Light adjustment device

A light adjustment device includes a plurality of liquid crystal cells each including a light adjustment region that polarizes light emitted from a light source, the liquid crystal cells being stacked in a direction in which the light is emitted. The liquid crystal cells each include a first substrate in which a plurality of first metal wires are provided, and a second substrate in which a plurality of second metal wires are provided and that sandwiches a liquid crystal layer with the first substrate.

BACKGROUND

1. Technical Field

The present invention relates to a light adjustment device.

2. Description of the Related Art

In a conventional illumination instrument, a light source such as an LED is combined with a thin lens provided with a prism pattern, and the distance between the light source and the thin lens is changed to change a light distribution angle. In such an illumination instrument, a small-sized motor is used to drive the thin lens to change the distance between the light source and the thin lens. For example, in a disclosed illumination instrument, the front of a transparent light bulb is covered by a liquid crystal light adjustment element, and the transmittance of a liquid crystal layer is changed to switch directly reaching light and scattering light (refer to Japanese Patent Application Laid-open Publication No. H02-65001, for example).

In a configuration including a liquid crystal cell, electrodes are provided on two substrates sandwiching a liquid crystal layer, and the orientation of liquid crystal molecules is controlled by applying drive voltage between the electrodes provided on the two substrates. An alignment film is provided in a region in which electrodes are provided to control the orientation of liquid crystal molecules, but in its peripheral region, the liquid crystal molecules cannot be controlled and thus orientation disorder and light leakage occur, which potentially leads to degradation of a light modulation function.

The present invention is intended to provide a light modulation device that can prevent degradation of a light modulation function.

SUMMARY

A light adjustment device according to an embodiment of the present disclosure includes a plurality of liquid crystal cells each including a light adjustment region that polarizes light emitted from a light source, the liquid crystal cells being stacked in a direction in which the light is emitted. The liquid crystal cells each include a first substrate in which a plurality of first metal wires are provided, and a second substrate in which a plurality of second metal wires are provided and that sandwiches a liquid crystal layer with the first substrate, the first metal wires are provided at intervals in a wiring layer on the first substrate, the second metal wires are provided at intervals in a wiring layer on the second substrate, and across the entire surface of a peripheral region outside the light adjustment region of at least one of the liquid crystal cells, light is blocked at gaps between the first metal wires by the second metal wires in the direction in which the light is emitted, and light is blocked at gaps between the second metal wires by the first metal wires in the direction in which the light is emitted.

A light adjustment device according to an embodiment in which a plurality of liquid crystal cells each including a light adjustment region that polarizes light emitted from a light source are stacked in a direction in which light is emitted is disclosed. The liquid crystal cells each include a first substrate, and a second substrate sandwiching a liquid crystal layer with the first substrate, and across the entire surface of a peripheral region outside the light adjustment region of at least one of the liquid crystal cells, a light-shielding layer is provided on a substrate closer to a light emission target among the first and second substrates.

DETAILED DESCRIPTION

Aspects (embodiments) of the invention will be described below in detail with reference to the accompanying drawings. Contents described below in the embodiments do not limit the present invention. Components described below include those that could be easily thought of by the skilled person in the art and those identical in effect. Components described below may be combined as appropriate. What is disclosed herein is merely exemplary, and any modification that could be easily thought of by the skilled person in the art as appropriate without departing from the gist of the invention is contained in the scope of the present invention. For clearer description, the drawings are schematically illustrated for the width, thickness, shape, and the like of each component as compared to an actual aspect in some cases, but the drawings are merely exemplary and do not limit interpretation of the present invention. In the present specification and drawings, any element same as that already described with reference to an already described drawing is denoted by the same reference sign, and detailed description thereof is omitted as appropriate in some cases.

FIG.1is a perspective view illustrating an example of an illumination instrument in which a light adjustment device according to an embodiment is provided. First, a light adjustment device1according to the embodiment will be schematically described below.

