JP2005091581A - Illuminating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illuminating device which is equipped with a semiconductor light emitting element and supplies illuminating light having no luminance irregularity and safe to human eyes. <P>SOLUTION: A light emitting unit 1 is constituted of a blue LED and a diffusing plate 3. The aspect ratios of the incident surface and the emitting surface of the diffusing plate 3 are made the same as the aspect ratio of the imaging area PA of a camera 5. By incorporating YAG-based fluorescent material into the diffusing plate 3, the diffusing plate 3 is constituted to diffuse and emit white light when blue light is made incident. The diffusing plate 3 is disposed to intervene between the blue LED and a light projection optical system 4. The light projection optical system 4 is positioned so that the diffusing plate 3 may be optically conjugate to a subject OB through the light projection optical system 4. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a lighting device using a semiconductor light emitting element.

In recent years, high-brightness LEDs, white LEDs, and the like have been developed in the field of semiconductor light-emitting devices, and their application range has expanded. For example, there is a camera flash device that uses an illumination device including a white LED instead of a conventionally used xenon discharge tube. This is because problems such as a xenon discharge tube that requires a capacitor for driving, a space in the camera being narrowed, and a danger due to high voltage flow can be eliminated by using a white LED. The light emitted from the white LED is irradiated to the subject via the light projecting optical system (for example, Patent Document 1).
JP 2002-148686 A

  However, leads and wires are disposed around the LED chip, and members that emit light (chips) and members that do not emit light (leads and wires) are mixed. Therefore, when the light emitted from the LED is emitted through the light projecting optical system, there is a problem that an image of the chip and its surrounding shadow is also projected on the subject side, resulting in uneven illumination brightness.

  Further, the LED chip is extremely small, and the illumination device composed of the white LED as described above is a small point light source as a light emitting source. When such a point light source emits high-luminance white light, when the subject is a human, the emitted light forms an image in the eye, causing damage to the retina of the eye.

  An object of the present invention is to solve the above problems, and to provide illumination light that has no luminance unevenness and is safe for human eyes in an illumination device including a semiconductor light emitting element as a light source.

  An illumination device according to the present invention is interposed between a semiconductor light emitting element, a light projecting optical system for irradiating a subject with light emitted from the semiconductor light emitting element, and the semiconductor light emitting element and the light projecting optical system. And diffusing means for diffusing the emitted light of the semiconductor light emitting element and guiding it to the light projecting optical system.

  Preferably, the diffusing unit is an optical element having a parallel plate shape, and has an entrance surface and an exit surface similar to the imaging region of the camera. According to this configuration, the light guided from the diffusing unit is not diffused beyond the imaging region of the camera, and the light from the diffusing unit can be efficiently supplied to the subject.

  Preferably, the diffusing unit is positioned at a position optically conjugate with the subject via the light projecting optical system. According to this configuration, a high exposure amount can be ensured in the subject.

  Alternatively, the light projecting optical system may be fixed in the optical axis direction of the light projecting optical system in accordance with a predetermined subject distance in a camera provided with the illumination device. Alternatively, the light projecting optical system may be movable in the optical axis direction of the light projecting optical system in accordance with the subject distance so that the diffusing unit forms an image on the subject.

  For example, the semiconductor light emitting element may be a semiconductor light emitting element that emits blue light. In this case, the diffusing unit includes a phosphor that diffuses white light and emits light when blue light is incident. The semiconductor light emitting element may be a semiconductor light emitting element that emits white light.

  As described above, according to the present invention, the diffusing means for diffusing the emitted light of the semiconductor light emitting element is interposed between the semiconductor light emitting element of the light source and the light projecting optical system. Accordingly, the uneven brightness between the chip of the semiconductor light emitting element and its periphery is diffused and eliminated, so that the uneven brightness of the subject is prevented. Further, since the emitted light of the semiconductor light emitting element is diffused by the diffusing means, it is safe because the emitted light does not form an image on the retina even when the subject is a human.

