JP2011129842A - Light source device, projection device and projection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain temperature environment wherein deterioration of an element is not caused by accurately measuring operation temperature of each semiconductor light emitting element when a plurality of semiconductor light emitting elements are driven intermittently in a time-division manner. <P>SOLUTION: A light source device includes LEDs 21 to 23, a projection image processing unit 15 which generates a rectangular-waveform timing signal indicating light emission start timings of respective light emission periods of the LEDs 21 to 23 and a timing which is a certain time before the end of light emission, and a projection light processing unit 28 which cyclically drives the LEDs 21 to 23 in a time-division manner corresponding to the respective light emission periods based upon the timing signal, measures respective voltage values of the LEDs 21 to 23 based upon an off timing of the timing signal, and adjusts respective drive currents of the LEDs 21 to 23 in accordance with the measurement results. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a light source device, a projection device, and a projection method suitable for a projector device using a semiconductor light emitting element.

  Techniques for accurately estimating the temperature of the semiconductor light emitting element include a first power supply process in which the current flowing through the semiconductor light emitting element is greater than zero and a second power supply process in which the current is greater than the first power supply process. Each of the plurality of power supply processes is repeatedly executed, and at least one of the current value and the voltage value is measured at least in each of the first power supply process and the second power supply process, and the plurality of currents are greater than zero. A device that estimates the temperature of a semiconductor light emitting element by using measurement results in each of the operating states is considered. (For example, Patent Document 1)

JP 2008-124303 A

  In a projector using a semiconductor light source of a plurality of colors including the technology described in the above-mentioned patent document, when the light source is pulse-driven, the semiconductor is measured by measuring the voltage using the falling portion at the end of the lighting timing signal as a trigger. The element temperature of the light source is estimated. This is a process for measuring a state in which the element temperature of the semiconductor light source is the highest by measuring in accordance with the falling timing which is the final part of the pulse waveform. As a result of the measurement, when it is estimated that the temperature of the element is higher than the standard, control such as lowering the driving current of the element is performed.

  However, when the falling portion of the lighting timing signal is used as a trigger, a slight time lag occurs between when the trigger is applied and when the voltage is actually measured. Therefore, at the time of actual measurement, the element temperature of the semiconductor light source has already started to decrease, and there is a problem that an accurate temperature cannot be measured.

  The present invention has been made in view of the above circumstances, and its object is to accurately measure the operating temperature of each semiconductor light emitting element when intermittently driving a plurality of semiconductor light emitting elements in a time-sharing manner. An object of the present invention is to provide a light source device, a projection device, and a projection method capable of maintaining a temperature environment that does not cause element degradation.

  According to the first aspect of the present invention, a semiconductor light emitting device, driving means for causing the semiconductor light emitting device to emit light in a time-sharing manner in a predetermined light emitting period, a light emission start timing of the light emitting period of the semiconductor light emitting device, and a predetermined time before the light emission end A timing signal generating means for generating a timing signal indicating the timing of the signal, and a measurement for measuring a voltage value of the semiconductor light emitting element based on a timing a predetermined time before the end of light emission of the timing signal provided from the timing signal generating means And a drive control means for adjusting the drive power of the semiconductor light emitting element driven by the drive means based on the measurement result obtained by the measurement means.

  According to a second aspect of the present invention, in the first aspect of the invention, the timing signal generation means sets a timing a predetermined time before the end of light emission in the light emission period according to the time required for measurement by the measurement means. The timing signal is generated.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the timing signal has a rectangular wave shape, and the timing signal generation means instructs the start of light emission by the driving means at the rising edge of the rectangular wave shape. And generating a timing signal for instructing measurement of the voltage value of the semiconductor light emitting element by the measuring means when the rectangular wave falls.

  According to a fourth aspect of the present invention, there are provided a plurality of semiconductor light emitting elements, driving means for causing the plurality of semiconductor light emitting elements to emit light in a time-sharing manner in units of a predetermined light emitting period, and light emission in each light emitting period of the plurality of semiconductor light emitting elements A timing signal generating means for generating a timing signal indicating a start timing and a timing a predetermined time before the end of light emission; and a plurality of the timing signals generated from the timing signal given by the timing signal generating means based on a timing a predetermined time before the end of the light emission. Measuring means for measuring each voltage value of the semiconductor light emitting element, drive control means for adjusting each driving power of the plurality of semiconductor light emitting elements driven by the driving means based on the measurement result obtained by the measuring means, and an image signal Using input means for input and light emitted from the plurality of semiconductor light emitting elements, and corresponding to image signals input by the input means. Characterized by comprising a projection means for projecting and forming an optical image.

