temperature of the light source detected by the detection unit; the temperature of the light source detected by the temperature detection unit; and the threshold set by the threshold current setting unit. An estimated lifetime calculating unit that calculates an estimated lifetime of the light source based on a current value, and the driving power source so that the amount of light emitted from the light source unit is maintained within a predetermined range. A drive current control unit that controls the drive current so that the current converges within a predetermined control range, and whether the drive current has converged within the control range within a predetermined time by the control of the drive current control unit. A convergence determination unit for determining, and when the convergence determination unit determines that the drive current does not converge within the control range, the accumulated usage time of the light source and the estimated lifetime calculated by the estimated lifetime calculation unit And a life determination unit that determines whether or not the accumulated usage time has reached the lifetime of the light source, and the lifetime determination unit determines that the cumulative usage time has reached the lifetime of the light source. A convergence range adjustment unit capable of performing stepwise adjustment to shift the control range by a predetermined amount in a direction in which the value of the drive current decreases so that the drive value current converges within the control range; Convergence range adjustment If the adjustment of the control range by is performed a predetermined number of times, and an optical apparatus characterized by having a drive stop unit that stops the driving of the light source.

  The invention according to claim 2 is the optical device according to claim 1, wherein the control unit is determined by the convergence determination unit that the drive current does not converge within the control range, and When it is determined by the lifetime determination unit that the accumulated usage time has not reached the lifetime of the light source, the apparatus further includes an error processing means for notifying the user that an error has occurred due to a factor other than the lifetime of the light source. Features.

  According to a third aspect of the present invention, in the optical device according to the first or second aspect, the control unit calculates a lifetime determination value that calculates a lifetime determination value that serves as a reference value for determining the lifetime of the light source. And a second lifetime determination unit that determines the lifetime of the light source by comparing the lifetime determination value calculated by the lifetime determination value calculation unit and the threshold current, and the convergence determination unit When it is determined that the threshold current has converged within the predetermined range, and the second life determination unit determines that the threshold current is greater than the life determination value, the convergence range adjustment unit is Adjustment is performed to shift the control range by a predetermined amount in a direction in which the value of the drive current decreases so that the drive current converges within the control range.

  According to a fourth aspect of the present invention, in the optical device according to the first aspect, the light source unit includes a plurality of light sources that emit light having different wavelengths, and the control unit includes the light sources of the light sources. A storage unit that stores a table that defines an adjustment amount of the control range; and the convergence range adjustment unit refers to the table and stores the control range so that the drive current converges within the control range. The adjustment is performed by shifting the driving current by a predetermined amount in the direction of decreasing.

  According to a fifth aspect of the present invention, in the optical device according to the third or fourth aspect, the control unit is configured such that the cumulative usage time is the lifetime of the light source by the lifetime determination unit or the second lifetime determination unit. When it is determined that the cumulative usage time has reached the lifetime of the light source, it is further provided with a notification unit that notifies the user that the cumulative use time has reached the lifetime of the light source.

  According to a sixth aspect of the present invention, the light beam emitted from the light source unit is scanned and incident on the retina of at least one eye of the user to display an image. The retinal scanning image display device according to any one of the above.

  According to the present invention, the lifetime of the light source can be accurately detected even if the value of the threshold current changes due to a change in the temperature of the light source.

It is explanatory drawing which shows the relationship between the drive current supplied to a semiconductor laser diode, and the light-emission quantity. It is explanatory drawing which shows the image display apparatus 1 of this embodiment. FIG. 3 is an explanatory diagram illustrating a scanning mode of laser light by an optical scanning unit of the image display device 1. It is explanatory drawing which shows arrangement | positioning of a photon detection part and a light-shielding part. It is the block diagram which showed the electric constitution of the control part. 5 is a flowchart showing processing at the time of starting the image display apparatus 1 according to the present embodiment. 5 is a flowchart illustrating processing during activation of the image display apparatus 1 according to the present embodiment.