As illustrated inFIG.1, the light adjustment device1of the present embodiment includes a first liquid crystal cell2and a second liquid crystal cell3.

An illumination instrument100includes the light adjustment device1and a light source4. The light source4emits light toward the light adjustment device1. The light source4is configured as, for example, a light emitting diode (LED).

InFIG.1, a direction on a plane of the light adjustment device1is defined as a Dx direction, and a direction orthogonal to the Dx direction on the plane of the light adjustment device1is defined as a Dy direction. A direction orthogonal to the Dx-Dy plane is defined as a Dz direction.

The Dz direction indicates the emission direction of light from the light source4. The illumination instrument100has a configuration in which the first liquid crystal cell2and the second liquid crystal cell3are stacked in the Dz direction. Hereinafter, a side where a radiation surface (or upper surface) through which light is radiated from the light adjustment device1in the Dz direction is positioned is also referred to as a radiation surface side (or upper surface side), and a side where a back surface (or lower surface) opposite the radiation surface (or upper surface) in the Dz direction is positioned is also referred to as an entrance surface side (or lower surface side).

An alignment film18and an alignment film19have rubbing directions different from each other as described later. The first liquid crystal cell2and the second liquid crystal cell3have the same configuration. In the present embodiment, the first liquid crystal cell2is a liquid crystal cell for p-wave polarized light. The second liquid crystal cell3is a liquid crystal cell for s-wave polarized light. Accordingly, flexible light adjustment control is possible. Note that the first liquid crystal cell2may be a liquid crystal cell for s-wave polarized light, and the second liquid crystal cell3may be a liquid crystal cell for p-wave polarized light. It suffices that one of the first liquid crystal cell2and the second liquid crystal cell3is a liquid crystal cell for p-wave polarized light and the other is a liquid crystal cell for s-wave polarized light.

The first liquid crystal cell2and the second liquid crystal cell3each include a first substrate5and a second substrate6.FIG.2is a schematic plan view of the first substrate when viewed in the Dz direction.FIG.3is a schematic plan view of the second substrate when viewed in the Dz direction.FIG.4is a perspective diagram of a liquid crystal cell in which the first substrate and the second substrate are placed over in the Dz direction.FIG.5is a sectional view along line A-A′ illustrated inFIG.4.

As illustrated inFIG.5, the first liquid crystal cell2and the second liquid crystal cell3each include a liquid crystal layer8between the first substrate5and the second substrate6, the liquid crystal layer8being circumferentially sealed by a sealing member7.

The liquid crystal layer8modulates light passing through the liquid crystal layer8in accordance with the state of an electric field. The liquid crystal layer8may be a horizontal electric field mode such as fringe field switching (FFS) as a form of in-plane switching (IPS) or may be a vertical electric field mode. For example, liquid crystals of various modes such as twisted nematic (TN), vertical alignment (VA), and electrically controlled birefringence (ECB) may be used and are not limited by the kind and configuration of the liquid crystal layer8.

As illustrated inFIG.2, a plurality of drive electrodes10aand10b, a plurality of metal wires11aand11bthat supply drive voltage applied to the drive electrodes10, and a plurality of metal wires11cand11dthat supply drive voltage applied to a plurality of drive electrodes13aand13b(refer toFIG.3) provided on the second substrate6to be described later are provided on the liquid crystal layer8side of a base material9of the first substrate5illustrated inFIG.5. The metal wires11a,11b,11c, and11dare provided in a wiring layer of the first substrate5. The metal wires11a,11b,11c, and11dare provided at intervals in the wiring layer on the first substrate5. Hereinafter, the drive electrodes10aand10bare also simply referred to as “drive electrodes10”. The metal wires11a,11b,11c, and11dare also referred to as “first metal wires11”. As illustrated inFIG.2, the drive electrodes10on the first substrate5extend in the Dx direction (first direction).

