JP7036436B2 - Light propagation device, light display device and lighting device using the light propagation device - Google Patents

Description

The present invention relates to a light propagation device, an optical display device using the light propagation device, and a lighting device.

Since the light propagation device can be non-contact processed and irradiated, it is used in various fields such as processing, medical treatment, and lighting, and is required to be used for further versatility.

As an example of such an optical propagation device, a device that collects laser light output from a plurality of optical fibers by a coupler and outputs the laser light from one optical fiber has been published (see, for example, Patent Document 1).

FIG. 9 is a schematic view showing the light propagation apparatus 100 according to the embodiment of Patent Document 1. The light propagation device 100 is mainly composed of a plurality of laser light sources 101, an optical fiber combiner 102, and an end cap 103 for light emission. The optical fiber combiner 102 corresponds to a coupler, and is referred to as a coupler in the description of Patent Document 1. An optical fiber 104 is optically coupled to the laser light source 101, and the optical fiber 104 is used as an input optical fiber for the coupler 102. Further, the output optical fiber 105 is extended from the coupler 102 to be used as the output optical fiber of the optical propagation device 100.

The laser light emitted from each laser light source 101 propagates through the optical fiber 104 and is incident on the coupler 102, is collected by the coupler 102, is emitted to the output optical fiber 105, and is incident on the light emission end cap 103. .. The laser beam incident on the output light emitting end cap 103 is emitted from the output surface of the light emitting end cap 103.

Japanese Unexamined Patent Publication No. 2015-022133

Since the coupler 102 is used in the light propagation apparatus 100 of Patent Document 1, the manufacturing cost has risen.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an optical propagation apparatus capable of collecting light emitted from a plurality of light sources without using a coupler and reducing manufacturing costs. ..

The above problems are solved by the following invention. That is, the light propagation device of the present invention is formed of at least a plurality of light sources, a MEMS optical switch, a switching control device, and an optical waveguide, each light source has a fixed output, and the wavelength region of the emitted light is 445 nm or more and 700 nm or less. The MEMS optical switch is an n × m optical switch having n (n ≧ 2) input ports and m (m ≧ 1) output ports, and each light source is optically coupled to each input port. At the same time, each optical waveguide is optically coupled to each output port, each input port is switched in a fixed cycle by a switching control device, and each input port is optically coupled to each optical waveguide in each cycle. Then, the light emitted from the light source is propagated to the optical waveguide, the MEMS optical switch is provided with a mirror, the angle of the mirror is controlled by applying a voltage, and each of the input ports is sent to each of the optical waveguides at regular intervals. Optically coupled, above Vp (V) and below Vs (V) on the way from the initial voltage Vp (V) to the set voltage Vs (V) that controls the mirror angle to the desired set value angle. A certain voltage V'(V) is applied to the mirror, and Vs (V) is applied when the mirror swings to a set value angle by applying V'(V).

According to the optical propagation apparatus of the present invention, it is possible to reduce the manufacturing cost by collecting the light emitted from a plurality of light sources by using a MEMS optical switch instead of the coupler.

FIG. 1 is a schematic diagram showing a light propagation apparatus according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing the operation of the MEMS optical switch in the optical propagation apparatus of FIG. FIG. 3 is an optical output-switching time graph when the mirror of the MEMS optical switch in the optical propagation apparatus of the present invention resonates. FIG. 4 is an optical output-switching time graph when the mirror of the MEMS optical switch in the optical propagation apparatus of the present invention is driven by high-speed switching. FIG. 5 is an explanatory diagram showing an optical output operation to the optical waveguide in the optical propagation device of FIG. 1, and is an explanatory diagram showing an example of hue adjustment. FIG. 6 is an explanatory diagram showing an optical output operation to the optical waveguide in the optical propagation device of FIG. 1, and is an explanatory diagram showing an example of brightness adjustment. FIG. 7 is an explanatory diagram showing an optical output operation to the optical waveguide in the optical propagation device of FIG. 1, and is an explanatory diagram showing an example of saturation adjustment. FIG. 8a is a partial side view of the optical diffusion fiber, which is an example of the optical waveguide in the optical waveguide of FIG. FIG. 8b is a cross-sectional view of the light diffusion fiber of FIG. 8a as viewed from the cut surface AA direction. FIG. 8b also shows a schematic partial enlarged view of an enlarged portion surrounded by a curve in the inner annular core region. FIG. 9 is a schematic diagram showing an embodiment of a conventional light propagation device.