  The optical device described below is intended to determine the lifetime of a light source that emits a light beam, and to stop driving the light source when it is determined that the light source has reached the lifetime.

  In particular, in order to accurately determine the lifetime of a light source, it is important to quickly grasp the current-light emission characteristics of the light source and determine the lifetime of the light source based on individual differences in the light source and the current temperature. It is.

  First, in order to facilitate understanding of the image display device described below, the current-light emission amount characteristic of the semiconductor laser diode will be briefly described as an example of the current-light emission amount characteristic of the light source.

[About current-emission quantity characteristics]

  In the image display apparatus 1 according to the present embodiment, the maximum value of the intensity of light incident on the observer's eyes 90 is defined in order to appropriately display an image that is visually recognized by the observer. Here, the light emission amount of the lasers 21, 22, 23 (corresponding to the “light source” of the present invention) for obtaining the light having the maximum intensity is set to “Lop” as shown in FIG. A current value to be supplied to the lasers 21, 22 and 23 (hereinafter referred to as “maximum current value”) is defined as Iop.

  The light emission characteristics of the lasers 21, 22, and 23 change due to heat generated when the laser light is emitted, changes in the outside air temperature, and the like. For example, the characteristic changes from a characteristic indicated by a broken line in FIG. 1B to a characteristic indicated by a solid line due to a temperature change. That is, the threshold current value Ith increases from Ith1 to Ith2. Further, the maximum current value Iop also increases from Iop1 to Iop2.

  Therefore, it is necessary to adjust the current supplied to the lasers 21, 22, and 23 in accordance with the change in the light emission characteristics of the lasers 21, 22, and 23 in order to appropriately display an image that is viewed by the observer.

  Since the light emission characteristics of the lasers 21, 22, and 23 have linearity in a region where the threshold current value is greater than or equal to Ith, the current-light emission of the lasers 21, 22, and 23 is measured by measuring two or more points in this region. As the quantity characteristic, the threshold current value Ith and the maximum current value Iop can be detected.

For example, when the characteristic indicated by the broken line in FIG. 1B changes from the characteristic indicated by the broken line to the characteristic indicated by the solid line due to a temperature change, the drive current of the maximum current value Iop1 and the half current value Iop1 / 2 when the characteristic indicated by the broken line is obtained. When supplied to 21, 22, 23, the light emission amounts of the lasers 21, 22, 23 are La, Lb. At this time, by calculating the following equation (1), the slope θ of the characteristic indicated by the solid line after the change can be obtained. Here, description will be made assuming that the characteristics of the lasers 21, 22, and 23 are the same.
θ = tan ⁻¹ [(La−Lb) / (Iop1−Iop1 / 2)] (1)

If the light emission amount Lth2 at the threshold current value Ith2 is small enough to be ignored, the approximate threshold current value Ith2 of the characteristic indicated by the solid line after the change can be expressed by the following equation (2).
Ith2≈Iop1-La / tan θ (2)

From the above formulas (1) and (2), the approximate maximum characteristic current value Iop2 indicated by the solid line after the change can be expressed by the following formula (3).
Iop2≈ (Lop / tan θ) + Ith2 (3)

  In this way, by supplying the drive current to the lasers 21, 22, and 23 by changing the current value by two or more points, the current-light emission amount of the lasers 21, 22, and 23 even when the characteristics change due to a temperature change or the like. The threshold current value Ith and the maximum current value Iop can be detected as characteristics.

  The above calculation is merely an example, and the threshold current value Ith and the maximum current value Iop can be detected by other calculations.

  Hereinafter, preferred embodiments of the present invention will be described more specifically with reference to the drawings. In the following description, a light source unit having a light source that emits light having an intensity corresponding to a supplied current and an optical scanning unit that two-dimensionally scans the light emitted from the light source are scanned by the optical scanning unit. The retinal scanning image display device that displays an image by projecting the image forming light onto at least one retina of the user will be mainly described, but the present invention is not limited to this. For example, the present invention is applied not only to an image projection device that displays an image by projecting image forming light scanned by a light scanning unit onto a screen surface, but also to other image display devices that scan light to display an image. can do.

