Spatial phase modulator, processing apparatus, and information processing apparatus

Abstract

A spatial phase modulator according to an embodiment of the present disclosure generates a desired image by modulating the phase of light. This spatial phase modulator is provided with a laminate formed by laminating a plurality of pixel electrodes, a first alignment film, a liquid crystal layer, a second alignment film, and a common electrode in this order. The liquid crystal layer includes liquid crystal molecules having negative dielectric anisotropy. The first alignment film and the second alignment film are configured such that the pretilt angle θt of the liquid crystal molecules satisfies 0° < θt0 ≤ 80°.

Description

Technical Field

[0001] The present disclosure relates to a spatial light modulator, a processing apparatus, and an information processing apparatus.

Background Art

[0002] A spatial light modulator that modulates the phase of light to generate a desired image can control the interference of light. Therefore, the spatial light modulator is expected to have a wide range of applications such as a stereoscopic display and laser processing. The spatial light modulator has a panel structure in which a liquid crystal layer is sandwiched between electrodes, and it is possible to analogously control the phase of incident light by controlling the voltage applied to the liquid crystal layer.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

[0004] In order to modulate only the phase of light, it is important that when a voltage is applied, the liquid crystal molecules tilt only in the polar angle direction with respect to the pixel electrode. When the liquid crystal molecules rotate in the azimuthal angle direction with respect to the pixel electrode, the polarization state of the light (incident light) incident on the spatial light modulator changes, and the light (emergent light) emitted from the spatial light modulator has a polarization state different from that of the incident light. As a result, light that does not contribute to interference is generated as the emergent light, and thus the light utilization efficiency decreases. Therefore, it is desirable to provide a spatial light modulator capable of improving the light utilization efficiency, as well as a processing apparatus and an information processing apparatus including the same.

[0005] In one embodiment of the present disclosure, a spatial phase modulator is a modulator that modulates the phase of light to generate a desired image. This spatial phase modulator comprises a laminate in which a plurality of pixel electrodes, a first alignment film, a liquid crystal layer, a second alignment film, and a common electrode are stacked in this order. The liquid crystal layer contains liquid crystal molecules having negative dielectric anisotropy. The first and second alignment films are configured such that the pre-tilt angle θt0 of the liquid crystal molecules satisfies 0° < θt0 ≤ 80°.

[0006] A processing apparatus according to one embodiment of the present disclosure is an apparatus that uses a spatial phase modulator to generate a desired image by modulating the phase of light. In this processing apparatus, the spatial phase modulator has the same configuration as the spatial phase modulator described above.

[0007] An information processing device according to one embodiment of the present disclosure is a device that uses one or more spatial phase modulators to modulate the phase of light and generate a desired image. In this information processing device, the spatial phase modulator has the same configuration as the spatial phase modulator described above.

[0008] In a spatial phase modulator, processing apparatus, and information processing apparatus according to one embodiment of the present disclosure, the first alignment film and the second alignment film are configured such that the pre-tilt angle θt0 of the liquid crystal molecules satisfies 0° < θt0 ≤ 80°. This suppresses the rotation of the liquid crystal molecules in the azimuthal direction. [Brief explanation of the drawing]

[0009] [Figure 1] (A) This diagram illustrates reverse tilt. (B) This diagram illustrates the interaction between the curvature of equipotential lines and the elastic force of the liquid crystal layer. [Figure 2] This figure shows an example of a cross-sectional configuration of a spatial phase modulator according to one embodiment of the present disclosure. [Figure 3] Figure 2 shows an example of a planar configuration of the spatial phase modulator. [Figure 4] (A) This is a magnified view of the liquid crystal molecules in Figures 2 and 3. (B) This is a magnified view of the liquid crystal molecules that are undergoing rotation in the azimuthal direction. [Figure 5]This figure shows a modified example of the cross-sectional configuration of the spatial phase modulator shown in Figure 1. [Figure 6] This figure shows a modified example of the cross-sectional configuration of the spatial phase modulator shown in Figure 1. [Figure 7] This figure shows a modified example of the cross-sectional configuration of the spatial phase modulator shown in Figure 1. [Figure 8] This is a magnified diagram showing liquid crystal molecules when an electric field is applied. [Figure 9] This diagram illustrates an example of the relationship between the voltage difference between two pixels and rotation in the azimuth direction. [Figure 10] This diagram illustrates an example of the relationship between liquid crystal materials and the angle required to suppress reverse tilt. [Figure 11] This diagram illustrates an example of the relationship between the thickness of the liquid crystal layer and the angle required to suppress reverse tilt. [Figure 12] Figure 1 is a diagram illustrating an example of the operation of a spatial phase modulator. [Figure 13] Figure 1 shows an example of the operation of a spatial phase modulator. [Figure 14] Figure 1 shows an example of applying the spatial phase modulator to a laser processing machine. [Figure 15] Figure 1 shows an example of applying the spatial phase modulator to optical computing. [Figure 16] This block diagram shows an example of a schematic configuration of a vehicle control system. [Figure 17] This is an explanatory diagram showing an example of the installation location of the external information detection unit and the imaging unit. [Modes for carrying out the invention]

[0010] The forms for implementing this disclosure will be described in detail below with reference to the drawings. The explanation will be given in the following order. 1. Background (Figure 1(A), Figure 1(B)) 2. Embodiments (Figures 2 to 13) 3. Application Examples (Figures 14-17)

[0011] <1. Background> A spatial light modulator that modulates the phase of light to generate a desired image can control the interference of light. Therefore, spatial light modulators are expected to have a wide range of applications such as stereoscopic displays and laser processing. The spatial light modulator has a panel structure with a liquid crystal layer sandwiched between electrodes, and it is possible to analogously control the phase of incident light by controlling the voltage applied to the liquid crystal layer. In order to modulate only the phase of light, it is important that the liquid crystal molecules tilt only in the polar angle direction with respect to the pixel electrodes when a voltage is applied. When the liquid crystal molecules rotate in the azimuthal angle direction with respect to the pixel electrodes, the polarization state of the light incident on the spatial light modulator (incident light) changes, and the light emitted from the spatial light modulator (emitted light) has a polarization state different from that of the incident light. As a result, light that does not contribute to interference is generated as the emitted light, and the utilization efficiency of light decreases.