As illustrated inFIG.3, the drive electrodes13aand13band a plurality of metal wires14aand14bthat supply drive voltage applied to the drive electrodes13are provided on the liquid crystal layer8side of a base material12of the second substrate6illustrated in FIG. The metal wires14aand14bare provided in a wiring layer of the second substrate6. The metal wires14aand14bare provided at intervals in the wiring layer on the second substrate6. Hereinafter, the drive electrodes13aand13bare also simply referred to as “drive electrodes13”. The metal wires14aand14bare also referred to as “second metal wires14”. As illustrated inFIG.3, the drive electrodes13on the second substrate6extend in the Dy direction (second direction).

The drive electrodes10and13are translucent electrodes formed of a translucent conductive material (translucent conductive oxide) such as indium tin oxide (ITO). The first substrate5and the second substrate6are translucent substrates such as glass or resin. The first metal wires11and the second metal wires14are formed of at least one metallic material such as aluminum (Al), copper (Cu), silver (Ag), molybdenum (Mo), or an alloy thereof. The first metal wires11and the second metal wires14may be multilayered bodies of a plurality of stacked layers using one or more of these metallic materials. At least one metallic material such as aluminum (Al), copper (Cu), silver (Ag), molybdenum (Mo), or an alloy thereof has a lower resistance than translucent conductive oxide such as ITO.

The metal wire11aof the first substrate5and the metal wire14aof the second substrate6are coupled to each other through a conduction part15asuch as a via. The metal wire11dof the first substrate5and the metal wire14bof the second substrate6are coupled to each other through a conduction part15bsuch as a via.

Coupling (flex-on-board) terminal parts16aand16bthat are coupled to non-illustrated flexible printed circuits (FPCs) are provided in regions on the first substrate5, the regions not overlapping the second substrate6in the Dz direction. The coupling terminal parts16aand16beach include four coupling terminals corresponding to the metal wires11a,11b,11c, and11d, respectively.

The coupling terminal parts16aand16bare provided in the wiring layer of the first substrate5. Drive voltage to be applied to the drive electrodes10aand10bon the first substrate5and the drive electrodes13aand13bon the second substrate6is supplied to the first liquid crystal cell2and the second liquid crystal cell3from an FPC coupled to the coupling terminal part16aor16b. Hereinafter, the coupling terminal parts16aand16bare also simply referred to as “coupling terminal parts16”.

As illustrated inFIG.4, in the first liquid crystal cell2and the second liquid crystal cell3, the first substrate5and the second substrate6overlap each other in the Dz direction (light emission direction), and the drive electrodes10on the first substrate5intersect the drive electrodes13on the second substrate6when viewed in the Dz direction. In the first liquid crystal cell2and the second liquid crystal cell3thus configured, the orientation of liquid crystal molecules17in the liquid crystal layer8can be controlled by supplying drive voltage to the drive electrodes10on the first substrate5and the drive electrodes13on the second substrate6. A region in which the orientation of the liquid crystal molecules17in the liquid crystal layer8can be controlled is referred to as a “light adjustment region AA”. Light transmitting through the light adjustment region AA of the first liquid crystal cell2and the second liquid crystal cell3can be controlled by changing refractive index distribution of the liquid crystal layer8in the light adjustment region AA. A region in which the liquid crystal layer8is sealed by the sealing member7outside a light adjustment region200is referred to as a “peripheral region GA” (refer toFIG.5).

As illustrated inFIG.5, in the light adjustment region of the first substrate5, the drive electrodes10(inFIG.5, the drive electrode10a) are covered by the alignment film18. In the light adjustment region of the second substrate6, the drive electrodes13(inFIG.5, the drive electrodes13aand13b) are covered by the alignment film19. As described above, the alignment films18and19have rubbing directions different from each other.

FIG.6Ais a diagram illustrating the rubbing direction of the alignment film of the first substrate.FIG.6Bis a diagram illustrating the rubbing direction of the alignment film of the second substrate.