  According to a fifth aspect of the present invention, in the invention of the fourth aspect, the timing signal has a rectangular wave shape, and the timing signal generating means is a timing for instructing the start of light emission by the driving means at the rising edge of the rectangular wave shape. A signal is generated, and a timing signal for instructing measurement of the voltage value of the semiconductor light emitting element by the measuring means is generated at the fall of the rectangular wave.

  According to a sixth aspect of the present invention, a plurality of semiconductor light emitting elements, an input unit for inputting an image signal, and light emitted from the plurality of semiconductor light emitting elements, and color light corresponding to the image signal input at the input unit. A timing signal indicating a light emission start timing of each of the light emission periods of the plurality of semiconductor light emitting elements and a timing a predetermined time before the light emission end, wherein the projection method includes a projection unit that forms and projects an image. A timing signal generation step for generating the plurality of semiconductor light emitting elements in a time-sharing manner corresponding to each light emission period based on the timing signal generated in the timing signal generation step, and the timing Each voltage value of the plurality of semiconductor light emitting elements is measured based on the timing signal given in the signal generation process a certain time before the end of light emission. That the measuring step, characterized in that a drive control step of the measurement results obtained in the measurement step adjusting each driving power of the plurality of semiconductor light emitting elements driven by the driving step.

  According to the present invention, when intermittently driving a plurality of semiconductor light emitting elements in a time-sharing manner, it is possible to accurately measure the operating temperature of each semiconductor light emitting element and maintain a temperature environment that does not cause deterioration of the elements. Become.

1 is a block diagram showing a functional circuit configuration of an entire data projector apparatus according to an embodiment of the present invention. The figure explaining the basic concept of the operation | movement which concerns on the same embodiment. The timing chart which shows the control content of the operation | movement which concerns on the same embodiment.

  An embodiment in which the present invention is applied to a data projector apparatus of DLP (Digital Light Processing) (registered trademark) system will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a schematic functional configuration of a data projector apparatus 10 according to the present embodiment.
Reference numeral 11 denotes an input / output connector unit including, for example, a pin jack (RCA) type video input terminal, a D-sub15 type RGB input terminal, and a USB (Universal Serial Bus) connector.

  Image signals of various standards input from the input / output connector unit 11 are input to an image conversion unit 13 that is also generally referred to as a scaler via an input / output interface (I / F) 12 and a system bus SB.

  The image conversion unit 13 unifies the input image signal into an image signal of a predetermined format suitable for projection, appropriately writes it in the video RAM 14 which is a buffer memory for display, and then reads out the written image signal. The image is sent to the projection image processing unit 15.

  At this time, data such as symbols indicating various operation states for OSD (On Screen Display) is also superimposed on the image signal by the video RAM 14 as necessary, and the processed image signal is read out to the projection image processing unit 15. Sent.

  The projection image processing unit 15 multiplies a frame rate according to a predetermined format, for example, 60 [frames / second], the number of color component divisions, and the number of display gradations, in accordance with the transmitted image signal. The micromirror element 16 that is a spatial light modulation element is displayed and driven by high-speed time-division driving.

  The micromirror element 16 performs display operation by individually turning on and off each inclination angle of a plurality of micromirrors arranged in an array, for example, XGA (lateral 1024 pixels × vertical 768 pixels) at high speed. Then, an optical image is formed by the reflected light.

  On the other hand, R, G, B primary color lights are emitted cyclically from the light source unit 17 in a time-sharing manner. The primary color light from the light source unit 17 is totally reflected by the mirror 18 and applied to the micromirror element 16.

  Then, an optical image is formed by the reflected light from the micromirror element 16, and the formed optical image is projected and displayed on a screen (not shown) to be projected through the projection lens unit 19.

  The light source unit 17 includes a light emitting diode (hereinafter referred to as “R-LED”) 21 that emits red (R) light, a light emitting diode (hereinafter referred to as “G-LED”) 22 that emits green (G) light, and blue ( B) It has a light emitting diode (hereinafter referred to as “B-LED”) 23 that emits light.

  The red light emitted from the R-LED 21 passes through the dichroic mirror 24, is converted into a luminous flux having a substantially uniform luminance distribution by the integrator 25, and is then sent to the mirror 18.

  The green light emitted from the G-LED 22 is reflected by the dichroic mirror 26, then reflected by the dichroic mirror 24, and sent to the mirror 18 via the integrator 25.