[Outline of image display device]
The configuration of the retinal scanning image display apparatus 1 (hereinafter referred to as “image display apparatus 1”) of the present embodiment will be described with reference to FIG. FIG. 2 is an explanatory diagram showing the image display device 1 of the present embodiment, and FIG. 3 is a diagram for explaining a scanning mode of laser light by the optical scanning unit of the image display device 1.

  As shown in FIG. 2, the image display apparatus 1 of the present embodiment includes a drive control unit 10, a light source unit 20, a light combining unit 30, an optical fiber 40, an optical scanning unit 50, and a relay optical 60. ing.

  The drive control unit 10 controls the image signal supply circuit 11 that generates each signal as an element for synthesizing an image based on the image signal S input from the outside, and the light source unit by controlling the image signal supply circuit 11 20 includes a control unit 12 that adjusts the intensity of light emitted from 20, an R laser driver 16, a G laser driver 17, and a B laser driver 18.

  The laser drivers 16, 17, and 18 are respectively based on the red (R), green (G), and blue (B) image signals 13r, 13g, and 13b transmitted as image signals from the image signal supply circuit 11. The light source unit 20 is driven so as to emit laser light of each color whose intensity is modulated.

  The light source unit 20 includes, as a plurality of light sources corresponding to the three primary colors, an R laser 21 that emits red (R) laser light, a G laser 22 that emits green (G) laser light, and blue (B). And a B laser 23 that emits the laser beam.

  These R laser 21, G laser 22, and B laser 23 emit laser light having an intensity corresponding to the value of the current (drive current) supplied from the R laser driver 16, G laser driver 17, and B laser driver 18. For example, it can be configured as a semiconductor laser or a solid-state laser with a harmonic generation mechanism. If a semiconductor laser is used, the drive current can be directly modulated to modulate the intensity of the laser beam. However, if a solid-state laser is used, each laser is equipped with an external modulator, and the intensity of the laser beam is modulated. Need to do.

  The light source unit 20 includes a temperature sensor 85 that measures the temperature of the light source unit 20 and is connected to the control unit 12 provided in the drive control unit 10 described above. The temperature sensor 85 functions as a temperature detection unit that detects the temperature of the light source unit. The drive control unit 10 and the light source unit 20 constitute an optical device 45.

  The light combining unit 30 includes a collimating optical system 31 that collimates the laser beams emitted from the lasers 21, 22, and 23 into parallel light, a dichroic mirror 32 that combines the collimated laser beams, and a combined laser beam. Is coupled to the optical fiber 40.

  The optical scanning unit 50 includes a collimating optical system 51 that guides laser light propagated from the light source unit 20 through the light combining unit 30 and the optical fiber 40 to the horizontal scanning unit 52, and laser light collimated by the collimating optical system 51. A horizontal scanning unit 52 that scans in the horizontal direction using the scanning element 52a, a relay optical 53 that guides the laser beam scanned by the horizontal scanning unit 52 to the vertical scanning unit 54, and a scan that is scanned by the horizontal scanning unit 52 and relay optical And a vertical scanning unit 54 that scans the laser beam incident through 53 in the vertical direction by using a galvano mirror 54a.

  In this optical scanning unit, the horizontal scanning unit 52 is a high-speed scanning unit that performs horizontal scanning of the laser beam at a high speed relative to the horizontal direction, which is the first scanning direction, for each scanning line of an image to be displayed. A scanning element 52a that scans the laser beam in the horizontal direction by the reflecting surface 52b, and a horizontal scanning control circuit 52c that controls driving of the scanning element 52a are provided.