  FIG. 1 is a diagram schematically showing a relative positional relationship between a light emitting unit and a light projecting optical system that constitute an illumination apparatus to which the first embodiment according to the present invention is applied. The light emitting unit 1 includes a blue LED 2 that emits blue light and a diffusion plate 3. The diffusing plate 3 is a flat plate-like optical element, and its entrance surface 3a and exit surface 3b are rectangular as shown in FIG. The aspect ratio of the entrance surface 3a and the exit surface 3b is the same as the aspect ratio of the shooting area for one shooting frame of the camera used with the illumination device, and the ratio of the long side: short side is 3: 2. In other words, the entrance surface 3a and the exit surface 3b of the diffusing plate 3 are similar to the imaging region of the camera. The diffusion plate 3 contains a YAG (Yttrium Aluminum Garnet) fluorescent material. When blue light emitted from the blue LED 2 enters from the incident surface 3a, the blue light is converted into white light by the fluorescent material, diffused, and emitted from the emission surface 3b. That is, the diffusion plate 3 also functions as a secondary light emitter. Although only one blue LED 2 is shown in FIG. 1, the present invention is not limited to this, and a plurality of blue LEDs 2 may be provided.

  White light diffused and emitted from the exit surface 3 b of the diffusion plate 3 is guided to the subject as illumination light through the light projecting optical system 4. FIG. 2 shows an optical path diagram until the light emitted from the light emitting unit 1 reaches the subject OB. In FIG. 2, the blue LED 2 described above is supported by a support member 2a. In FIG. 2, a dotted line PA indicates an imaging region. As described above, the diffusing plate 3 has a similar shape to the imaging area PA. The light projecting optical system 4 is fixed so that the diffusion plate 3 is optically conjugate with the subject OB. That is, the light projecting optical system 4 is fixed at a position where the diffusion plate 3 forms an image on the subject OB via the light projecting optical system 4. The subject distance in this case is an average predetermined subject distance in the camera 5 used with the illumination device of the first embodiment. In order to clarify the relative relationship between the imaging region on the subject OB, the diffusing plate 3, and the light projecting optical system 4, the imaging region is shown in an inclined angle in FIG. 1 and 2, the light projecting optical system 4 is schematically shown in order to clearly show the relative positional relationship between the light projecting optical system 4 and other elements.

  FIG. 3 is a block diagram of the camera 5 according to the present invention. The CPU 10 controls the entire camera. When a power button provided on a camera body (not shown) is operated and the main switch SWMAIN is turned on, supply of power is started. When a shutter button (not shown) provided on the camera body is half-pressed, the photometry switch SWS is turned on. When the photometry switch SWS is turned on, the CPU 10 executes photometry processing and distance measurement processing. That is, the exposure value is calculated based on the input from the photometric device 11, and the aperture value, shutter speed, and charge accumulation time of the image sensor 13 necessary for photographing are calculated based on the exposure value. Further, a driving amount of a focusing lens (not shown) is calculated based on an input from the distance measuring device 12 and a driving signal is output to the focus driving circuit 14.

  When the shutter button is fully pressed, the release switch SWR is turned on. When the release switch SWR is turned on, the CPU 10 drives the shutter unit drive circuit 15 according to the aperture value calculated by the photometry process, and outputs a control signal to the image sensor drive circuit 16 according to the charge accumulation time. The shutter unit drive circuit 15 outputs a drive signal to the shutter unit 17 in accordance with the input control signal. The image sensor drive circuit 16 outputs a drive signal to the image sensor 13 in accordance with the input control signal. The image sensor 13 photoelectrically converts an optical image of a subject formed in the light receiving area and outputs an analog image signal. The A / D converter 18 A / D converts the analog image signal and outputs the digital image signal to the CPU 10.

  The digital image signal input to the CPU 10 is temporarily stored in the DRAM 19 as image data. The stored image data is appropriately read from the DRAM 19 when performing predetermined image processing. The EEPROM 20 stores various data for controlling the camera 5. When the main switch SWMAIN is turned on, various data are read from the EEPROM 20, stored in the RAM in the CPU 10, and used for control by the CPU 10.

  An LCD 21 provided on the back of the camera body is connected to the CPU 10. Various data such as shooting conditions and date are displayed on the LCD 21 under the control of the CPU 10.