[0012] In a spatial light modulator, when liquid crystal molecules having positive dielectric anisotropy are used, rotation in the azimuthal angle direction of the liquid crystal molecules is inevitably caused by a fringe electric field in a direction orthogonal to the alignment direction of the liquid crystal molecules in principle. On the other hand, the alignment of liquid crystal molecules having negative dielectric anisotropy has not been elucidated. Therefore, the inventor of the present application analyzed the alignment of liquid crystal molecules having negative dielectric anisotropy using a prototype device, and as a result, it was confirmed that rotation in the azimuthal angle direction also occurs in liquid crystal molecules having negative dielectric anisotropy.

[0013] As a result of considering the principle of rotation in the azimuthal angle direction in liquid crystal molecules having negative dielectric anisotropy, the inventor of the present application found the following two principles.

[0014] Figure 1(A) is a diagram illustrating principle 1. Figure 1(B) is a diagram illustrating principle 2. In Figures 1(A) and 1(B), LC are liquid crystal molecules, E1 is a pixel electrode, E2 is a common electrode, solid lines are equipotential lines, and arrows are fringe electric fields. In Figure 1(A), the area enclosed by the dashed line shows where rotation in the azimuthal direction occurs in the liquid crystal molecule LC due to "principle 1" when a relatively small voltage difference is applied between the pixel electrode E1 and the common electrode E2. In Figure 1(B), the area enclosed by the dashed line shows where rotation in the azimuthal direction occurs in the liquid crystal molecule LC due to "principle 2" when a relatively large voltage difference is applied between the pixel electrode E1 and the common electrode E2.

[0015] (Principle 1) ~Reverse tilt caused by fringe electric field~ In the liquid crystal layer, it is desirable for electric field lines to be generated perpendicularly from the pixel electrode E1 to the common electrode E2. However, between two pixel electrodes E1 with significantly different applied voltages, electric field lines are generated from one pixel electrode E1 to the other pixel electrode E2 (arrows in Figure 1(A)). When a force that reverses the pre-tilt is applied to the liquid crystal molecules LC by the electric field corresponding to these electric field lines, the liquid crystal molecules LC rotate in the opposite direction to the pre-tilt, and a reverse tilt occurs. This force rotates the liquid crystal molecules LC by 180° in the azimuthal direction, and furthermore, the surrounding liquid crystal molecules LC are also affected by the reverse tilt of the liquid crystal molecules LC due to the elastic force of the liquid crystal layer, and rotate in the azimuthal direction (areas enclosed by dashed lines in Figure 1(A)).

[0016] (Principle #2) ~Interaction between the curvature of equipotential lines and the elastic force of the liquid crystal layer~ When different voltages are applied to two adjacent pixel electrodes E1 and E2, the equipotential lines within the liquid crystal layer are curved. Assuming that the rotation of the liquid crystal molecules LC in the azimuthal direction is zero, the liquid crystal molecules LC, possessing negative dielectric anisotropy, should rotate under the force of the electric field so that their major axes become parallel to the equipotential lines (the black-shaded liquid crystal molecules in Figure 1(B)). However, because the equipotential lines are curved, the liquid crystal molecules LC enter a bent orientation state, resulting in high elastic energy (the area enclosed by the dashed line in Figure 1(B)). The lowest elastic energy occurs when the liquid crystal molecules rotate 90° in the azimuthal direction. Therefore, the curved electric field exerts a force that rotates the liquid crystal molecules 90° in the azimuthal direction, causing them to rotate 90° in that direction (the area enclosed by the dashed line in Figure 1(B)).

[0017] In light of the two principles described above, the inventors of this application investigated a method to suppress the rotation of liquid crystal molecules in the azimuthal direction by increasing their free energy when they rotate in the azimuthal direction. One such method is to strengthen the anchoring strength of the alignment film. However, there are limitations to controlling the anchoring strength of the alignment film, and improvement solely through strengthening the anchoring force is not practical.

[0018] The inventors of this application discovered through simulations and experiments that rotation in the azimuth direction caused by the curvature of the electric field can be triggered by reverse tilt. From this, the inventors realized that preventing reverse tilt is crucial to solving part of the problem of rotation in the azimuth direction. Therefore, the inventors of this application propose the following invention, which focuses on suppressing reverse tilt.

[0019] <2. Embodiments> [composition] Figure 2 shows an example of a cross-sectional configuration of a spatial phase modulator 1 according to one embodiment of the present disclosure. The spatial phase modulator 1 is an optical device that modulates the phase of light to generate a desired image. The spatial phase modulator 1 includes, for example, a laminate 10 formed by stacking a plurality of pixel electrodes 11, an alignment film 12, a liquid crystal layer 13, an alignment film 14, and a common electrode 15 in that order, as shown in Figure 2. The spatial phase modulator 1 further includes, for example, a pair of glass substrates 20, 30 that sandwich the laminate 10, as shown in Figure 2.

[0020] Multiple pixel electrodes 11 and alignment films 12 are laminated on the surface of a glass substrate 20, and a common electrode 15 and alignment film 14 are laminated on the surface of a glass substrate 30. The glass substrates 20 and 30 are arranged facing each other with the multiple pixel electrodes 11, alignment films 12 and 14, and common electrode 15 in between. The multiple pixel electrodes 11 are arranged two-dimensionally on the surface of the glass substrate 20 with predetermined gaps between them. The pixel electrodes 11 are, for example, several tens of micrometers × several tens of micrometers in size.

[0021] Between the alignment film 12 and the alignment film 14, a liquid crystal layer 13 is formed in contact with the alignment films 12 and 14. The liquid crystal layer 13 contains liquid crystal molecules 13a having negative dielectric anisotropy. Here, "negative dielectric anisotropy" means that when an electric field is applied, the short axis of the liquid crystal molecule becomes parallel to the direction of the electric field. "Positive dielectric anisotropy" means that when an electric field is applied, the long axis of the liquid crystal molecule becomes parallel to the direction of the electric field.

