Display device capable of multi-depth expression

Abstract

A display device capable of multi-depth expression is provided, which includes: an image forming device configured to form an image; an optical system configured to provide an output image by combining light containing an external scenery with an image formed by the image forming device; and a drive device configured to adjust the distance between the image forming device and the optical system, wherein the drive device includes: a fixed frame; a movable frame facing the fixed frame and being movable; an actuator configured to change the distance between the fixed frame and the movable frame; and a fixing member configured to fix the distance between the fixed frame and the movable frame, wherein the image forming device is fixed to the movable frame.

Description

Technical Field

[0001] Example embodiments of the present disclosure relate to a display device capable of multi-depth expression, and more particularly, to a display device capable of multi-depth expression and configured to reduce power consumption in a depth retention state. Background Art

[0002] The 3D image display technology has been used in various fields, and recently, the application of the 3D image display technology has also been extended to image devices related to virtual reality (VR) displays and augmented reality (AR) displays.

[0003] Head-mounted displays that provide VR are already commercially available and widely used in the entertainment industry. In addition, head-mounted displays have been developed into types suitable for use in the fields of medical, education, and other industries.

[0004] AR displays, as an advanced form of VR displays, are image devices that combine the real world with VR and enable interaction between reality and VR. The interaction between reality and VR is based on the function of providing real-time information about real situations, and further enhancing the effect of reality by superimposing virtual objects or information on the real world environment.

[0005] In these devices, stereoscopic technology is generally used to display three-dimensional (3D) images, and in this case, alignment of a display with an optical system may be a problem in the process of changing the distance between the display and the optical system for multi-depth expression. Therefore, attempts are made to find a 3D image display method for more precise alignment between the display and the optical system. Summary of the invention

[0006] One or more example embodiments provide a display device capable of multi-depth expression and having an actuator structure for reducing power consumption in a depth hold state.

[0007] Additional aspects will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of example embodiments of the disclosure.

[0008] According to one aspect of an example embodiment, a display device is provided, comprising: an image forming device configured to form an image; an optical system configured to provide an output image by combining light containing an external scenery with an image formed by the image forming device; and a driving device configured to adjust a distance between the image forming device and the optical system, wherein the driving device comprises: a fixed frame; a movable frame facing the fixed frame and being movable; an actuator configured to change a distance between the fixed frame and the movable frame; and a fixing member configured to fix a distance between the fixed frame and the movable frame, wherein the image forming device is fixed to the movable frame.

[0009] The actuator may include: a first elastic bridge having a curved surface protruding toward a fixed frame; a second elastic bridge having a curved surface protruding toward a movable frame; and a first variable length element fixed between both ends of the first elastic bridge and between both ends of the second elastic bridge and having a variable length.

[0010] The first variable length element may include a shape memory alloy or an electroactive polymer, and the length of the first variable length element may be changed based on electrical control.

[0011] The first elastic bridge may have an elastic restoring force in a direction in which a radius of curvature of the first elastic bridge increases, and a central portion of the first elastic bridge is fixed to the fixing frame.

[0012] The second elastic bridge may have an elastic restoring force in a direction in which a radius of curvature of the second elastic bridge increases, and a central portion of the second elastic bridge is fixed to the movable frame.

[0013] The fixing member may include a pair of side frames respectively fixed to opposite side edges of the fixing frame.

[0014] The pair of side frames may extend from the fixed frame toward the movable frame, and the pair of side frames may have fixed ends fixed to the fixed frame and free ends opposite to the fixed ends.

[0015] The pair of side frames may include a plurality of protrusions protruding from surfaces of the free ends and provided at different distances from the fixed frame, the plurality of protrusions being configured to contact opposite sides of the movable frame and inhibit movement of the movable frame.

[0016] The pair of side frames may be configured such that free ends of the pair of side frames facing each other move away from each other when the distance between the fixed frame and the movable frame changes, and move toward each other when the distance between the fixed frame and the movable frame is maintained.

[0017] A pair of side frames may include bimetallic elements or piezoelectric elements that bend or stretch respectively based on temperature control or electrical control, and the pair of side frames may bend when the distance between the fixed frame and the movable frame changes, and may stretch when the distance between the fixed frame and the movable frame is maintained.

[0018] The fixed member may also include a second variable length element fixed between the fixed end and the free end and having a variable length, a pair of side frames may have an elastic restoring force in the direction in which the free ends face each other, and the second variable length element fixed between the fixed end and the free end may shrink based on the change in the distance between the fixed frame and the movable frame.

[0019] The fixed member may include: a pair of first rods configured to rotate and provided at two side edges of the fixed frame; and a pair of second rods configured to rotate and provided at two side edges of the movable frame, wherein ends of the pair of first rods and ends of the pair of second rods are configured to contact each other and interfere with each other, and ends of the pair of second rods correspond to ends of the pair of first rods.

[0020] The fixing member may be configured to switch between a first state in which a pair of first rods and a pair of second rods corresponding to the pair of first rods are fixed in a straight line with each other and a second state in which a pair of first rods and a pair of second rods corresponding to the pair of first rods are fixed at an inclined angle relative to each other.

[0021] The fixing member may switch from the second state to the first state based on an increase in the distance between the fixing frame and the movable frame, and switch from the first state to the second state based on a decrease in the distance between the fixing frame and the movable frame.

[0022] The ends of a pair of first rods may include a recess and a blocking member surrounding the recess, wherein the width of each of the ends of a pair of second rods is smaller than the width of each of the recesses, and each of the ends of a pair of second rods is provided in each of the recesses, wherein the fixing member is configured so that the ends of the pair of second rods contact the bottom surface of the recess in a first state and contact the inner wall of the blocking member in a second state.

[0023] The ends of a pair of second rods may include a recess and a blocking member surrounding the recess, wherein the width of each of the ends of a pair of first rods is smaller than the width of each of the recesses, and each of the ends of a pair of first rods is provided in each of the recesses, wherein the fixing member is configured so that the ends of the pair of first rods contact the bottom surface of the recess in a first state and contact the inner wall of the blocking member in a second state.

[0024] The fixing member may further include a second variable length element, which is respectively connected between the two side edges of the fixing frame and the ends of a pair of first rods and has a variable length respectively. The second variable length elements respectively connected between the two side edges of the fixing frame and the ends of the pair of first rods can be contracted based on the fixing member switching from the first state to the second state.

[0025] The fixed member may further include a second variable length element, which is respectively connected between the two side edges of the movable frame and the ends of a pair of second rods and has a variable length. The second variable length elements respectively connected between the two side edges of the movable frame and the ends of the pair of second rods can be contracted based on the fixing member switching from the first state to the second state.

[0026] The ends of a pair of first rods and the ends of a pair of second rods can have complementary shapes and are configured to engage with each other, and the ends of the pair of second rods correspond to the ends of the pair of first rods, wherein the fixing member can also include a second variable length element, the second variable length elements are respectively connected between the two side edges of the movable frame and the ends of the pair of second rods and have variable lengths respectively, and wherein the second variable length elements respectively connected between the two side edges of the movable frame and the ends of the pair of second rods can be contracted based on the fixing member switching from the first state to the second state.

[0027] The fixed member may include: a pair of first rods configured to rotate and provided at two side edges of the fixed frame; and a pair of second rods configured to rotate and provided at two side edges of the movable frame, wherein ends of the pair of first rods and ends of the pair of second rods are configured to contact each other and interfere with each other, and ends of the pair of second rods correspond to ends of the pair of first rods.

[0028] The actuator may include: first variable length elements connected between the fixed frame and the inner side surfaces of the pair of first rods and having variable lengths respectively; and second variable length elements connected between the fixed frame and the outer side surfaces of the pair of first rods and having variable lengths respectively.

[0029] The fixing member can be configured to switch between a first state and a second state, in which a pair of first rods and a pair of second rods corresponding to the pair of first rods are fixed in a straight line with each other, and a second state in which a pair of first rods and a pair of second rods corresponding to the pair of first rods are fixed at an inclined angle relative to each other, wherein based on an increase in the distance between the fixed frame and the movable frame, the first variable length element is shortened and the second variable length element is elongated to switch the fixing member from the second state to the first state, and based on a decrease in the distance between the fixed frame and the movable frame, the first variable length element is elongated and the second variable length element is shortened to switch the fixing member from the first state to the second state.

