JP4678528B2 - Illumination device for display device and liquid crystal display device including the same - Google Patents

Description

  The present invention relates to a lighting device for a display device and a liquid crystal display device including the same, and is suitable for use in a vehicle display device.

  As a conventional lighting device for a display device for a vehicle, a light emitting diode as a light source is disposed so as to face the side surface of the light guide plate, and light incident on the side surface of the light guide plate from the light emitting diode is illuminated from the surface of the light guide plate. An illumination device that emits light is known. Here, since the light emitting diode generates heat with light emission, the components of the display device to which the illumination device is applied may be deteriorated by receiving heat from the light emitting diode.

The inventor has proposed an illumination device that aims to suppress deterioration of components of a display device by improving heat dissipation of a wiring board on which a light emitting diode is mounted (see Patent Document 1). Specifically, the wiring board on which the light emitting diode is mounted is configured as a metal wiring board based on a metal plate.
JP 2004-279262 A

  The present inventor goes one step further than the above prior art, instead of a metal wiring board based on a metal plate, a heat radiating member having a heat radiating fin or the like for releasing heat generated by a light emitting diode into the air, An illumination device for a display device that includes a heat transfer member that thermally connects a light emitting diode and a heat dissipation member was studied. Thereby, it becomes possible to arrange | position a thermal radiation member in the position away from the component of the display apparatus, and, for this reason, a component becomes difficult to receive a thermal influence more.

  However, when the lighting device for display device is attached to the display device or the vehicle, an operator may touch a heat radiating member to damage a mechanically weak portion of the heat radiating member, such as a heat radiating fin. This problem is solved by covering the periphery of the heat dissipation member with a protective case.

  However, there arises a problem that the heat radiation performance of the heat radiating member is lowered by the protective case. This is because when the periphery of the heat radiating member is covered with the protective case, the air that has received the heat released from the heat radiating member is less likely to flow out of the protective case.

  This problem is limited to an illumination device for a display device in which a light emitting diode is disposed so as to face the side surface of the light guide plate, and light incident on the side surface of the light guide plate from the light emitting diode is emitted as illumination light from the surface of the light guide plate. is not. That is, this problem is a problem common to display device illumination devices that include a light source and a heat dissipation member that releases heat generated by the light source into the air.

  The present invention has been made in view of the above points, and in a display device illumination device including a light source and a heat dissipation member that dissipates heat generated by the light source, and a liquid crystal display device including the same, a heat dissipation member includes: It aims at protecting mechanically, suppressing the fall of the thermal radiation performance.

  In order to achieve the above object, the present invention employs the following technical means.

The illumination device for a display device according to claim 1 of the present invention holds a light source, a control circuit for controlling turning on / off of the light source, a wiring board on which the control circuit is mounted, a light source and a wiring board. An upper case, a lower case that is disposed behind the wiring board via a space, a heat radiating member that is disposed outside the lower case, and that releases heat into the air, is fixed to the lower case, covers the periphery of the heat radiating member, and radiates heat A protective case that mechanically protects the member, and a heat transfer member that is disposed outside the upper case and the lower case, and thermally connects the light source and the heat dissipation member to transmit heat generated by the light source to the heat dissipation member; The heat dissipating member includes a passage through which air flows, and the heat dissipating member receives heat released from the heat dissipating member while the air passes through the passage from the passage entrance to the passage exit of the passage. The protective case includes a case inlet for allowing air to flow into the passage entrance from the outside of the protective case, and a case outlet for allowing air flowing out of the passage outlet to flow out of the protective case. The passage outlet is formed so as to include the passage inlet in the direction of flowing into the passage inlet, and the case outlet is formed so as to include the passage outlet in the direction of air flowing out of the passage outlet.

  In this configuration, since the protective case covers the periphery of the heat dissipation member, the heat dissipation member can be mechanically protected.

  In this configuration, the case entrance is formed so as to include the passage entrance in the direction in which air flows into the passage entrance. Thereby, the air which has not received heat from the heat radiating member can flow from the case entrance to the passage entrance of the heat radiating member without being greatly disturbed by the protective case.