[0022] Figure 3 shows an example of a planar configuration of the spatial phase modulator 1. In Figure 3, liquid crystal molecules 13a are projected onto the glass substrate 30. Figure 4(A) shows a magnified view of liquid crystal molecules 13a without an electric field applied. The alignment films 12 and 14 regulate the orientation direction Da and pre-tilt angle θt0 of the liquid crystal molecules 13a, and are, for example, inorganic alignment films formed by oblique deposition. The orientation direction Da refers to the long axis direction of the projected image when the liquid crystal molecules 13a are projected onto the XY plane (pixel electrode 11). The orientation direction Da is, for example, parallel to the X axis. The pre-tilt angle θt0 refers to the angle (pole angle) between the long axis of the liquid crystal molecules 13a and the XY plane (pixel electrode 11) when no voltage is applied between the pixel electrode 11 and the common electrode 15.

[0023] For reference, Figure 4(B) shows what happens when a voltage difference ΔV occurs between two adjacent pixel electrodes 11 and the liquid crystal molecules 13a rotate in the azimuthal direction. In Figure 4(B), the rotation angle θa represents the maximum rotation angle in the azimuthal direction of the liquid crystal molecules 13a contained in the central region in the thickness direction of the liquid crystal layer 13 when the voltage difference between two adjacent pixel electrodes 11 changes from 0 volts to ΔV volts. When the rotation angle θa is zero, it means that the orientation direction Da does not change. Therefore, in this case, when linearly polarized light having a polarization plane parallel to the orientation direction Da is transmitted through the liquid crystal layer 13, the liquid crystal layer 13 has the effect of modulating only the phase of the transmitted linearly polarized light without changing its polarization state.

[0024] In the spatial phase modulator 1, the orientation direction Da of the liquid crystal molecules 13a (more precisely, the orientation direction Da when the voltage difference between two adjacent pixel electrodes 11 is 0 volts) is parallel to the polarization plane of the linearly polarized light (incident light L1) incident on the spatial phase modulator 1. The alignment films 12 and 14 are configured such that the pre-tilt angle θt0 of the liquid crystal molecules 13a is less than or equal to a predetermined angle θth. The angle θth will be described in detail later.

[0025] The spatial phase modulator 1 may further include a linear polarizer 40 on the glass substrate 30, for example, as shown in Figure 5. The polarization axis (transmission axis) of the linear polarizer 40 is parallel to the orientation direction Da of the liquid crystal molecules 13a. If the spatial phase modulator 1 is a transmissive modulator, the spatial phase modulator 1 may further include a linear polarizer 50 on the back surface of the glass substrate 20, for example, as shown in Figure 6, having a polarization axis (transmission axis) parallel to the polarization axis (transmission axis) of the linear polarizer 40. If the spatial phase modulator 1 is a reflective modulator, the spatial phase modulator 1 may further include a reflective mirror layer 60 on the back surface of the glass substrate 20 that reflects incident light L1, for example, as shown in Figure 7. In the spatial phase modulator 1, an AR (Anti-Reflection) layer may be provided on the surface on the glass substrate 30 side to prevent unwanted reflection of incident light L1.

[0026] Next, we will explain the tilt angles θt and θth of liquid crystal molecule 13a.

[0027] Figure 8 shows a magnified view of the liquid crystal molecule 13a. Figure 8 illustrates the liquid crystal molecule 13a when a fixed voltage (e.g., 0V) is applied to the common electrode 15 and an on-voltage (e.g., 4V) is applied to the pixel electrode 11. The tilt angle θt refers to the angle (polar angle) between the long axis of the liquid crystal molecule 13a and the XY plane (pixel electrode 11). The tilt angle θt changes according to the difference between the voltage applied to the pixel electrode 11 and the voltage applied to the common electrode 15. The tilt angle θt when no voltage is applied to the pixel electrode 11 and the common electrode 15 is called the pre-tilt angle θt0.

[0028] Figure 9 shows an example of the relationship between the voltage difference ΔV between two adjacent pixel electrodes 11 and the rotation angle θa of the liquid crystal molecule 13a in the azimuthal direction. Note that Figure 9 shows experimental results when the liquid crystal molecule 13a is liquid crystal material A as shown in Figure 10 (described later), and the thickness of the liquid crystal layer 13 is 3 μm. When the pre-tilt angle θt0 was set to 81° and the voltage difference ΔV was varied from 0V to 5V, as shown in Figure 9, no reverse tilt occurred in the liquid crystal molecule 13a in the low-voltage region (0V to 2V), but rotation in the azimuthal direction occurred in the high-voltage region (2V to 5V). On the other hand, when the pre-tilt angle θt0 was set to 82° and the voltage difference ΔV was varied from 0V to 5V, as shown in Figure 9, reverse tilt occurred in the liquid crystal molecule 13a in the low-voltage region, followed by rotation in the azimuthal direction in the high-voltage region. From this, it can be seen that when the pre-tilt angle θt0 is 81° or less, reverse tilt does not occur in the liquid crystal molecule 13a.

[0029] Incidentally, if reverse tilt occurs in adjacent pixels, even with an applied voltage that would normally not cause rotation in the azimuthal direction, the propagation of the liquid crystal's elastic force causes azimuthal rotation similar to that in the high-voltage region. Therefore, by suppressing the occurrence of reverse tilt, it is possible to suppress the azimuthal rotation that was occurring around it. Also, if the pre-tilt angle θt0 of the liquid crystal molecule 13a is reduced (i.e., the liquid crystal molecule 13a is tilted), the effective anchoring force becomes stronger as the pre-tilt angle θt0 of the liquid crystal molecule 13a decreases, making it possible to suppress reverse tilt. Accordingly, by setting the pre-tilt angle θt0 of the liquid crystal molecule 13a to a predetermined angle θth or less, it is possible to completely suppress the rotation of the liquid crystal molecule 13a in the azimuthal direction. In other words, in Figure 9, angle θth refers to the upper limit of the pre-tilt angle θt0 (81°) at which reverse tilt does not occur even when the voltage difference ΔV between two adjacent pixel electrodes 11 is changed from 0 volts to 5 volts (when the voltage difference ΔV is changed within the range of normal use).

[0030] Figure 10 shows the angle θth when using four types of liquid crystal materials that are generally available as liquid crystal molecules 13a having negative dielectric anisotropy. Figure 10 shows experimental results when the thickness of the liquid crystal layer 13 is 3 μm. Figure 11 shows an example of the relationship between the thickness of the liquid crystal layer 13 and the angle θth at which reverse tilt does not occur. Figure 11 shows experimental results when using liquid crystal material A from Figure 10. From Figures 10 and 11, it can be seen that the upper limit of the pre-tilt angle θt0 at which reverse tilt does not occur (angle θth) is 80°, regardless of the liquid crystal material or the thickness of the liquid crystal layer 13.