[0030] The actuator may include: a first variable length element connected between the movable frame and the inner side surfaces of the pair of second rods and having variable lengths respectively; and a second variable length element connected between the movable frame and the outer side surfaces of the pair of second rods and having variable lengths respectively.

[0031] The display apparatus may further include a processor configured to determine a distance between the image forming device and the optical system based on depth information of an image to be displayed, and to control the driving device.

[0032] The display device may be a virtual reality (VR), augmented reality (AR), or mixed reality (MR) display device implemented as a head-mounted device, a glasses-type device, or a goggle-type device.

[0033] According to another aspect of an example embodiment, a display device is provided, comprising: an image forming device configured to form an image; an optical system configured to combine the image formed by the image forming device with light provided from outside the display device to provide an output image; and a driving device configured to change the distance between the image forming device and the optical system, wherein the driving device comprises: a fixed frame; a movable frame facing the fixed frame and being movable; an actuator configured to control the distance between the fixed frame and the movable frame based on an applied voltage; and a fixing member configured to fix the distance between the fixed frame and the movable frame.

[0034] When the distance between the fixed frame and the movable frame changes, a voltage is applied, and when the distance between the fixed frame and the movable frame is maintained, no voltage is applied. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The above and / or other aspects, features and advantages of example embodiments will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:

[0036] Figure 1 is a diagram schematically illustrating a structure and operation of a display device according to an example embodiment;

[0037] Figure 2A and Figure 2B is a view schematically showing a structure and operation of a driving device according to an example embodiment;

[0038] Figure 3A and Figure 3B is a view schematically illustrating a structure and operation of a fixing member according to another example embodiment;

[0039] Figure 4A and Figure 4B is a view schematically illustrating a structure and operation of a driving device according to another example embodiment;

[0040] Figure 5A and Figure 5B is a view schematically illustrating a structure and operation of a driving device according to another example embodiment;

[0041] Fig. 6A and Figure 6B is a view schematically illustrating a structure and operation of a driving device according to another example embodiment;

[0042] Fig. 7A and Figure 7B is a view schematically illustrating a structure and operation of a driving device according to another example embodiment;

[0043] Fig. 8A and Figure 8B is a view schematically illustrating a structure and operation of a driving device according to another example embodiment;

[0044] Fig. 9 is a view schematically showing a structure of a display device according to another example embodiment;

[0045] Fig.10 is a view schematically showing a structure of a display device according to another example embodiment;

[0046] Fig.11 is a diagram schematically illustrating a structure and operation of a display device according to another example embodiment; and

[0047] Fig.12 is a view schematically illustrating structures of an image forming device and a driving device of a display apparatus according to another example embodiment. DETAILED DESCRIPTION

[0048] Reference will now be made in detail to the example embodiments shown in the accompanying drawings, in which the same reference numerals always refer to the same elements. In this regard, the example embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Therefore, aspects are explained below by describing only the example embodiments with reference to the accompanying drawings. When used herein, the term "and / or" includes any and all combinations of one or more related listed items. Statements such as "at least one of ..." modify the entire column of elements when following a column of elements, without modifying the individual elements in the column. For example, the statement "at least one of a, b, and c" should be understood to include only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c.

[0049] Hereinafter, a display device capable of multi-depth expression will be described with reference to the accompanying drawings. In the accompanying drawings, the same reference numerals refer to the same elements, and the sizes of the elements may be exaggerated for clarity of illustration. The example embodiments described herein are for illustrative purposes only, and various modifications may be made thereto. In the following description, when an element is referred to as being "above" or "on" another element in a hierarchical structure, it may be directly on the upper side, lower side, left side, or right side of the other element while in contact with the other element, or may be on the upper side, lower side, left side, or right side of the other element without contacting the other element.

[0050] Figure 1 is a schematic diagram schematically illustrating the structure and operation of a display device 100 according to an example embodiment. Figure 1 The display device 100 of this example embodiment may include: an image forming device 110 configured to form an image; a combiner member 130, such as a lighting system, an optical system, or an optical device, configured to provide an image formed by the image forming device 110 together with light containing an external landscape and propagating from the external landscape; a drive device 120 configured to adjust a distance between the image forming device 110 and the combiner member 130; and a processor 140 configured to control the image forming device 110 and the drive device 120 according to information about the depth of the image to be displayed.

[0051] The image forming device 110 forms an image by modulating light according to information about an image to be provided to a viewer. The image formed by the image forming device 110 may be, for example, a stereoscopic image, a holographic image, a light field image, or an integrated photography (IP) image provided to the left and right eyes of the viewer, respectively, and may include a multi-view image or a super multi-view image. In addition, the image formed by the image forming device 110 may be a general two-dimensional image, but the embodiment is not limited thereto.

[0052] For example, the image forming device 110 may include a liquid crystal on silicon (LCoS) device, a liquid crystal display (LCD) device, an organic light emitting diode (OLED) display device, or a digital micromirror device (DMD). In addition, the image forming device 110 may include a next generation display device such as a micro LED display device or a quantum dot (QD) LED display device. When the image forming device 110 is a self-emitting display device such as an OLED display device or a micro LED, the image forming device 110 may include only one display panel. When the image forming device 110 is a non-emitting display device such as an LCoS device or an LCD device, the image forming device 110 may also include a light source configured to provide illumination light and a beam splitter configured to adjust the path of the illumination light.

[0053] The combiner member 130 may change the path of the image formed by the image forming device 110 and output the image so that the image may have a size suitable for the viewer's field of view and may be transmitted to the viewer's eyes. The combiner member 130 may include a focusing optical system 131, and may also include a beam splitter 132 configured to change the path of light by splitting the light. The focusing optical system 131 may be an imaging member having a refractive power and configured to magnify or reduce the image formed by the image forming device 110. Figure 1 In the embodiment, the focusing optical system 131 is shown as a concave mirror, but the embodiment is not limited thereto. For example, the focusing optical system 131 may be provided as a combination of a convex lens, a concave lens, etc.

[0054] The beam splitter 132 may be a half mirror that transmits a portion of the incident light and reflects another portion of the incident light. However, embodiments are not limited thereto. For example, the beam splitter 132 may be a polarization beam splitter that transmits or reflects the incident light according to the polarization of the incident light. When the beam splitter 132 is a polarization beam splitter, an additional optical element for polarization conversion may be further included in the combiner member 130.

[0055] like Figure 1 As shown, the combiner member 130 may have an integrated structure in which the focusing optical system 131 and the beam splitter 132 are fixed by a transparent light guide plate 133. For example, the beam splitter 132 may be arranged inside the light guide plate 133 in a diagonal direction, and the end of the light guide plate 133 may have a convex curved surface. By coating the convex curved surface of the light guide plate 133 with a reflective film, a concave mirror may be formed on the end of the light guide plate 133. In this example embodiment, the image formed by the image forming device 110 enters the interior of the light guide plate 133 through the light entry surface of the light guide plate 133. Thereafter, the image may be transmitted through the beam splitter 132, magnified and reflected by the focusing optical system 131, and then reflected by the beam splitter 132 onto the eyes of the viewer. However, this is an example, and the structure of the combiner member 130 is not limited thereto.

[0056] The combiner member 130 can not only transmit the light L10 containing the image formed by the image forming device 110 to the eyes of the viewer, but also transmit the light L20 containing the front external scenery and propagating from the front external scenery to the eyes of the viewer. For example, the light guide plate 133 and the beam splitter 132 of the combiner member 130 can be configured to transmit the light L20 containing the external scenery and propagating from the external scenery. The light L20 propagating from the outside does not contain an artificial image displayed by a separate display device, but contains an actual foreground existing in front of the viewer. Therefore, the viewer can simultaneously recognize the actual foreground and the virtual image artificially generated by the image forming device 110. Therefore, the display device 100 can be used as a perspective display. In this regard, the display device 100 of this example embodiment can be used to realize augmented reality (AR) or mixed reality (MR). For example, the display device 100 of this example embodiment can be a near-eye AR display device.

[0057] The combiner member 130 is not limited to the shape and structure shown. Additional optical elements may be further provided to transmit the image formed by the image forming device 110 to the pupil of the viewer together with the real environment image in front of the viewer, and optical windows having various shapes and structures may be adopted.

