JP7703953B2 - Optical Switch - Google Patents

Description

The present invention relates to an optical switch.

Optical switches that use light to switch between on and off are used in a variety of technical fields.

Patent No. 6256966

There is a demand for optical switches that can be switched on and off quickly.

The present invention provides a first wire grid polarizer including a first transparent substrate and a plurality of first metal wires extending in a first direction along a surface of the first transparent substrate and arranged at predetermined intervals in a second direction along the surface of the first transparent substrate, the first metal wires being orthogonal to the first direction; a second wire grid polarizer disposed to face the first wire grid polarizer and including a second transparent substrate and a plurality of second metal wires extending in the first direction along the surface of the second transparent substrate and orthogonal to the first direction and arranged at predetermined intervals in the second direction along the surface of the second transparent substrate; and a third wire grid polarizer extending in the second direction along the surface of the third transparent substrate and arranged at predetermined intervals in the second direction. the third wire grid polarizer having a plurality of third metal wires arranged at predetermined intervals in the first direction along a surface of the third transparent substrate and perpendicular to the second direction; a fourth wire grid polarizer arranged so as to face the third wire grid polarizer and having a plurality of fourth metal wires on a fourth transparent substrate, the fourth wire grid polarizer extending in the second direction along the surface of the fourth transparent substrate and perpendicular to the second direction and arranged at predetermined intervals in the first direction along the surface of the fourth transparent substrate; and a slide drive unit sliding the first or second wire grid polarizer in the second direction and sliding the third or fourth wire grid polarizer in the first direction.
In the above-mentioned optical switch, when the slide drive unit is in a first state in which each second metal wire in the plurality of second metal wires is positioned in the center of the spacing between two adjacent first metal wires in the plurality of first metal wires, the first wire grid polarizer and the second wire grid polarizer block the second polarized light in incident light having a predetermined wavelength band that includes a first polarized light and a second polarized light and allows the first polarized light to exit from the second transparent substrate.
In the above optical switch, when the slide drive unit positions each of the second metal wires at the same position in the second direction of each of the multiple first metal wires to place each of the first metal wires facing each of the second metal wires, the first wire grid polarizer and the second wire grid polarizer emit the first polarized light and the second polarized light of the incident light from the second transparent substrate.
In the above optical switch, the slide drive unit sets each of the plurality of fourth metal wires in a third state in which it is positioned at the center of the spacing between two adjacent third metal wires in the plurality of third metal wires, and when the first polarized light is incident on the third transparent substrate as incident light, the third wire grid polarizer and the fourth wire grid polarizer block the first polarized light so as to prevent the first polarized light from exiting the fourth transparent substrate.
In the above optical switch, the slide drive unit positions each of the fourth metal wires at the same position in the first direction of each of the multiple third metal wires to place each of the third metal wires facing each other in a fourth state, and when the first polarized light and the second polarized light are incident on the third transparent substrate as incident light, the third wire grid polarizer and the fourth wire grid polarizer emit the first polarized light and the second polarized light from the fourth transparent substrate.
The optical switch further includes a slide controller that switches between an OFF state in which light of the predetermined wavelength band in the incident light incident on the first transparent substrate is not emitted from the fourth transparent substrate by controlling the slide driver to set the first wire grid polarizer and the second wire grid polarizer in the first state and the third wire grid polarizer and the fourth wire grid polarizer in the third state, and an ON state in which light of the predetermined wavelength band in the incident light incident on the first transparent substrate is emitted from the fourth transparent substrate by controlling the slide driver to set the first wire grid polarizer and the second wire grid polarizer in the second state and the third wire grid polarizer and the fourth wire grid polarizer in the fourth state.

The optical switch of the present invention can be switched on and off at high speed.