As illustrated inFIGS.6A and6B, the rubbing direction of the alignment film18of the first substrate and the rubbing direction of the alignment film19of the second substrate intersect each other in a plan view. Specifically, the rubbing direction of the alignment film18of the first substrate5illustrated inFIG.6Ais orthogonal to the direction in which the drive electrodes10aand10bextend. The rubbing direction of the alignment film19of the second substrate6illustrated inFIG.6Bis orthogonal to the direction in which the drive electrodes13aand13bextend.

Note that, in the present embodiment, as illustrated inFIG.2, the coupling terminal parts16aand16bin different orientations are provided in a region extending in the Dx direction and a region extending in the Dy direction, respectively, on the first substrate5in which the first substrate5and the second substrate6do not overlap each other in the Dz direction. Accordingly, FPCs can be coupled to the first liquid crystal cell2and the second liquid crystal cell3in different directions, which improves operability.

The illumination instrument100can be downsized when used with the light adjustment device1according to the present embodiment described above in the structure illustrated inFIG.1.

Although the present embodiment describes the configuration in which one first liquid crystal cell2for p-wave polarized light and one second liquid crystal cell3for s-wave polarized light are stacked, the present invention is not limited to the configuration, and for example, a plurality of combinations of stacked first liquid crystal cell2and second liquid crystal cell3may be provided. For example, two combinations of stacked first liquid crystal cell2and second liquid crystal cell3may be provided, in other words, two liquid crystal cells for p-wave polarized light and two liquid crystal cells for s-wave polarized light may be provided so that light adjustment control can be more flexibly performed.

First Embodiment

The peripheral region GA outside the light adjustment region AA is a region in which the above-described light adjustment control is impossible. Thus, orientation disorder of the liquid crystal molecules17occurs in the peripheral region GA outside the light adjustment region AA. The first metal wires11on the first substrate5and the second metal wires14on the second substrate6in the peripheral region GA provide more light shieldability than translucent conductive oxide such as ITO, but as illustrated inFIG.5, for example, light leakage occurs from the gaps between the first metal wires11on the first substrate5, which potentially leads to degradation of a light adjustment function.

FIG.7is a plan view of the peripheral region on a first substrate of a light adjustment device according to a first embodiment when viewed in the Dz direction.FIG.8is a plan view of the peripheral region on a second substrate of the light adjustment device according to the first embodiment when viewed in the Dz direction.FIG.9is a perspective diagram in which the first and second substrates of the light adjustment device according to the first embodiment are placed over in the Dz direction.FIG.10is a sectional view along line B-B′ illustrated inFIG.9. Note that, inFIGS.7,8, and9, illustration in the light adjustment region AA is omitted for simplification.

In the configuration of the first embodiment illustrated inFIGS.7,8,9, and10, as illustrated in the perspective diagram illustrated inFIG.9, across the entire surface of the peripheral region GA outside the light adjustment region AA, light is blocked at the gaps between the first metal wires11(metal wires11a,11b,11c, and11d) on a first substrate5aby the second metal wires14(metal wires14aand14b) on the second substrate6in the light emission direction (Dy direction). In addition, light is blocked at the gaps between the second metal wires14(metal wires14aand14b) on the second substrate6by the first metal wires11(metal wires11a,11b,11c, and11d) on the first substrate5ain the light emission direction (Dy direction). Accordingly, the first metal wires11on the first substrate5aare partially superimposed on the second metal wires14on the second substrate6in the Dz direction.

The widths of the first metal wires11on the first substrate5aand the second metal wires14on the second substrate6are, for example, approximately 10 [μm], and the widths of superimposition parts SP at which the first metal wires11on the first substrate5aand the second metal wires14on a second substrate6aare superimposed are, for example, approximately 5 [μm].

Note that, for example, when the widths of the first metal wires11on the first substrate5aand the second metal wires14on the second substrate6aare too large, an ESD problem such as electrostatic discharge failure is likely to occur. Thus, as illustrated in, for example,FIG.8, slits SL are desirably provided at the second metal wires14on the second substrate6a(the first metal wires11on the first substrate5a) to avoid the too large wire widths.