[0031] Based on the above, the alignment films 12 and 14 are configured such that the pre-tilt angle θt0 of the liquid crystal molecule 13a satisfies the following equation. 0° < θt0 ≤ 80°

[0032] The lower limit of the pre-tilt angle θt0 corresponds to the lower limit at which the pre-tilt direction of the liquid crystal molecule 13a can be controlled to be constant. In phase modulation, a contrast ratio like that of a light bulb is not necessary; it is sufficient to be able to distinguish the phase difference, so it is not a problem if the upper limit of the pre-tilt angle θt0 is not close to 90°.

[0033] [Operation] Next, the operation of the spatial phase modulator 1 will be explained.

[0034] (transmissive type) Figure 12 shows an example of operation when the spatial phase modulator 1 is a transmissive modulator. A voltage set for each pixel electrode 11 is applied to each pixel electrode 11. Then, the tilt angle θt of the liquid crystal molecules 13a changes according to the difference between the voltage applied to the pixel electrode 11 and the voltage applied to the common electrode 15. When linearly polarized light (incident light L1) having a polarization plane parallel to the orientation direction of the liquid crystal molecules 13a is incident on the glass substrate 30 side surface (light incident surface S1) of the spatial phase modulator 1, the incident light L1 is phase-modulated without rotating the polarization plane as it passes through the liquid crystal layer 13, and the phase-modulated light is emitted to the outside as emitted light L2 from the glass substrate 20 side surface (light output surface S2).

[0035] (reflective type) Figure 13 shows an example of operation when the spatial phase modulator 1 is a reflective modulator. A voltage set for each pixel electrode 11 is applied to each pixel electrode 11. Then, the tilt angle θt of the liquid crystal molecules 13a changes according to the difference between the voltage applied to the pixel electrode 11 and the voltage applied to the common electrode 15. Linearly polarized light (incident light L1) having a polarization plane parallel to the orientation direction of the liquid crystal molecules 13a is incident on the glass substrate 30 side surface (light incident surface S1) of the spatial phase modulator 1. The incident light L1 may be incident at an oblique angle to the light incident surface S1, as shown in Figure 13, or it may be incident perpendicular to the light incident surface S1. When the incident light L1 is incident on the light incident surface S1, the incident light L1 is transmitted through the liquid crystal layer 13, reflected by the reflective mirror layer 60, and then transmitted through the liquid crystal layer 13 again and emitted to the outside from the glass substrate 30 side surface (light emission surface S2). In this state, the incident light L1 is phase-modulated without rotating its plane of polarization, and the phase-modulated light is emitted to the outside as the outgoing light L2.

[0036] [effect] Next, we will explain the effect of the spatial phase modulator 1.

[0037] In this embodiment, the alignment films 12 and 14 are configured such that the pre-tilt angle θt of the liquid crystal molecules 13a satisfies 0° < θt0 ≤ 80°. As a result, in the low-voltage region, the rotation of the liquid crystal molecules in the azimuthal direction is suppressed, thereby improving the efficiency of light utilization. Furthermore, in the high-voltage region, the rotation of the liquid crystal molecules in the azimuthal direction triggered by reverse tilt is suppressed, thereby improving the efficiency of light utilization.

[0038] <2. Application Examples> Next, an example of the application of the spatial phase modulator 1 according to the above embodiment will be described.

[0039] [Application Example A] Figure 14 shows a schematic configuration example of a laser processing machine 100 equipped with a spatial phase modulator 1. The laser processing machine 100 is a device that forms a modified region on an object 200 by irradiating the object 200 with laser light La. The laser processing machine 100 includes a support section 110 for supporting the object 200, a light source section 120, a spatial phase modulator 1, mirrors 130 and 140, an imaging optical system 150, and a focusing section 160. In this application example, the spatial phase modulator 1 is a reflective type modulator.

[0040] The support portion 110 supports the object 200, for example, by adsorbing the object 200, so that the surface of the object 200 is parallel to the XY plane. The support portion 110 is movable in both the X and Y directions and is rotatable within the XY plane.

[0041] The light source unit 120 emits laser light La, for example, by a pulse oscillation method. The laser light La is linearly polarized light. The light source unit 120 emits the laser light La such that when the laser light La is incident on the spatial phase modulator 1 via a mirror 130 or the like, the polarization plane of the laser light La is parallel to the orientation direction D1 of the liquid crystal molecules 13a.

[0042] Mirror 130 reflects the laser beam La and directs it onto the light incident surface S1 of the spatial phase modulator 1. The laser beam La reflected by mirror 130 is incident on the light incident surface S1 of the spatial phase modulator 1. In the spatial phase modulator 1, the laser beam La passes through the liquid crystal layer 13, is reflected by the reflective mirror layer 60, and the reflected light (laser beam Lb) passes through the liquid crystal layer 13 and is emitted to the outside. At this time, the laser beam La is phase-modulated without rotating its plane of polarization, and the phase-modulated light (laser beam Lb) is emitted to the outside from the light incident surface S1, which also serves as the light emission surface S2.

[0043] The mirror 140 reflects the laser light Lb and directs it into the focusing unit 160 via the imaging optical system 150. The imaging optical system 150 is a bilateral telecentric optical system in which the reflective surface of the spatial phase modulator 1 and the entrance pupil surface of the focusing unit 150 are in an imaging relationship. As a result, the laser light Lb modulated by the spatial phase modulator 1 is imaged (imposed) on the entrance pupil surface of the focusing unit 150. The focusing unit 150 focuses the laser light Lb and irradiates the surface of the object 200, projecting the image formed on the entrance pupil surface onto the surface of the object 200 at a predetermined magnification. As a result, a modified region of the projected image pattern is formed on the surface of the object 200.

[0044] In this application example, the image that forms the basis of the pattern to be created in the modified region is formed by the spatial phase modulator 1. This makes it possible to realize a low-power laser processing machine 100.