FIG. 1 illustrates a configuration of an optical switch according to an embodiment. 2 is a perspective view illustrating first and second wire grid polarizers in an optical switch according to an embodiment. FIG. 13 is a perspective view showing third and fourth wire grid polarizers in the optical switch of the embodiment. FIG. 1A and 1B are diagrams illustrating the functions of the first and second wire grid polarizers. 1A is a diagram showing the positional relationship between metal wires and the state of emitted light from the second wire grid polarizer when the first and second wire grid polarizers are in State 1. FIG. 13A and 13B are diagrams showing the positional relationship between the metal wires and the state of light emitted from the second wire grid polarizer when the first and second wire grid polarizers are in State 2. 1 is a characteristic diagram showing the relationship between wavelength and the proportion of horizontal polarization when the first and second wire grid polarizers are in states 1 and 2. FIG. FIG . 13 is a diagram showing the positional relationship of the metal wires and the state of emitted light from the fourth wire grid polarizer when the first and second wire grid polarizers are in state 1 and the third and fourth wire grid polarizers are in state 3 . FIG . 13 is a diagram showing the positional relationship of the metal wires and the state of emitted light from the fourth wire grid polarizer when the first and second wire grid polarizers are in state 2 and the third and fourth wire grid polarizers are in state 4 . 4A and 4B are characteristic diagrams showing the relationship between wavelength and the proportion of transmitted light, illustrating the off and on states of visible light by an optical switch according to an embodiment. FIG. 1 is a diagram showing an advanced configuration of the optical switch according to an embodiment. FIG. 9 shows the positional relationship of the metal wires and the state of emitted light from the fourth wire grid polarizer when the first and second wire grid polarizers are in state 1 and the third and fourth wire grid polarizers are in state 3, and the third and fourth wire grid polarizers are rotated 90 degrees with respect to the first and second wire grid polarizers. FIG. 9 shows the positional relationship of the metal wires and the state of emitted light from the fourth wire grid polarizer when the first and second wire grid polarizers are in state 1 , the third and fourth wire grid polarizers are in state 3, and the third and fourth wire grid polarizers are rotated 0 degrees relative to the first and second wire grid polarizers. 13 is a characteristic diagram showing the relationship between the rotation angles of the third and fourth wire grid polarizers and the proportion of transmitted light that is output as light emitted from the fourth wire grid polarizer. FIG. FIG. 2 is a diagram showing a configuration of a polarizer according to an embodiment. FIG. 2 is a diagram illustrating a configuration of an optical filter according to an embodiment. FIG. 13 is a diagram showing the first and second wire grid polarizers being continuously changed between state 1 and state 2. FIG. 13 is a characteristic diagram showing the relationship between wavelength and proportion of transmitted light when the first and second wire grid polarizers are continuously changed between state 1 and state 2, and the third and fourth wire grid polarizers are continuously changed between state 3 and state 4 . FIG. 1 illustrates a house having a window according to an embodiment installed therein. FIG. 2 is a diagram showing a window configuration according to an embodiment. FIG. 1 is a diagram illustrating a configuration of a head mounted display according to an embodiment.

The optical switch, polarizer, optical filter, window, and head-mounted display of each embodiment will be described below with reference to the attached drawings.

<Optical switch>
1 to 11 disclose an optical switch that can be switched on and off at high speed. FIG. 1 shows an optical switch 101 according to one embodiment. The optical switch 101 includes first to fourth wire grid polarizers 11 to 14. The first wire grid polarizer 11 and the second wire grid polarizer 12 are arranged close to each other but do not contact each other, constituting a first pair of wire grid polarizers. The third wire grid polarizer 13 and the fourth wire grid polarizer 14 are arranged close to each other but do not contact each other, constituting a second pair of wire grid polarizers.

The first wire grid polarizer 11 and the second wire grid polarizer 12 are formed by depositing a plurality of metal wires 11b and 12b of aluminum or the like at a predetermined interval on transparent substrates 11a and 12a such as glass substrates. If the transparent substrate 11a is the first transparent substrate, the transparent substrate 12a is the second transparent substrate, and if the metal wire 11b is the first metal wire, the metal wire 12b is the second metal wire. In order to bring the metal wire 11b of the first wire grid polarizer 11 and the metal wire 12b of the second wire grid polarizer 12 close to each other, the first wire grid polarizer 11 and the second wire grid polarizer 12 are arranged with the surfaces on which the metal wires 11b and 12b are provided facing each other.

As shown in the perspective view of FIG. 2, the metal wires 11b and 12b extend in the Y direction (first direction) along the surfaces of the transparent substrates 11a and 12a, respectively, and are arranged at a predetermined interval in the X direction (second direction) along the surfaces of the transparent substrates 11a and 12a. The X direction is the horizontal direction, and the Y direction is the vertical direction perpendicular to the X direction.

The third wire grid polarizer 13 and the fourth wire grid polarizer 14 are formed by depositing a plurality of metal wires 13b and 14b of aluminum or the like at a predetermined interval on transparent substrates 13a and 14a such as glass substrates. If the transparent substrate 13a is the third transparent substrate, the transparent substrate 14a is the fourth transparent substrate, and if the metal wire 13b is the third metal wire, the metal wire 14b is the fourth metal wire. In order to bring the metal wire 13b of the third wire grid polarizer 13 and the metal wire 14b of the fourth wire grid polarizer 14 close to each other, the third wire grid polarizer 13 and the fourth wire grid polarizer 14 are arranged with the surfaces on which the metal wires 13b and 14b are provided facing each other.

As shown in the perspective view of FIG. 3, the metal wires 13b and 14b extend in the X direction along the surfaces of the transparent substrates 13a and 14a, respectively, and are arranged at a predetermined interval in the Y direction along the surfaces of the transparent substrates 13a and 14a. That is, the first wire grid polarizer 11 and the second wire grid polarizer 12, and the third wire grid polarizer 13 and the fourth wire grid polarizer 14 are rotated by 90 degrees relative to each other.