[0058] As described above, the image formed by the image forming device 110 reaches the eyes of the viewer along a propagation path in which the image is transmitted through the beam splitter 132, reflected by the focusing optical system 131, and then reflected by the beam splitter 132. In the propagation path, the viewer recognizes a virtual image formed on the virtual image plane VP at a position in front of the viewer, and the depth of the virtual image recognized by the viewer varies depending on the position of the virtual image plane VP.

[0059] The display device 100 of this example embodiment can change the position of the virtual image plane VP to reflect the depth of the image to be displayed, rather than fixing the position of the virtual image plane VP. To this end, the display device 100 may include a drive device 120 configured to change the position of the image forming device 110. The drive device 120 can move the image forming device 110 in parallel so that the distance between the image forming device 110 and the focusing optical system 131 of the combiner member 130 can be changed. Then, when the position of the image forming device 110 is changed in the direction A1, the position of the virtual image plane VP can be changed in the direction A2. For example, when the image forming device 110 moves away from the focusing optical system 131 of the combiner member 130, the depth of the image perceived by the viewer can increase by an amount from the virtual image plane VP to the virtual image plane VP'.

[0060] The processor 140 may generate a light modulation signal SG1 and a drive signal SG2 to be sent to the image forming device 110 and the drive device 120, respectively, based on information about an image to be recognized by a viewer. The image forming device 110 and the drive device 120 may be controlled by the light modulation signal SG1 and the drive signal SG2 generated by the processor 140, respectively. For example, the image forming device 110 forms an image based on the light modulation signal SG1 provided from the processor 140. In addition, the drive device 120 adjusts the position of the image forming device 110 based on the drive signal SG2 provided from the processor 140, so that the virtual image plane VP can be positioned according to the depth of the image formed by the image forming device 110. To this end, the processor 140 may generate the drive signal SG2 by determining the distance between the image forming device 110 and the combiner member 130 based on information about the depth of the image included in the light modulation signal SG1 to be sent to the image forming device 110.

[0061] For each of a plurality of frame images to be provided to a viewer, the image information may include pixel-specific data related to color values ​​of a plurality of pixels and depth information associated with the position of a virtual image plane VP on which the image is to be formed, respectively. The processor 140 may generate an electrical signal for realizing a color value determined by referring to the pixel-specific data included in the image information as a light modulation signal SG1. In addition, the processor 140 may generate a drive signal SG2 to position the image forming device 110 so that the virtual image plane VP may be formed at a position corresponding to a representative depth value set with reference to the depth information. When the light modulation signal SG1 and the drive signal SG2 generated by the processor 140 are sent to the image forming device 110 and the drive device 120, respectively, the viewer may recognize the image from the position of the virtual image plane VP corresponding to the depth of the image.

[0062] In addition, the drive signal SG2 for driving the drive device 120 may be transmitted after a predetermined delay time from the transmission time of the light modulation signal SG1. For example, the predetermined delay time may be set to be greater than the convergence adjustment time of the viewer's eyes, which is the time required for the human eye to perceive an image at a changed depth position.

[0063] The driving device 120 employed in the display apparatus 100 of this example embodiment may include a shape-variable material to widen the position driving range of the image forming device 110 while minimizing the volume of the driving device 120. For example, the driving device 120 may move the image forming device 110 while changing its shape according to a signal applied to the driving device 120. For such a variable shape, the driving device 120 may include a material whose shape changes under certain conditions. For example, Figure 2A and Figure 2B2 is a view schematically illustrating a structure and operation of a driving device 120 according to an example embodiment.

[0064] Reference Figure 2A , the driving device 120 may include: a fixed frame 11, fixed to the inside of the display device 100; a movable frame 12, arranged to face the fixed frame 11 and be movable; an actuator 20, configured to change the distance between the fixed frame 11 and the movable frame 12; and a fixing member 30, configured to fix the distance between the fixed frame 11 and the movable frame 12. The fixed frame 11 and the movable frame 12 may have a flat plate shape parallel to each other. The movable frame 12 may be configured to be movable in a direction perpendicular to a surface facing the fixed frame 11. In addition, the driving device 120 may further include a driving circuit for applying a driving voltage to the actuator 20 under the control of the processor 140.

[0065] The image forming device 110 may be fixed to a lower surface of the movable frame 12, and may face a light entrance surface of the combiner member 130. For example, the image forming device 110 may be a display panel of a self-emissive display device.

[0066] The actuator 20 may be configured to move the movable frame 12 to change the distance between the fixed frame 11 and the movable frame 12. For example, the actuator 20 may include: a first elastic bridge 21 having a curved surface convex toward the fixed frame 11; a second elastic bridge 22 having a curved surface convex toward the movable frame 12; and a variable length element 23 fixed between both ends of the first elastic bridge 21 and both ends of the second elastic bridge 22 and having a variable length.

[0067] The first elastic bridge 21 and the second elastic bridge 22 may include a plate-shaped elastic material such as metal or plastic. Since both ends of the first elastic bridge 21 and the second elastic bridge 22 are respectively fixed to a variable length element 23 shorter than the length of the first elastic bridge 21 and the length of the second elastic bridge 22, the first elastic bridge 21 and the second elastic bridge 22 may be bent into an arc shape by the variable length element 23. Therefore, each of the first elastic bridge 21 and the second elastic bridge 22 has an elastic restoring force in a direction in which its radius of curvature increases. The convex center portion of the first elastic bridge 21 may be fixed to the lower surface of the fixed frame 11, for example, by using a fixing plate 24. In addition, the convex center portion of the second elastic bridge 22 may be fixed to the upper surface of the movable frame 12, for example, by using a fixing plate 25. Then, when the first elastic bridge 21 and the second elastic bridge 22 are elastically deformed, the convex center portion of the first elastic bridge 21 may not move on the lower surface of the fixed frame 11, and the convex center portion of the second elastic bridge 22 may not move on the upper surface of the movable frame 12.

[0068] Variable length element 23 can be configured to change length by electrical control.For example, variable length element 23 can include the material that is variable and forms predetermined shape by certain driving signal, such as shape memory alloy (SMA) or electroactive polymer.SMA can include for example nickel titanium (Ni-Ti) alloy, copper zinc (Cu-Zn) alloy, gold cadmium (Au-Cd) alloy, indium titanium (In-Ti) alloy etc.In this case, when driving voltage is applied to variable length element 23, heat can be generated in variable length element 23, and variable length element 23 can shrink due to heat.In addition, when driving voltage is not applied to variable length element 23, variable length element 23 can extend to its original length.

[0069] The fixing member 30 that fixes the distance between the fixed frame 11 and the movable frame 12 while preventing the movable frame 12 from moving may include, for example, a pair of side frames 13a respectively fixed to both side edges of the fixed frame 11. Each of the pair of side frames 13a may include a plate-shaped elastic material extending in a direction from the fixed frame 11 toward the movable frame 12. In addition, the pair of side frames 13a may include a fixed end fixed to the fixed frame 11 and a free end opposite to the fixed end. The free ends of the pair of side frames 13a may face both sides of the movable frame 12.

[0070] In addition, the pair of side frames 13a may include a plurality of first protrusions 13b and a second protrusion 13c protruding from the surface of the free end so that the first protrusions 13b and the second protrusions 13c can contact both sides of the movable frame 12 to inhibit the movable frame 12 from moving. The first protrusions 13b and the second protrusions 13c may be located at different distances from the fixed frame 11 in the direction from the fixed frame 11 toward the movable frame 12. For example, the first protrusion 13b may be arranged at a first distance from the fixed frame 11, and the second protrusion 13c may be arranged at a second distance from the fixed frame 11, the second distance being greater than the first distance. Therefore, when both sides of the movable frame 12 contact the first protrusions 13b, the movable frame 12 may be fixed at the first distance from the fixed frame 11, and when both sides of the movable frame 12 contact the second protrusions 13c, the movable frame 12 may be fixed at the second distance from the fixed frame 11.

[0071] In the initial state, the variable length element 23 may not be contracted. Figure 2AAs shown, both sides of the movable frame 12 can be located between the first protrusion 13b and the second protrusion 13c. Because of the elastic restoring force of the first elastic bridge 21 and the second elastic bridge 22, the movable frame 12 can be forced to move toward the fixed frame 11. Therefore, both sides of the movable frame 12 are in contact with the first protrusion 13b, and due to the first protrusion 13b, it does not move further toward the fixed frame 11, so that the position of the movable frame 12 is fixed. Then, the image forming device 110 fixed to the movable frame 12 is also fixed at a relatively far position from the combiner member 130.