  In this configuration, the case outlet is formed so as to include the passage outlet in a direction in which air flows out from the passage outlet. Thereby, the air which received the heat released from the heat radiating member can flow out from the passage outlet of the heat radiating member through the case outlet without being greatly disturbed by the protective case.

  The inflow of air from the case entrance to the entrance of the passage and the outflow of air from the exit of the passage through the case exit are not greatly disturbed by the protective case. Can be suppressed.

As a result, the heat dissipation member can be mechanically protected while suppressing a decrease in the heat dissipation performance.
Moreover, since the heat radiating member is arrange | positioned on the outer side of the lower case, the component of a display apparatus becomes difficult to receive the influence of the heat from a heat radiating member. Furthermore, by extending the heat transfer member, the heat radiating member can be arranged at a position away from the component parts of the display device to which the display device illumination device according to the present invention is applied. For this reason, the component of a display apparatus becomes difficult to receive the influence of the heat from a heat radiating member.

The illumination device for a display device according to claim 2 of the present invention is configured such that the protective case covers the periphery of the heat radiating member and mechanically protects the heat radiating member at a portion excluding the case entrance and the case exit. In this configuration, the protective case is configured to mechanically protect the heat dissipation member by covering the periphery of the heat dissipation member at a portion excluding the case entrance and the case exit. Thereby, a heat radiating member can be protected more mechanically.

  The illumination device for a display device according to claim 3 of the present invention is characterized in that the case outlet is disposed above the case entrance.

  Here, since the air which received the heat released from the heat radiating member is thermally expanded and its density is lowered, the air tends to rise more than the air not receiving heat from the heat radiating member. For this reason, the air which received the heat released from the heat dissipation member is more likely to flow out of the protective case through the case outlet disposed above the case entrance. As a result, the deterioration of the heat dissipation performance of the heat dissipation member due to the protective case can be further suppressed.

  According to a fourth aspect of the present invention, there is provided a lighting device for a display device, comprising a blower that generates a flow of air that flows in from a case entrance, passes through a passage, and flows out from the case exit.

  Thereby, the flow of air flowing in from the case entrance, passing through the passage, and flowing out from the case exit can be promoted. As a result, the deterioration of the heat dissipation performance of the heat dissipation member due to the protective case can be further suppressed.

  The illumination device for a display device according to claim 5 of the present invention is characterized in that the heat dissipation member includes a plurality of fins arranged in parallel, and the passage includes a gap between the fins.

  Even with this configuration, the above-described effects can be obtained.

A liquid crystal display device according to claim 6 is a liquid crystal display device including the display device illumination device according to any one of claims 1 to 5 , wherein the liquid crystal panel is disposed behind the liquid crystal panel. And a light guide member that guides light emitted from the light source to the liquid crystal panel to transmit and illuminate the liquid crystal panel, and the upper case houses the liquid crystal panel and the light guide member.

  Hereinafter, a case where the illumination device for a display device according to the present invention is applied to a combination meter 1 mounted on an automobile will be described with reference to the drawings.

(Constitution)
The combination meter 1 is disposed in front of the driver's seat of the automobile and displays various vehicle information related to the automobile. As shown in FIG. 1, the combination meter 1 according to the present embodiment includes a speedometer 2 that displays the traveling speed of an automobile, a speedometer 3 that displays an engine speed, and navigation information and road traffic information between them. Etc., and a liquid crystal display device 4 which is a display device for displaying the above.

  In FIG. 2, the liquid crystal display device 4 includes a liquid crystal panel 41, a light guide plate 42 as a light guide member, and a display device illumination device. The display device illumination device includes a light emitting diode 43 that is a light source, a heat pipe 48 that is a heat transfer member, a heat dissipation fin 5 that is a heat dissipation member, and a protective case 6.

  The light guide plate 42 is formed in a flat plate shape from, for example, a colorless and transparent acrylic resin, and is disposed behind the liquid crystal panel 41 (on the right side in FIG. 2). The light guide plate 42 guides the light from the light emitting diode 43 incident from the side surface 42 a to the inside according to the optical path P, guides the light to the liquid crystal panel 41, and illuminates the liquid crystal panel 41.

  For example, the reflection sheet 45 formed from a resin film colored white is disposed on the back surface (right surface in FIG. 2) of the light guide plate 42. The reflection sheet 45 reflects light traveling in the light guide plate 42 toward the liquid crystal panel 41 along the optical path P.

