JP5428710B2 - Light source device, projection device, and projection method - Google Patents

Description

  The present invention relates to a light source device, a projection device, and a projection method suitable for a projector device and the like.

  Conventionally, as a projector for suppressing the occurrence of glare of continuous light projected on a screen and improving the reliability of the entire apparatus, a light source device that emits laser light toward a projection surface, and the light source device A scanning unit that scans the laser beam; a light diffusing member that diffuses the laser beam scanned by the scanning unit; and a condensing unit that condenses the laser beam emitted from the light diffusing member on the projection surface. Is considered. (Patent Document 1)

JP 2007-025466 A

  In an apparatus using laser light as a light source, a speckled pattern called speckle noise occurs, and the image may appear to flicker.

  This speckle noise appears due to interference of scattered light by irradiating laser light onto a diffusely reflecting surface such as a rough surface of metal or plastic, and the laser light has a single wavelength and the same phase. It is light and is a peculiar phenomenon that occurs because of its very high coherence.

  In the case of a projector using laser light as a light source, the speckle noise is reduced by inserting a diffusing member into the optical system, including the technology described in the above patent document, but always irradiates a constant amount of light. As a result, speckle noise cannot be completely suppressed, and flickering in the projected image cannot be avoided.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a light source capable of reliably suppressing the generation of speckle noise associated with a laser light source without taking a complicated configuration. An apparatus, a projection apparatus, and a projection method are provided.

The present invention includes a light source that generates laser light, a wavelength conversion unit that periodically repeats a period of emission without changing the wavelength of the laser light, and a period of emission after converting the wavelength of the laser light. The light source control means for intermittently driving the light source during a period in which the wavelength conversion means emits the laser light without changing the wavelength.

  According to the present invention, it is possible to reliably suppress the occurrence of speckle noise associated with a laser light source without adopting a complicated configuration.

1 is a block diagram showing a functional configuration of an entire data projector apparatus according to an embodiment of the present invention. The perspective view which shows the external appearance structure of the semiconductor laser part which concerns on the same embodiment. The perspective view which shows the external appearance structure of the color wheel and motor which concern on the same embodiment. 6 is a timing chart illustrating the relationship between R, G, and B fields constituting one frame of a color image according to the embodiment and the light emission timing of a laser diode.

  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.
An input / output connector unit 11 includes, 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, which is a spatial light modulation element (SLM), is driven to display by high-speed time division driving.

  The micromirror element 16 is turned on / off individually at a high speed by tilting angles of a plurality of micromirrors arranged in an array, for example, XGA (1024 horizontal pixels × vertical 768 pixels), thereby reflecting the reflected light. A light image is formed.

  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 semiconductor laser unit (LDU) 21 including a group of laser diodes that emit blue laser beams having the same wavelength.

  FIG. 2 is a perspective view showing an external configuration of the semiconductor laser section 21. As shown in FIG. As shown in the figure, the semiconductor laser section 21 has a plurality of, for example, six laser diodes 21a to 21f. A total of six laser diodes 21a to 21f shown in 2 rows × 3 columns are used as monochromatic laser light sources having the same emission characteristics and the same emission direction. In this embodiment, blue laser light is used as described above. To emit.

  The blue laser light emitted from the semiconductor laser unit 21 passes through the dichroic mirror 22 and is irradiated to one point on the circumference of the color wheel 24 through the lens 23.

  The color wheel 24 is rotated by a motor (M) 25. On the circumference of the color wheel 24 irradiated with the laser light, a red fluorescent reflector 24R, a green fluorescent reflector 24G, and a blue diffuser 24B are formed in a ring shape.

  FIG. 3 is a perspective view showing the external configuration of the color wheel 24 and the motor 25. As shown in the figure, the red fluorescent reflector 24R has a mirror light image on the surface (not shown) opposite to the side irradiated with the laser light, and the phosphor applied by the blue laser light irradiation is a red light. The excited red light is emitted so as to be reflected in the direction in which the laser light has been irradiated.

  Similarly, the green fluorescent reflecting plate 24G has a mirror structure on the surface (not shown) opposite to the side irradiated with the laser beam, and the phosphor applied by the blue laser beam irradiation excited the green light. The green light is emitted so as to be reflected in the direction in which the laser light has been irradiated.