The first feature in the embodiment of the present invention is the following configuration. That is, in the present invention, the light propagation device is formed of at least a plurality of light sources, a MEMS optical switch, a switching control device, and an optical waveguide. Each light source has a fixed output, and the wavelength region of the emitted light is 445 nm or more and 700 nm or less. The MEMS optical switch is equipped with a mirror and is an optical switch to which MEMS (Micro Electro Electro Mechanical Systems) technology is applied. The number of input ports is n (n ≧ 2) and the number of output ports is m (m ≧ 1). This is an n × m optical switch. In the optical propagation device, each light source is optically coupled to each input port, and each optical waveguide is optically coupled to each output port. Each input port is switched in a fixed cycle by the switching control device, each input port is optically coupled to each optical waveguide in each cycle, and the light emitted from the light source is propagated to the optical waveguide.

According to such a configuration, it is possible to reduce the manufacturing cost by collecting the light emitted from a plurality of light sources by using a MEMS optical switch instead of the coupler.

The present invention may have the following configuration as a second feature. That is, in the present invention, the MEMS optical switch includes a mirror, the angle of the mirror is controlled by applying a voltage, and each input port is optically coupled to each optical waveguide at regular intervals. Then, in the present invention, in the process of transitioning from the initial voltage Vp (V) to the set voltage Vs (V) that controls the angle of the mirror to a desired set value angle, the voltage exceeds Vp (V) and is less than Vs (V). A voltage V'(V) is applied to the mirror, and Vs (V) may be applied when the mirror swings to a set value angle by applying V'(V).

According to the configuration having such a second feature, it is possible to prevent the resonance of the mirror, so that ringing to the optical output of the emitted light propagating in the optical waveguide is prevented. Therefore, the switching time for switching the input port is shortened, and high-speed switching operation becomes possible. By enabling high-speed switching operation, it has become possible to prevent light flicker recognition in applications that require visual recognition by the naked eye of humans.

The present invention may have the following configuration as a third feature. That is, in the present invention, while each input port is optically coupled to each optical waveguide at regular intervals, the switching control device transfers the emitted light to the optical waveguide during the propagation time of the emitted light to each optical waveguide. The duty ratio of the on / off time of propagation of is may be changed.

According to the configuration shown in this third feature, the light emitted from the optical waveguide to the outside can be adjusted to the emitted light having an arbitrary hue, lightness, and saturation according to the change value of the duty ratio. Will be.

The present invention may have the following configuration as a fourth feature. That is, in the present invention, the optical waveguide may be formed of an optical fiber.

According to the configuration shown in the fourth feature, it is possible to emit light from the end face of the optical fiber.

The present invention may have the following configuration as a fifth feature. That is, in the present invention, the optical fiber may be formed of a light diffusion fiber while having the fourth feature.

According to the configuration shown in this fifth feature, it is possible to radiate light over the side surface of the optical fiber.

Further, by forming the optical waveguide with an optical fiber, it is possible to obtain an effect that the optical waveguide can be installed in an arbitrary shape due to the flexibility of the optical fiber. Such an effect can be obtained even when the optical fiber is an optical diffusion fiber.

In the present invention, the optical fiber is defined as a fiber that propagates light and emits light from an end face to emit light. Further, in the present invention, the optical diffusion fiber is defined as an optical fiber that emits light from a side surface.

The present invention may have the following configuration as a sixth feature. That is, in the present invention, the period over all the input ports may be set to 15 msec.

According to the configuration shown in this sixth feature, it is possible to prevent the recognition of flicker of emitted light by the human naked eye.

The present invention may have the following configuration as a seventh feature. That is, the present invention may be an optical display device in which the light source includes three individual light sources for each of RGB.

According to the configuration shown in the seventh feature, it is possible to realize an optical display device capable of arbitrarily adjusting the hue, lightness, and saturation of full color.

The present invention may have the following configuration as an eighth feature. That is, the present invention may be an optical propagation device having the configuration shown in the seventh feature and having a resolution of 256 divisions in which the duty ratio is changed at regular intervals.

According to the configuration shown in the eighth feature, it is possible to form an optical display device capable of displaying with emitted light of true color (about 16.77 million colors).

