JP4176059B2 - Projection type image display device - Google Patents

Description

  The present invention relates to a projection-type image display device, and more particularly to a projection-type image display device having a configuration for projecting light that is deflected and modulated by elements that can take on and off states having different reflection directions.

  As means for increasing the resolution in a projection-type image display device, a technique is disclosed in which, for example, the optical path is shifted for each field to increase the apparent resolution without increasing the number of pixels of an image forming device such as an LCD. Yes.

  For example, Patent Document 1 discloses a projection-type image display device in which one or a plurality of different light shift elements are provided on at least one of an incident side and an emission side of a projection lens, and further has no projection lens. In a configuration in which light from a plurality of projection type image display device modules is incident on one projection lens by a plurality of mirrors to superimpose a projection image, an optical shift element is provided between the plurality of projection type image display device modules and the mirror. A provided projection type image display apparatus is disclosed.

  Patent Document 2 discloses a projection type in which the image height is shifted by an arbitrary distance in the pixel arrangement direction by a light deflecting unit using a Bragg diffraction element having a polymer-dispersed liquid crystal structure disposed immediately before the screen. An image display device is disclosed.

  In Patent Document 3, a variable prism is disposed on the optical path behind the liquid crystal panel, and the glass path of the variable prism is displaced in synchronization with a vertical synchronization signal or the like under the control of the control circuit. There has been disclosed a liquid crystal projector which is shifted to achieve high resolution.

  Further, in Patent Document 4, an optical axis conversion element composed of two wedge prisms is arranged in front of the liquid crystal panel, and a drive mechanism composed of a piezoelectric element and a moving coil provided between these wedge prisms is used as a vertical synchronization signal. An optical axis conversion device and a video projector are disclosed in which a high resolution is achieved by shifting an optical path by synchronizing and vibrating.

Moreover, although it is not a projection type image display apparatus, FIG. 6 of Patent Document 5 describes various pixel shifting methods, which can be easily applied to a projection type image display apparatus. An example of this application is as shown in FIG.
FIG. 8 shows a configuration example in which a conventional technique is applied to a DLP projection type image display apparatus using DMD. In FIG. 8, 1 is a light source, 2 is a color wheel, 3 is a rod integrator, 4 is a condenser lens, 5 is a prism block, 51 is a first prism constituting a prism block, and 52 is a prism block constituting a prism block. 2 is a total reflection prism, 52a is a total reflection surface of the total reflection prism, 6 is a display element, 7 is a projection lens, and 12 is a wedge-shaped optical axis changing element. In addition, an air gap of several μm to several hundred μm is actually provided between the first prism 51 and the second prism 52.

A general DLP (Digital Light Processing) projection-type image display apparatus time-divides light from a lamp serving as a light source into three primary colors of RGB using a color wheel, and enters the three primary colors thus time-divided to generate a projection image. It has DMD (Digital Micromirror Device).
The DMD has a large number (for example, millions) of micro-mirrors constituting an image integrated on a single chip. Then, by controlling the individual micromirrors according to the image information and switching the light reflection direction between the on state and the off state, only the desired reflected light is converged on the screen so that a desired projection image can be projected. Yes.

  Each micromirror that constitutes the DMD can switch the reflection direction of incident light to two directions independently. The reflection direction is switched by on / off control of image information input to the DMD with each micromirror as a pixel.

  The color wheel functions as a color separation means for color-separating the light source light. A fan-shaped R, G, B color separation filter is arranged on a disk, and the incident light source is rotated by rotating it. The light is color-separated into R, G, and B in a time division manner, and each monochromatic light is sequentially incident on the DMD.

  In the configuration of FIG. 8, the light emitted from the light source 1 passes through the color wheel 2 for color separation as described above, and is emitted from the prism block 5 by the illumination optical system including the rod integrator 3 and the condenser lens 4. The light is reflected by the total reflection surface 52 a and condensed on the display element 6. As the display element 6, the DMD described above is used, and the reflected light is deflected based on the input image information.