The positional relationship between the first pair of wire grid polarizers consisting of the first wire grid polarizer 11 and the second wire grid polarizer 12 and the second pair of wire grid polarizers consisting of the third wire grid polarizer 13 and the fourth wire grid polarizer 14 may be reversed. When the positional relationship is reversed, the X direction is the first direction and the Y direction is the second direction.

The optical switch 101 further includes a slide control unit 15, and slide drive units 16 and 17 controlled by the slide control unit 15. The slide drive unit 16 drives the second wire grid polarizer 12 to slide in the X direction. The slide drive unit 17 drives the fourth wire grid polarizer 14 to slide in the Y direction. The slide drive units 16 and 17 slide the second wire grid polarizer 12 and the fourth wire grid polarizer 14 by a slide mechanism using an electric field or a magnetic field, respectively.

The slide control unit 15 controls the slide driving units 16 and 17 in response to the input slide instruction signal.

The optical switch 101 may be configured such that the slide drive unit 16 drives the first wire grid polarizer 11 to slide in the X direction, and the slide drive unit 17 drives the third wire grid polarizer 13 to slide in the Y direction.

Figure 4 shows how the first wire grid polarizer 11 and the second wire grid polarizer 12 act on incident visible light Lin. Visible light has a wavelength of 380 nm to 760 nm. Visible light with a wavelength of 380 nm to 760 nm is an example of light in a specified wavelength band.

The distance between two adjacent metal wires 11b is approximately 380 nm, and the distance between two adjacent metal wires 12b is also approximately 380 nm. Each metal wire 12b is located at the center of the two metal wires 11b in the X direction. The distance d between metal wires 11b and 12b is sufficiently smaller than the distance between metal wires 11b and 12b in the X direction, which is 190 nm. Metal wires 11b and 12b have a predetermined distance so that they do not come into contact even when metal wires 11b and 12b are placed opposite each other.

The incident light Lin includes horizontally polarized light HPL indicated by solid lines and vertically polarized light VPL indicated by dashed lines. When the first wire grid polarizer 11 and the second wire grid polarizer 12 are arranged so that each metal wire 12b extending in the Y direction is located in the center of two adjacent metal wires 11b, the vertically polarized light VPL is mostly blocked by the first wire grid polarizer 11 and the second wire grid polarizer 12. Therefore, the output light L12, which is mostly horizontally polarized light HPL, is emitted downstream of the first wire grid polarizer 11 and the second wire grid polarizer 12.

As shown in Fig. 5A, when the second wire grid polarizer 12 is not slid by the slide driving unit 16, each metal wire 12b is located at the center of two adjacent metal wires 11b in the Y direction. The state shown in Fig. 5A is referred to as state 1 (first state) . When the first wire grid polarizer 11 and the second wire grid polarizer 12 are in state 1, as described in Fig. 4, when the incident light Lin including the horizontally polarized light HPL and the vertically polarized light VPL is incident on the first wire grid polarizer 11 and the second wire grid polarizer 12, the exit light L12 which is mostly horizontally polarized light HPL is emitted. In state 1, the amount of light is 1/2 or less.

As shown in Fig. 5B, the second wire grid polarizer 12 is slid by the slide driver 16 to position each metal wire 12b at the same position as each metal wire 11b in the X direction, so that each metal wire 11b faces each metal wire 12b. The state shown in Fig. 5B is State 2 (second state) . When the first wire grid polarizer 11 and the second wire grid polarizer 12 are in State 2, if incident light Lin including horizontally polarized light HPL and vertically polarized light VPL is incident on the first wire grid polarizer 11 and the second wire grid polarizer 12, the vertically polarized light VPL is not blocked by the first wire grid polarizer 11 and the second wire grid polarizer 12.

Therefore, in state 2, the second wire grid polarizer 12 emits output light L12' containing horizontally polarized light HPL and vertically polarized light VPL. However, the amount of light is reduced by the amount blocked by the metal wires 11b and 12b, to, for example, 89%.

Figure 6 shows the relationship between wavelength and the proportion of horizontally polarized HPL in states 1 and 2. In state 1, the distance in the X direction between metal wire 11b and metal wire 12b is 190 nm, so at wavelengths less than 380 nm, horizontally polarized HPL and vertically polarized VPL mostly pass through the first wire grid polarizer 11 and the second wire grid polarizer 12. At wavelengths of 380 nm or more, vertically polarized VPL cannot pass through the gap between metal wires 11b and 12b, and the proportion of horizontally polarized HPL increases sharply as the wavelength becomes longer.

In state 2, for wavelengths less than 760 nm, the horizontally polarized light HPL and the vertically polarized light VPL pass almost entirely through the first wire grid polarizer 11 and the second wire grid polarizer 12. For wavelengths of 760 nm or more, the vertically polarized light VPL cannot pass through the gaps between the metal wires 11b and 12b, and the proportion of horizontally polarized light HPL increases sharply as the wavelength becomes longer.