The present invention may have the following configuration as a ninth feature. That is, the present invention comprises a light propagating device having the first feature or a light propagating device having the first feature and having at least one or more features from the second feature to the eighth feature. It may be a display device.

According to the configuration shown in the ninth feature, it is possible to realize an optical display device having each effect described in the eighth feature from the first feature.

The present invention may have the following configuration as a tenth feature. That is, the present invention comprises a light propagating device having the first feature or a light propagating device having the first feature and at least one or more features from the second feature to the seventh feature. It may be a device.

According to the configuration shown in the tenth feature, it is possible to realize a lighting device having each of the above-mentioned effects described in the first feature to the seventh feature.

Hereinafter, the light propagation apparatus according to the embodiment of the present invention will be described with reference to FIGS. 1 to 8. The light propagation device 1 of the first embodiment is formed of at least a plurality of light sources 2, a MEMS optical switch 3, a switching control device 4, and an optical waveguide 5.

The light propagation device 1 includes three individual light sources 2a, 2b, and 2c as the light source 2. The light sources 2a, 2b, and 2c emit light of a color corresponding to RGB (Red, Green, Blue), respectively. Therefore, the wavelength region of the light emitted from the light source 2 is 445 nm or more and 700 nm or less. A semiconductor laser is used as an example for each of the light sources 2a, 2b, and 2c of the light propagation apparatus 1, and an LD (Laser Diode) is used. The light emitted from each of the light sources 2a, 2b, and 2c has a fixed output. Therefore, the wavelength region of the light emitted from the red light source 2a is fixed to one wavelength of 635 nm or more and 690 nm or less. The wavelength region of the light emitted from the green light source 2b is fixed to one wavelength of 520 nm or more and 532 nm or less. Further, the wavelength region of the light output from the blue light source 2c is fixed to any one of 445 nm to 450 nm, 460 nm, and 473 nm.

A light emitting diode (LED) may be used for each of the light sources 2a, 2b, and 2c, and the wavelength region of the light emitted from the red light source 2a when the LED is used is fixed to one wavelength of 650 nm or more and 700 nm or less. Will be done. Further, the wavelength region of the light emitted from the green light source 2b is fixed to one wavelength of 505 nm or more and 560 nm or less. Further, the wavelength region of the light output from the blue light source 2c is fixed to one wavelength of 450 nm or more and 470 nm or less.

Since the light emitted from each of the light sources 2a, 2b, and 2c has a fixed output, variable control of the light output becomes unnecessary, and the control device of the light source 2 can be omitted.

One ends of cables 6a, 6b, and 6c having optical fibers are optically coupled to the emission sides of the light sources 2a, 2b, and 2c, respectively. Further, the other ends of the cables 6a, 6b, 6c are optically coupled to the three input ports 11 (11a, 11b, 11c) of the MEMS optical switch 3, respectively. An optical waveguide other than an optical fiber may be used instead of the cables 6a, 6b, and 6c. The light emitted from the light sources 2a, 2b, and 2c propagates in the cables 6a, 6b, and 6c, and is incident on the input ports 11a, 11b, and 11c of the MEMS optical switch 3.

In the MEMS optical switch 3 of the optical propagation device 1, the number of input ports is n = 3 (n ≧ 2), the number of output ports is m = 1 (m ≧ 1), and the selection pattern of the number of ports is n × m. (Street) An existing n × m (3 × 1 in the example of FIG. 1) optical switch. One end of both ends of each cable 6a, 6b, 6c is coupled to the exit side of each light source 2a, 2b, 2c, and the other end of each cable 6a, 6b, 6c is the input port 11a, 11b of the MEMS optical switch 3. , 11c, so that the light sources 2a, 2b, and 2c are optically coupled to the input ports 11a, 11b, and 11c of the MEMS optical switch 3. Further, an off port 13 is provided alongside the input ports 11a, 11b, and 11c, and FIG. 1 shows a state in which the MEMS optical switch 3 is switched to the off port 13.

On the other hand, an optical waveguide 5 is optically coupled to each output port 12. In the example shown in FIG. 1 and the like, since the MEMS optical switch 3 has one output port 12, one optical waveguide 5 is optically coupled to one output port in the optical propagation device 1. An optical fiber or a light diffusion fiber is used as an example of the optical waveguide 5.