[0072] When the driving device 120 applies a driving voltage to the variable length element 23 under the control of the processor 140, the variable length element 23 contracts so that both ends of the first elastic bridge 21 can be pulled close to each other, and both ends of the second elastic bridge 22 can be pulled close to each other. Then, due to the contraction force of the variable length element 23, the curvature radius of the first elastic bridge 21 and the curvature radius of the second elastic bridge 22 are reduced. Therefore, the movable frame 12 can be forced to move away from the fixed frame 11.

[0073] In this case, the free ends of a pair of side frames 13a are driven away from each other. To this end, the pair of side frames 13a may include a bimetallic element or a piezoelectric element that is bendable or extendable by temperature control or electrical control. For example, the pair of side frames 13a may be bent into a curved shape when a driving voltage is applied thereto, and may be stretched into a straight shape when the driving voltage is not applied thereto. In this case, when the distance between the fixed frame 11 and the movable frame 12 changes, the driving device 120 may apply a driving voltage to the pair of side frames 13a under the control of the processor 140 to bend the pair of side frames 13a, so that the free ends of the pair of side frames 13a facing each other may move away from each other, as shown in FIG. Figure 2B Then, the movable frame 12 moves away from the fixed frame 11 while being pushed by the second elastic bridge 22 .

[0074] Thereafter, when the movable frame 12 passes the position of the second protrusion 13c, the driving device 120 stops applying the driving voltage to the variable length element 23 and the driving voltage to the pair of side frames 13a under the control of the processor 140. As a result, the pair of side frames 13a stretch into a straight shape, and the free ends of the pair of side frames 13a become close to each other. In addition, due to the elastic restoring force of the first elastic bridge 21 and the second elastic bridge 22, the movable frame 12 can be forced to move toward the fixed frame 11. Therefore, both sides of the movable frame 12 are in contact with the second protrusion 13c and do not move further toward the fixed frame 11 due to the second protrusion 13c, so that the position of the movable frame 12 is fixed. Then, as shown in Figure 2BAs shown, the image forming device 110 fixed to the movable frame 12 is fixed at a position larger than Figure 2A The position shown is closer to the combiner member 130 .

[0075] When the image forming device 110 is Figure 2B Move back to the position shown Figure 2A When the movable frame 12 is in the position shown in the figure, the driving device 120 applies the driving voltage only to the pair of side frames 13a under the control of the processor 140. Then, as the pair of side frames 13a bend, the free ends of the pair of side frames 13a move away from each other. At this time, due to the elastic restoring force of the first elastic bridge 21 and the second elastic bridge 22, the movable frame 12 can be forced to move toward the fixed frame 11. Then, when the movable frame 12 passes the position of the second protrusion 13c, the driving device 120 stops applying the driving voltage to the pair of side frames 13a. As a result, as the pair of side frames 13a stretch into a straight shape, the two side surfaces of the movable frame 12 are stuck by the first protrusion 13b.

[0076] As described above, the pair of side frames 13a are operated in a bent state having a bent shape when the distance between the fixed frame 11 and the movable frame 12 is changed, and in a straight state when the distance between the fixed frame 11 and the movable frame 12 is maintained. Therefore, when the distance between the fixed frame 11 and the movable frame 12 is changed, the free ends of the pair of side frames 13a facing each other move away from each other, thereby allowing the movable frame 12 to move. When the distance between the fixed frame 11 and the movable frame 12 is maintained, the free ends of the pair of side frames 13a facing each other become closer to each other than in the bent state, so that the fixed frame 11 is caught by the first protrusion 13b or the second protrusion 13c and may not move.

[0077] In addition, when the image forming device 110 is Figure 2A Move to the position shown Figure 2B When the image forming device 110 is in the position shown in FIG. Figure 2B Move to the position shown Figure 2A When the image forming device 110 is fixed in the position shown in FIG. Figure 2A The location shown or Figure 2B While in the position shown, no voltage is applied to both the variable length member 23 and the pair of side frames 13a.

[0078] Therefore, in the display device 100 of this exemplary embodiment, power is consumed only when the position of the image forming device 110 is changed to change the depth of the image viewed by the viewer. When the depth of the image is maintained, power is not consumed because the position of the image forming device 110 is fixed using the fixing member 30. Therefore, according to this exemplary embodiment, the power consumption of the display device 100 can be reduced when the depth of the image is maintained.

[0079] Meanwhile, the pair of side frames 13a is not limited to the bimetallic element or the piezoelectric element. For example, Figure 3A and Figure 3B is a view schematically showing the structure and operation of a fixing member 30 according to another exemplary embodiment. Figure 3A and Figure 3B , the fixing member 30 may further include a variable length element 26 fixed between the free ends and the fixed ends of the pair of side frames 13a. In this case, each of the pair of side frames 13a may include a plate-like material having an elastic restoring force, such as metal or plastic. For example, each of the pair of side frames 13a may have an elastic restoring force in the direction in which the pair of side frames 13a extend. For example, the pair of side frames 13a may have an elastic restoring force in the direction in which the free ends of the pair of side frames 13a facing each other approach each other.

[0080] When the distance between the fixed frame 11 and the movable frame 12 is changed, the driving device 120 applies a driving voltage to the variable length element 26 under the control of the processor 140 to cause the variable length element 26 to contract, such as Figure 3A Then, the free ends of the pair of side frames 13a move away from each other while being bent. When the distance between the fixed frame 11 and the movable frame 12 is maintained, the driving voltage is not applied to the variable length element 26, as shown in FIG. Figure 3B Then, the length of the variable length member 26 increases, and the pair of side frames 13a are straightened due to their elastic restoring force. Therefore, the free ends of the pair of side frames 13a become closer to each other than when they are bent.

[0081] Figure 4A and Figure 4B Schematically illustrates the structure and operation of a driving device 120a according to another exemplary embodiment. Figure 4A and Figure 4B The driving device 120a may include: a fixed frame 11, fixed to the inside of the display device 100; a movable frame 12, arranged to face the fixed frame 11 and be movable; an actuator 20, configured to change the distance between the fixed frame 11 and the movable frame 12; and a fixing member 40, configured to fix the distance between the fixed frame 11 and the movable frame 12. Figure 4A and Figure 4BThe driving device 120a shown is different from the fixing member 40 in terms of the structure of the fixing member 40. Figure 2A and Figure 2B A drive device 120 is shown.

[0082] The fixing member 40 may include a pair of first rods 31 rotatably arranged at both side edges of the fixed frame 11, and a pair of second rods 32 rotatably arranged at both side edges of the movable frame 12. For example, the pair of first rods 31 may be rotatably fixed to the lower surface of the fixed frame 11 via hinges 33, and the pair of second rods 32 may be rotatably fixed to the upper surface of the movable frame 12 via hinges 34.

[0083] In order to adjust the distance between the fixed frame 11 and the movable frame 12, the ends of a pair of first rods 31 and the corresponding ends of a pair of second rods 32 can be configured to contact each other and interfere with each other. For example, the ends of a pair of first rods 31 may include a recess 31a and a stopper 31b around the recess 31a. In addition, the ends of a pair of second rods 32 may be placed in the recess 31a corresponding to the pair of first rods 31. The width of the ends of a pair of second rods 32 may be respectively less than the width of the recess 31a corresponding to the pair of first rods 31, so that the ends of a pair of second rods 32 can move within a predetermined range inside the recess 31a. That is, in the recess 31a, there may be a predetermined gap between the ends of a pair of second rods 32 and the stopper 31b. The recess 31a and the ends of a pair of second rods 32 may have a straight shape, but are not limited thereto, and may have, for example, a circular or polygonal shape. For example, the recess 31a may be provided in the form of a circular hollow cylinder or a polygonal hollow cylinder, and the ends of the pair of second rods 32 may be provided in the form of a cylindrical column or a polygonal solid column.

[0084] exist Figure 4A and Figure 4B In the embodiment, the recess 31a and the stopper 31b are formed at the pair of first rods 31, but the embodiment is not limited thereto. In another example embodiment, the recess 31a and the stopper 31b may be formed at the pair of second rods 32 instead of the pair of first rods 31.