The image light emitted from the display element 6 by DMD is incident on the total reflection prism 52 of the prism block 5. The total reflection prism 52 allows only the light in the DMD on state to selectively enter the entrance pupil of the projection lens 7 and project an image on the screen. Here, a wedge-shaped optical axis changing element 12 according to the invention of Patent Document 1 is disposed between the total reflection prism 52 and the projection lens 7. By this wedge-shaped optical axis changing element 12, the angle is changed so as to change the optical axis by 1/2 of the pixel, and each field is displayed in synchronization with the angle, so that the number of pixels can be doubled.
JP-A-6-82608 JP 2002-156617 A JP-A-7-104278 Japanese Patent Laid-Open No. 7-240932 Japanese Patent Laid-Open No. 6-197297

  However, in the above conventional technique, in order to obtain a high resolution by shifting pixels, it is necessary to add another optical element for shifting pixels in addition to the conventional configuration. This new optical element causes a problem that the loss of light increases, and the new optical element causes a problem that the projection type image display apparatus becomes large and the manufacturing cost also increases.

  The present invention has been made in view of the above circumstances, and provides a projection-type image display device that can obtain a high-resolution projection image with a simple configuration without increasing light loss. It is for the purpose.

In order to solve the above-mentioned problem, a first technical means includes a light source, a light collecting means for collecting light from the light source, and an element that can take on and off states having different reflection directions. In a projection-type image display device comprising a display element that deflects and modulates light condensed in accordance with image information and a projection lens that projects light that has been deflected and modulated by the display element, reflection reflected in an on state changing the slope variable total reflection prism for reflecting light to the projection lens, the total tilt of the reflecting prism and possess an angle changing means for changing in synchronization with the image information, in synchronization with the image information the inclination of the total reflection prism Thus, the optical path of the light emitted from the projection lens is shifted in synchronization with the image information .

  According to a second technical means, in the first technical means, the projection type image display apparatus has color separation means for color-separating light from the light source into RGB on an optical path from the light source to the display element. Is a DMD (Digital Micromirror Device) composed of micromirrors that individually switch the reflection direction of incident light between an on state and an off state according to image information.

  The third technical means is characterized in that, in the first or second technical means, a piezoelectric actuator is used as the angle changing means.

  According to a fourth technical means, in the first or second technical means, a voice coil motor is used as the angle changing means.

  According to a fifth technical means, in the first or second technical means, an electrostatic actuator is used as the angle changing means.

  A sixth technical means is any one of the first to fifth technical means, wherein the total reflection prism is held rotatably on an axis passing through the center of gravity of the total reflection prism. It is.

  A seventh technical means is any one of the first to fifth technical means, wherein the total reflection prism is rotatably held on an axis passing through the intersection of the reflection surface of the total reflection prism and the optical axis of the projection lens. It is characterized by being.

  The eighth technical means is characterized in that, in any one of the first to fifth technical means, the total reflection prism is held by a hinge formed of an elastic material made of a polymer compound. .

  According to the projection type image display device of the present invention, it is not necessary to use an additional optical element for shifting the pixels to obtain a high resolution, so that a bright projection image with a high resolution can be obtained without increasing light loss. Will be able to. Further, a space for an additional optical element is not required, and the projection type image display apparatus can be reduced in size and manufacturing cost can be reduced.

  In addition, by using a piezoelectric actuator as an angle changing means for shifting the pixel by changing the angle of the reflecting surface of the total reflection prism, the device can be further simplified, and the device can be downsized and the manufacturing cost can be reduced. In addition, the mechanical noise is further reduced, and the pixel shift switching speed is improved to improve the image quality.

In addition, a device can be manufactured at a lower cost by using a voice coil motor as the angle changing means for shifting the pixels.
In addition, the apparatus can be miniaturized by using an electrostatic actuator as the angle changing means for shifting the pixel.
Further, the total reflection prism used for shifting the pixels has a rotation axis on the axis passing through the center of gravity of the total reflection prism, so that the pixel shift switching speed is further improved, leading to an improvement in image quality.
Further, the total reflection prism has a rotation axis on the axis formed by the intersection of the reflection surface and the optical axis of the projection lens, thereby minimizing the focus shift caused by the pixel shift and improving the image quality. Further, it is not necessary to use an expensive bearing, and the apparatus can be configured at a lower cost.
Further, by holding the total reflection prism by a hinge formed of an elastic material made of a polymer compound, the total reflection prism can be rotatably installed with a simple configuration.