With such a configuration, light leakage attributable to orientation disorder of the liquid crystal molecules17can be prevented in the peripheral region GA outside the light adjustment region AA.

Note that, when a first liquid crystal cell2aand a second liquid crystal cell3aare stacked to constitute the light adjustment device1, the configuration of the first embodiment illustrated inFIGS.7,8,9, and10may be applied to at least one of the liquid crystal cells. More preferably, the configuration of the first embodiment illustrated inFIGS.7,8,9, and10is desirably applied to the second liquid crystal cell3acloser to a target object of light emission from the illumination instrument100. For example, in a configuration including a plurality of combinations of stacked first liquid crystal cell2aand second liquid crystal cell3a, the configuration of the first embodiment illustrated inFIGS.7,8,9, and10is desirably applied to a liquid crystal cell closer to a target object of light emission from the illumination instrument100.

With the above-described configuration of the first embodiment, light leakage attributable to orientation disorder of the liquid crystal molecules17can be prevented in the peripheral region GA outside the light adjustment region AA, and thus degradation of a light adjustment function can be prevented.

Second Embodiment

FIG.11is a plan view of the peripheral region on a second substrate of a light adjustment device according to a second embodiment when viewed in the Dz direction.FIG.12is a perspective diagram in which a first substrate and the second substrate of the light adjustment device according to the second embodiment are placed over in the Dz direction.FIG.13is a sectional view along line C-C′ illustrated inFIG.12. Note that, in the following description, any constituent component identical to that described above in the first embodiment is denoted by the same reference sign and duplicate description thereof is omitted, and any difference from the first embodiment will be described. InFIGS.11and12, illustration of the light adjustment region AA is omitted for simplification.

In the configuration of the second embodiment illustrated inFIGS.11,12, and13, a light-shielding layer20is provided on a second substrate6bacross the entire surface of the peripheral region GA outside the light adjustment region AA.

The light-shielding layer20is provided on the liquid crystal layer8side of a base material12aof the second substrate6b. The liquid crystal layer8side of the base material12aof the second substrate6bon which the light-shielding layer20is provided is covered by a flattening film21. The flattening film21is, for example, a resin insulating film made of an organic material. The drive electrodes13and the second metal wires14are provided on the liquid crystal layer8side of the flattening film21.

The light-shielding layer20is made of, for example, a black resin material. The light-shielding layer20is not limited to a black resin material but may be made of, for example, a metallic material having light shieldability.

With such a configuration, light leakage attributable to orientation disorder of the liquid crystal molecules17can be prevented in the peripheral region GA outside the light adjustment region AA.

Note that, when a first liquid crystal cell2band a second liquid crystal cell3bare stacked to constitute the light adjustment device1, the configuration of the second embodiment illustrated inFIGS.11,12, and13may be applied to at least one of the liquid crystal cells. More preferably, the configuration of the first embodiment illustrated inFIGS.11,12, and13is desirably applied to the second liquid crystal cell3bcloser to a target object of light emission from the illumination instrument100. For example, in a configuration including a plurality of combinations of stacked first liquid crystal cell2band second liquid crystal cell3b, the configuration of the second embodiment illustrated inFIGS.11,12, and13is desirably applied to a liquid crystal cell closer to a target object of light emission from the illumination instrument100.

With the above-described configuration of the second embodiment, light leakage attributable to orientation disorder of the liquid crystal molecules17can be prevented in the peripheral region GA outside the light adjustment region AA, and thus degradation of a light adjustment function can be prevented.

Preferable embodiments of the present disclosure are described above, but the present disclosure is not limited to such embodiments. Contents disclosed in the embodiments are merely exemplary, and various kinds of modifications are possible without departing from the scope of the present disclosure. Any modification performed as appropriate without departing from the scope of the present disclosure belongs to the technical scope of the present disclosure.