7A , each metal wire 14b is located at the center in the Y direction between two adjacent metal wires 13b when the fourth wire grid polarizer 14 is not slid by the slide driver 17. The first wire grid polarizer 11 and the second wire grid polarizer 12 are in State 1. The third wire grid polarizer 13 and the fourth wire grid polarizer 14 are in State 3 (third state) in which each metal wire 13b is located at the center in the Y direction between two adjacent metal wires 14b.

The third wire grid polarizer 13 and the fourth wire grid polarizer 14 are rotated 90 degrees relative to the first wire grid polarizer 11 and the second wire grid polarizer 12. Therefore, the horizontally polarized light HPL of the emitted light L12 from the first wire grid polarizer 11 and the second wire grid polarizer 12 becomes the vertically polarized light VPL for the third wire grid polarizer 13 and the fourth wire grid polarizer 14.

7A , the output light Lout from the third wire grid polarizer 13 and the fourth wire grid polarizer 14 drops sharply at wavelengths of 380 nm or more. That is, in FIG. 7A , the first wire grid polarizer 11 and the second wire grid polarizer 12 are in state 1 , and the third wire grid polarizer 13 and the fourth wire grid polarizer 14 are in state 3 , which is an off state that hardly transmits visible light.

7B , the fourth wire grid polarizer 14 is slid by the slide driver 17 so that each metal wire 14b is positioned at the same position in the Y direction as each metal wire 13b, and each metal wire 13b faces each metal wire 14b. The first wire grid polarizer 11 and the second wire grid polarizer 12 are in state 2. The third wire grid polarizer 13 and the fourth wire grid polarizer 14 are in state 4 (fourth state) in which each metal wire 13b and each metal wire 14b are positioned at the same position in the Y direction.

When the output light L12' containing horizontally polarized light HPL and vertically polarized light VPL is incident on the third wire grid polarizer 13 and the fourth wire grid polarizer 14, the horizontally polarized light HPL and vertically polarized light VPL are not blocked by the third wire grid polarizer 13 and the fourth wire grid polarizer 14. Therefore, output light Lout containing horizontally polarized light HPL and vertically polarized light VPL is emitted from the fourth wire grid polarizer 14. However, the amount of light is further reduced by the amount blocked by the metal wires 13b and 14b.

The amount of light in the first wire grid polarizer 11 and the second wire grid polarizer 12 is, for example, 89%, and the third wire grid polarizer 13 and the fourth wire grid polarizer 14 further increase this to, for example, 89%, so that the amount of light of the emitted light Lout in the entire optical switch 101 is about 80% of the incident light Lin.

7B, the horizontally polarized light HPL and the vertically polarized light VPL are transmitted at an amount of about 80% at wavelengths less than 760 nm, and the amount of light transmitted is rapidly reduced at wavelengths of 760 nm or more. That is, in FIG. 7B, the first wire grid polarizer 11 and the second wire grid polarizer 12 are in state 2 , and the third wire grid polarizer 13 and the fourth wire grid polarizer 14 are in state 4 , which is an on state that transmits most of the visible light.

The optical switch 101 can select between an initial state in which the second wire grid polarizer 12 and the fourth wire grid polarizer 14 are not slid, and a state in which the second wire grid polarizer 12 and the fourth wire grid polarizer 14 are slid by the slide drivers 16 and 17.

As a result, as shown in FIG. 8, the optical switch 101 can be switched between an OFF state, in which it transmits almost no visible light with wavelengths of 380 nm to 760 nm, and an ON state, in which it transmits almost all visible light. The OFF state and ON state can be switched simply by sliding the second wire grid polarizer 12 and the fourth wire grid polarizer 14 using the slide drivers 16 and 17, so the optical switch 101 can be switched between the OFF state and the ON state at high speed.

The initial state of the first wire grid polarizer 11 and the second wire grid polarizer 12 may be such that the X-direction positions of each metal wire 11b and each metal wire 12b are the same. The initial state of the third wire grid polarizer 13 and the fourth wire grid polarizer 14 may be such that the Y-direction positions of each metal wire 13b and each metal wire 14b are the same.

The optical switch 101 shown in FIG. 1 can be expanded to form the optical switch 102 shown in FIG. 9. The optical switch 102 is configured by adding a rotation control unit 18 and a rotation drive unit 19 to the optical switch 101 shown in FIG. 1. The rotation drive unit 19 can rotate the third wire grid polarizer 13 and the fourth wire grid polarizer 14 under the control of the rotation control unit 18. The rotation control unit 18 controls the rotation drive unit 19 in response to an input rotation instruction signal.

The first to fourth wire grid polarizers 11 to 14 are turned on as described above, and the rotation control unit 18 controls the rotation drive unit 19 to rotate the third wire grid polarizer 13 and the fourth wire grid polarizer 14 to any rotation angle between 0 degrees and 90 degrees.