Further, the switching control device 4 is electrically connected to the MEMS optical switch 3 via wiring. The switching control device 4 controls the switching operation of the MEMS optical switch 3 so as to select at least one of the plurality of input ports 11a, 11b, 11c. According to this control, the MEMS optical switch 3 selects one of a plurality of light sources 2a, 2b, and 2c, and causes light incident from each of the selected light sources 2a, 2b, and 2c to be incident on the optical waveguide 5. That is, the input ports 11a, 11b, and 11c are optically coupled to the optical waveguide 5 according to the control by the switching control device 4, and the light emitted from the light sources 2a, 2b, and 2c is propagated to the optical waveguide 5.

The switching control device 4 switches the input ports 11a, 11b, 11c of the MEMS optical switch 3 in a fixed cycle, and optically couples the input ports 11a, 11b, 11c to the optical waveguide 5 in each cycle. , The light emitted from the light sources 2a, 2b, and 2c propagates to the optical waveguide 5. Therefore, each input port 11a, 11b, 11c is optically coupled to the optical waveguide 5 at regular intervals.

The cycle for switching the input ports 11a, 11b, 11c of the MEMS optical switch 3 can be set according to the field of use of the optical propagation device 1. Since the light propagation device 1 uses a light source 2 in the visible light wavelength region (445 nm or more and 700 nm or less), as an example of the field of use, an optical display device or a lighting device that needs to detect the emitted light with the naked eye of a human being. Can be mentioned. In such fields of use, in order to prevent the recognition of flicker of emitted light by the human eye, the period Ta over all input ports 11a, 11b, 11c exceeds 60 Hz (66.7 Hz) as shown in FIGS. 5 to 7. (Period 15 msec)) is preferable. Further, the period Tb for switching the input ports 11a, 11b, 11c of the MEMS optical switch 3 is Ta / the number of input ports (Tb = 5 msec (5 msec) in the optical propagation device 1).

The MEMS optical switch 3 is provided with a mirror, and the mirror angle is controlled by applying a voltage, and the mirror angle change pattern is controlled to be a periodic pattern at the fixed cycle. The direction of the reflected light is changed, and the input ports 11a, 11b, and 11c are periodically optically coupled to the optical waveguide 5. From the initial voltage Vp (V), a set voltage Vs (V) that controls the angle of the mirror to a desired set value angle is applied, but the mirror has a mechanical resonance frequency characteristic. Therefore, when the input voltage value is directly transitioned from Vp (V) to Vs (V), the mirror resonates, and in the process of damping vibration from the resonance swing width and converging to the set value angle, as shown in FIG. Ringing occurs in the optical output of the emitted light propagated through the waveguide 5. Therefore, the switching time for switching between the input ports 11a, 11b, and 11c becomes redundant.

Therefore, in the present invention, the voltage V'(V) which is more than Vp (V) and less than Vs (V) is applied to the mirror during the transition from Vp (V) to Vs (V). The voltage value of V'(V) is a voltage value at which the maximum swing width of the mirror becomes the set value angle when the V'(V) is applied to the mirror. By applying V'(V) during the transition and swinging the mirror to the set value angle in advance, and applying Vs (V) when the mirror swings to the set value angle, the mirror is directly moved from the initial state. The applicant has found by verification that resonance at a set value angle is prevented. That is, in a state where the mirror swings to a predetermined value angle by applying V'(V), the mirror tries to swing to a predetermined value angle by applying Vs (V), so that resonance of the mirror can be prevented.

Since it is possible to prevent the resonance of the mirror, ringing to the optical output of the emitted light propagating to the optical waveguide 5 is prevented as shown in FIG. Therefore, the switching time for switching the input port 11 is shortened, and high-speed switching operation becomes possible. By enabling high-speed switching operation, each input port 11a, 11b, 11c of the MEMS optical switch 3 can be switched, for example, with a period Tb = 5 msec, which is called an optical display device or a lighting device. It has become possible to prevent light flicker recognition in applications that require visual recognition by the naked eye.

Further, depending on the resonance frequency of the mirror (for example, when the resonance frequency is 1 kHz), a high-order low-pass filter or notch filter becomes unnecessary. Further, when the circuit for driving the MEMS optical switch 3 is an analog circuit, it is not necessary to configure a digital filter in the circuit for driving the MEMS optical switch 3. Therefore, the affinity between the MEMS optical switch 3 and the analog circuit for driving the MEMS optical switch 3 is good, and it is possible to suppress the drive circuit from becoming complicated.