Embodiments of a projection type image display apparatus according to the present invention will be specifically described below with reference to the accompanying drawings. In the present invention, in order to prevent the illumination light that illuminates the display element using the light deflection type DMD and the on-state light reflected by the DMD from interfering with each other, the already introduced total reflection prism itself is shifted in pixels. It is also used as an element. In other words, the present invention includes angle changing means for changing the tilt of the total reflection prism in synchronization with the image information.
In all the drawings for explaining the embodiments, parts having the same functions as those in FIG. 8 for explaining the prior art are given the same reference numerals as those in FIG.

(Embodiment 1)
FIG. 1 is a schematic configuration diagram for explaining an embodiment of a projection type image display apparatus according to the present invention, in which 8 is an eccentric cam connected to a motor, 9 is an arm, and 9a is a rotating arm. A shaft 10 is pivotally supported, 10 is a spring, and 11 is a rotation shaft of the total reflection prism 52. The configuration of FIG. 1 realizes high resolution by driving the total reflection prism 52 itself and shifting the optical path of the image light without using the wedge-shaped optical axis changing element of Patent Document 1 in the configuration of FIG. It is. Also in FIG. 1, an air gap of several μm to several hundred μm is actually provided between the first prism 51 and the second prism (total reflection prism) 52 as in FIG.

The light emitted from the light source 1 is color-separated by the color wheel 2 for color separation, and is condensed on the display element 6 via the prism block 5 by the illumination optical system including the rod integrator 3 and the condenser lens 4. As the display element 6, the DMD described above is used, and the reflected light is deflected based on input image information.
The image light emitted from the display element 6 enters the total reflection prism 52 of the prism block 5 and is reflected by the total reflection surface 52a. By the action of the total reflection prism 52, only light in the DMD on state can selectively enter the entrance pupil of the projection lens 7 and an image can be projected onto a screen or the like.

The total reflection prism 52 is mounted on an optical box, and is attached to the rotation shaft 11 so as to be able to rotate left and right by a bearing provided in the optical box. With this configuration, the angle of the reflecting surface 52a of the total reflection prism 52 can be changed.
As an angle changing means for changing the angle of the total reflection surface 52 a of the total reflection prism 52, a motor including the arm 9, the spring 10, and the eccentric cam 8 is provided. Here, one end of the arm 9 is coupled (or contacted) to one end of the total reflection prism 52. The arm 9 is pivotally supported around a shaft 9a, and the other end of the arm 9 is biased by a spring 10 at the end of the arm 9 that is coupled to the total reflection prism 52. The end portion is always pressed against the eccentric cam 8. Further, the spring 10 and the total reflection prism 52 may be urged toward the end of the arm 9.

  The eccentric cam 8 is connected to a rotating shaft of a motor (not shown), and the eccentric cam 8 is rotated according to the rotation of the rotating shaft of the motor, and the arm 9 is swung around the shaft 9a. Since one end of the arm 9 a is coupled to the total reflection prism 52, the angle of the total reflection surface 52 a of the total reflection prism 52 changes according to the swinging operation of the arm 9. At this time, the angle of the total reflection surface 52a of the total reflection prism 52 can be changed in synchronization with the image field switching signal by appropriately controlling the number of rotations of the motor. If the angle of the total reflection prism 52 is changed so that the optical axis is changed by, for example, 1/2 of the pixel and each field is displayed in synchronization therewith, it is possible to display twice as many pixels. A high-resolution projection image can be realized.

(Embodiment 2)
As the angle changing means for changing the angle of the total reflection surface 52a of the total reflection prism 52 as in the first embodiment, not only a configuration in which the arm 9 is driven by a motor but also various drive means can be applied. It is. In the present embodiment, a piezoelectric actuator is used as an angle changing unit that changes the angle of the total reflection surface 52a of the total reflection prism 52.

  FIG. 2 is a schematic view of a main part of a projection type image display apparatus for explaining a configuration example of the present invention using a piezoelectric actuator as means for driving a total reflection prism. In FIG. 2, reference numeral 13 denotes a piezoelectric actuator. . In the present embodiment, the piezoelectric actuator 13 for changing the inclination of the total reflection surface 52a of the total reflection prism 52 is provided in the prism block 5 portion of the projection type image display apparatus shown in FIG.