  The remaining blue diffusion plate 24B is formed of a polished glass-like transmission member, and the irradiated blue laser light is transmitted while being scattered.

  When the red fluorescent reflector 24R or the green fluorescent reflector 24G of the color wheel 24 is at the laser light irradiation position, red light or green light is excited by the laser light irradiation. The excited red light or green light is reflected by the color wheel 24 and then reflected by the dichroic mirror 22 through the lens 23.

  Thereafter, the red light or green light is reflected by the mirror 27 via the lens 26, reflected by the dichroic mirror 29 via the lens 28, and then light flux having a substantially uniform luminance distribution by the integrator 31 via the lens 30. Then, the light is totally reflected by the mirror 32 and sent to the mirror 18.

  In addition, when the blue diffusion plate 24B of the color wheel 24 is in the laser light irradiation position, the laser light is transmitted through the color wheel 24 while being diffused by the diffusion plate 24B, and then totally reflected by the mirror 34 via the lens 33. Is done. Thereafter, the blue light is transmitted through the dichroic mirror 29 through the lens 35, is converted into a luminous flux having a substantially uniform luminance distribution by the integrator 29 through the lens 30, and then totally reflected by the mirror 32. 18 is sent.

  As described above, the dichroic mirrors 22 and 29 both transmit blue light and reflect green light and red light.

  The projection light processing unit 36 controls the light emission timing of the semiconductor laser unit 21 of the light source unit 17 and the rotation of the color wheel 24 by the motor 25. The projection light processing unit 36 controls the light emission timing of the semiconductor laser unit 21 and the rotation of the color wheel 24 according to the timing of the image data given from the projection image processing unit 15.

  The CPU 37 controls all the operations of the above circuits. The CPU 37 is directly connected to the main memory 38 and the program memory 39. The main memory 38 is composed of a DRAM and functions as a work memory for the CPU 37. The program memory 39 is composed of an electrically rewritable nonvolatile memory, and stores an operation program executed by the CPU 37, various fixed data, and the like. The CPU 37 uses the main memory 38 and the program memory 39 to execute a control operation in the data projector device 10.

The CPU 37 executes various projection operations according to key operation signals from the operation unit 40.
The operation unit 40 includes a key operation unit provided on the main body of the data projector device 10 and a laser light receiving unit that receives infrared light between a remote controller (not shown) dedicated to the data projector device 10. A key operation signal based on a key operated by the key operation unit or a remote controller is directly output to the CPU 37.

  The CPU 37 is further connected to the audio processing unit 41 via the system bus SB. The sound processing unit 41 includes a sound source circuit such as a PCM sound source, converts the sound data given during the projection operation into an analog signal, drives the speaker unit 42 to emit a loud sound, or generates a beep sound or the like if necessary.

Next, the operation of the above embodiment will be described.
FIG. 4 is a timing chart illustrating the relationship between the R, G, and B fields that make up one frame of a color image and the light emission timings of the laser diodes 21 a to 21 f that make up the semiconductor laser unit 21.

FIG. 4A shows the timing of each field of R, G, and B constituting one frame of a color image during the projection operation.
In the R field at the head of one frame, the red fluorescent reflector 24R of the color wheel 24 is positioned on the optical path of the blue laser light emitted from the semiconductor laser unit 21. Red light is excited by irradiating the phosphor applied to the red fluorescent reflector 24R with blue laser light.

  The excited red light is reflected by the dichroic mirror 29 through the path of the lens 23, the dichroic mirror 22, the lens 26, the mirror 27, and the lens 28, and further passes through the lens 30, the integrator 31, the mirror 32, and the mirror 18. The micromirror element 16 is irradiated.

  During the R field period, the micromirror element 16 displays a gradation image corresponding to red light by driving the projection image processing unit 15. Therefore, a red light image is formed by the reflected light, and the formed red light image is enlarged by the projection lens unit 19 and projected onto a screen (not shown) to be projected.

  In the R field period, as shown in FIGS. 4B to 4G, in the semiconductor laser unit 21, all the six laser diodes 21a to 21f are driven to emit light throughout the period.