Fig. 10A shows the same state as Fig. 7A. The first wire grid polarizer 11 and the second wire grid polarizer 12 are in state 1 , and the third wire grid polarizer 13 and the fourth wire grid polarizer 14 are in state 3. The third wire grid polarizer 13 and the fourth wire grid polarizer 14 are in the same state as Fig. 1, rotated 90 degrees with respect to the first wire grid polarizer 11 and the second wire grid polarizer 12. At this time, the optical switch 102 is in an off state in which it hardly transmits visible light.

Figure 10B shows the state in which the third wire grid polarizer 13 and the fourth wire grid polarizer 14 are rotated 0 degrees by the rotation drive unit 19 from the state in Figure 10A. The state rotated 0 degrees refers to the state in which the third wire grid polarizer 13 and the fourth wire grid polarizer 14, which are rotated 90 degrees, are rotated 90 degrees so that the third wire grid polarizer 13 and the fourth wire grid polarizer 14 are oriented in the same direction as the first wire grid polarizer 11 and the second wire grid polarizer 12.

In this state, the emitted light L12, which is mostly horizontally polarized light HPL emitted from the first wire grid polarizer 11 and the second wire grid polarizer 12, passes through the third wire grid polarizer 13 and the fourth wire grid polarizer 14, except for the portion blocked by the metal wires 13b and 14b. Emitted light Lout, which is mostly horizontally polarized light HPL, is emitted from the third wire grid polarizer 13 and the fourth wire grid polarizer 14.

Figure 11 shows the relationship between the rotation angle of the third wire grid polarizer 13 and the fourth wire grid polarizer 14 and the proportion of transmitted light emitted as the emitted light Lout. If the rotation angle of the third wire grid polarizer 13 and the fourth wire grid polarizer 14 is 0 degrees, the proportion of transmitted light is a maximum of approximately 40%. As described above, the transmittance of the incident light Lin, which includes horizontally polarized light HPL and vertically polarized light VPL, through the first wire grid polarizer 11 to the fourth wire grid polarizer 14 as a whole is approximately 80%, so with only horizontally polarized light HPL, the proportion of transmitted light is approximately 40%.

As shown in FIG. 11, as the rotation angle of the third wire grid polarizer 13 and the fourth wire grid polarizer 14 approaches 90 degrees from 0 degrees, the proportion of transmitted light gradually decreases from approximately 40% to 0%.

The optical switch 102 shown in FIG. 9 has the advantage of being able to quickly switch between an off state that transmits almost no visible light and an on state that transmits almost all visible light, as well as being able to adjust the amount of light transmitted in the on state.

<Polarizer>
Fig. 12 discloses a polarizer capable of switching between horizontal and vertical polarization at high speed. Fig. 12 shows a polarizer 200 according to an embodiment. In the polarizer 200 shown in Fig. 12, the same parts as those in the optical switch 101 shown in Fig. 1 are designated by the same reference numerals, and the description thereof may be omitted.

In FIG. 12, a selection instruction signal is input to the selection control unit 21 to select whether the emitted light Lout is horizontally polarized HPL or vertically polarized VPL. When a selection instruction signal to make the emitted light Lout horizontally polarized HPL is input, the selection control unit 21 instructs the slide control unit 15 to make the emitted light Lout horizontally polarized HPL.

When instructed to set the output light Lout to horizontally polarized light HPL, the slide controller 15 drives the second wire grid polarizer 12 and the fourth wire grid polarizer 14 to set the first wire grid polarizer 11 and the second wire grid polarizer 12 to State 1 and the third wire grid polarizer 13 and the fourth wire grid polarizer 14 to State 4. The slide controller 15 keeps the second wire grid polarizer 12 in its initial state and slides the fourth wire grid polarizer 14 to State 4. In this way, the polarizer 200 is in a horizontally polarized light output state (first polarization output state) that outputs horizontally polarized light HPL (first polarization).

When instructed to set the output light Lout to vertical polarization VPL, the slide controller 15 drives the second wire grid polarizer 12 and the fourth wire grid polarizer 14 to set the first wire grid polarizer 11 and the second wire grid polarizer 12 to State 2 and the third wire grid polarizer 13 and the fourth wire grid polarizer 14 to State 3. The slide controller 15 slides the second wire grid polarizer 12 to State 2 and leaves the fourth wire grid polarizer 14 in its initial state. In this way, the polarizer 200 is in a vertical polarization output state (second polarization output state) that outputs vertical polarization VPL (second polarization).

The polarizer 200 shown in FIG. 12 can switch between horizontally polarized light HPL and vertically polarized light VPL for the emitted light Lout. The polarizer 200 can switch between the horizontally polarized light emission state and the vertically polarized light emission state simply by sliding the second wire grid polarizer 12 and the fourth wire grid polarizer 14 using the slide drive units 16 and 17, so the polarizer 200 can quickly switch between the horizontally polarized light emission state and the vertically polarized light emission state.