The blue light emitted from the B-LED 23 is reflected by the mirror 27, then passes through the dichroic mirror 26, is then reflected by the dichroic mirror 24, and is sent to the mirror 18 through the integrator 25.
The dichroic mirror 24 transmits red light while reflecting green light and blue light. The dichroic mirror 26 reflects green light while transmitting blue light.

  The projection light processing unit 28 controls the light emission timing of each of the LEDs 21 to 23 of the light source unit 17 and the waveform of the drive signal. The projection light processing unit 28 controls the light emission operations of the LEDs 21 to 23 according to the R, G, and B timing signals given from the projection image processing unit 15 and the control of the CPU 31 described later.

  The projection light processing unit 28 detects the drive voltages of the LEDs 21 to 23 in accordance with the control of the CPU 31 described later, and outputs the detection result to the CPU 31.

  The CPU 31 controls all the operations of the above circuits. The CPU 31 is directly connected to the main memory 32 and the program memory 33. The main memory 32 is composed of a DRAM and functions as a work memory for the CPU 31. The program memory 33 is composed of an electrically rewritable nonvolatile memory, and stores an operation program executed by the CPU 31 and various fixed data. The CPU 31 uses the main memory 32 and the program memory 33 to execute a control operation in the data projector device 10.

The CPU 31 executes various projection operations in response to key operation signals from the operation unit 34.
The operation unit 34 includes a key operation unit provided in the main body of the data projector device 10 and a laser light receiving unit that receives infrared light from a remote controller (not shown) dedicated to the data projector device 10. The operation unit 34 directly outputs a key operation signal based on a key operated by a user with a key operation unit of the main body or a remote controller to the CPU 31.

  The CPU 31 is further connected to the audio processing unit 35 via the system bus SB. The sound processing unit 35 includes a sound source circuit such as a PCM sound source. The audio processing unit 35 converts the audio data given during the projection operation into an analog signal, drives the speaker unit 36 to make it louder, or generates a beep sound or the like as necessary.

Next, the operation of the above embodiment will be described.
FIG. 2 shows a basic concept of drive control of the semiconductor light emitting device according to this embodiment.

  FIG. 2A shows a basic waveform of a timing signal that the projection image processing unit 15 gives to the projection light processing unit 28. When the LEDs (21 to 23) emit light during one field period, the projection image processing unit 15 outputs a timing signal that is turned off earlier by the time Tm than the end timing of the field as shown in the figure.

The time Tm is fixedly set according to the time required for the projection light processing unit 28 to measure the voltage at the LEDs (21 to 23), for example, about several tens [μsec].
Receiving the timing signal from the projection image processing unit 15, the projection light processing unit 28 starts driving the LEDs (21 to 23) with a constant current value using the rising portion of the timing signal as a trigger.

  FIG. 2B shows a change in voltage in the LEDs (21 to 23) accompanying the constant current driving of the projection light processing unit 28. FIG. In a semiconductor light emitting device regardless of LED and LD (semiconductor laser), when driven at a constant current, the voltage decreases as the device temperature increases.

  Therefore, at the beginning of the field period, the voltage value increases instantaneously from the state of heat dissipation cooling during the intermittent period until then, and then the voltage decreases as the element accumulates heat and gradually increases in temperature. To do. For this reason, it is possible to estimate the temperature of the element by measuring the voltage value without directly measuring the temperature of the element.

  The timing signal from the projection image processing unit 15 is turned off earlier by the time Tm earlier than the end of the field period. The projection light processing unit 28 measures the voltage of the LED (21 to 23) in synchronization with the timing signal being turned off, and drives the LED (21 to 23) at the time when the measurement is completed, that is, simultaneously with the end of the field period. Exit.

  Based on the measurement result, the projection light processing unit 28 estimates the maximum temperature of the LED (21-23) in the field period, and controls the current value when the LED (21-23) is driven next.

  As described above, the timing at which the timing signal from the projection image processing unit 15 is turned off is the timing at which the field period ends by the time Tm required for the voltage measurement of the LEDs (21 to 23) in the projection light processing unit 28. It is set to be advanced.

  Therefore, the projection light processing unit 28 ends the current drive to the LEDs (21 to 23) after a time Tm elapses from the falling edge of the timing signal that triggers the voltage measurement start to the end of the voltage measurement. Thus, it is possible to realize the light emission drive of the LEDs (21 to 23) accurately synchronized with the field period.