  As a result of photometry by the photometry device 11, when it is determined that the amount of the subject light is insufficient, the CPU 10 outputs a flash emission control signal to the flash drive mechanism 22.

  FIG. 4 is a block diagram of the flash drive mechanism 22. A drive signal for controlling light emission of the blue LED 3 input from the CPU 10 is input to the PWM circuit 102, and a pulse signal having a predetermined pulse width is generated. That is, the PWM circuit 102 generates a pulse signal having a desired duty ratio and frequency in accordance with a control signal from the CPU 10. A pulse signal from the PWM circuit 102 is input to the drive pulse generation circuit 103. The drive pulse generation circuit 103 shapes the voltage value and current value of the pulse signal into predetermined values suitable for LED driving and outputs them as drive signals. The drive signal output from the drive pulse generation circuit 103 is output to the blue LED 2 of the light emitting unit 1 via the power MOSFET 104 and the resistor R. Thereby, the blue LED 2 is driven and blue light is emitted. The blue light emitted from the blue LED 2 is converted into white light by the diffusion plate 3 as described above, diffused, and guided to the light projecting optical system 4.

  As described above, according to the first embodiment, the diffusing plate 3 is disposed between the blue LED 2 that is a light source and the light projecting optical system 4, and the light emitted from the blue LED 2 is diffused to project light. Guided to system 4. Therefore, it is possible to prevent the image of the member around the chip of the blue LED 2 from being projected onto the projection optical system 4 and projected onto the subject OB. Further, when the subject is a human, the point light source of the chip of the blue LED 2 is prevented from forming an image on the retina.

  The aspect ratio of the entrance surface 3 a and the exit surface 3 b of the diffuser plate 3 matches the aspect ratio of the film of the camera 5. Therefore, the emitted light from the blue LED 2 can be used efficiently as irradiation light.

  The diffusing plate 3 is positioned so as to form an image on the subject OB via the light projecting optical system 4. Therefore, a high exposure amount on the subject OB can be ensured.

  FIG. 5 is a block diagram of a flash drive mechanism 200 to which the second embodiment of the present invention is applied. In the second embodiment, the flash drive mechanism 200 is connected to the same CPU 10 as in the first embodiment shown in FIG. The configuration other than the flash drive mechanism 200 around the CPU is the same as the block diagram of FIG. Further, in FIG. 5, the same components as those of the flash drive mechanism 22 of the first embodiment are denoted by the same reference numerals. That is, also in the second embodiment, the light emitting unit 1 includes the blue LED 2 and the diffusion plate 3.

  A control signal for the blue LED 2 and a control signal for the light projecting optical system 4 are input to the flash drive mechanism 200 from the CPU 10. The control signal for the blue LED 2 is output to the blue LED 2 via the PWM circuit 102, the drive pulse generation circuit 103, the power MOSFET 104, and the resistor R, as in the first embodiment. A control signal of the light projecting optical system 4 is input to the light projecting optical system driving device 201. In the light projecting optical system driving device 201, the drive source of the light projecting optical system 4 is driven based on the input control signal. As a result, the light projecting optical system 4 is driven in a predetermined driving direction by a predetermined driving amount. The amount of displacement of the light projecting optical system 4 is detected by the light projecting optical system driving device 201 and input to the CPU 10. The CPU 10 calculates the driving amount of the light projecting optical system 4 based on the displacement amount, and outputs it to the light projecting optical system action device 201 as the control signal.

  FIG. 6 is a diagram illustrating a configuration of the light projecting optical system 4 and a configuration of the light projecting optical system driving device 201. The light projecting optical system 4 includes a protective lens 40 and first to third zooming lenses 41, 42, and 43. The first zooming lens 41 is supported by the moving frame 202. The guide pin 203 of the moving frame 202 is disposed in the zoom cam groove 205 of the cam ring 204. When the rotational motion of a drive source (not shown) is transmitted to the cam ring 205 via the gear 206, the moving frame 202 is guided by the guide pin 203 and displaced along the optical axis OP of the light projecting optical system 4. . As a result, the first zooming lens 41 moves along the optical axis OP, and the magnification ratio of the light projecting optical system 4 changes. That is, the enlargement ratio of the light projecting optical system 4 is controlled according to the moving direction and moving amount of the first zooming lens 41. The moving direction and the moving amount of the first zooming lens 41 are calculated based on the subject distance measured by the distance measuring process.