The switching control device 4 is formed by a logic circuit. The control circuit is composed of, for example, a frequency dividing circuit by a flip-flop counter of a logic circuit. The off time in the period Tb is set by logical decoding according to the color designation of RGB three colors with a clock (Clock: for example 3.2 kHz) of a predetermined frequency, and the emitted light is propagated to the optical waveguide 5 over the period Tb. Change the duty ratio of the on / off time. The switching control device 4 switches the mirror from the off port 13 to the input port 11. Therefore, the switching control device 4 implements a pattern in which the input ports 11a, 11b, and 11c are sequentially optically coupled to the optical waveguide 5 at a constant period Tb, and is turned on / on in the propagation time of the emitted light to the optical waveguide 5. The off-time duty ratio is changed.

As shown by an arrow in FIG. 2, when the input port 11a is connected from the red light source 2a and the blue light source 2c is switched to, the light source 2a is switched again. By switching the input ports 11a, 11b, and 11c in the period Ta = 15 msec and Tb = 5 msec, the human naked eye does not feel the flicker in the light emitted from the optical waveguide 5. Therefore, the light emitted from the optical waveguide 5 to the outside is perceived by the naked eye as the emitted light having an arbitrary hue, lightness, and saturation according to the change value of the duty ratio.

FIG. 5 shows an example of adjusting the hue when the duty ratio is changed. In the pattern (a) of FIG. 5, the duty ratio in the period Tb at each input port 11a, 11b, 11c is set to 50%, and the on-time of each RGB light source 2a, 2b, 2c is made uniform, and white light is used. Is shown as an example of emitting light from the optical wave guide 5. The part with hatching indicates the off time, and the part without hatching indicates the on time.

In the pattern (b) of FIG. 5, only the R (red) light source 2a has an on-time of 100% (duty ratio 100%) in the period Tb, and the remaining G (green) light source 2b and B (blue) light source 2c have a period Tb. An example is shown in which red light is emitted from the optical waveguide 5 with the on-time in the inside set to 0% (duty ratio 0%).

In the pattern (c) of FIG. 5, the on-time of the R (red) light source 2a in the period Tb is 100% (duty ratio 100%), and the on-time of the G (green) light source 2b in the period Tb is 50%. An example is shown in which orange light is emitted from the optical waveguide 5 with (duty ratio 50%) and the on-time of the remaining B (blue) light source 2c in the period Tb being 0% (duty ratio 0%).

Of course, the adjustment of the hue is not limited to the example of FIG. 5, and the duty ratios of the RGB light sources 2a, 2b, and 2c can be adjusted within the range of 0% to 100%.

FIG. 6 shows an example of adjusting the brightness when the duty ratio is changed. In the pattern (a) of FIG. 6, the duty ratio in the period Tb at each input port is set to 50%, the on-time of each of the RGB light sources 2a, 2b, and 2c is made uniform, and the brightness of white light is 50%. Is shown as an example of emitting light from the optical wave guide 5.

In the pattern (b) of FIG. 6, the on-time in the period Tb at each input port is set to 100% (duty ratio 100%), and the on-time of each of the RGB light sources 2a, 2b, and 2c is made uniform. An example of emitting white light having a brightness of 100% from the optical waveguide 5 is shown.

Of course, the adjustment of the brightness is not limited to the example of the white light shown in FIG. 6, and the duty ratios of the RGB light sources 2a, 2b, and 2c can be adjusted within the range of 0% to 100%.

FIG. 7 shows an example of adjusting the saturation according to the duty ratio change. In the pattern (a) of FIG. 7, the on-time of the R (red) light source 2a in the period Tb is 100% (duty ratio 100%), and the on-time of the G (green) light source 2b in the period Tb is 50. % (Duty ratio 50%), and the on-time in the period Tb of the remaining B (blue) light source 2c is 0% (duty ratio 0%), and an example of emitting orange light from the optical waveguide 5 is shown.

In the pattern (b) of FIG. 7, the on-time of the R (red) light source 2a in the period Tb is 60% (duty ratio 60%), and the on-time of the G (green) light source 2b in the period Tb is 30%. As (duty ratio 30%) (the on-time of the remaining B (blue) light source 2c in the period Tb is 0% (duty ratio 0%) and does not change), the orange color formed by the pattern shown in FIG. 7 (a). An example is shown in which orange light, which is less saturated than light, is emitted from the optical waveguide 5.