  Further, in this optical scanning unit, the vertical scanning unit 54 scans the laser beam in the second scanning direction, which is a direction intersecting or orthogonal to the first scanning direction, for each frame of the image to be displayed. The laser beam functions as a low-speed scanning unit that vertically scans the laser beam from the first horizontal scanning line toward the last horizontal scanning line at a low speed relative to the vertical direction, which is the second scanning direction, via the relay optical 53. The galvano mirror 54a that scans the incident laser beam in the vertical direction by the reflecting surface 54b, and the vertical scanning control circuit 54c that controls the driving of the galvano mirror 54a.

  The horizontal scanning control circuit 52 c is connected to the image signal supply circuit 11 and swings the reflection surface 52 b of the scanning element 52 a in synchronization with the horizontal synchronization signal 14 output from the image signal supply circuit 11. The vertical scanning control circuit 54 c is connected to the image signal supply circuit 11 and swings the reflection surface 54 b of the galvanomirror 54 a in synchronization with the vertical synchronization signal 15 output from the image signal supply circuit 11.

  In the image display device 1 according to the present embodiment, the laser light incident from the light source unit 20 via the light combining unit 30 and the optical fiber 40 is obtained by the horizontal scanning unit 52 and the vertical scanning unit 54 included in the optical scanning unit 50. By scanning in the first scanning direction and a second scanning direction substantially perpendicular to the first scanning direction, scanning is performed in a two-dimensional direction (two-dimensional scanning) to form an image in units of frames.

  That is, as shown in FIG. 3A, the scanning element 52a that oscillates at a relatively high speed is oscillated by the horizontal scanning control circuit 52c to reciprocate the incident light beam in the horizontal direction X. The laser beam scanned in the horizontal direction by the scanning element 52 a is incident on the vertical scanning unit 54 via the relay optical 53. The galvano mirror 54a of the vertical scanning unit 54 is swung in a sawtooth shape by the vertical scanning control circuit 54c, and scans the incident laser beam in the vertical direction Y. The laser beam in the effective scanning range Z scanned in the vertical direction by the galvanometer mirror 54 a is incident on the pupil 91 of the user via the relay optics 60.

  FIG. 3B shows the maximum scanning range W (range formed by the horizontal maximum scanning range W1 and the vertical maximum scanning range W2) and the effective scanning range Z (horizontal effective scanning range Z2 and the galvano mirror 54a). The relationship with the range formed by the vertical effective scanning range Z3) is shown. Here, the “maximum scanning range” means the maximum range in which the scanning element 52a and the galvano mirror 54a can scan light.

  Of the maximum scanning range W of the scanning element 52a and the galvanometer mirror 54a, laser light (hereinafter referred to as “image forming”) that is intensity-modulated in accordance with the image signal S from the light source unit 20 at a timing where the scanning position is within the effective scanning range Z The light is emitted in the effective scanning range Z by the horizontal scanning unit 52 and the vertical scanning unit 54. Thereby, the image forming light for one frame is scanned. This scanning is repeated for each frame image. FIG. 3B virtually shows a locus γ of the laser beam scanned by the horizontal scanning unit 52 and the vertical scanning unit 54 when it is assumed that the laser beam is always emitted from the light source unit 20. Yes. In the following description, the range Z1 excluding the effective scanning range Z in the maximum scanning range W is referred to as “invalid scanning range Z1”.

  In the present embodiment, the scanning element 52a is used for the horizontal scanning unit 52 and the galvano mirror 54a is used for the vertical scanning unit 54 to scan the image light in the horizontal direction and the vertical direction. Needless to say, any driving method such as piezoelectric driving, electromagnetic driving, or electrostatic driving may be used as long as the reflecting surface is swung (rotated) so as to scan. A polygon mirror may be used as an alternative to the galvanometer mirror 54a.

  As shown in FIG. 2, the relay optical 60 includes a first lens 60a and a second lens 60b. The relay optical 60 converges laser light, which is image-forming light scanned by the optical scanning unit 50, so that the user's The light enters the eye 90 from the pupil 91 and projects an image based on the image signal S onto the retina of the user's eye 90.