  Accordingly, speckle noise is generated if the object irradiated with the laser light from the laser diodes 21a to 21f is a surface of a member that diffuses and reflects at the same wavelength, such as a rough surface of metal or plastic, for example. The light energy of the laser light is absorbed by the phosphor applied to the red fluorescent reflector 24R, and the red light is excited instead in a form of frequency conversion. Therefore, it is possible to reliably avoid the generation of speckle noise.

  The same applies to the G field following the R field, and the green fluorescent reflector 24G of the color wheel 24 is positioned on the optical path of the blue laser light emitted from the semiconductor laser unit 21. Green light is excited by irradiating the phosphor applied to the green fluorescent reflector 24G with blue laser light.

  The excited green light is reflected by the dichroic mirror 29 through the path of the lens 23, the dichroic mirror 22, the lens 26, the mirror 27, and the lens 28, and further passes through the lens 30, the integrator 31, the mirror 32, and the mirror 18. The micromirror element 16 is irradiated.

  During the G field period, the micromirror element 16 displays a gradation image corresponding to green light by driving the projection image processing unit 15. Therefore, a green light image is formed by the reflected light, and the formed green light image is enlarged by the projection lens unit 19 and projected onto a screen (not shown) to be projected.

  Also during the G field period, as shown in FIGS. 4B to 4G, in the semiconductor laser unit 21, all of the six laser diodes 21a to 21f are driven to emit light throughout the period.

  Accordingly, the light energy of the laser light is absorbed by the phosphor applied to the green fluorescent reflector 24G, and the green light is excited instead of being frequency-converted, so that the generation of speckle noise can be reliably avoided.

  In the subsequent B field, the blue diffusion plate 24B of the color wheel 24 is positioned on the optical path of the blue laser light emitted from the semiconductor laser section 21. Therefore, the blue laser light is transmitted while diffusing the blue diffusion plate 24B without changing the wavelength.

  The blue light transmitted through the blue diffusion plate 24B passes through the path of the lens 33, the mirror 34, and the lens 35, passes through the dichroic mirror 29, and further passes through the lens 30, the integrator 31, the mirror 32, and the mirror 18 to become microscopic. The mirror element 16 is irradiated.

During the B field period, the micromirror element 16 displays a gradation image corresponding to blue light by driving the projection image processing unit 15. Therefore, a blue light image is formed by the reflected light, and the formed blue light image is enlarged by the projection lens unit 19 and projected onto a screen (not shown) to be projected.

  In the B field period, as shown in FIGS. 4B to 4G, the semiconductor laser unit 21 always emits four of the six laser diodes 21a to 21f, and the remaining two. Are intermittently driven cyclically while sequentially switching the light emission position in short time units so as to stop light emission.

  Specifically, the laser diodes 21a and 21d, the laser diodes 21b and 21e, and the laser diodes 21c and 21f are set as a set, and the set for stopping the lighting is cyclically switched. Assume that intermittent light emission drive is performed by four laser diodes.

  Thus, even if speckle noise occurs due to the diffusion of the laser light in the blue diffusion plate 24B by switching the light emission positions of the laser diodes 21a to 21f at a short cycle within the B field period, the generation position thereof Since it moves in a very short time unit, it cannot be perceived at all by the human naked eye.

  As a result, it is possible to reliably avoid the generation of speckle noise that can be perceived by the human naked eye.

  The time ratio of each field of R, G, and B in one frame of the image is such that the red fluorescent reflector 24R, the green fluorescent reflector 24G, and the blue diffuser of the color wheel 24 that are rotationally driven by the motor 25 at a constant speed. It is determined by the central angle of 24B.

  In the present embodiment, as shown in FIG. 4A, an example in which the time is set to be longer in the order of R> G> B is shown, but this is the case of the laser diodes 21a to 21f constituting the light source. The light emission intensity and the oscillation frequency, and the fluorescence characteristics of the phosphors applied to the red fluorescent reflection plate 24R and the green fluorescent reflection plate 24G are appropriately set.

  As described in detail above, according to the present embodiment, it is possible to reliably suppress generation of speckle noise by intermittent driving of the laser diodes 21a to 21f constituting the semiconductor laser unit 21 without adopting a complicated configuration. Become.