Of course, the adjustment of saturation is not limited to the example of orange light shown in FIG. 7, and can be adjusted within the range of 0% to 100% of each duty ratio of the RGB light sources 2a, 2b, and 2c.

The optical fiber used as an example of the optical waveguide 5 is composed of a core and a clad having a refractive index lower than the refractive index of the core, and has a structure in which the core is surrounded by the clad. Further, as the optical fiber used as an example of the optical waveguide 5, a single mode type optical fiber having an isotropic refractive index distribution can be used. As the single mode type optical fiber, for example, a quartz optical fiber or a plastic optical fiber can be used. By using such an optical fiber in the optical propagation device 1, it becomes possible to emit light from the end face of the optical fiber, and a desired optical display device or lighting device can be provided.

Further, examples of the optical diffusion fiber used as an example of the optical waveguide 5 include those having the structures shown in FIGS. 8a and 8b. FIG. 8a is a partial side view of a light diffusing fiber having a plurality of voids in the core of a light diffusing fiber having a central axis (“center line”) 5a (hereinafter, referred to as “light diffusing fiber 5” as necessary). be. FIG. 8b is a cross-sectional view of the light diffusion fiber 5 when viewed from the cut surface AA direction of FIG. 8a. The light diffusion fiber 5 may be, for example, any one of various types of optical fibers having a nanosize fiber region having a periodic or aperiodic nanosize structure 5c (eg, voids). In the embodiments illustrated in FIGS. 8a and 8b, the light diffusion fiber 5 has a core 7 divided into three parts or regions. These core regions are the solid central portion 7a, the nanostructured ring portion (inner annular core region) 7b, and the outer solid portion 7c surrounding the inner annular core region 7b.

The clad 8 surrounds the core 7. The clad 8 may have a low index of refraction to provide a high numerical aperture (NA). The clad 8 may be a low refractive index polymer such as UV or thermosetting fluoroacrylate or silicon.

The coating 9 is designed to improve the distribution and / or properties of light passing through the clad 8 from the core 7. The outer surface of the clad 8 or the outer surface of the coating 9 represents the side surface 5b of the light diffusion fiber 5, and the light propagating through the light diffusion fiber 5 is emitted from the side surface 5b by scattering to the outside.

The inner annular 7b of the core 7 contains a glass substrate (“glass”) 10 in which a plurality of nano-sized structures (eg, “voids”) 5c are located. The nano-sized structure 5c may employ a void structure, as illustrated in detail in the inset to illustrate a partially enlarged state of the inner annular core region 7b shown in FIG. 8b, inside the core 7. In the annular core region 7b, a plurality of nano-sized structures (eg, "voids") 5c are aperiodically arranged therein. As another example, the voids 5c may be periodically arranged like a photonic crystal optical fiber, and the voids 5c are typically about 1 × 10 ^-8 m to 1 × 10 ^-5 m. Has a diameter between. The voids 5c may be arranged aperiodically, i.e. randomly. Glass 10 is fluorine-doped silica or undoped pure silica.

The nano-sized structure 5c scatters light from the core 7 toward the outer surface of the light diffusion fiber 5. Therefore, light is scattered and radiated from the side surface 5b along the direction of the central axis 5a of the light diffusion fiber 5 over the length of the side surface 5b. This scattered light makes it possible to provide a desired light display device or lighting device. It is desirable that the light diffusion fiber 5 emits uniformly scattered light over its length.

By using such an optical fiber or an optical diffusion fiber, it is possible to install the optical waveguide 5 in an arbitrary shape due to the flexibility of the optical fiber. In addition, other optical waveguides may be used instead of the optical fiber and the optical diffusion fiber.

The optical waveguide 5 may be optically coupled directly to the output port of the MEMS optical switch 3, or may be optically coupled via a separate optical fiber for connection.