  Here, when the scanning position of the optical scanning unit 50 is within the effective scanning range Z shown in FIG. 3B, the drive control unit 10 sequentially supplies a drive current corresponding to the image signal S to the laser 21, 22 and 23, and image forming light is sequentially emitted from the lasers 21, 22, and 23. Accordingly, the image forming light is incident on the optical scanning unit 50 via the light combining unit 30 and the optical fiber 40 and is two-dimensionally scanned in the effective scanning range Z by the optical scanning unit 50. Then, the image forming light that is two-dimensionally scanned by the light scanning unit 50 is incident on the user's eye 90 from the pupil 91 via the relay optics 60, and the image forming light is projected onto the retina 92. . As a result, the user can recognize the image formed by the image forming light projected on the retina 92.

  The laser light scanned by the optical scanning unit 50 is converged by the first lens 60a of the relay optical 60, and an intermediate image plane is formed between the first lens 60a and the second lens 60b. On the intermediate image surface formed in the relay optical 60, a light shielding unit 70 that defines the effective scanning range Z and the invalid scanning range Z1 is disposed.

  As shown in FIG. 4, a light detection unit 80 is disposed in the invalid scanning range Z1 at the upper center of the light shielding unit 70, and detects inspection light to be described later scanned outside the effective scanning range Z. I am doing so. In FIG. 2, the light detection unit 80 is configured to be provided in the invalid scanning range Z1 above the effective scanning range Z. However, the arrangement position of the light detection unit 80 is not limited to this, For example, it may be provided in the invalid scanning range Z1 below the effective scanning range Z or may be provided in both the invalid scanning range Z1 above and below.

  The light detection unit 80 outputs a voltage according to the intensity of the received inspection light to the control unit 12 as a BD signal 82, and the control unit 12 outputs the voltage from the light source unit 20 based on the BD signal 82. The intensity of the emitted laser beam is adjusted.

[Electrical configuration of control unit]
Next, the configuration of the control unit 12 provided in the drive control unit 10 will be described with reference to FIG. FIG. 5 is a block diagram showing an electrical configuration of the control unit.

  The control unit 12 includes a CPU 100, a ROM 101, a RAM 102, an RTC (Real Time Clock) 103, a light detection unit interface 104, a temperature sensor interface 105, and a peripheral device interface 107, and a system bus 108. Are connected to each other.

  The ROM 101 is executed by the CPU 100 to execute a program according to a flowchart to be described later, and information defining the relationship between the temperature of the light source and the threshold current Ith for the light source (hereinafter referred to as the light source unit temperature). -Threshold current value Ith correlation information) is stored.

  In particular, in the present embodiment, correlation equations of temperature and threshold current value Ith corresponding to each of the R laser 21, G laser 22, and B laser 23 (correlation equation for R laser, correlation equation for G laser, correlation equation for B laser) Is stored in the ROM 101 as light source section temperature-threshold current value Ith correlation information (corresponding to a “table” of the present invention).

  The ROM 101 stores a life determination value serving as a reference value for determining the life of the R laser 21, the G laser 22, or the B laser 23. This lifetime determination value is a value about 1.2 to 1.3 times the threshold current value Ith.

  The RAM 102 functions as a temporary storage area for storing various flags to be referred to when the CPU 100 executes the program stored in the ROM 101. Examples of the flag stored in the RAM 102 include a convergence determination flag indicating whether or not the drive current converges within the control range. The actual handling of the flag in the program will be described later in detail using the flowcharts shown in FIGS.

  The RTC 103 is a circuit for measuring time, and the time measured by the RTC 103 can be acquired by the CPU 100.

  The photodetection unit interface 104 is responsible for connection with the photodetection unit 80, and plays a role of converting the received light signal transmitted from the photodetection unit 80 into a voltage value and writing it to the RAM 102.

  The temperature sensor interface 105 is connected to the temperature sensor 85 and plays a role of converting a signal transmitted from the temperature sensor 85 into a temperature value and writing it to the RAM 102.