[0045] [Application Example B] Figure 15 shows a schematic configuration example of an optical computing device 300 equipped with a spatial phase modulator 1. The optical computing device 300 is a device that decodes an image (e.g., a number) input to a light bulb 320, and includes, for example, a light source unit 310, a light bulb 320, a plurality of spatial phase modulators 1, and a detection unit 330. In the optical computing device 300, the plurality of spatial phase modulators 1 are superimposed with a predetermined gap between them.

[0046] The light source unit 310 irradiates the light bulb 320 with laser light. The light bulb 320 is, for example, a light-transmitting optical modulator, and generates image light in a pattern corresponding to the externally input control signal (image data) by modulating the light intensity of the laser light incident from the light source unit 310 based on the externally input control signal. The light bulb 320 irradiates the generated image light onto the first spatial phase modulator 1. The image light is phase-modulated by the first spatial phase modulator 1, and the resulting light is irradiated onto the second spatial phase modulator 1. The light irradiated onto the second spatial phase modulator 1 is phase-modulated by the second spatial phase modulator 1, and the resulting light is irradiated onto the third spatial phase modulator 1. In this way, the image light is phase-modulated by each spatial phase modulator 1, and the light output from the last spatial phase modulator 1 is detected by the detection unit 330. The detection unit 330 estimates the image data input to the light bulb 320 based on the input light.

[0047] In this application example, the light source unit 310 and the light bulb 320 may be omitted, and image light input from an external source may be directed onto the first spatial phase modulator 1. Alternatively, in this application example, the light source unit 310 and the light bulb 320 may be omitted, and a light-transmitting sheet of paper with characters or pictures drawn on it may be placed on the light incident surface of the first spatial phase modulator 1, and the ambient light transmitted through the sheet of paper may be detected by the first spatial phase modulator 1.

[0048] In this application example, the phase distribution that determines the processing content in the optical computing system 300 is formed by the spatial phase modulator 1. This makes it possible to realize an optical computing system 300 that is low power consumption and whose computation content can be changed.

[0049] [Application Example C] The technology disclosed herein can be applied to a variety of products. For example, the technology disclosed herein may be implemented as a device mounted on any type of mobile vehicle, such as automobiles, electric vehicles, hybrid electric vehicles, motorcycles, bicycles, personal mobility devices, airplanes, drones, ships, robots, construction machinery, or agricultural machinery (tractors).

[0050] Figure 16 is a block diagram showing a schematic configuration example of a vehicle control system 7000, which is an example of a mobile control system to which the technology described herein can be applied. The vehicle control system 7000 comprises a plurality of electronic control units connected via a communication network 7010. In the example shown in Figure 16, the vehicle control system 7000 comprises a drive system control unit 7100, a body system control unit 7200, a battery control unit 7300, an external information detection unit 7400, an internal information detection unit 7500, and an integrated control unit 7600. The communication network 7010 connecting these plurality of control units may be an in-vehicle communication network compliant with any standard such as CAN (Controller Area Network), LIN (Local Interconnect Network), LAN (Local Area Network), or FlexRay®.

[0051] Each control unit comprises a microcomputer that performs calculations according to various programs, a storage unit that stores programs executed by the microcomputer or parameters used in various calculations, and a drive circuit that drives various controlled devices. Each control unit is equipped with a network interface for communication with other control units via the communication network 7010, and a communication interface for communication with devices or sensors inside or outside the vehicle via wired or wireless communication. Figure 16 illustrates the functional configuration of the integrated control unit 7600, which includes a microcomputer 7610, a general-purpose communication interface 7620, a dedicated communication interface 7630, a positioning unit 7640, a beacon receiver 7650, an in-vehicle equipment interface 7660, an audio / image output unit 7670, an in-vehicle network interface 7680, and a storage unit 7690. Other control units similarly include a microcomputer, a communication interface, and a storage unit.

[0052] The drivetrain control unit 7100 controls the operation of devices related to the vehicle's drivetrain according to various programs. For example, the drivetrain control unit 7100 functions as a control device for generating driving force for the vehicle, such as an internal combustion engine or a drive motor; a driving force transmission mechanism for transmitting driving force to the wheels; a steering mechanism for adjusting the steering angle of the vehicle; and a braking device for generating braking force for the vehicle. The drivetrain control unit 7100 may also function as a control device such as ABS (Antilock Brake System) or ESC (Electronic Stability Control).

[0053] A vehicle state detection unit 7110 is connected to the drivetrain control unit 7100. The vehicle state detection unit 7110 includes, for example, a gyro sensor for detecting the angular velocity of the vehicle's axial rotational motion, an acceleration sensor for detecting the vehicle's acceleration, or at least one of the sensors for detecting the amount of operation of the accelerator pedal, the amount of operation of the brake pedal, the steering angle of the steering wheel, the engine speed, or the rotational speed of the wheels. The drivetrain control unit 7100 performs calculations using signals input from the vehicle state detection unit 7110 and controls the internal combustion engine, drive motor, electric power steering system, brake system, etc.

[0054] The body system control unit 7200 controls the operation of various devices mounted on the vehicle body according to various programs. For example, the body system control unit 7200 functions as a control device for a keyless entry system, a smart key system, a power window system, or various lamps such as headlights, reverse lights, brake lights, turn signals, or fog lights. In this case, the body system control unit 7200 may receive radio waves transmitted from a portable device that replaces a key or signals from various switches. The body system control unit 7200 receives these radio waves or signals and controls the vehicle's door lock system, power window system, lamps, etc.

[0055] The battery control unit 7300 controls the secondary battery 7310, which is the power source for the drive motor, according to various programs. For example, the battery control unit 7300 receives information such as battery temperature, battery output voltage, or remaining battery capacity from the battery device equipped with the secondary battery 7310. The battery control unit 7300 uses these signals to perform calculations and controls the temperature of the secondary battery 7310 or the cooling device provided in the battery device.

[0056] The external information detection unit 7400 detects information from outside the vehicle equipped with the vehicle control system 7000. For example, at least one of the imaging unit 7410 and the external information detection unit 7420 is connected to the external information detection unit 7400. The imaging unit 7410 includes at least one of the following: a ToF (Time Of Flight) camera, a stereo camera, a monocular camera, an infrared camera, and other cameras. The external information detection unit 7420 includes at least one of the following: an environmental sensor for detecting the current weather or climate, or an ambient information detection sensor for detecting other vehicles, obstacles, or pedestrians around the vehicle equipped with the vehicle control system 7000.