  The circumferential surface of the tooth of the gear 206 is painted, and a reflective photo interrupter 209 is disposed at a position facing the tooth surface of the gear 206 that has been painted black. The photo interrupter 209 detects the amount of rotation of the cam ring 204 based on a change in the amount of reflected light emitted toward the tooth surface of the gear 206 and outputs a detection signal. Based on the detection signal from the photo interrupter 209, the CPU 10 changes the current position of the first zooming lens 41 from a predetermined initial position (the position of the first zooming lens 41 when the subject distance is infinite). The amount is grasped and the drive control is performed.

  FIG. 7 and FIG. 8 are flowcharts showing a shooting processing procedure in the camera to which the second embodiment is applied. In step S100, ON / OFF of the photometric switch SWS is checked. If it is confirmed that the above shutter button is pressed halfway and the photometric switch SWS is turned on, the process proceeds to step S102. In step S102, the above-mentioned photometric process based on the measurement result of the photometric device 11 is executed. Based on the result of this photometric processing, an exposure value is calculated in step S104, and a shutter speed is calculated in step S106.

  Next, in step S108, the subject distance is calculated based on the measurement result of the distance measuring device 12. In step S110, the moving direction and moving amount of the photographing lens (not shown) are calculated and determined based on the subject distance, and in step S112, the first zooming lens 41 of the light projecting optical system 4 is determined based on the subject distance. The moving direction and moving amount are calculated and determined. In step S112, as with the photographing lens, the position of the first zooming lens 41 is set so that the position of the light projecting optical system 4 is set through the light projecting optical system 4 so that the diffusing plate 3 is imaged on the subject OB. The moving direction and moving amount are calculated.

  In step S114, whether the release switch SWR is on or off is checked. If it is confirmed that the shutter button is fully pressed and the release switch SWR is turned on, the process proceeds to step S116.

  In step S116, it is determined whether it is necessary to irradiate flash light based on the result of the photometric process in step S102. When the brightness of the subject is sufficient and it is not necessary to irradiate the flash light, the process proceeds to step S117, the photographing lens is driven to perform the focusing operation, and then the process proceeds to step S118, where the subject image photographing process is started. In step S118, driving of the shutter unit 17 is started. Next, in step S120, the image sensor 13 is driven, and photoelectric conversion processing of the optical image of the subject is executed. When the charge accumulation time calculated based on the photometric result has elapsed, the driving of the shutter unit 17 is stopped in step S122, the driving of the image sensor 13 is stopped in step S124, and the subject image capturing process is terminated, and step S100 is completed. Return to.

  On the other hand, if it is determined in step S116 that the brightness of the subject is insufficient and the flash light needs to be irradiated, the process proceeds to step S126 in FIG. In step S126, the photographic lens is driven based on the moving direction / movement amount of the photographic lens calculated in step S110. Next, in step S128, based on the movement direction / movement amount of the first zooming lens 41 of the light projection optical system 4 calculated in step S112, the first zooming lens 41 is the above-described light projection optical system driving device 201. Driven by.

  After the photographing lens and the first zooming lens 41 are driven, the process proceeds to step S130. In step S130, supply of drive current to the blue LED 2 of the light emitting unit 1 is started, and irradiation of the flash light to the subject by the light emitting unit 1 is started. Next, the process proceeds to step S132, and the subject image capturing process is started. In step S132, driving of the shutter unit 17 is started. In step S134, the image sensor 13 is driven, and photoelectric conversion processing of the optical image of the subject is executed. When the charge accumulation time calculated based on the photometric result has elapsed, the driving of the shutter unit 17 is stopped in step S136.