  For example, a diffusion sheet 44 formed of a translucent resin film or the like is disposed on the surface of the light guide plate 42 (the left surface in FIG. 2). The diffusion sheet 44 diffuses and reflects the light reflected from the reflection sheet 45 and emitted from the light guide plate 42, thereby uniformizing the luminance of the light emitted from the light guide plate 42.

  The eight light emitting diodes 43 are mounted on the wiring board 46 as shown in FIG. 3, and are arranged to face the side surface 42a of the light guide plate 42 as shown in FIG. The number of light emitting diodes 43 is not limited to eight.

  The wiring board 8 is arranged behind the reflection sheet 45 (on the right side in FIG. 2), and a control device 9 composed of a microcomputer or the like is mounted on the wiring board 8. The control device 9 controls the operation of the liquid crystal panel 41 and the turning on / off of the light emitting diode 43. The wiring board 46 is connected to the wiring board 8 by electric wiring (not shown).

  Further, a part of the control device 9 (transistor, limiting resistor, etc.) for controlling turning on / off of the light emitting diode 43 can be mounted on the wiring board 46. In this case, in addition to the heat generated by the light emitting diodes 43, the heat radiating fins 5 to be described later release heat generated by the transistors mounted on the wiring board 46 and the limiting resistance into the air.

  The liquid crystal panel 41, the light guide plate 42, and the like are housed in a housing composed of a design plate 71, an upper case 72, a lower case 73, and a transparent cover 74, and the light emitting diode 43 is held in the housing. Specifically, the wiring board 46 on which the light emitting diode 43 is mounted is fixed to the upper case 72.

  Hereinafter, the configuration of the illumination device for a display device including the light emitting diode 43, the heat pipe 48, the heat radiation fin 5, and the protective case 6 will be described.

  A plate 47 made of, for example, aluminum having high thermal conductivity thermally connects the wiring board 46 on which the light emitting diode 43 is mounted and the heat pipe. The plate 47 has a shape similar to that of the wiring board 46 and is fixed to the wiring board 46 with screws or the like.

  A heat pipe 48 formed of a pipe having a high thermal conductivity, for example, copper or copper alloy, thermally connects the light emitting diode 43 and the radiation fin 5. The heat pipe 48 is disposed outside the upper case 72 and the lower case 73, and one end thereof is fixed to the plate 47 by welding or the like, and the other end is fixed to the radiating fin 5 by welding or the like. A through hole 53 (FIG. 5A) is formed in the radiating fin 5, and the other end of the heat pipe 48 is inserted into the through hole 53 and fixed to the radiating fin 5 by welding or the like, as shown in FIG. . Further, water having a volume of about 10% of the pipe internal space of the heat pipe 48 is accommodated in the pipe as a refrigerant.

  Heat generated by the light emitting diodes 43 (including heat generated when transistors and limiting resistors are mounted on the wiring board 46) is transmitted to the heat pipe 48 via the wiring board 46 and the plate 47. The The heat pipe 48 is configured such that the heat transmitted to the heat pipe 48 is transmitted to the heat radiating fins 5 using latent heat of evaporation and condensation of water in the heat pipe 48.

  Thereby, the heat transmitted to the heat pipe 48 is not radiated much from the heat pipe 48 but is transmitted to the heat radiating fins 5. That is, the light guide plate 42, the control device 9, and the like that are components of the liquid crystal display device 4 are not easily affected by the heat from the heat pipe 48.

  The heat dissipating fins 5 made of, for example, aluminum having high thermal conductivity are arranged outside the casing formed by the design plate 71, the upper case 72, the lower case 73, and the transparent cover 74, that is, outside the lower case 73. Established. The radiating fin 5 receives the heat generated by the light emitting diode 43 through the wiring substrate 46, the plate 47, and the heat pipe 48, and releases the heat into the air.

  By extending the heat pipe 48, it is possible to dispose the heat radiating fins 5 at positions away from the light guide plate 42 and the control device 9 and the like. For this reason, the light guide plate 42 and the control device 9 and the like are radiated fins. 5 is less affected by heat. Further, since the radiating fins 5 are arranged outside the lower case 73, the light guide plate 42, the control device 9, and the like are less affected by the heat from the radiating fins 5.