  The peripheral device interface 107 is responsible for operation control and signal transmission / reception of peripheral devices connected to the control unit 12, and the image signal supply circuit 11 is connected to the peripheral device interface 107.

  The peripheral device interface 107 plays a role of transmitting to the image signal supply circuit 11 an instruction such as a current value to be supplied to the light source unit 20 determined by the CPU 100.

[Processing flow of control unit]
Next, the process in the control part 12 in the optical apparatus 45 is demonstrated using FIG. 6, FIG. FIG. 6 is a flowchart showing processing at the time of starting the image display apparatus 1 according to the present embodiment, and FIG. 7 is a flowchart showing processing during startup of the image display apparatus 1 according to the present embodiment.

  First, in order to facilitate explanation of the flowchart, a convergence determination flag stored in the RAM 102 and referred to by the CPU 100 during processing will be described.

  The convergence determination flag indicates whether or not the drive current converges within a predetermined control range, and takes a value of “0” or “1”. “0: Do not converge”, “1: Converge” Means.

  The CPU 100 executes the following processing while referring to the flag described above.

  First, the main flow will be described with reference to FIG. The CPU 100 of the control unit 12 first executes an initial setting process such as permitting access to the RAM 102 and initializing the work area (step S10). At this time, the CPU 100 sets the value of the convergence determination flag in the RAM 102 to “0”.

  Next, the CPU 100 executes a temperature measurement process (step S11). Here, the CPU 100 causes the temperature sensor 85 to detect the temperature of the R laser 21 immediately after the optical device 45 is activated, and stores the detected temperature of the R laser 21 in the ROM 101 of the control unit 12 as temperature information.

  Next, the CPU 100 executes a drive current read process (step S12). Here, the CPU 100 sets the threshold current value Ith of the R laser 21 based on the temperature information stored in the ROM 101 and the light source unit temperature-threshold current value Ith correlation information, and is set based on the threshold current value Ith. Read the drive current value.

  Next, the CPU 100 executes a drive current automatic control process (step S13). When this process ends, the process moves to a step S14.

  In step S14, the CPU 100 determines whether or not the drive current converges within the control range. If the CPU 100 determines that the drive current converges within the control range (step S14: Yes), the process proceeds to step S15. .

  In step S15, the CPU 100 sets the value of the convergence determination flag stored in the RAM 102 to “1”, and the process proceeds to step S16.

  Next, the CPU 100 executes a life determination process (step S16). In this process, the CPU 100 compares the drive current value with the life determination value stored in the ROM 101, and determines that the drive current value is greater than the life determination value (step S16: Yes). To step S17.

  On the other hand, when the CPU 100 determines in step S16 that the value of the drive current is equal to or less than the life determination value (step S16: No), the CPU 100 proceeds to the next process.

  In step S17, the CPU 100 compares the estimated lifetime with the accumulated light source time. In this process, the CPU 100 calculates the estimated life based on the temperature of the R laser 21, G laser 22 or B laser 23 detected by the temperature sensor 85 and the threshold current value Ith set by the threshold current setting unit. . In addition, the CPU 100 reads the accumulated usage time stored in the ROM 101. Then, the CPU 100 compares the estimated lifetime value with the accumulated usage time value.

  If the CPU 100 determines in step S17 that the estimated lifetime value is greater than the cumulative usage time value (step S17: Yes), it determines that there is an estimated lifetime, and proceeds to the next process.

  On the other hand, if the CPU 100 determines in step S17 that the estimated lifetime value is less than or equal to the cumulative usage time value (step S17: No), the CPU 100 determines that there is no estimated lifetime and proceeds to step S18.

  In step S18, the CPU 100 shifts the control range. In this process, the CPU 100 shifts the control range by three times in the direction in which the drive current decreases with respect to the initial value of the drive current. When this process ends, the process proceeds to step S19.

  In step S19, the CPU 100 executes notification processing. In this process, the CPU 100 notifies that the accumulated usage time has reached the lifetime of the light source. When this process ends, the process proceeds to the next process.