  Further, in the above-described embodiment, the semiconductor laser unit 21 is described as configured by a plurality of, for example, six laser diodes 21a to 21f. However, by using a plurality of laser light sources that oscillate at the same wavelength as described above, By intermittently driving while sequentially switching the light emission positions at intervals, it is possible to more reliably suppress the generation of speckle noise.

  Note that the present invention does not limit the number of elements constituting the laser light source and the number of them that temporarily stop light emission.

  Further, only one laser light source may be used as the light source, and the one laser diode may be intermittently driven during the period when speckle noise is expected to occur. Even taking into account that 24B moves (rotates) relative to the laser beam, it is possible to sufficiently suppress the generation of speckle noise at a perceptible level.

  Furthermore, although the above embodiment has been described with respect to the case where the present invention is applied to the single-plate DLP (registered trademark) data projector apparatus 10, the present invention does not limit the projection system of the data projector apparatus. The present invention can be similarly applied to a liquid crystal projector apparatus that forms a light image using a monochrome liquid crystal panel of a type, and can be similarly applied not only to a data projector apparatus but also to, for example, a rear projection television receiver.

  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 (scaler), 14 ... Video RAM, 15 ... Projection image processing part, 16 ... Micromirror element (SLM), 17 ... light source unit, 18 ... mirror, 19 ... projection lens unit, 21 ... semiconductor laser unit (LDU), 21a to 21f ... laser diode, 22 ... dichroic mirror, 23 ... lens, 24 ... color wheel, 24B ... Blue diffuser plate, 24G ... Green phosphor reflector, 25 ... Motor (M), 26 ... Lens, 27 ... Mirror, 28 ... Lens, 29 ... Dichroic mirror, 30 ... Lens, 31 ... Integrator, 32 ... Mirror, 33 ... Lens, 34 ... Mirror, 35 ... Lens, 36 ... Projection light processing unit, 37 ... CPU, 38 ... Main memory 39 ... program memory, 40 ... operation unit, 41 ... audio processing unit, 42 ... speaker, SB ... system bus.

Claims (7)

A light source that generates laser light;
Wavelength converting means for periodically repeating a period of emitting without changing the wavelength of the laser light, and a period of converting and emitting the wavelength of the laser light;
A light source device comprising: a light source control means for intermittently driving the light source during a period in which the wavelength conversion means emits the laser light without changing its wavelength. The light source has a plurality of laser light emitting elements,
The light source control means cyclically intermittently drives the plurality of laser light emitting elements while switching the light emission positions of the plurality of laser light emitting elements during the period in which the wavelength conversion means emits the laser light without changing the wavelength. The light source device according to claim 1 . A light source that generates laser light;
Wavelength converting means for periodically repeating a period of emitting without changing the wavelength of the laser light, and a period of converting and emitting the wavelength of the laser light;
A light source control means for intermittently driving the light source during a period of emission without changing the wavelength of the laser light by the wavelength conversion means;
An input means for inputting an image signal;
A projection apparatus comprising: projection means for forming and projecting a color light image corresponding to an image signal input by the input means using light emitted from the wavelength conversion means. The light source has a plurality of laser light emitting elements,
The light source control means cyclically intermittently drives the plurality of laser light emitting elements while switching the light emission positions of the plurality of laser light emitting elements during the period in which the wavelength conversion means emits the laser light without changing the wavelength. The projection apparatus according to claim 3, wherein:   5. The projection apparatus according to claim 3, wherein the laser beam is a blue laser beam.   The wavelength conversion means is a color wheel, and a red fluorescent reflector, a green fluorescent reflector, and a blue diffuser are combined into a ring shape on the circumference of the color wheel irradiated with the laser light. The projection apparatus according to claim 5, wherein the projection apparatus is formed. A light source that generates laser light, a wavelength conversion unit that periodically repeats a period of emission without changing the wavelength of the laser light, and a period of emission after converting the wavelength of the laser light, and an image signal are input A projection method in a projection apparatus including a projection unit that forms and projects a color light image corresponding to an image signal input by the input unit using light emitted from the input unit and the wavelength conversion unit. ,
A projection method comprising: a light source control step of intermittently driving the light source during a period in which the wavelength conversion unit emits the laser light without changing the wavelength.

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