  As shown in FIG. 4, the radiating fin 5 includes a plurality of fins 51 arranged in parallel, and a passage 52 through which air flows is a gap 52 between the fins 51, as shown in FIGS. 4 and 5. Configured as a set of The radiating fin 5 is configured to receive heat released from the radiating fin 5 while air passes through the passage 52 from the passage inlet 52 a of the passage 52 to the passage outlet 52 b of the passage 52.

  For example, the protective case 6 made of a heat-resistant resin such as polyacetal resin or metal covers the periphery of the radiation fin 5 and mechanically disposes the radiation fin 5 as shown in FIGS. 2, 3, and 4 (a). It is fixed to the lower case 73 so as to protect it. As shown in FIGS. 2 and 4, the protective case 6 includes a case entrance 61 for allowing air to flow from the outside of the protective case 6 to the passage entrance 52 a of the radiating fin 5, and air flowing out from the passage exit 52 b is a protective case. And a case outlet for flowing out of the apparatus.

  The case outlet 62 is disposed above the case inlet 61 as shown in FIGS. 2, 4 (b), and 5 (b). Here, the air that has received the heat released from the heat radiating fins 5 is thermally expanded and its density decreases, so that it tends to rise more than air that has not received heat from the heat radiating fins 5. For this reason, the air that has received the heat released from the radiating fin 5 is more likely to flow out of the protective case 6 through the case outlet 62 disposed above the case inlet 61. As a result, it is possible to suppress a decrease in the heat radiation performance of the heat radiation fin 5 due to the protective case 6.

  That is, in FIG. 5B, air flows from the case entrance 61 to the passage entrance 52a in the direction of the arrow F1 along the vertical direction, and from the passage exit 52b to the direction of the arrow F2 along the vertical direction. It flows out through the outlet 62.

  The case inlet 61 is formed so as to include the passage inlet 52a in the direction in which air flows into the passage inlet 52a (the direction of the arrow F1 in FIG. 5B). Specifically, the case entrance 61 is formed so as to include the radiation fins 5 as shown in FIG. As a result, air that has not received heat from the radiating fin 5 can flow from the case entrance 61 to the passage entrance 52 a of the radiating fin 5 without being greatly disturbed by the protective case 6.

  The case outlet 62 is formed so as to include the passage outlet 52b in the direction in which air flows out from the passage outlet 52b (the direction of the arrow F2 in FIG. 5B). Specifically, the case outlet 62 is formed larger than the heat radiating fins 5 as shown in FIG. As a result, the air that has received the heat released from the radiating fin 5 can flow out from the passage outlet 52 b of the radiating fin 5 through the case outlet 62 without being greatly disturbed by the protective case 6.

  The inflow of air from the case entrance 61 to the passage entrance 52a and the outflow of air from the passage exit 52b through the case exit 62 are not greatly hindered by the protection case 6, so The deterioration of the heat dissipation performance can be suppressed.

  Further, the protective case 6 is configured to cover the periphery of the radiation fin 5 and mechanically protect the radiation fin 5 at a portion excluding the case inlet 61 and the case outlet 62. As a result, the radiating fin 5 can be mechanically protected while suppressing a decrease in its radiating performance.

  In addition, the mechanical strength of the protective case 6 can be increased by providing the reinforcing part 63 shown in FIG. The protective case 6 is fixed to the lower case 73 on the side where the reinforcing portion 63 is provided.

(Modification)
In the above-described example shown in FIG. 5A, the case inlet 61 and the case outlet 62 are formed so as to include the heat radiating fins 5. However, the present invention is not limited to this. As shown in FIG. 7, the case inlet 61 and the case outlet 62 are formed so as to include both the fins 51 and the passages 52, but can be formed so as not to include a part of the radiating fins 5. . The effect mentioned above can be acquired also by this.

  Further, as shown in FIG. 8, the case inlet 61 and the case outlet 62 are formed so as to include the passage 52, but can be formed so as not to include a part of the fin 51. The effect mentioned above can be acquired also by this.