  Next, in step S138, whether the release switch SWR is on or off is checked. When it is confirmed that the shutter button is fully pressed and the release switch SWR is kept on, the process returns to step S132, and the photographing processes of steps S132 to S136 are repeated. If it is confirmed in step S138 that the release switch SWR is OFF, the process proceeds to step S140. In step S140, the driving of the blue LED 2 is stopped, and the flash light irradiation is stopped. Next, in step S142, the driving of the image sensor 13 is stopped, the subject image capturing process is terminated, and the process returns to step S100.

  As described above, according to the second embodiment, the first zooming lens 41 of the light projecting optical system 4 is driven according to the subject distance, and the enlargement ratio of the light projecting optical system 4 is controlled. Therefore, as shown in FIG. 9, when the subject distance is short (FIG. 9 (a)) and when the subject distance is long (FIG. 9 (b)), the diffusion plate 3 always forms an image on the subject OB. Be made. As a result, the flash light supplied from the light emitting unit 1 can be constantly and efficiently irradiated onto the subject OB.

  In 1st and 2nd embodiment, although blue LED2 is used, it does not restrict to this. A white LED that emits white light may be used instead of the blue LED 2. When a white LED is used, it is not necessary to use a material containing a fluorescent material for the diffusing plate 3, and any optical element that diffuses and emits incident light may be used. Note that the diffusion plate used in combination with the white LED also has an incident surface and an exit surface having the same aspect ratio as that of the film photographing area, and is optically conjugate with the subject via the projection optical system 4. Needless to say, it is provided. Further, the aspect ratio of the diffusion plate 4 can be changed according to the camera to be used. For example, it may be set to 4: 3 for a television camera and 16: 9 for a high-definition television camera.

It is a figure which shows typically the relative positional relationship of the light emission unit to which 1st Embodiment concerning this invention is applied, and a light projection optical system. It is a figure which shows typically the relative positional relationship of a light emission unit, a light projection optical system, and a to-be-photographed object. It is a block diagram of the camera used with a light emission unit. It is a block diagram of the flash drive mechanism of the first embodiment. It is a block diagram of the flash drive mechanism of the second embodiment. It is a figure which shows the structure of a light projection optical system and its drive device. It is a flowchart which shows the first half of the imaging | photography process sequence in the camera with which 2nd Embodiment is applied. It is a flowchart which shows the second half of the imaging | photography process sequence in the camera with which 2nd Embodiment is applied. It is a figure which shows typically the relative positional relationship of a light emission unit, a light projection optical system, and a to-be-photographed object.

Explanation of symbols

1 Light emitting unit 2 Blue LED
3 Diffuser 4 Projection optical system 10 CPU
22, 200 Flash drive mechanism 40 Protective lens 41 First zooming lens 42 Second zooming lens 43 Third zooming lens 201 Projection optical system drive device

Claims (7)

A semiconductor light emitting device;
A light projecting optical system for irradiating the subject with the emitted light emitted from the semiconductor light emitting element;
An illuminating device comprising: a diffusing unit interposed between the semiconductor light emitting element and the light projecting optical system, and diffusing the emitted light to guide the light to the light projecting optical system.   The illuminating device according to claim 1, wherein the diffusing unit is an optical element having a parallel plate shape, and has an incident surface and an output surface similar to an imaging region of a camera.   The illumination device according to claim 2, wherein the diffusing unit is positioned at a position optically conjugate with the subject via the light projecting optical system.   The light projecting optical system is fixed in the optical axis direction of the light projecting optical system so that the diffusing unit forms an image on the subject in accordance with a predetermined subject distance in a camera used with the illumination device. The lighting device according to claim 3.   4. The light projecting optical system according to claim 3, wherein the light projecting optical system is movable in an optical axis direction of the light projecting optical system in accordance with a subject distance so that the diffusing unit forms an image on the subject. Lighting equipment. The semiconductor light emitting element is a semiconductor light emitting element that emits blue light,
The illumination device according to claim 1, wherein the diffusing unit includes a phosphor that diffuses white light when blue light is incident thereon. The lighting device according to claim 1, wherein the semiconductor light emitting element is a semiconductor light emitting element that emits white light.

Images