  FIG. 3 shows three field periods of R, G, and B that make up one image frame, and the timing of drive control of each of the LEDs 21 to 23. As shown in FIG. 3A, it is assumed that one image frame is configured in the order of R field, G field, and B field.

  The projection image processing unit 15 displays each primary color image on the micromirror element 16 corresponding to the same field period, while the projection light processing unit 28 is shown in FIGS. 3B to 3D. R timing signal, G timing signal, and B timing signal are transmitted.

  These timing signals are turned off earlier by the time Tm earlier than the end of each field period as described in FIG.

  In the R field, the projection light processing unit 28 starts light emission by supplying a constant current to the R-LED 21 in synchronization with the rise of the R timing signal shown in FIG. Thereafter, when the R timing signal is turned off, the voltage of the R-LED 21 that is driven by the turning off of the R timing signal as a trigger is measured.

  FIG. 3 (H) shows a change in driving voltage of the R-LED 21. As shown in FIG. 2B, the voltage applied to the R-LED 21 gradually decreases from the initial high state in the field period even when the current is constant, with heating by light emission.

  At timing t31 when the R timing signal is turned off, the projection light processing unit 28 measures the voltage value. Then, along with the end of the measurement after the elapse of Tm from the timing t31 and the end of the R field period, the drive current to the R-LED 21 is turned off as shown in FIG. The drive voltage is also turned off at the same time.

  The same applies to the subsequent G field and B field. In the process in which the projection light processing unit 28 drives the G-LED 22 and B-LED 23 to emit light, the drive voltage is measured immediately before the end of each field period.

  Each measurement result obtained by the projection light processing unit 28 is sent to the CPU 31. CPU31 estimates the maximum temperature in the field period of the said LED (21-23) with the voltage value as a measurement result sent from the projection light process part 28. FIG. The CPU 31 determines a current value for driving the LEDs (21 to 23) in each field of the next image frame based on the estimation result, and sends the determination result to the projection light processing unit 28.

  As described above, the measurement result of the projection light processing unit 28 is output to the CPU 31, and the CPU 31 receiving the result determines the drive current of the next LED (21 to 23) from the measurement result, and the projection light processing unit 28. In this case, a series of control processes from measurement to determination of the next current value may be executed in the projection light processing unit 28.

  For example, a voltage value as a measurement result and a drive current value in consideration of the LED temperature estimated from the voltage value are held in the projection light processing unit 28 in the form of a lookup table, and the projection light processing unit 28 performs measurement. From the result, the next drive current value may be read with reference to the lookup table, and the drive with the current value read in the next frame may be executed.

  As described in detail above, according to the present embodiment, when intermittently driving a plurality of semiconductor light emitting elements, for example, LEDs 21 to 23 that emit light of primary colors R, G, and B, in time division, the operating temperature of each element is accurately set. It is possible to maintain a temperature environment that does not cause deterioration of the device.

  In particular, in the above-described embodiment, the timing for starting the measurement of the LEDs 21 to 23 is set to be earlier than the field end timing according to the time Tm required for the measurement by the projection light processing unit 28. The temperature rise can be measured in the form of a voltage value, and at the same time as the measurement is finished, the driving of the LEDs 21 to 23 can be finished and the next field driving can be immediately started.

  In the present invention, as in the above-described embodiment, the voltage measurement is started by using the falling timing of the R, G, B timing signals slightly earlier than the light emission field period as a trigger. In this way, by using the timing signal falling edge that is a minute time earlier than the light emission field period as a trigger, a signal for instructing light emission stop at the end of the light emission field period after that minute time can be easily obtained. Can be generated. For example, since the minute time Tm is a fixed value, it is only necessary to install a capacitor circuit that delays by Tm based on the fall of the timing signal.

  Further, for example, when the data projector apparatus 10 has a plurality of projection modes having different widths of R, G, and B light emission field periods in one frame, and the projection mode is changed from a certain projection mode to a different projection mode. The light emission field period is also changed according to the projection mode. However, the voltage measurement instruction is issued as in the above embodiment in which the fall of the timing signal a minute time Tm before the light emission field period is a trigger for voltage measurement, and the light emission end trigger is Tm after the fall of the timing signal. By outputting based on the fall of the timing signal, accurate voltage measurement is possible even when the light emission field period is changed in this way.

  In the above embodiment, the current value to be applied to the LEDs (21 to 23) is driven by a constant current value waveform. However, the present invention is not limited to this, and for example, a current value taking into account a decrease in luminance due to heat generation. A waveform, that is, a current value waveform such that the current value gradually increases right after light emission may be set.