As in the first embodiment, the total reflection prism 52 is mounted on an optical box, and is attached to the rotation shaft 11 so as to be turnable to the left and right by a bearing provided on the optical box. With this configuration, the angle of the total reflection surface 52a of the total reflection prism 52 can be changed.
As a configuration for controlling the angle of the total reflection surface 52 a of the total reflection prism 52, it is on the lower back side of the total reflection surface 52 a of the total reflection prism 52 and between the first prism 51 and the total reflection prism 52. A piezoelectric actuator 13 is attached to the actuator. The piezoelectric actuator 13 is installed so that the displacement direction thereof coincides with the direction in which the total reflection prism 52 is rotated around the rotation shaft 11. Alternatively, an appropriate drive transmission member may be interposed between the piezoelectric actuator 13 and the total reflection prism 52 to rotate the total reflection prism 52 around the rotation shaft 11. Thereby, the angle of the total reflection surface 52 a of the total reflection prism 52 can be controlled by controlling the voltage applied to the piezoelectric actuator 13.

  Then, by appropriately controlling the voltage applied to the piezoelectric actuator 13, the angle of the total reflection surface 52 a of the total reflection prism 52 can be changed in synchronization with the image field switching signal. If the angle of the total reflection prism 52 is changed so that the optical axis is changed by, for example, 1/2 of the pixel and each field is displayed in synchronization therewith, it is possible to display twice as many pixels. A high-resolution projection image can be realized.

As is well known, the piezoelectric actuator 13 is an element that is displaced by applying a voltage, and the displacement can be controlled by controlling the level of the applied voltage.
As the piezoelectric actuator, for example, a piezoelectric substrate, a piezoelectric film, an insulating film, a shield film, an electrode, or the like can be used. An external electrode and an internal electrode are arranged in a stacked structure of ceramic layers, and a voltage is applied. Is applied to displace the piezoelectric film. The configuration of the piezoelectric actuator applied to the present invention is not particularly limited as long as the angle of the total reflection surface 52a of the total reflection prism 52 can be controlled according to the applied voltage.

(Embodiment 3)
In this embodiment, a voice coil motor (VCM) is used as an angle changing unit that changes the angle of the total reflection surface 52a of the total reflection prism 52. A voice coil motor is an actuator that converts magnetic energy into mechanical energy using magnetic flux, and functions as a driving device that gives a linear motion to an object. Therefore, the voice coil motor can be applied as a driving means for the total reflection prism of the present invention. it can.

  FIG. 3 is a schematic diagram of a main part of a projection type image display apparatus for explaining a configuration example of the present invention using a voice coil motor as an angle changing means for changing the angle of the total reflection surface 52a of the total reflection prism 52. In the figure, reference numeral 14 denotes a voice coil motor. In the present embodiment, the voice coil motor 14 for changing the inclination of the total reflection surface 52a of the total reflection prism 52 is provided on the upper back side of the total reflection prism 52 of the projection type image display apparatus shown in FIG.

Similar to the first and second embodiments, the total reflection prism 52 is mounted on an optical box, and is attached to the rotation shaft 11 so as to be turnable to the left and right by a bearing provided in the optical box. With this configuration, the angle of the total reflection surface 52a of the total reflection prism 52 can be changed.
As a configuration for controlling the angle of the total reflection surface 52 a of the total reflection prism 52, the voice coil motor 14 is attached to the upper back side of the total reflection surface 52 a of the total reflection prism 52. The voice coil motor 14 is installed so that the displacement direction thereof coincides with the direction in which the total reflection prism 52 is rotated around the rotation shaft 11. Further, an appropriate drive transmission member may be interposed between the voice coil motor 14 and the total reflection prism 52 so that the total reflection prism 52 is rotated around the rotation shaft 11. Thereby, the angle of the total reflection surface 52 a of the total reflection prism 52 can be controlled by controlling the current applied to the voice coil motor 14.

  Then, by appropriately controlling the current applied to the voice coil motor 14, the angle of the total reflection surface 52a of the total reflection prism 52 can be changed in synchronization with the image field switching signal. If the angle of the total reflection prism 52 is changed so that the optical axis is changed by, for example, 1/2 of the pixel and each field is displayed in synchronization therewith, it is possible to display twice as many pixels. A high-resolution projection image can be realized.