Depending on how the polarizer 200 is configured, the vertically polarized light VPL may be the first polarization, the vertically polarized light exit state may be the first polarization exit state, and the horizontally polarized light HPL may be the second polarization, and the horizontally polarized light exit state may be the second polarization exit state.

<Optical filter>
Fig. 13 discloses an optical filter capable of changing the transmission wavelength band. Fig. 13 shows an optical filter 300 according to one embodiment. In the optical filter 300 shown in Fig. 13, the same parts as those in the optical switch 101 shown in Fig. 1 are denoted by the same reference numerals, and the description thereof may be omitted.

In FIG. 13, a transmission wavelength instruction signal is input to the slide control unit 15. The transmission wavelength instruction signal does not need to be an instruction signal that directly instructs the wavelength to be transmitted by the optical filter 300, but may be an instruction signal that widens the band of wavelengths to be transmitted by a specified band toward the 760 nm wavelength side, or narrows the band by a specified band toward the 380 nm wavelength side.

The optical filter 300 is in the off state when the first wire grid polarizer 11 and the second wire grid polarizer 12 are in state 1 and the third wire grid polarizer 13 and the fourth wire grid polarizer 14 are in state 3. It is assumed that a transmitted wavelength instruction signal is input to the slide control unit 15 to instruct it to widen the band of wavelengths to be transmitted by a predetermined band toward the 760 nm side.

14 , the slide controller 15 slides the second wire grid polarizer 12 a predetermined distance in the X direction so as to bring the first wire grid polarizer 11 and the second wire grid polarizer 12 closer to State 2. Although not shown in the figure, the slide controller 15 slides the fourth wire grid polarizer 14 a predetermined distance in the Y direction so as to bring the third wire grid polarizer 13 and the fourth wire grid polarizer 14 closer to State 4. The distance by which the second wire grid polarizer 12 and the fourth wire grid polarizer 14 are slid is a distance that depends on the band of transmitted wavelengths to be expanded.

As described in FIG. 8, the optical switch 101 selects between an off state in which almost no visible light with wavelengths between 380 nm and 760 nm is transmitted, and an on state in which almost all visible light is transmitted. In contrast, the optical filter 300 can widen the wavelength band through which the optical filter 300 transmits visible light toward the 760 nm side or narrow it toward the 380 nm side by varying the distance by which the second wire grid polarizer 12 and the fourth wire grid polarizer 14 are slid, as shown in FIG. 15.

When the band of wavelengths that transmit visible light is narrowed toward the 380 nm wavelength side, the optical filter 300 emits blue-tinted emitted light Lout. When the band of wavelengths that transmit visible light is widened toward the 760 nm side, the optical filter 300 emits white emitted light Lout.

According to the optical filter 300 shown in FIG. 13, the color tone can be continuously changed by changing the transmission wavelength band of the emitted light Lout from the optical filter 300.

<Windows>
Fig. 16 and Fig. 17 disclose a window capable of changing the state of light transmission. As shown in Fig. 16, a window 400 of one embodiment is installed in a house 410. The house 410 is located near a water surface 420 such as the sea, a lake, or a river. In Fig. 16, sunlight SL includes horizontally polarized light HPL and vertically polarized light VPL. When sunlight SL is reflected by the water surface 420, the reflected light RSL is mostly horizontally polarized light HPL. Even when snow is present instead of the water surface 420, when sunlight SL is reflected by the snow, the reflected light RSL is mostly horizontally polarized light HPL.

Figure 17 shows a window 400 according to one embodiment. In the window 400 shown in Figure 17, the same parts as those in the optical switch 101 shown in Figure 1, the polarizer 200 shown in Figure 12, or the optical filter 300 shown in Figure 13 are designated by the same reference numerals, and their description may be omitted.

In FIG. 17, the window glass 401 is composed of the first wire grid polarizer 11 to the fourth wire grid polarizer 14, which are similar to those in the optical switch 101 or the polarizer 200. The first wire grid polarizer 11 to the fourth wire grid polarizer 14, the slide control unit 15, and the slide drive units 16 and 17 constitute an optical switch similar to the optical switch 101 shown in FIG. 1.

The pane 401 of the window 400 can therefore select between an off state in which it transmits almost no visible light with wavelengths between 380 nm and 760 nm, and an on state in which it transmits almost all visible light. In other words, the window 400 can switch between a state in which the inside of the house 410 cannot be seen from the outside of the pane 401, and a state in which the outside of the pane 401 can be seen from the inside of the house 410, and vice versa.

As shown by the dashed line in FIG. 17, a selection instruction signal is input to select whether the emitted light Lout is horizontally polarized light HPL or vertically polarized light VPL, and a selection control unit 21 may be provided to instruct the slide control unit 15 to make the emitted light Lout horizontally polarized light HPL or vertically polarized light VPL. When the selection control unit 21 is provided, the first wire grid polarizer 11 to the fourth wire grid polarizer 14, the slide control unit 15, the slide drive units 16 and 17, and the selection control unit 21 constitute a polarizer similar to the polarizer 200 shown in FIG. 12.