[0085] The fixing member 40 may have a first state in which the pair of first rods 31 and the pair of second rods 32 corresponding to the pair of first rods 31 are fixed in a straight line with each other, and a second state in which the pair of first rods 31 and the pair of second rods 32 corresponding to the pair of first rods 31 are fixed at an inclined angle relative to each other. In the first state, the end portions of the pair of second rods 32 contact the bottom surfaces of the depressions 31a corresponding thereto of the pair of first rods 31, and the pair of first rods 31 and the pair of second rods 32 are inhibited from further moving. In addition, in the second state, the end portions of the pair of second rods 32 contact the inner walls of the stoppers 31b corresponding thereto of the pair of first rods 31, and at the same time, the portions of the stoppers 31b of the pair of first rods 31 contact the side walls of the pair of second rods 32 corresponding thereto, so that the pair of first rods 31 and the pair of second rods 32 may be inhibited from further moving.

[0086] like Figure 4A As shown, the fixed member 40 is initially in a second state in which a pair of first rods 31 and a pair of second rods 32 corresponding to the pair of first rods 31 are fixed at an inclined angle relative to each other. In the second state, the movable frame 12 is closer to the fixed frame 11. Therefore, the image forming device 110 fixed to the lower surface of the movable frame 12 is away from the light entrance surface of the combiner member 130. Although the movable frame 12 can be forced to move toward the fixed frame 11 due to the elastic restoring force of the first elastic bridge 21 and the second elastic bridge 22, because the ends of the pair of second rods 32 are in contact with the inner wall of the stopper of the pair of first rods 31, the position of the movable frame 12 can be fixed, thereby being suppressed from moving.

[0087] When the driving device 120a applies a driving voltage to the variable length element 23 under the control of the processor 140, the variable length element 23 contracts so that both ends of the first elastic bridge 21 can be pulled close to each other, and both ends of the second elastic bridge 22 can be pulled close to each other. Then, the curvature radius of the first elastic bridge 21 and the curvature radius of the second elastic bridge 22 are reduced due to the contraction force of the variable length element 23. Therefore, the movable frame 12 can be forced to move away from the fixed frame 11.

[0088] Then, if Figure 4B As shown, the fixed member 40 enters a first state in which a pair of first rods 31 and a pair of second rods 32 corresponding to the pair of first rods 31 are fixed in a straight line with each other. In the first state, the movable frame 12 is farther away from the fixed frame 11 than in the second state. Therefore, the image forming device 110 fixed to the lower surface of the movable frame 12 is closer to the light entrance surface of the combiner member 130.

[0089] After the pair of first rods 31 and the pair of second rods 32 corresponding to the pair of first rods 31 are completely arranged in line with each other, the driving device 120a can stop applying the driving voltage to the variable length element 23. Then, the movable frame 12 can be forced toward the fixed frame 11 by the elastic restoring force of the first elastic bridge 21 and the second elastic bridge 22. However, because the ends of the pair of second rods 32 are in contact with the bottom surfaces of the recesses 31a of the pair of first rods 31 and are thus suppressed from moving, the position of the movable frame 12 can be fixed.

[0090] In addition, the fixing member 30 may further include a variable length element 35 respectively connected between the two side edges of the fixing frame 11 and the ends of the pair of first rods 31. For example, the variable length element 35 may be connected between the upper surface of the fixing frame 11 and the outer wall of the stopper 31b of the pair of first rods 31. When a driving voltage is applied to the variable length element 35, the variable length element 35 may be contracted. Therefore, as the ends of the pair of first rods 31 are pulled, the pair of first rods 31 may rotate in the outward direction on both sides of the fixing frame 11.

[0091] When the image forming device 110 is Figure 4B Move to the position shown Figure 4A When the variable length element 35 is in the position shown, the driving device 120a applies a driving voltage to the variable length element 35 under the control of the processor 140. Then, as the variable length element 35 contracts, the pair of first rods 31 rotates in the outward direction on both sides of the fixed frame 11. In addition, as the pair of first rods 31 rotate, the pair of second rods 32 also rotates in the outward direction on both sides of the fixed frame 11. When the pair of first rods 31 and the pair of second rods 32 rotate by a predetermined angle, the ends of the pair of second rods 32 contact the inner walls of the stoppers 31b of the pair of first rods 31 corresponding thereto, and at the same time, the portions of the stoppers 31b of the pair of first rods 31 contact the side surfaces of the pair of second rods 32 corresponding thereto. Therefore, the pair of first rods 31 and the pair of second rods 32 are suppressed from moving, so that the movable frame 12 can be fixed.

[0092] As described above, when the fixed member 40 changes from the second state to the first state, the distance between the fixed frame 11 and the movable frame 12 increases. In this case, the image forming device 110 moves closer to the light entrance surface of the combiner member 130. When the fixed member 40 changes from the second state to the first state, the driving voltage is applied only to the actuator 20. When the fixed member 40 changes from the first state to the second state, the distance between the fixed frame 11 and the movable frame 12 decreases. In this case, the image forming device 110 is further away from the light entrance surface of the combiner member 130 than in the first state. When the fixed member 40 changes from the first state to the second state, the driving voltage is applied only to the variable length element 35. In addition, when the distance between the fixed frame 11 and the movable frame 12 is maintained, power is not consumed.

[0093] Figure 5A and Figure 5B 1 is a view schematically showing the structure and operation of a driving device 120b according to another exemplary embodiment. In addition to the structure of the fixing member 50, Figure 5A and Figure 5B The structure of the driving device 120b shown is similar to Figure 4A and Figure 4B The illustrated drive device 120a is similarly structured.

[0094] Reference Figure 5A and Figure 5B , the fixing member 50 may include a pair of first rods 36 rotatably arranged at both side edges of the fixed frame 11, and a pair of second rods 37 rotatably arranged at both side edges of the movable frame 12. For example, the pair of first rods 36 may be rotatably fixed to the lower surface of the fixed frame 11 via the hinge 33, and the pair of second rods 37 may be rotatably fixed to the upper surface of the movable frame 12 via the hinge 34. The ends of the pair of first rods 36 and the ends of the pair of second rods 37 corresponding thereto may have complementary shapes to engage with each other. For example, the ends of the pair of first rods 36 may have a step shape, and the ends of the pair of second rods 37 corresponding thereto may have a step shape complementary to the step shape of the ends of the pair of first rods 36.

[0095] The fixing member 50 may have a first state in which the pair of first rods 36 and the pair of second rods 37 corresponding to the pair of first rods 36 are fixed in line with each other, and a second state in which the pair of first rods 36 and the pair of second rods 37 corresponding to the pair of first rods 36 are fixed at an inclined angle relative to each other. In the first state, the ends of the pair of first rods 36 are engaged with the ends of the pair of second rods 37 corresponding thereto, so that the pair of first rods 36 and the pair of second rods 37 are restrained from further moving. In this case, the side surfaces 36a of the ends of the pair of first rods 36 are parallel to and closely contacted with the side surfaces 37a of the ends of the pair of second rods 37 corresponding thereto. In addition, the end surfaces 36b of the ends of the pair of first rods 36 are in contact with the stopper surfaces 37c of the ends of the pair of second rods 37 corresponding thereto, and the end surfaces 37b of the pair of second rods 37 are in contact with the stopper surfaces 36c of the ends of the pair of first rods 36 corresponding thereto. In the second state, the end surfaces 36 b of the ends of the pair of first rods 36 contact the side surfaces 37 a of the ends of the pair of second rods 37 corresponding thereto, and thus the pair of first rods 36 and the pair of second rods 37 are restrained from further moving.

[0096] In addition, the fixing member 50 may include: a first stopper 41, which is arranged on the lower surface of the fixed frame 11 to limit the rotation angle of the pair of first rods 36; and a second stopper 42, which is arranged on the upper surface of the movable frame 12 to limit the rotation angle of the pair of second rods 37. The first stopper 41 protrudes from the lower surface of the fixed frame 11 around the hinge 33 of the pair of first rods 36. Therefore, when the pair of first rods 36 contact the first stopper 41 while the rotation angle of the pair of first rods 36 increases, the rotation of the pair of first rods 36 is limited. The second stopper 42 protrudes from the upper surface of the movable frame 12 around the hinge 34 of the pair of second rods 37. Therefore, when the pair of second rods 37 contact the second stopper 42 while the rotation angle of the pair of second rods 37 increases, the rotation of the pair of second rods 37 is limited. The first stopper 41 and the second stopper 42 may also be applied to Figure 4A and Figure 4B Example implementation shown.