  In the above embodiment, the case where the three primary color LEDs 21 to 23 are used as light source elements has been described. However, the present invention is not limited to LEDs, and can be similarly applied to an LD (semiconductor laser). The device type or the number of components of the device is not limited as long as it is a device using this or a driving method of the device.

  In addition, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention in the implementation stage. Further, the functions executed in the above-described embodiments may be combined as appropriate as possible. The above-described embodiment includes various stages, and various inventions can be extracted by an appropriate combination of a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, if the effect is obtained, a configuration from which the constituent requirements are deleted can be extracted as an invention.

  DESCRIPTION OF SYMBOLS 10 ... Data projector apparatus, 11 ... Input / output connector part, 12 ... Input / output interface (I / F), 13 ... Image conversion part, 14 ... Video RAM, 15 ... Projection image processing part, 16 ... Micromirror element, 17 ... Light source unit, 18 ... mirror, 19 ... projection lens unit, 21 ... R-LED, 22 ... G-LED, 23 ... B-LED, 24 ... dichroic mirror, 25 ... integrator, 26 ... dichroic mirror, 27 ... mirror, 28 ... Projection light processing unit, 31 ... CPU, 32 ... main memory, 33 ... program memory, 34 ... operation unit, 35 ... audio processing unit, 36 ... speaker unit, SB ... system bus.

Claims (6)

A semiconductor light emitting device;
Driving means for causing the semiconductor light emitting element to emit light in a time-sharing manner in a predetermined light emitting period;
A timing signal generating means for generating a timing signal indicating a light emission start timing of the light emission period of the semiconductor light emitting element and a predetermined time before the light emission end;
Measuring means for measuring a voltage value of the semiconductor light emitting element based on a timing a predetermined time before the end of light emission of the timing signal given from the timing signal generating means;
A light source device comprising: drive control means for adjusting drive power of a semiconductor light emitting element driven by the drive means based on a measurement result obtained by the measurement means.   2. The light source according to claim 1, wherein the timing signal generation means generates a timing signal in which a timing a predetermined time before the end of light emission in the light emission period is set according to a time required for measurement by the measurement means. apparatus. The timing signal is a rectangular wave,
The timing signal generating means generates a timing signal for instructing start of light emission by the driving means at the rising edge of the rectangular waveform, and instructs the measurement means to measure the voltage value of the semiconductor light emitting element at the falling edge of the rectangular waveform. 3. The light source device according to claim 1, wherein a timing signal is generated. A plurality of semiconductor light emitting elements;
Driving means for causing the plurality of semiconductor light emitting elements to emit light in a time-sharing manner in units of a predetermined light emission period;
Timing signal generating means for generating a timing signal indicating a light emission start timing and a predetermined time before the light emission end of each light emission period of the plurality of semiconductor light emitting elements;
Measuring means for measuring each voltage value of the plurality of semiconductor light emitting elements based on a timing a predetermined time before the end of light emission of the timing signal given from the timing signal generating means;
Drive control means for adjusting each drive power of a plurality of semiconductor light emitting elements driven by the drive means according to the measurement result obtained by the measurement means;
An input means for inputting an image signal;
A projection apparatus comprising: projection means that uses light emitted from the plurality of semiconductor light emitting elements to form and project an optical image corresponding to an image signal input by the input means. The timing signal is a rectangular wave,
The timing signal generating means generates a timing signal for instructing start of light emission by the driving means at the rising edge of the rectangular waveform, and instructs the measurement means to measure the voltage value of the semiconductor light emitting element at the falling edge of the rectangular waveform. The projection apparatus according to claim 4, wherein a timing signal is generated. A plurality of semiconductor light emitting devices, an input unit for inputting image signals, and a projection for forming and projecting a color light image corresponding to the image signals input by the input unit using light emitted from the plurality of semiconductor light emitting devices. A projection method with a projection device comprising a unit,
A timing signal generation step of generating a timing signal indicating a light emission start timing and a predetermined time before the light emission end in each light emission period of the plurality of semiconductor light emitting elements;
Based on the timing signal generated in the timing signal generation step, a driving step of cyclically driving the plurality of semiconductor light emitting elements in a time division manner corresponding to each light emission period;
A measurement step of measuring each voltage value of the plurality of semiconductor light emitting elements based on a timing a predetermined time before the end of light emission of the timing signal given in the timing signal generation step;
And a drive control step of adjusting each drive power of the plurality of semiconductor light emitting elements driven in the drive step based on a measurement result obtained in the measurement step.

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