  If the CPU 100 determines in step S14 that the drive current does not converge within the control range (step S14: Yes), the process proceeds to step S20.

  In step S20, the CPU 100 executes a timeout process. When this process ends, the process proceeds to step S21.

  In step S21, the CPU 100 executes a life determination process. In addition, since this process is the same process as the lifetime determination process in step S16 mentioned above, description is abbreviate | omitted. In this process, when the CPU 100 determines that the value of the drive current is larger than the life determination value (step S21: Yes), the process proceeds to step S22.

  In step S22, the CPU 100 executes an error notification process. In this process, the CPU 100 executes an error notification indicating that it does not originate from the light source unit. Note that the notification performed in step S22 is not particularly limited. For example, the notification may be performed by a sound such as a warning sound, and image forming light is emitted from the light source unit with a preset current value. As a result, the user may be allowed to visually recognize the warning image.

  In step S21, when the CPU 100 determines that the value of the drive current is equal to or less than the life determination value (step S21: No), the process proceeds to step S23.

  In step S23, the CPU 100 compares the estimated lifetime of the light source with the accumulated usage time, and if it is determined that the estimated lifetime is greater than the accumulated usage time (step S23: Yes), the CPU 100 determines that the light source has not reached the lifetime. Then, the process proceeds to step S22, and an error notification process is executed.

  On the other hand, when the CPU 100 determines that the estimated lifetime is equal to or shorter than the accumulated usage time (step S23: No), the CPU 100 determines that the light source has reached the lifetime and shifts the processing to step S24.

  In step S24, the CPU 100 shifts the control range. In this process, the CPU 100 performs adjustment to shift the control range by a predetermined amount in the direction in which the value of the drive current decreases so that the drive current converges within the control range. In other words, the control range is shifted a predetermined number of times in the direction in which the value of the drive current decreases, and control is performed so that the drive current converges within the control range. As described above, for the purpose of using the LD as long as possible when the light source reaches the end of its life, adjustment is made to reduce the light amount by performing a process of reducing the drive current. When this process ends, the process moves to a step S25.

  In step S25, the CPU 100 records the lifetime. When this process ends, the process moves to a step S26.

  In step S26, the CPU 100 determines whether or not the control range shift is 2 times or less, and if it is determined that the control range shift is 2 times or less (step S26: Yes), the process proceeds to step S14. To migrate.

  On the other hand, if the CPU 100 determines that the shift of the control range is three times or more (step S26: No), the process proceeds to step S27.

  In step S27, the CPU 100 executes a life error notification process. In this process, the CPU 100 executes an error notification indicating that the light source unit 20 has a lifetime. The notification performed in step S27 is not particularly limited. For example, the notification may be performed by a sound such as a warning sound, and image forming light is emitted from the light source unit with a preset current value. As a result, the user may be allowed to visually recognize the warning image.

  Next, the actual movement of the image display apparatus 1 having the above-described configuration will be described with reference to FIG.

[Adjustment operation of the light source by the drive controller]
FIG. 7 is a flowchart showing processing during activation of the image display apparatus 1 according to the present embodiment.

  Next, the CPU 100 executes a temperature measurement process (step S30). Here, the CPU 100 causes the temperature sensor 85 to detect the temperature of the R laser 21 in which the optical device 45 is activated, and stores the detected temperature of the R laser 21 in the ROM 101 of the control unit 12 as temperature information.

  Next, the CPU 100 stores the detected temperature information in the histogram corresponding area of the ROM 101 (step S31).

Next, the CPU 100 calculates an average temperature based on the temperature information stored in the histogram corresponding area (step S32). In this process, the CPU 100 performs the following equation (4).
temp _{n + 1} = [temp _n × (Lt2-1) + α] / Lt2 Expression (4)
Is used to calculate the average temperature.

  Next, the CPU 100 executes an estimated lifetime reading process (step S33). In this process, the CPU 100 reads the estimated lifetime from the average temperature.

  Next, the CPU 100 executes a cumulative measurement number reading process (step S34).