[0097] In addition, the fixing member 50 may further include variable length elements 35 respectively connected between the two side edges of the fixing frame 11 and the ends of the pair of first rods 36. The variable length elements 35 are contracted by electrical control to switch the fixing member 50 from the first state to the second state.

[0098] Figure 5A and Figure 5B The operation of the drive device 120b shown is similar to Figure 4A and Figure 4B The operation of the drive device 120a shown is similar. Figure 5AAs shown, the fixed member 50 is initially in a second state in which a pair of first rods 36 and a pair of second rods 37 corresponding to the pair of first rods 36 are fixed at an inclined angle relative to each other. In the second state, the image forming device 110 fixed to the lower surface of the movable frame 12 is further away from the light entrance surface of the combiner member 130 than in the first state. Although the movable frame 12 can be forced to move toward the fixed frame 11 by the elastic restoring force of the first elastic bridge 21 and the second elastic bridge 22, because the end surface 36b of the end of the pair of first rods 36 is in contact with the side surface 37a corresponding to the end of the pair of second rods 37, the pair of first rods 36 is in contact with the first stopper 41, and the pair of second rods 37 is in contact with the second stopper 42, the pair of first rods 36 and the pair of second rods 37 are inhibited from further moving. Therefore, the position of the movable frame 12 can be fixed.

[0099] When the depth of the image displayed on the image forming device 110 changes, the processor 140 controls the driving device 120b to apply a driving voltage to the variable length element 23. Then, because the variable length element 23 contracts to further bend the first elastic bridge 21 and the second elastic bridge 22, the movable frame 12 may be forced to move in a direction away from the fixed frame 11. As a result, as shown in FIG. Figure 5B As shown, the fixing member 50 enters a first state in which the pair of first rods 36 and the pair of second rods 37 corresponding to the pair of first rods 36 are fixed in a straight line with each other. At this time, the ends of the pair of first rods 36 and the ends of the pair of second rods 37 are engaged with each other, so that the pair of first rods 36 and the pair of second rods 37 are inhibited from further moving. Therefore, the position of the movable frame 12 can be fixed.

[0100] When the image forming device 110 is Figure 5B Move to the position shown Figure 5A When the variable length element 35 is in the position shown, the driving device 120b applies a driving voltage to the variable length element 35 under the control of the processor 140. Then, as the variable length element 35 contracts, the pair of first rods 36 rotate in the outward direction on both sides of the fixed frame 11. In addition, as the pair of second rods 37 are pushed by the pair of first rods 36, the pair of second rods 37 also rotate in the outward direction on both sides of the fixed frame 11. When the pair of first rods 36 and the pair of second rods 37 rotate by a predetermined angle, the end surfaces 36b of the ends of the pair of first rods 36 contact the side surfaces 37a of the ends of the pair of second rods 37 corresponding thereto, and thus the pair of first rods 36 and the pair of second rods 37 are inhibited from further moving.

[0101] Fig. 6A and Figure 6B 1 is a view schematically showing the structure and operation of a driving device 120c according to another exemplary embodiment. In addition to the structure of the fixing member 60, Fig. 6A and Figure 6B The structure of the driving device 120c shown is similar to Figure 5A and Figure 5B The structure of the driving device 120b shown is similar. Fig. 6A and Figure 6B , the fixing member 60 may include a pair of first rods 46 rotatable and arranged at both side edges of the fixed frame 11, and a pair of second rods 47 rotatable and arranged at both side edges of the movable frame 12. The ends of the pair of first rods 46 and the ends of the pair of second rods 47 corresponding thereto may have complementary shapes to engage with each other. For example, the ends of the pair of first rods 46 may have a step shape, and the ends of the pair of second rods 47 corresponding thereto may have a step shape complementary to the step shape of the ends of the pair of first rods 46.

[0102] and Figure 5A and Figure 5B Compared with the pair of first rods 36 and the pair of second rods 37 shown, Fig. 6A and Figure 6B The pair of first rods 46 and the pair of second rods 47 shown have shapes that are reversed left and right, respectively. Therefore, in the second state where the pair of first rods 46 and the pair of second rods 47 corresponding thereto are fixed at an inclined angle to each other, the end surfaces 47b of the ends of the pair of second rods 47 are in contact with the side surfaces 46a corresponding thereto of the ends of the pair of first rods 46. In the first state where the pair of first rods 46 and the pair of second rods 47 corresponding thereto are fixed in a straight line to each other, the side surfaces 46a of the ends of the pair of first rods 46 are parallel to and in close contact with the side surfaces 47a corresponding thereto of the ends of the pair of second rods 47, the end surfaces 46b of the ends of the pair of first rods 46 are in contact with the stopper surfaces 47c corresponding thereto of the ends of the pair of second rods 47, and the end surfaces 47b of the ends of the pair of second rods 47 are in contact with the stopper surfaces 46c corresponding thereto of the ends of the pair of first rods 46.

[0103] In addition, the fixing member 60 may further include a variable length element 35 respectively connected between the two side edges of the movable frame 12 and the ends of the pair of second rods 47. When the fixing member 60 is changed from the first state to the second state, the variable length element 35 contracts, and thus the pair of second rods 47 rotate in the outward direction on both sides of the movable frame 12. In addition, as the pair of first rods 46 are pushed by the pair of second rods 47, the pair of first rods 46 also rotate in the outward direction on both sides of the movable frame 12.

[0104] Fig. 7A and Figure 7B is a view schematically showing the structure and operation of a driving device 120d according to another example embodiment. Fig. 7A and Figure 7BThe driving device 120d may include: a fixed frame 11, fixed to the inside of the display device 100; a movable frame 12, arranged to face the fixed frame 11 and be movable; an actuator 70, configured to change the distance between the fixed frame 11 and the movable frame 12; and a fixing member 80, configured to fix the distance between the fixed frame 11 and the movable frame 12.

[0105] The fixing member 80 may include a pair of first rods 31 rotatably disposed at both side edges of the fixed frame 11, and a pair of second rods 32 rotatably disposed at both side edges of the movable frame 12. Ends of the pair of first rods 31 and ends corresponding thereto of the pair of second rods 32 may be configured to contact each other and interfere with each other. Fig. 7A and Figure 7B In the embodiment, the fixing member 80 is shown to include Figure 4A and Figure 4B The first rod 31 and the second rod 32 are the same pairs as those shown, but are not limited thereto. The fixing member 80 may include Figure 5A and Figure 5B The pair of first rods 36 and the pair of second rods 37 shown or Fig. 6A and Figure 6B A pair of first rods 46 and a pair of second rods 47 are shown.

[0106] The actuator 70 may include: a first variable length element 38 connected between the fixed frame 11 and the inner side surface of the pair of first rods 31; and a second variable length element 39 connected between the fixed frame 11 and the outer side surface of the pair of first rods 31. The length of the first variable length element 38 and the length of the second variable length element 39 can be changed by electrical control. For example, when a driving voltage is applied to the first variable length element 38 and the second variable length element 39, the first variable length element 38 and the second variable length element 39 can shrink and reduce the length. The first variable length element 38 and the second variable length element 39 can be connected to the opposite side surfaces of the ends of the pair of first rods 31. For example, the first variable length element 38 can be connected between the inner side surface of the pair of first rods 31 and the near center portion of the lower surface of the fixed frame 11. In addition, the second variable length element 39 can be connected between the outer side surface of the pair of first rods 31 and the near edge portion of the lower surface of the fixed frame 11.

[0107] The fixing member 80 may have a first state in which the pair of first rods 31 and the pair of second rods 32 corresponding to the pair of first rods 31 are fixed in a straight line with each other, and a second state in which the pair of first rods 31 and the pair of second rods 32 corresponding to the pair of first rods 31 are fixed at an inclined angle relative to each other. When the distance between the fixed frame 11 and the movable frame 12 is reduced, the first variable length element 38 may be extended and the second variable length element 39 may be shortened, as shown in FIG. Fig. 7A As shown, the fixing member 80 can be switched from the first state to the second state. To this end, the driving device 120d can apply a driving voltage to the second variable length element 39 under the control of the processor 140. After the fixing member 80 is switched to the second state, the application of the driving voltage to the second variable length element 39 can be stopped.