Further, by dividing the resolution for changing the duty ratio at regular intervals of Tb into 256, it is possible to form an optical display device capable of displaying with emitted light of true color (about 16.77 million colors). Is possible. In order to obtain 24-bit (8 bits x RGB) true color, it is necessary to set the resolution of duty ratio change to 8 bits. The minimum duty ratio control time at this time is 5 msec / 256 = about 20 μsec. However, although it is shortened as described above, since there is a switching time for switching the input ports 11a, 11b, 11c in the MEMS optical switch 3, the duty ratio control becomes invalid within the switching time. Therefore, the minimum duty ratio control time for actually controlling and displaying 16.77 million colors is derived by {5 msec- (switching time)} / 256. Assuming that the shortened switching time is 0.5 msec, the minimum duty ratio control time for actually controlling 16.77 million colors is calculated as (5 msec-0.5 msec) / 256, which is about 17. It will be 5 μs.

As described above, according to the optical propagation apparatus 1 of the present invention, the MEMS optical switch 3 is used instead of the coupler to collect the light emitted from the plurality of light sources 2a, 2b, and 2c, thereby reducing the manufacturing cost. Is possible.

In the light propagation apparatus 1 of the present embodiment, a mode in which three individual light sources 2a, 2b, and 2c are provided for each RGB as the light source 2 has been described, but the present invention is not limited to this embodiment, and the present invention is not limited to this embodiment, and two or less light sources 2 are individually provided. It may be formed by the light source of. However, in order to realize the input port switching operation based on the periods Ta and Tb, the light source 2 is formed by at least two individual light sources.

However, by forming the light source 2 with three individual light sources for each RGB, it becomes possible to realize a light propagation device, an optical display device, or a lighting device capable of arbitrarily adjusting the hue, brightness, and saturation of full color, which is the most desirable. ..

Further, in the optical propagation device 1, the number of output ports 12 installed is 1, and one optical waveguide 5 is provided. However, the number of output ports 12 installed is 2 or more, and a plurality of optical waveguides are provided. Is also good. Then, the hue, brightness, and saturation of the emitted light propagating from each output port 12 to each optical waveguide may be arbitrarily changed according to the above embodiment.

The output (power) value from the light source 2 may be arbitrarily set to a required level in consideration of the coupling efficiency with the input port 11 and the optical waveguide 5 and the insertion loss.

In the present invention, when the hue of the emitted light is deviated due to the difference in insertion loss (IL) due to the wavelength dependence of the mirror reflectance of the MEMS optical switch, the correction duty ratio control is performed for each light source according to the difference in IL. You may go. When there are a plurality of light sources, the duty ratios of the other light sources may be corrected with one of the light sources as a reference. For example, the IL difference is red (R) -2dB, green (G) -5dB, blue (B) -8dB, and the correction duty ratio is controlled. When the B light source is used as a reference, R is 25% and G is 50% duty ratio. Then, you can check the operation. Alternatively, white light may be emitted to the optical waveguide without correction and observed with the naked eye, and the duty ratio may be corrected only for a specific light source depending on which light source has a strong hue visually.

Examples of the present invention will be described below, but the present invention is not limited to the following examples.

In this embodiment, the light source includes three individual LD light sources for each RGB. Each individual light source had a fixed output of 100% (80 mW). The wavelength of the light source composed of the red LD was set to 638 nm, the light source composed of the green LD was set to 520 nm, and the light source composed of the blue LD was set to 450 nm. Therefore, the number n of input ports of the MEMS optical switch is set to 3. The number m of one output port was set to 1.

In the mirror of the MEMS optical switch of this embodiment, the mirror swings once (degree) when the initial voltage Vp = 0 (V) to 25 (V) is applied. The 1 degree was set as the set value angle, and the maximum change in the resonance angle was ± 0.5 degrees. At this time, the set voltage is 25 (V). Then, it was observed that when the set voltage 25 (V) was applied directly from Vp, a switching time of 20 msec was required. The reason is that when a direct pulse drive is performed, a voltage signal having a wide frequency band due to harmonics is obtained, and resonance occurs due to the resonance frequency component (about 1 kHz).

In this embodiment, when V'(V) is applied to the mirror, it is driven by a step voltage. V'is a voltage value such that the maximum deflection angle of the mirror is a set value angle of 1 degree (degree), and is set to 12 (V). When this V'(12 (V)) voltage is applied to the mirror and the mirror swings to the maximum once, the set voltage 25 (V) is applied to reduce the switching time of the input port by 0.5 m. It was observed that it could be shortened to seconds.