[0057] The environmental sensor may be at least one of the following: a raindrop sensor for detecting rain, a fog sensor for detecting fog, a sunshine sensor for detecting the degree of sunlight, and a snow sensor for detecting snowfall. The ambient information detection sensor may be at least one of the following: an ultrasonic sensor, a radar device, and a LIDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging) device. These imaging unit 7410 and external information detection unit 7420 may be provided as independent sensors or devices, or as a device in which multiple sensors or devices are integrated.

[0058] Here, Figure 17 shows examples of the installation locations of the imaging unit 7410 and the external information detection unit 7420. The imaging units 7910, 7912, 7914, 7916, and 7918 are installed, for example, at least one of the following locations on the vehicle 7900: the front nose, side mirrors, rear bumper, back door, and the upper part of the windshield inside the passenger compartment. The imaging unit 7910 installed on the front nose and the imaging unit 7918 installed on the upper part of the windshield inside the passenger compartment mainly acquire images of the front of the vehicle 7900. The imaging units 7912 and 7914 installed on the side mirrors mainly acquire images of the sides of the vehicle 7900. The imaging unit 7916 installed on the rear bumper or back door mainly acquires images of the rear of the vehicle 7900. The imaging unit 7918 installed on the upper part of the windshield inside the passenger compartment is mainly used for detecting preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, or lanes.

[0059] Figure 17 shows an example of the imaging range of each imaging unit 7910, 7912, 7914, and 7916. Imaging range a shows the imaging range of imaging unit 7910 located on the front nose, imaging ranges b and c show the imaging ranges of imaging units 7912 and 7914 located on the side mirrors, respectively, and imaging range d shows the imaging range of imaging unit 7916 located on the rear bumper or back door. For example, by superimposing the image data captured by imaging units 7910, 7912, 7914, and 7916, an overhead view image of the vehicle 7900 can be obtained.

[0060] The external information detection units 7920, 7922, 7924, 7926, 7928, and 7930, which are installed on the front, rear, sides, corners, and the upper part of the windshield inside the vehicle 7900, may be, for example, ultrasonic sensors or radar devices. The external information detection units 7920, 7926, and 7930, which are installed on the front nose, rear bumper, back door, and the upper part of the windshield inside the vehicle 7900, may be, for example, LIDAR devices. These external information detection units 7920 to 7930 are mainly used to detect preceding vehicles, pedestrians, or obstacles.

[0061] Returning to Figure 16, the explanation continues. The external information detection unit 7400 causes the imaging unit 7410 to capture images of the area outside the vehicle and receives the captured image data. The external information detection unit 7400 also receives detection information from the connected external information detection unit 7420. If the external information detection unit 7420 is an ultrasonic sensor, radar device, or LIDAR device, the external information detection unit 7400 emits ultrasonic waves or electromagnetic waves and receives information on the received reflected waves. Based on the received information, the external information detection unit 7400 may perform object detection processing such as detecting people, vehicles, obstacles, signs, or characters on the road surface, or distance detection processing. Based on the received information, the external information detection unit 7400 may perform environmental recognition processing to recognize rainfall, fog, or road surface conditions. Based on the received information, the external information detection unit 7400 may calculate the distance to an object outside the vehicle.

[0062] Furthermore, the external information detection unit 7400 may perform image recognition processing or distance detection processing to recognize people, vehicles, obstacles, signs, or characters on the road surface based on the received image data. The external information detection unit 7400 may perform distortion correction or alignment processing on the received image data, and may also synthesize image data captured by different imaging units 7410 to generate an overhead view image or a panoramic image. The external information detection unit 7400 may also perform viewpoint transformation processing using image data captured by different imaging units 7410.

[0063] The in-vehicle information detection unit 7500 detects information inside the vehicle. The in-vehicle information detection unit 7500 is connected to, for example, a driver status detection unit 7510 that detects the driver's state. The driver status detection unit 7510 may include a camera that images the driver, a biosensor that detects the driver's biometric information, or a microphone that collects sounds inside the vehicle. The biosensor is installed, for example, on the seat or steering wheel and detects the biometric information of a passenger sitting in the seat or a driver holding the steering wheel. Based on the detection information input from the driver status detection unit 7510, the in-vehicle information detection unit 7500 may calculate the driver's level of fatigue or concentration, or determine whether the driver is dozing off. The in-vehicle information detection unit 7500 may perform processing such as noise cancellation on the collected audio signals.

[0064] The integrated control unit 7600 controls the overall operation of the vehicle control system 7000 according to various programs. An input unit 7800 is connected to the integrated control unit 7600. The input unit 7800 is implemented by a device that can be operated by the passenger, such as a touch panel, buttons, a microphone, a switch, or a lever. The integrated control unit 7600 may also receive data obtained by voice recognition of voice input from the microphone. The input unit 7800 may be a remote control device using infrared or other radio waves, or an external device such as a mobile phone or PDA (Personal Digital Assistant) that is compatible with the operation of the vehicle control system 7000. The input unit 7800 may be a camera, in which case the passenger can input information by gesture. Alternatively, data obtained by detecting the movement of a wearable device worn by the passenger may be input. Furthermore, the input unit 7800 may include, for example, an input control circuit that generates an input signal based on the information input by the passenger using the above input unit 7800 and outputs it to the integrated control unit 7600. Passengers and others can input various data or instruct the vehicle control system 7000 to perform processing operations by operating this input unit 7800.

[0065] The memory unit 7690 may include a ROM (Read Only Memory) for storing various programs executed by a microcomputer, and a RAM (Random Access Memory) for storing various parameters, calculation results, or sensor values. The memory unit 7690 may also be implemented using a magnetic storage device such as an HDD (Hard Disk Drive), a semiconductor storage device, an optical storage device, or a magneto-optical storage device.

[0066] The general-purpose communication interface 7620 is a general-purpose communication interface that mediates communication between the vehicle and various devices present in the external environment 7750. The general-purpose communication interface 7620 may implement cellular communication protocols such as GSM (Global System of Mobile communications), WiMAX (registered trademark), LTE (registered trademark) (Long Term Evolution), or LTE-A (LTE-Advanced), or other wireless communication protocols such as wireless LAN (also known as Wi-Fi (registered trademark)) or Bluetooth (registered trademark). The general-purpose communication interface 7620 may connect to devices (e.g., application servers or control servers) located on an external network (e.g., the Internet, a cloud network, or a carrier-specific network) via, for example, a base station or access point. The general-purpose communication interface 7620 may also connect to terminals located near the vehicle (e.g., terminals for drivers, pedestrians, or shops, or MTC (Machine Type Communication) terminals) using, for example, P2P (Peer To Peer) technology.