[0108] In addition, when the distance between the fixed frame 11 and the movable frame 12 increases, the first variable length element 38 can be shortened and the second variable length element 39 can be extended, so that the fixed member 80 can be switched from the second state to the first state. To this end, the driving device 120d can apply a driving voltage to the first variable length element 38 under the control of the processor 140. After the fixed member 80 is switched to the first state, the application of the driving voltage to the first variable length element 38 can be stopped.

[0109] Fig. 8A and Figure 8B is a view schematically showing the structure and operation of a driving device 120e according to another example embodiment. Fig. 7A and Figure 7B , the first variable length member 38 and the second variable length member 39 are shown to be connected between the fixed frame 11 and the pair of first rods 31. However, the embodiment is not limited thereto. Fig. 8A and Figure 8B As shown, the first variable length member 38 may be connected between the near center portion of the upper surface of the movable frame 12 and the inner side surfaces of the pair of second rods 32. In addition, the second variable length member 39 may be connected between the near edge portion of the upper surface of the movable frame 12 and the outer side surfaces of the pair of second rods 32. In addition to the configurations of the first variable length member 38 and the second variable length member 39, Fig. 8A and Figure 8B The driving device 120e shown has Fig. 7A and Figure 7B The drive device 120d shown has the same structure and operation.

[0110] The above-described display device 100 may provide an image to only one eye of a viewer. However, the display device may be configured to provide an image to both eyes of a viewer. For example, Fig. 9Schematically shows the structure of a display device 200 according to another exemplary embodiment. Fig. 9 , the display device 200 of this example embodiment may include: a left-eye image forming device 110L configured to form a left-eye image; a left-eye combiner member 130L configured to provide the left-eye image together with light containing an external scenery and propagating from the external scenery to a viewer; a left-eye drive device 120L configured to adjust the distance between the left-eye image forming device 110L and the left-eye combiner member 130L; a right-eye image forming device 110R configured to form a right-eye image; the right-eye combiner member 130R configured to provide the right-eye image together with light containing an external scenery and propagating from the external scenery to a viewer; and a right-eye drive device 120R configured to adjust the distance between the right-eye image forming device 110R and the right-eye combiner member 130R.

[0111] also, Fig.10 Schematically shows the structure of a display device 300 according to another exemplary embodiment. Fig.10 , the display device 300 of this example embodiment may include: a left-eye image forming device 110L configured to form a left-eye image; a left-eye combiner member 130L configured to provide the left-eye image to a viewer together with light containing an external scene and propagating from the external scene; a right-eye image forming device 110R configured to form a right-eye image; a right-eye combiner member 130R configured to provide the right-eye image to a viewer together with light containing an external scene and propagating from the external scene; and a driving device 120RL configured to adjust the positions of the left-eye image forming device 110L and the right-eye image forming device 110R. The driving device 120RL may simultaneously adjust the distance between the right-eye image forming device 110R and the right-eye combiner member 130R and the distance between the left-eye image forming device 110L and the left-eye combiner member 130L.

[0112] The above-mentioned combiner member 130 may have an integrated structure in which the focusing optical system 131 and the beam splitter 132 are fixed by a transparent light guide plate 133. However, the structure of the combiner member 130 is not limited thereto, and may have various other structures. For example, Fig.11 is a schematic diagram showing the structure and operation of a display device 400 according to another example embodiment. Fig.11 , the display apparatus 400 may include an image forming device 110 , a combiner member 230 , a driving device 120 , and a processor 140 .

[0113] The combiner member 230 may include a beam splitter 232 and a concave mirror 231. The beam splitter 232 may be a semi-reflective mirror that reflects a portion of the incident light and transmits another portion of the incident light, or may be a polarization beam splitter that reflects light having a first linear polarization component and transmits light having a second linear polarization component perpendicular to the first linear polarization component. The concave mirror 231 is configured to reflect light propagating from the beam splitter 232 to focus the light on the eyes of the viewer. In addition, the concave mirror 231 may be configured to transmit light propagating from the outside to the eyes of the viewer. To this end, the concave mirror 231 may have a concave reflective surface 231a facing the beam splitter 232 and a light transmitting surface 231b opposite to the reflective surface 231a.

[0114] Furthermore, when the image forming device 110 is a non-emissive image forming device such as an LCoS device or an LCD device, elements other than the display panel may also be fixed to the movable frame 12. For example, Fig.12 FIG. 1 schematically shows the configuration of an image forming device 110 and a driving device 120 of a display apparatus 500 according to another exemplary embodiment. Fig.12 , a light source 301 configured to provide illumination light, a beam splitter 302 configured to adjust a path of the illumination light, and a spatial light modulator 310 may be fixed together to the movable frame 12 .

[0115] The display device according to the above-mentioned example embodiment can constitute a wearable device. In other words, the display device can be applied to a wearable device. For example, the display device can be applied to a head-mounted display (HMD), a glasses-type display, a goggle-type display, etc. The wearable electronic device to which the display device of the above-mentioned example embodiment is applied can be operated in conjunction with a smartphone. The display device can be a head-mounted, glasses-type or goggle-type VR display device, an AR display device, or an MR display device that can provide VR or provide a virtual image together with a real external scenery.

[0116] In addition, the display device can be provided in a smartphone, and the smartphone can be used as a VR, AR or MR display device. For example, the display device can be applied to a small electronic device such as a mobile electronic device. In addition, the display device can be used in various other fields. For example, the display device can be used in the field of VR, AR or MR and in other fields. For example, the display device can also be applied to a small television or a small monitor configured to be worn by a user.

[0117] Although a display device capable of multi-depth expression has been described according to example embodiments with reference to the accompanying drawings, the example embodiments are merely examples, and those of ordinary skill in the art will appreciate that various modifications and other equivalent embodiments may be made therein without departing from the spirit and scope of the present disclosure. Therefore, the example embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. The scope of the present disclosure is not limited by the above description, but by the appended claims, and all differences within the equivalent range of the scope of the present disclosure should be deemed to be included within the scope of the present disclosure.

[0118] It should be understood that the embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. The description of features or aspects within each example embodiment should generally be considered applicable to other similar features or aspects in other embodiments. Although example embodiments have been described with reference to the accompanying drawings, it will be understood by those of ordinary skill in the art that various changes in form and details may be made herein without departing from the spirit and scope defined by the appended claims.

[0119] This application claims the priority benefit of Korean Patent Application No. 10-2019-0138196 filed on October 31, 2019 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety.

Claims

1. A display device, comprising: an image forming device configured to form an image; an optical system configured to provide an output image by combining light containing an external scene with an image formed by the image forming device; as well as a driving device configured to adjust the distance between the image forming device and the optical system, The driving device comprises: Fixed frame; a movable frame facing the fixed frame and being movable; an actuator configured to change a distance between the fixed frame and the movable frame; and a fixing member configured to fix the distance between the fixed frame and the movable frame, wherein the image forming device is fixed to the movable frame, The actuator comprises: a first elastic bridge having a continuously curved surface convex toward the fixed frame; a second elastic bridge having a continuously curved surface convex toward the movable frame; and a first variable length element, fixed between both ends of the first elastic bridge and between both ends of the second elastic bridge to extend from a first end point of the first elastic bridge and the second elastic bridge to a second end point of the first elastic bridge and the second elastic bridge, and having a variable length, wherein the fixing member comprises a pair of side frames respectively fixed to opposite side edges of the fixing frame, The pair of side frames extend from the fixed frame toward the movable frame, and have fixed ends fixed to the fixed frame and free ends opposite to the fixed ends.

2. The display device according to claim 1, wherein the first variable-length element comprises a shape memory alloy or an electroactive polymer, and Wherein a length of the first variable length element changes based on heat applied to the first variable length element. 3 . The display device of claim 1 , wherein the first elastic bridge has an elastic restoring force in a direction in which a radius of curvature of the first elastic bridge increases, and a central portion of the first elastic bridge is fixed to the fixing frame. 4 . The display device of claim 3 , wherein the second elastic bridge has an elastic restoring force in a direction in which a radius of curvature of the second elastic bridge increases, and a central portion of the second elastic bridge is fixed to the movable frame.

5. The display device according to claim 1, wherein the pair of side frames include a plurality of protrusions protruding from the surface of the free end and provided at different distances from the fixed frame, the plurality of protrusions being configured to contact opposite sides of the movable frame and inhibit movement of the movable frame.