  As shown in FIG. 9A, when the heat radiating fins 5 are formed in a parallelogram, the case inlet 61 and the case outlet 62 are formed in a parallelogram according to this. Further, instead of the case entrance 61 and the case exit 62, the case entrance 61 a and the case exit 62 a can be formed in a rectangular shape so as to include the radiation fins 5. In any case, the above-described effects can be obtained.

  When the heat dissipating fins 5 are formed in a parallelogram in the vertical direction as shown in FIG. 9B, the air flows in the direction of the arrow F3 inclined with respect to the vertical direction in FIG. 9B. It flows into the passage entrance 52a from the entrance 61, and flows out from the passage exit 52b through the case exit 62 in the direction of the arrow F4 inclined with respect to the vertical direction.

  In this case, the case entrance 61 is formed so as to include the passage entrance 52a in the direction in which air flows into the passage entrance 52a (the direction of the arrow F3 in FIG. 9B). Further, the case outlet 62 is formed so as to include the passage outlet 52b in the direction in which air flows out from the passage outlet 52b (the direction of the arrow F4 in FIG. 9B).

  Further, instead of the case entrance 61 and the case exit 62, a case entrance 61a is formed to be large so as to include the case entrance 61 as shown in FIG. 9B, and the case exit 62a is included to include the case exit 62. It is also possible to make it large. In any case, the above-described effects can be obtained.

  When the radiating fins 5 are formed in a shape curved in the vertical direction as shown in FIG. 10, the air flows from the case entrance 61 to the passage entrance 52a in the direction of the arrow F5 inclined with respect to the vertical direction in FIG. And flows out from the passage outlet 52b through the case outlet 62 in the direction of the arrow F6 inclined with respect to the vertical direction.

  In this case, the case entrance 61 is formed so as to include the passage entrance 52a in the direction in which air flows into the passage entrance 52a (the direction of the arrow F5 in FIG. 10). That is, the case entrance 61 is formed so as to include the passage entrance 52a along an auxiliary line indicated by a broken line (an auxiliary line parallel to the arrow F5).

  Further, the case outlet 62 is formed so as to include the passage outlet 52b in the direction in which air flows out from the passage outlet 52b (the direction of the arrow F6 in FIG. 10). That is, the case outlet 62 is formed so as to include the passage outlet 52b along an auxiliary line indicated by a broken line (an auxiliary line parallel to the arrow F6). Thereby, the above-mentioned effect can be acquired.

  In addition, as long as the function of the protective case 6 for mechanically protecting the radiating fin 5 and the mechanical strength of the protective case 6 can be ensured, the through holes other than the case inlet 61 and the case outlet 62 are provided in the protective case shown in FIG. 6 may be formed on each of the surfaces N1, N2, and N3.

  Further, the blower 10 can be arranged at the case entrance 61 of the protective case 6 as shown in FIG. The blower 10 includes a blower case 10a, an impeller 10b accommodated in the blower case 10a, and an electric motor 10c. The impeller 10 b is driven by the electric motor 10 c to cause air to flow into the case inlet 61, pass through the heat radiation fin 5 (passage 52), and flow out from the case outlet 62. In other words, the blower 10 generates an air flow that flows in from the case inlet 61, passes through the passage 52, and flows out of the case outlet 62.

  Thereby, the flow of air flowing in from the case inlet 61, passing through the passage 52, and flowing out from the case outlet 62 can be promoted. As a result, the deterioration of the heat dissipation performance of the heat dissipation fin 5 due to the protective case 6 can be further suppressed.

  As described above, the illumination device for a display device according to the present invention covers the periphery of the light emitting diode 43 that is a light source, the heat dissipating fin 5 that is a heat dissipating member that releases heat generated by the light emitting diode 43 into the air, and the heat dissipating fin 5. A protective case 6 that mechanically protects the radiating fin 5, the radiating fin 5 includes a passage 52 through which air flows, and the radiating fin 5 passes through the passage 52 from the passage entrance 52 a of the passage 52 to the passage 52. The protective case 6 is configured to receive heat released from the heat radiating fins 5 while passing to the passage outlet 52b, and the protective case 6 has a case inlet 61 for allowing air to flow into the passage inlet 52a from the outside of the protective case 6, and a passage A case outlet 62 for allowing the air flowing out from the outlet 52b to flow out from the protective case 6, and the case inlet 61 is a direction in which air flows into the passage inlet 52a. It is formed to include Oite passage inlet 52a, casing outlet 62, air is formed to include a passageway outlet 52b in a direction flowing out from the passage outlet 52b.