The switching control device is formed by a logic circuit, and the control circuit is composed of a frequency dividing circuit by a flip-flop counter of the logic circuit. The cycle Ta over all input ports was set to 15 msec (66.7 Hz), and the cycle Tb for switching each input port of the MEMS optical switch was set to 5 msec. By changing the duty ratio of the on / off time, the hue, lightness, and saturation of the emitted light emitted from the optical waveguide were adjusted. The resolution for changing the duty ratio was set to 4 bits.

The clock (Clock) set the off time by logical decoding according to the color specification at 3.2 kHz, and the MEMS optical switch was controlled by the switching control device.

The 3 × 1 MEMS optical switch has an insertion loss (IL) difference due to the wavelength dependence of the mirror reflectance. However, in this embodiment, a MEMS optical switch using a mirror having a small wavelength dependence was used (Δ0.5 dB). This prevented the hue of the emitted light from shifting, and made it unnecessary to correct the duty ratio.

As the optical waveguide, a light diffusion fiber (numerical aperture (> 0.5), core diameter 170 μm, outer diameter 230 μm) was used, and the hue, brightness, and saturation of the scattered light from the side surface of the fiber were observed.

In this embodiment, 13 colors were reproduced by changing the duty ratio as shown in Table 1 below. The duty ratios of each of the RGB light sources in Table 1 indicate the ratio of the on-time within the period Tb (“R-duty” indicates the duty ratio of the R light source, hereinafter G. The same applies to the light source and the B light source). In Table 1, blue-green refers to Cyanogen Green, and patina refers to Cyanogen Blue.

As a result of observing the hues of the 13 colors of emitted light emitted from the light diffusion fiber, it was confirmed that visually good results were obtained.

1 Optical propagation device 2, 2a, 2b, 2c Light source 3 MEMS optical switch 4 Switching control device 5 Optical waveguide, optical diffusion fiber 5a Central axis of optical diffusion fiber 5b Side surface of optical diffusion fiber 5c Nano-sized structure of optical diffusion fiber (void) )
6a, 6b, 6c cable 7 Optical diffusion fiber core 7a Solid center part 7b Inner annular core region 7c Outer solid part 8 Optical diffusion fiber clad 9 Optical diffusion fiber coating 10 Glass substrate 11, 11a, 11b, 11c Input Port 12 Output port 13 Off port

Claims (9)

The optical propagation device is composed of at least a plurality of light sources, a MEMS optical switch, a switching control device, and an optical waveguide.
Each light source has a fixed output, and the wavelength range of the emitted light is 445 nm or more and 700 nm or less.
The MEMS optical switch is an n × m optical switch in which the number of input ports is n (n ≧ 2) and the number of output ports is m (m ≧ 1).
Each light source is optically coupled to each input port, and each optical waveguide is optically coupled to each output port.
Each input port is switched in a fixed cycle by the switching control device, each input port is optically coupled to each optical waveguide in each cycle, and the emitted light from the light source is propagated to the optical waveguide.
The MEMS optical switch has a mirror and is equipped with a mirror.
The angle of the mirror is controlled by applying voltage,
Each of the input ports is optically coupled to each of the optical waveguides at regular intervals.
During the transition from the initial voltage Vp (V) to the set voltage Vs (V) that controls the angle of the mirror to the desired set value angle, the voltage V'(V) is more than Vp (V) and less than Vs (V). ) Is applied to the mirror,
An optical propagation device in which Vs (V) is applied when the mirror swings to a set value angle by applying V'(V) . While each of the input ports is optically coupled to each of the optical waveguides at regular intervals,
The light propagation according to claim 1, wherein the switching control device changes the duty ratio of the on / off time of propagation of the emitted light to the optical waveguide in the propagation time of the emitted light to each optical waveguide. Device. The optical propagation apparatus according to claim 1 or 2, wherein the optical waveguide is an optical fiber. The optical propagation apparatus according to claim 3, wherein the optical fiber is an optical diffusion fiber. The optical propagation apparatus according to any one of claims 1 to 4, wherein the period over all the input ports is 15 msec. The light propagation apparatus according to any one of claims 1 to 5, wherein the light source includes three individual light sources for each of RGB. The light propagation apparatus according to claim 2, wherein the light source includes three individual light sources for each of RGB, and the resolution at which the duty ratio is changed at regular intervals is 256 divisions. An optical display device including the light propagation device according to any one of claims 1 to 7. A lighting device including the light propagation device according to any one of claims 1 to 6.

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