When the window 400 outputs the light Lout from the window glass 401 into the interior of the house 410 in response to a selection instruction signal as horizontally polarized light HPL, the glittering water surface 420 can be seen from inside the house 410 through the window glass 401 due to the reflection of the horizontally polarized light HPL. When the window 400 outputs the light Lout from the window glass 401 into the interior of the house 410 in response to a selection instruction signal as vertically polarized light VPL, the horizontally polarized light HPL reflected by the water surface 420 can hardly be seen, so the water below the water surface 420 can be seen.

Furthermore, a transmission wavelength instruction signal similar to that of the optical filter 300 shown in FIG. 13 may be input to the slide control unit 15 to vary the distance by which the second wire grid polarizer 12 and the fourth wire grid polarizer 14 are slid. In this way, the first wire grid polarizer 11 to the fourth wire grid polarizer 14, the slide control unit 15, and the slide drive units 16 and 17 constitute an optical filter similar to the optical filter 300 shown in FIG. 13.

This allows the color of the emitted light Lout emitted from the window glass 401 into the interior of the house 410 to be continuously changed, making it possible to select the color of the light brought into the interior of the house 410 from a bluish color to white.

In this way, the window 400 shown in Figure 17 allows the light transmission state to be changed.

<Head-mounted display>
Fig. 18 discloses a head mounted display capable of switching an image viewed by a user. Fig. 18 shows a head mounted display 500 according to an embodiment. The head mounted display 500 is a head mounted display for augmented reality (AR). In the head mounted display 500 shown in Fig. 18, the same parts as those of the optical switch 101 shown in Fig. 1 or the polarizer 200 shown in Fig. 12 are given the same reference numerals, and the description thereof may be omitted.

The head mounted display 500 includes left and right vertical polarizing filters 51L and 51R (first polarizing filters) into which external light is incident, left and right image display units 52L and 52R, left and right horizontal polarizing filters 53L and 53R (second polarizing filters), and left and right half mirrors 54L and 54R. The head mounted display 500 also includes left and right wire grid structures 55L and 55R arranged in front of the user's left eye EL and right eye ER, a slide control unit 15, slide drive units 16 and 17, and a selection control unit 21.

The wire grid structures 55L and 55R have a first wire grid polarizer 11 to a fourth wire grid polarizer 14 similar to those in the optical switch 101 or the polarizer 200.

The wire grid structure 55L or 55R, the slide control unit 15, and the slide drive units 16 and 17 constitute an optical switch similar to the optical switch 101 shown in FIG. 1. The wire grid structure 55L or 55R, the slide control unit 15, the slide drive units 16 and 17, and the selection control unit 21 constitute a polarizer similar to the polarizer 200 shown in FIG. 12.

Let us assume that the optical switch in the head mounted display 500 is in the on state, which transmits almost all visible light through the wire grid structures 55L and 55R. At this time, the vertical polarizing filters 51L and 51R emit the vertically polarized light VPL of the light incident from outside, and the vertically polarized light VPL passes through the half mirrors 54L and 54R and the wire grid structures 55L and 55R to enter the left eye EL and the right eye ER.

The image display units 52L and 52R display virtual images for AR. The virtual images displayed on the image display units 52L and 52R are viewed by the left eye EL and the right eye ER. The image light emitted from the image display units 52L and 52R is incident on the horizontal polarizing filters 53L and 53R, which emit the horizontally polarized light HPL of the incident image light. The image light that has become the horizontally polarized light HPL is reflected by the half mirrors 54L and 54R, passes through the wire grid structures 55L and 55R, and is incident on the left eye EL and the right eye ER.

Therefore, when the optical switch is in the on state, the user of the head mounted display 500 can see a composite image in which a virtual image is superimposed on the real scenery.

If the polarizer in the head mounted display 500 sets the light emitted from the wire grid structures 55L and 55R to horizontal polarization HPL, the user can see only the virtual image. If the polarizer sets the light emitted from the wire grid structures 55L and 55R to vertical polarization VPL, the user can see only the real scene.

In this way, with the head mounted display 500 shown in FIG. 18, the user can switch between a composite image in which a virtual image is superimposed on a real scene, only the virtual image, and only the image of the real scene, and view the image of the selected scene. It is also possible to block the user's view by turning off the optical switch.

In FIG. 18, horizontal polarizing filters 53L and 53R may be placed in place of the vertical polarizing filters 51L and 51R, and vertical polarizing filters 51L and 51R may be placed in place of the horizontal polarizing filters 53L and 53R. In this case, the horizontal polarizing filters 53L and 53R are the first polarizing filters, and the vertical polarizing filters 51L and 51R are the second polarizing filters. Also in this case, if the polarizer sets the light emitted from the wire grid structures 55L and 55R to horizontal polarized light HPL, the user can see only the real scenery. If the polarizer sets the light emitted from the wire grid structures 55L and 55R to vertical polarized light VPL, the user can see only the virtual image.