For example, the voice coil motor 14 has a structure in which a movable coil having a conducting wire wound around a bobbin is movably mounted on a center yoke, and a magnet is disposed on the inner surface of a cylindrical stator yoke facing the movable coil. Therefore, when a forward / reverse current is passed through the movable coil, a driving force is generated, and the movable coil can be driven in the forward / reverse direction. Thereby, the displacement of the movable coil can be controlled by controlling the current applied to the voice coil motor.
The configuration of the voice coil motor applied to the present invention is not particularly limited as long as the angle of the total reflection surface 52a of the total reflection prism 52 can be controlled according to the applied current.

(Embodiment 4)
FIG. 4 is a schematic diagram of a main part of a projection type image display apparatus for explaining an example of the configuration of the present invention using an electrostatic actuator as an angle changing means for changing the angle of the total reflection surface 52a of the total reflection prism 52. In the figure, 15 is an electrostatic actuator. In the present embodiment, the electrostatic actuator 15 for changing the inclination of the total reflection surface 52a of the total reflection prism 52 is provided on the lower back side of the total reflection prism 52 of the projection type image display apparatus shown in FIG. .

  Similar to the first to third embodiments, the total reflection prism 52 is mounted on an optical box, and is attached to the rotation shaft 11 so as to be turnable to the left and right by a bearing provided in the optical box. With this configuration, the angle of the total reflection surface 52a of the total reflection prism 52 can be changed.

  As a configuration for controlling the angle of the total reflection surface 52 a of the total reflection prism 52, it is on the lower back side of the total reflection surface 52 a of the total reflection prism 52 and between the first prism 51 and the total reflection prism 52. The electrostatic actuator 15 is attached to the. The electrostatic actuator 15 is installed so that the displacement direction thereof coincides with the direction in which the total reflection prism 52 is rotated around the rotation shaft 11. Alternatively, an appropriate drive transmission member may be interposed between the electrostatic actuator 15 and the total reflection prism 52 to rotate the total reflection prism 52 around the rotation shaft 11. Thus, by controlling the voltage applied to the electrostatic actuator 15, the angle of the total reflection surface 52a of the total reflection prism 52 can be controlled.

  Then, by appropriately controlling the voltage applied to the electrostatic actuator 15, the angle of the total reflection surface 52a of the total reflection prism 52 can be changed in synchronization with the image field switching signal. If the angle of the total reflection prism 52 is changed so that the optical axis is changed by, for example, 1/2 of the pixel and each field is displayed in synchronization therewith, it is possible to display twice as many pixels. A high-resolution projection image can be realized.

As is well known, the electrostatic actuator 15 has a pair of electrodes provided via an air gap, one electrode works as a diaphragm, and an electrostatic force works between the electrodes by applying a voltage between the electrodes. When the diaphragm is deformed and the voltage is removed, the diaphragm returns to its original state by the elastic force. Thereby, the displacement of the diaphragm can be controlled by controlling the voltage applied to the electrostatic actuator.
The configuration of the electrostatic actuator applied to the present invention is not particularly limited as long as the angle of the total reflection surface 52a of the total reflection prism 52 can be controlled according to the applied voltage.

  As a means for changing the angle of the total reflection surface 52a of the total reflection prism 52, not only the first to third embodiments but also an optimum driving means can be applied as appropriate. In the first to third embodiments, a piezoelectric actuator is preferable if priority is given to response speed, and a voice coil motor is preferable if priority is given to cost. Further, there is a possibility that the size can be further reduced if an electrostatic actuator is used.

FIG. 5 is a view for explaining an example of an arrangement position of the rotation shaft 11 that rotatably holds the total reflection prism 52.
Various means are conceivable as means for holding the angle of the total reflection prism 52 variably, but in order to minimize the moment of inertia when the total reflection prism 52 is rotated and to improve the response to the driving force due to the drive reduction. In this case, it is preferable that the center of gravity of the total reflection prism 52 coincides with the rotation axis 11 thereof.

FIG. 6 is a diagram for explaining another example of the arrangement position of the rotation shaft 11 that rotatably holds the total reflection prism 52.
In order to minimize the focus shift when the total reflection prism 52 is rotated, the rotation shaft 11 is provided on the intersection of the total reflection surface 52 a of the total reflection prism 52 and the optical axis of the projection lens 7. Is preferred.