6. The display device according to claim 1, wherein the pair of side frames are configured so that the free ends of the pair of side frames facing each other move away from each other when the distance between the fixed frame and the movable frame changes, and move toward each other when the distance between the fixed frame and the movable frame is maintained.

7. The display device according to claim 6, wherein the pair of side frames include a bimetallic element or a piezoelectric element which is bent or stretched based on temperature control or electrical control, respectively, and wherein the pair of side frames bend when a distance between the fixed frame and the movable frame is changed, and extend when a distance between the fixed frame and the movable frame is maintained.

8. The display device according to claim 6, wherein the fixing member further comprises a second variable length element fixed between the fixing end and the free end and having a variable length, wherein the pair of side frames have elastic restoring force in a direction in which the free ends face each other, and The second variable length element fixed between the fixed end and the free end contracts when the distance between the fixed frame and the movable frame changes.

9. The display device according to claim 1, wherein the fixing member comprises: a pair of first rods configured to rotate and provided at both side edges of the fixed frame; as well as a pair of second rods configured to rotate and provided at both side edges of the movable frame, wherein ends of the pair of first rods and ends of the pair of second rods are configured to contact each other and interfere with each other, and the ends of the pair of second rods correspond to the ends of the pair of first rods.

10. The display device according to claim 9, wherein the fixing member is configured to switch between a first state and a second state, in which the pair of first rods and the pair of second rods corresponding to the pair of first rods are fixed in a straight line with each other, and in the second state, the pair of first rods and the pair of second rods corresponding to the pair of first rods are fixed at an inclined angle relative to each other.

11. The display device according to claim 10, wherein the fixing member switches from the second state to the first state based on an increase in the distance between the fixing frame and the movable frame, and switches from the first state to the second state based on a decrease in the distance between the fixing frame and the movable frame.

12. The display device according to claim 10, wherein the ends of the pair of first rods include a recess and a stopper surrounding the recess, wherein the width of each of the end portions of the pair of second rods is smaller than the width of each of the recesses, and each of the end portions of the pair of second rods is provided in each of the recesses, and The fixing member is configured such that the end portions of the pair of second rods are in contact with the bottom surface of the recess in the first state, and are in contact with the inner wall of the stopper in the second state.

13. The display device according to claim 10, wherein the ends of the pair of second rods include a recess and a stopper surrounding the recess, wherein a width of each of the end portions of the pair of first rods is smaller than a width of each of the recesses, and each of the end portions of the pair of first rods is provided in each of the recesses, and The fixing member is configured such that the end portions of the pair of first rods are in contact with the bottom surface of the recess in the first state, and are in contact with the inner wall of the stopper in the second state.

14. The display device according to claim 10, wherein the fixing member further comprises second variable length elements, which are respectively connected between two side edges of the fixing frame and the ends of the pair of first rods and respectively have variable lengths, and Based on the switching of the fixing member from the first state to the second state, the second variable-length elements respectively connected between the two side edges of the fixing frame and the ends of the pair of first rods are contracted.

15. The display device according to claim 10, wherein the fixing member further comprises second variable length elements which are respectively connected between two side edges of the movable frame and the ends of the pair of second rods and respectively have variable lengths, and Wherein, based on the switching of the fixing member from the first state to the second state, the second variable-length elements respectively connected between the two side edges of the movable frame and the ends of the pair of second rods are contracted.

16. The display device according to claim 10, wherein the ends of the pair of first rods and the ends of the pair of second rods have complementary shapes and are configured to engage with each other, the ends of the pair of second rods corresponding to the ends of the pair of first rods, wherein the fixing member further comprises second variable length elements, which are respectively connected between two side edges of the movable frame and the ends of the pair of second rods and respectively have variable lengths, and Wherein, based on the switching of the fixing member from the first state to the second state, the second variable-length elements respectively connected between the two side edges of the movable frame and the ends of the pair of second rods are contracted.

17. A display device comprising: an image forming device configured to form an image; an optical system configured to provide an output image by combining light containing an external scene with an image formed by the image forming device; as well as a driving device configured to adjust the distance between the image forming device and the optical system, The driving device comprises: Fixed frame; a movable frame facing the fixed frame and being movable; an actuator configured to change a distance between the fixed frame and the movable frame; and a fixing member configured to fix the distance between the fixed frame and the movable frame, wherein the image forming device is fixed to the movable frame, The fixing member comprises: a pair of first rods configured to rotate and provided at both side edges of the fixed frame; and a pair of second rods configured to rotate and provided at both side edges of the movable frame, wherein the ends of the pair of first rods and the ends of the pair of second rods are configured to contact each other and interfere with each other, the ends of the pair of second rods corresponding to the ends of the pair of first rods, The actuator comprises: first variable-length elements connected between the fixing frame and inner side surfaces of the pair of first rods and respectively having variable lengths; and The second variable-length elements are connected between the fixing frame and the outer side surfaces of the pair of first rods and have variable lengths respectively.

18. The display device according to claim 17, wherein the fixing member is configured to switch between a first state in which the pair of first rods and the pair of second rods corresponding to the pair of first rods are fixed in a straight line with each other and a second state in which the pair of first rods and the pair of second rods corresponding to the pair of first rods are fixed at an inclined angle relative to each other, wherein the first variable length element is shortened and the second variable length element is lengthened based on an increase in the distance between the fixed frame and the movable frame to switch the fixed member from the second state to the first state, and Based on a reduction in the distance between the fixed frame and the movable frame, the first variable length element is extended and the second variable length element is shortened to switch the fixing member from the first state to the second state.

19. A display device comprising: an image forming device configured to form an image; an optical system configured to provide an output image by combining light containing an external scene with an image formed by the image forming device; as well as a driving device configured to adjust the distance between the image forming device and the optical system, The driving device comprises: Fixed frame; a movable frame facing the fixed frame and being movable; an actuator configured to change a distance between the fixed frame and the movable frame; and a fixing member configured to fix the distance between the fixed frame and the movable frame, wherein the image forming device is fixed to the movable frame, The fixing member comprises: a pair of first rods configured to rotate and provided at both side edges of the fixed frame; and a pair of second rods configured to rotate and provided at both side edges of the movable frame, wherein the ends of the pair of first rods and the ends of the pair of second rods are configured to contact each other and interfere with each other, the ends of the pair of second rods corresponding to the ends of the pair of first rods, The actuator comprises: first variable-length elements connected between the movable frame and inner side surfaces of the pair of second rods and having variable lengths respectively; and The second variable-length members are connected between the movable frame and the outer side surfaces of the pair of second rods and have variable lengths respectively.

20. The display device according to any one of claims 1, 17 and 19, further comprising a processor configured to determine the distance between the image forming device and the optical system based on depth information of an image to be displayed, and control the driving device.

21. The display device according to any one of claims 1, 17 and 19, wherein the display device is a virtual reality (VR), augmented reality (AR) or mixed reality (MR) display device implemented as a head-mounted device, a glasses-type device or a goggle-type device.

22. A display device, comprising: an image forming device configured to form an image; an optical system configured to provide an output image by combining light emitted from the outside of the display apparatus with an image formed by the image forming device; as well as a driving device configured to change the distance between the image forming device and the optical system, The driving device comprises: Fixed frame; a movable frame facing the fixed frame and being movable; an actuator configured to control a distance between the fixed frame and the movable frame based on an applied voltage; and a fixing member configured to fix the distance between the fixed frame and the movable frame, The actuator comprises: a first elastic bridge having a continuously curved surface convex toward the fixed frame; a second elastic bridge having a continuously curved surface convex toward the movable frame; and a first variable length element, fixed between both ends of the first elastic bridge and between both ends of the second elastic bridge to extend from a first end point of the first elastic bridge and the second elastic bridge to a second end point of the first elastic bridge and the second elastic bridge, and having a variable length, wherein the fixing member comprises a pair of side frames respectively fixed to opposite side edges of the fixing frame, The pair of side frames extend from the fixed frame toward the movable frame, and have fixed ends fixed to the fixed frame and free ends opposite to the fixed ends.

23. The display device according to claim 22, wherein a voltage is applied to the actuator when the distance between the fixed frame and the movable frame changes, and no voltage is applied to the actuator when the distance between the fixed frame and the movable frame is maintained.

24. The display device of claim 23, wherein power consumed by the driving device when the distance between the fixed frame and the movable frame is maintained is less than power consumed by the driving device when the distance between the fixed frame and the movable frame is changed.

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