<Sunglasses>
17, the lens of sunglasses may have a similar structure to that of the window glass 401. By configuring the lens of the sunglasses with the first wire grid polarizer 11 to the fourth wire grid polarizer 14, it is possible to configure sunglasses that allow the user to choose between a state in which the view ahead is blocked and a state in which the view ahead is visible. With such sunglasses, the user can choose between viewing horizontally polarized light HPL or vertically polarized light VPL, and the color of the scenery viewed through the sunglasses can be changed.

The present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 11 First wire grid polarizer 11a, 12a, 13a, 14a Transparent substrate 11b, 12b, 13b, 14b Metal wire 12 Second wire grid polarizer 13 Third wire grid polarizer 14 Fourth wire grid polarizer 15 Slide control section 16, 17 Slide drive section 18 Rotation control section 19 Rotation drive section 21 Selection control section 51L, 51R Vertical polarizing filter 52L, 52R Image display section 53L, 53R Horizontal polarizing filter 54L, 54R Half mirror 55L, 55R Wire grid structure 101, 102 Optical switch 200 Polarizer 300 Optical filter 400 Window 500 Head mounted display EL, ER Eye

Claims (2)

a first wire grid polarizer including a first transparent substrate and a plurality of first metal wires extending in a first direction along a surface of the first transparent substrate and arranged at predetermined intervals in a second direction orthogonal to the first direction and along the surface of the first transparent substrate;
a second wire grid polarizer disposed opposite to the first wire grid polarizer, the second wire grid polarizer including a second transparent substrate and a plurality of second metal wires extending in the first direction along a surface of the second transparent substrate, perpendicular to the first direction, and arranged at predetermined intervals in the second direction along the surface of the second transparent substrate;
a third wire grid polarizer including a third transparent substrate and a plurality of third metal wires extending in the second direction along a surface of the third transparent substrate, perpendicular to the second direction, and arranged at predetermined intervals in the first direction along the surface of the third transparent substrate;
a fourth wire grid polarizer disposed opposite the third wire grid polarizer, the fourth wire grid polarizer including a fourth transparent substrate and including a plurality of fourth metal wires extending in the second direction along a surface of the fourth transparent substrate, perpendicular to the second direction, and arranged at predetermined intervals in the first direction along the surface of the fourth transparent substrate;
a slide driver that slides the first or second wire grid polarizer in the second direction and slides the third or fourth wire grid polarizer in the first direction;
Equipped with
when the slide driver is in a first state in which each second metal wire of the plurality of second metal wires is positioned at the center of a gap between two adjacent first metal wires of the plurality of first metal wires, the first wire grid polarizer and the second wire grid polarizer block the second polarized light in light having a predetermined wavelength band that is incident on the first transparent substrate and that includes a first polarized light and a second polarized light, and cause the first polarized light to exit from the second transparent substrate;
when the slide driver positions each of the second metal wires at the same position in the second direction as each of the first metal wires in the plurality of first metal wires to set the first metal wires and each of the second metal wires facing each other in a second state, the first wire grid polarizer and the second wire grid polarizer emit the first polarized light and the second polarized light in the incident light from the second transparent substrate,
when the slide driving unit sets each of the plurality of fourth metal wires to a third state in which the fourth metal wires are positioned at the center of a gap between two adjacent third metal wires of the plurality of third metal wires, and when the first polarized light is incident on the third transparent substrate as incident light, the third wire grid polarizer and the fourth wire grid polarizer block the first polarized light so as not to allow the first polarized light to exit from the fourth transparent substrate;
the slide driving unit positions each of the fourth metal wires at the same position in the first direction as each of the third metal wires in the plurality of third metal wires to set each of the third metal wires and each of the fourth metal wires facing each other, and when the first polarized light and the second polarized light are incident on the third transparent substrate as incident light, the third wire grid polarizer and the fourth wire grid polarizer emit the first polarized light and the second polarized light from the fourth transparent substrate,
a slide control unit that switches between an OFF state in which light of the predetermined wavelength band in the light incident on the first transparent substrate is not emitted from the fourth transparent substrate by controlling the slide driving unit to set the first wire grid polarizer and the second wire grid polarizer in the first state and the third wire grid polarizer and the fourth wire grid polarizer in the third state, and an ON state in which light of the predetermined wavelength band in the light incident on the first transparent substrate is emitted from the fourth transparent substrate by controlling the slide driving unit to set the first wire grid polarizer and the second wire grid polarizer in the second state and the third wire grid polarizer and the fourth wire grid polarizer in the fourth state.
Light switch. a rotation driver that rotates the third and fourth wire grid polarizers;
a rotation control unit that controls the rotation drive unit to rotate the third and fourth wire grid polarizers;
The optical switch of claim 1 further comprising:

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