FIG. 7 is a diagram for explaining another configuration example for variably holding the angle of the total reflection surface 52 a of the total reflection prism 52.
In order to simplify the structure in place of the configuration in which the total reflection prism 52 is pivotally supported on the rotating shaft 11 as described in the above embodiments, a portion close to the edge of the total reflection prism 52 is made of a polymer compound. You may make it hold | maintain with the hinge 16 using the elastic material by. For example, an elastomer can be used as the elastic material.
In the configuration shown in FIG. 7, the hinge 16 is applied to a configuration using the arm 9 as the angle changing means. However, the piezoelectric actuator, voice coil motor, or electrostatic actuator as described above is provided at an angle. Obviously, the hinge 16 may be applied to the configuration used as the changing means.

It is a schematic block diagram for demonstrating one Embodiment of the projection type image display apparatus of this invention. It is a principal part schematic diagram of the projection type image display apparatus for demonstrating the structural example of this invention using the piezoelectric actuator as a means to drive a total reflection prism. It is a principal part schematic diagram of the projection type image display apparatus for demonstrating the structural example of this invention using the voice coil motor as an angle change means to change the angle of the total reflection surface of a total reflection prism. It is a principal part schematic diagram of the projection type image display apparatus for demonstrating the example of a structure of this invention which used the electrostatic actuator as an angle change means to change the angle of the total reflection surface of a total reflection prism. It is a figure for demonstrating an example of the arrangement | positioning position of the rotating shaft which hold | maintains a total reflection prism so that rotation is possible. It is a figure for demonstrating the other example of the arrangement | positioning position of the rotating shaft which hold | maintains a total reflection prism so that rotation is possible. It is a figure for demonstrating the other structural example for hold | maintaining the angle of the total reflection surface of a total reflection prism variably. It is a figure which shows the structural example which applied the prior art to the DLP projection type image display apparatus using DMD.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Light source, 2 ... Color wheel, 3 ... Rod integrator, 4 ... Condensing lens, 5 ... Prism block, 6 ... Display element, 7 ... Projection lens, 8 ... Eccentric cam and motor, 9 ... Arm, 10 ... Spring DESCRIPTION OF SYMBOLS 11 ... Turning axis and bearing, 12 ... Wedge-shaped optical axis changing element, 13 ... Piezoelectric actuator, 14 ... Voice coil motor, 15 ... Electrostatic actuator, 16 ... Hinge by polymer compound, 51 ... First prism 52 ... Second prism (total reflection prism), 52a ... Total reflection surface.

Claims (8)

A light source, a light condensing means for condensing light from the light source, and an element that can take on and off states having different reflection directions, and deflecting the light collected by the light converging means according to image information In a projection-type image display device comprising a display element that modulates and a projection lens that projects light that is deflection-modulated by the display element,
Wherein possess an inclination variable total reflection prism that the light reflected by the on-state is reflected to the projection lens, and an angle changing means for changing in synchronization with the inclination of the total reflection prism to the image information,
A projection-type image display apparatus , wherein the optical path of light emitted from the projection lens is shifted in synchronization with the image information by changing the tilt of the total reflection prism in synchronization with the image information . The projection type image display device according to claim 1, wherein the projection type image display device has color separation means for color-separating light from the light source into RGB on an optical path from the light source to the display element. ,
The projection type image display device, wherein the display element is a DMD (Digital Micromirror Device) configured by a micromirror that individually switches a reflection direction of incident light between an on state and an off state according to image information.   3. The projection type image display apparatus according to claim 1, wherein a piezoelectric actuator is used for the angle changing means.   The projection type image display apparatus according to claim 1 or 2, wherein a voice coil motor is used for the angle changing means.   3. The projection type image display apparatus according to claim 1, wherein an electrostatic actuator is used for the angle changing means.   6. The projection type image display device according to claim 1, wherein the total reflection prism is rotatably held on an axis passing through the center of gravity of the total reflection prism. Type image display device.   6. The projection type image display device according to claim 1, wherein the total reflection prism is rotatable on an axis passing through an intersection between a reflection surface of the total reflection prism and the optical axis of the projection lens. A projection-type image display device that is held.   6. The projection type image display device according to claim 1, wherein the total reflection prism is held by a hinge formed of an elastic material made of a polymer compound. apparatus.

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