[0067] The Dedicated Communication I / F 7630 is a communication interface that supports communication protocols developed for use in vehicles. The Dedicated Communication I / F 7630 may implement standard protocols such as WAVE (Wireless Access in Vehicle Environment), DSRC (Dedicated Short Range Communications), or cellular communication protocols, which are combinations of lower-layer IEEE 802.11p and upper-layer IEEE 1609. The Dedicated Communication I / F 7630 typically performs V2X communication, a concept that includes one or more of the following: vehicle-to-vehicle communication, vehicle-to-infrastructure communication, vehicle-to-home communication, and vehicle-to-pedestrian communication.

[0068] The positioning unit 7640 performs positioning by receiving GNSS signals from GNSS (Global Navigation Satellite System) satellites (for example, GPS signals from GPS (Global Positioning System) satellites) and generates location information including the vehicle's latitude, longitude, and altitude. The positioning unit 7640 may also determine its current location by exchanging signals with a wireless access point, or it may acquire location information from a terminal such as a mobile phone, PHS, or smartphone that has a positioning function.

[0069] The beacon receiver 7650 receives radio waves or electromagnetic waves transmitted from, for example, a radio station installed on a road, and obtains information such as the current location, traffic congestion, road closures, or travel time. The functions of the beacon receiver 7650 may also be included in the dedicated communication interface 7630 described above.

[0070] The In-Vehicle Equipment I / F 7660 is a communication interface that mediates connections between the microcomputer 7610 and various in-vehicle equipment 7760 located inside the vehicle. The In-Vehicle Equipment I / F 7660 may establish a wireless connection using wireless communication protocols such as Wi-Fi, Bluetooth®, NFC (Near Field Communication), or WUSB (Wireless USB). Furthermore, the in-vehicle equipment I / F 7660 may establish a wired connection such as USB (Universal Serial Bus), HDMI (Registered Trademark) (High-Definition Multimedia Interface), or MHL (Mobile High-Definition Link) via connection terminals (and, if necessary, cables) not shown. The in-vehicle equipment 7760 may include, for example, at least one of the following: a mobile device or wearable device owned by a passenger, or an information device brought into or installed in the vehicle. The in-vehicle equipment 7760 may also include a navigation device that performs route searching to any destination. The in-vehicle equipment I / F 7660 exchanges control signals or data signals with these in-vehicle equipment 7760s.

[0071] The in-vehicle network interface 7680 is an interface that mediates communication between the microcomputer 7610 and the communication network 7010. The in-vehicle network interface 7680 transmits and receives signals and other data in accordance with a predetermined protocol supported by the communication network 7010.

[0072] The microcomputer 7610 of the integrated control unit 7600 controls the vehicle control system 7000 according to various programs based on information acquired via at least one of the general-purpose communication I / F 7620, dedicated communication I / F 7630, positioning unit 7640, beacon receiver 7650, in-vehicle equipment I / F 7660, and in-vehicle network I / F 7680. For example, the microcomputer 7610 may calculate control target values ​​for the drive force generator, steering mechanism, or braking device based on acquired in-vehicle and out-of-vehicle information and output control commands to the drive system control unit 7100. For example, the microcomputer 7610 may perform coordinated control aimed at realizing ADAS (Advanced Driver Assistance System) functions, including vehicle collision avoidance or impact mitigation, following driving based on distance between vehicles, maintaining vehicle speed, vehicle collision warning, or vehicle lane departure warning. Furthermore, the microcomputer 7610 may perform cooperative control for purposes such as autonomous driving, where the vehicle drives autonomously without driver intervention, by controlling the drive force generating device, steering mechanism, or braking device, etc., based on the acquired information about the vehicle's surroundings.

[0073] The microcomputer 7610 may generate three-dimensional distance information between the vehicle and surrounding structures, people, and other objects based on information acquired via at least one of the general-purpose communication I / F 7620, dedicated communication I / F 7630, positioning unit 7640, beacon receiver 7650, in-vehicle equipment I / F 7660, and in-vehicle network I / F 7680, and create local map information including surrounding information of the vehicle's current location. Furthermore, the microcomputer 7610 may predict dangers such as vehicle collision, proximity of pedestrians, or entry into a closed road based on the acquired information, and generate a warning signal. The warning signal may, for example, be a signal to generate a warning sound or illuminate a warning lamp.

[0074] The audio-image output unit 7670 transmits at least one of audio and image output signals to an output device capable of visually or audibly notifying the vehicle's occupants or those outside the vehicle. In the example in Figure 16, the output devices are exemplified as an audio speaker 7710, a display unit 7720, and an instrument panel 7730. The display unit 7720 may include, for example, at least one of an onboard display and a head-up display. The display unit 7720 may also have an AR (Augmented Reality) display function. The output device may be other devices other than these, such as headphones, wearable devices such as glasses-type displays worn by occupants, projectors, or lamps. If the output device is a display device, the display device visually displays the results obtained from various processes performed by the microcomputer 7610 or information received from other control units in various formats such as text, images, tables, and graphs. If the output device is an audio output device, the audio output device converts the audio signal, consisting of reproduced audio data or sound data, into an analog signal and outputs it audibly.

[0075] In the example shown in Figure 16, at least two control units connected via the communication network 7010 may be integrated into a single control unit. Alternatively, each control unit may be composed of multiple control units. Furthermore, the vehicle control system 7000 may include other control units not shown. Also, in the above description, some or all of the functions performed by one control unit may be assigned to other control units. In other words, as long as information is transmitted and received via the communication network 7010, predetermined calculation processing may be performed by any of the control units. Similarly, a sensor or device connected to one control unit may be connected to another control unit, and multiple control units may transmit and receive detection information to and from each other via the communication network 7010.