  Next, the CPU 100 stores the remaining estimated time (step S35). In this process, the CPU 100 causes the ROM 101 to store the remaining estimated time, Lt3 = Lt1-light source cumulative usage time, and average temperature temp.

  Next, the CPU 100 stands by until the next measurement (step S36).

  Finally, the description of the above-described embodiment is an example of the present invention, and the present invention is not limited to the above-described embodiment. For this reason, it is a matter of course that various modifications can be made in accordance with the design and the like as long as they do not depart from the technical idea according to the present invention, even if other than the above-described embodiment.

1 Image display device (retinal scanning image display device)
12 Control unit 20 Light source unit 21 R laser (light source)
22 G laser (light source)
23 B laser (light source)
85 Temperature sensor (temperature detection means)

Claims (6)

A light source unit having a light source;
Temperature detecting means for detecting the temperature of the light source;
A control unit for controlling a driving current input to the light source and determining a lifetime of the light source based on a detection result by the temperature detection unit;
The controller is
A threshold current setting unit configured to set a value of the threshold current from the temperature of the light source detected by the temperature detection unit based on the relationship between the temperature of the light source and the threshold current of the light source stored in advance;
An estimated lifetime calculating unit that calculates an estimated lifetime of the light source based on the temperature of the light source detected by the temperature detecting unit and the value of the threshold current set by the threshold current setting unit;
A drive current control unit that controls the drive current so that the drive current converges within a predetermined control range so that the amount of light emitted from the light source unit is maintained within a predetermined range;
A convergence determination unit that determines whether or not the drive current has converged within the control range within a predetermined time under the control of the drive current control unit;
When the convergence determination unit determines that the drive current does not converge within the control range, the cumulative use time of the light source is compared with the estimated lifetime calculated by the estimated lifetime calculation unit, A lifetime determination unit that determines whether or not the cumulative usage time has reached the lifetime of the light source;
When the lifetime determining unit determines that the accumulated usage time has reached the lifetime of the light source, the value of the drive current is reduced in the control range so that the drive value current converges within the control range. A convergence range adjustment unit capable of performing stepwise adjustment to shift a predetermined amount in the direction;
An optical device, comprising: a drive stopping unit that stops driving the light source when the control range is adjusted a predetermined number of times by the convergence range adjusting unit. The control unit determines that the drive current does not converge within the control range by the convergence determination unit, and determines that the cumulative use time has not reached the lifetime of the light source by the life determination unit. The optical apparatus according to claim 1, further comprising: an error processing unit that notifies the user that an error has occurred due to a factor other than the lifetime of the light source. The controller is
A lifetime determination value calculating unit that calculates a lifetime determination value serving as a reference value for determining the lifetime of the light source;
A second lifetime determination unit that determines the lifetime of the light source by comparing the lifetime determination value calculated by the lifetime determination value calculation unit and the threshold current;
When the convergence determination unit determines that the threshold current has converged within the predetermined range, and the second lifetime determination unit determines that the threshold current is greater than the lifetime determination value, the convergence range The adjustment unit performs an adjustment to shift the control range by a predetermined amount in a direction in which the value of the drive current decreases so that the drive current converges within the control range. An optical device according to 1. The light source unit includes a plurality of light sources that emit light having different wavelengths.
The control unit further includes a storage unit that stores a table that defines an adjustment amount of the control range of each light source,
The convergence range adjustment unit refers to the table and performs an adjustment to shift the control range by a predetermined amount in a direction in which the value of the drive current decreases so that the drive current converges within the control range. The optical device according to claim 1. When the controller determines that the accumulated usage time has reached the lifetime of the light source by the lifetime determination unit or the second lifetime determination unit, the user has reached the lifetime of the light source. The optical device according to claim 3, further comprising a notification unit that notifies the fact.   The retinal scanning according to claim 1, wherein the light beam emitted from the light source unit is scanned and incident on a retina of at least one eye of a user to display an image. Type image display device.

Images