[0076] Furthermore, the computer program for realizing each function of the spatial phase modulator 1, as explained using Figures 1 to 13, can be implemented in any control unit or the like. A computer-readable recording medium containing such a computer program can also be provided. Examples of recording media include magnetic disks, optical disks, magneto-optical disks, and flash memory. Alternatively, the computer program may be distributed via a network, for example, without using a recording medium.

[0077] In the vehicle control system 7000 described above, the spatial phase modulator 1, as described using Figures 1 to 13, can be used, for example, as the light source steering unit of a LiDAR environmental sensor. Furthermore, image recognition in the imaging unit can be performed using an optical computing unit that utilizes the spatial phase modulator 1, as described using Figures 1 to 13. When the spatial phase modulator 1, as described using Figures 1 to 13, is used as a highly efficient and high-brightness projection device, lines and characters can be projected onto the ground. Specifically, lines can be displayed to show the vehicle's position to people outside the vehicle when it is reversing, or a crosswalk can be illuminated to indicate the vehicle's path to pedestrians.

[0078] Furthermore, at least some of the components of the spatial phase modulator 1 described using Figures 1 to 13 may be implemented in a module for the integrated control unit 7600 shown in Figure 16 (for example, an integrated circuit module consisting of a single die). Alternatively, the spatial phase modulator 1 described using Figures 1 to 13 may be implemented by multiple control units of the vehicle control system 7000 shown in Figure 16.

[0079] The present disclosure has been described above with reference to embodiments and their applications, but the present disclosure is not limited to the above embodiments, and various modifications are possible. The effects described herein are merely illustrative. The effects of the present disclosure are not limited to those described herein. The present disclosure may have effects other than those described herein.

[0080] Furthermore, for example, this disclosure can take the following configuration. (1) A spatial phase modulator that modulates the phase of light to generate a desired image, The device comprises a laminate formed by stacking multiple pixel electrodes, a first alignment layer, a liquid crystal layer, a second alignment layer, and a common electrode in this order. The liquid crystal layer contains liquid crystal molecules having negative dielectric anisotropy. The first alignment film and the second alignment film are configured such that the pre-tilt angle θt0 of the liquid crystal molecules satisfies 0° < θt0 ≤ 80°. Spatial phase modulator. (2) A processing apparatus using a spatial phase modulator that modulates the phase of light to generate a desired image, The aforementioned spatial phase modulator is The laminate has multiple pixel electrodes, a first alignment layer, a liquid crystal layer, a second alignment layer, and a common electrode stacked in this order. The liquid crystal layer contains liquid crystal molecules having negative dielectric anisotropy. The first alignment film and the second alignment film are configured such that the pre-tilt angle θt0 of the liquid crystal molecules satisfies 0° < θt0 ≤ 80°. Processing equipment. (3) An information processing device using one or more spatial phase modulators that modulate the phase of light to generate a desired image, The aforementioned spatial phase modulator is The laminate has multiple pixel electrodes, a first alignment layer, a liquid crystal layer, a second alignment layer, and a common electrode stacked in this order. The liquid crystal layer contains liquid crystal molecules having negative dielectric anisotropy. The first alignment film and the second alignment film are configured such that the pre-tilt angle θt0 of the liquid crystal molecules satisfies 0° < θt0 ≤ 80°. Information processing device.

[0081] In a spatial phase modulator, processing apparatus, and information processing apparatus according to one embodiment of the present disclosure, the first alignment film and the second alignment film are configured such that the pre-tilt angle θt0 of the liquid crystal molecules satisfies 0° < θt0 ≤ 80°. This suppresses the rotation of the liquid crystal molecules in the azimuthal direction, thereby improving the efficiency of light utilization. The effects of the present disclosure are not necessarily limited to those described herein, but may be any of the effects described herein.

[0082] This application claims priority based on Japanese Patent Application No. 2021-123676, filed with the Japan Patent Office on 28 July 2021, and all contents of that application are incorporated herein by reference.

[0083] Those skilled in the art will understand that various modifications, combinations, subcombinations, and changes can be conceived depending on design requirements and other factors, and that these fall within the scope of the attached claims and their equivalents.

Claims

1. A spatial phase modulator that modulates the phase of light to generate a desired image, The laminate comprises a plurality of pixel electrodes arranged two-dimensionally in the row and column directions, a first alignment layer, a liquid crystal layer, a second alignment layer, and a common electrode, stacked in this order. The liquid crystal layer contains liquid crystal molecules having negative dielectric anisotropy. The first and second alignment films are composed of inorganic alignment films formed by oblique deposition, wherein the orientation direction of the liquid crystal molecules is either parallel to the row direction or parallel to the column direction, the pre-tilt angle θt0 of the liquid crystal molecules is in the anti-parallel direction, and the pre-tilt angle θt0 of the liquid crystal molecules is within a range where reverse tilt does not occur. Spatial phase modulator.

2. A processing apparatus using a spatial phase modulator that modulates the phase of light to generate a desired image, The spatial phase modulator is The laminate comprises a plurality of pixel electrodes arranged two-dimensionally in the row and column directions, a first alignment layer, a liquid crystal layer, a second alignment layer, and a common electrode, stacked in this order. The liquid crystal layer contains liquid crystal molecules having negative dielectric anisotropy. The first and second alignment films are composed of inorganic alignment films formed by oblique deposition, wherein the orientation direction of the liquid crystal molecules is either parallel to the row direction or parallel to the column direction, the pre-tilt angle θt0 of the liquid crystal molecules is in the anti-parallel direction, and the pre-tilt angle θt0 of the liquid crystal molecules is within a range where reverse tilt does not occur. Processing equipment.

3. An information processing device using one or more spatial phase modulators that modulate the phase of light to generate a desired image, The aforementioned spatial phase modulator is The laminate comprises a plurality of pixel electrodes arranged two-dimensionally in the row and column directions, a first alignment layer, a liquid crystal layer, a second alignment layer, and a common electrode, stacked in this order. The liquid crystal layer contains liquid crystal molecules having negative dielectric anisotropy. The first and second alignment films are composed of inorganic alignment films formed by oblique deposition, wherein the orientation direction of the liquid crystal molecules is either parallel to the row direction or parallel to the column direction, the pre-tilt angle θt0 of the liquid crystal molecules is in the anti-parallel direction, and the pre-tilt angle θt0 of the liquid crystal molecules is within a range where reverse tilt does not occur. Information processing device.

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