  Thereby, in the lighting device for a display device including the light source and the heat radiating member that radiates the heat generated by the light source, the heat radiating member can be mechanically protected while suppressing a decrease in the heat radiating performance.

  In addition, the present invention is not limited to the above-described example, and other various modifications can be considered.

FIG. 1 is a front view of a combination meter 1 to which a display device illumination device according to an embodiment of the present invention is applied. 2 is a cross-sectional view taken along line II-II in FIG. FIG. 3 is an enlarged back view of a portion III in FIG. 4A is a cross-sectional view taken along the line IVA-IVA of FIG. 3, and FIG. 4B is an enlarged view of the state in which the protective case 6 is removed from the IVB portion of FIG. FIG. 5A is a schematic diagram of FIG. 4A showing the arrangement relationship between the heat radiating fins 5 and the case inlets 61, and the heat radiating fins 5 and the case outlets 62, which are heat radiating members, and FIG. FIG. 5B is a schematic view of FIG. 4B showing the positional relationship between the passage 52a and the case inlet 61 and the passage 52b and the case outlet 62. FIG. 6 is a schematic perspective view of the protective case 6. FIG. 7 shows a first modification of FIG. FIG. 8 shows a second modification of FIG. FIG. 9 is a modification of FIG. FIG. 10 is a modification of FIG. FIG. 11 is a modification of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Combination meter, 2 Speedometer, 3 Tachometer 4 Liquid crystal display device (display device), 41 Liquid crystal panel, 42 Light guide plate (light guide member)
42a side surface, 43 light emitting diode (light source), 44 diffusion sheet, 45 reflection sheet 46 wiring board, 47 plate, 48 heat pipe (heat transfer member)
5 Heat radiation fin (heat radiation member), 51 Fin, 52 Crevice (passage)
52a Passage entrance, 52b Passage exit, 53 Through hole 6 Protective case, 61, 61a Case entrance, 62, 62a Case exit 63 Reinforcement part, 71 Design plate, 72 Upper case, 73 Lower case 74 Transparent cover, 8 Wiring board, 9 Control Device 10 Blower, 10a Blower case, 10b Impeller, 10c Electric motor

Claims (6)

A light source;
A control circuit for controlling turning on and off of the light source;
A wiring board on which the control circuit is mounted;
An upper case for holding the light source and the wiring board;
A lower case disposed via a space behind the wiring board;
A heat dissipating member disposed outside the lower case and releasing heat into the air;
A protective case that is fixed to the lower case and covers the periphery of the heat dissipation member to mechanically protect the heat dissipation member ;
A heat transfer member that is disposed outside the upper case and the lower case, and thermally connects the light source and the heat dissipation member to transmit heat generated by the light source to the heat dissipation member ;
The heat dissipation member includes a passage through which air flows,
The heat dissipation member is configured to receive heat released from the heat dissipation member while air passes through the passage from a passage entrance of the passage to a passage exit of the passage;
The protective case includes a case inlet for allowing air to flow into the passage entrance from the outside of the protective case, and a case outlet for allowing air flowing out of the passage outlet to flow out of the protective case,
The case entrance is formed to include the passage entrance in a direction in which air flows into the passage entrance,
The illumination device for a display device, wherein the case outlet is formed so as to include the passage outlet in a direction in which air flows out from the passage outlet.   2. The protective case is configured to mechanically protect the heat radiating member by covering the periphery of the heat radiating member at a portion excluding the case entrance and the case outlet. The illumination device for display apparatuses as described.   The lighting device for a display device according to claim 1, wherein the case outlet is disposed above the case inlet.   4. The blower according to claim 1, further comprising a blower that generates a flow of air that flows in from the case entrance, passes through the passage, and flows out from the case exit. 5. Lighting device for display device. The heat dissipation member includes a plurality of fins arranged in parallel,
The said channel | path is provided with the clearance gap between the said fins, The illuminating device for display apparatuses as described in any one of Claim 1 thru | or 4 characterized by the above-mentioned. A liquid crystal display device comprising the display device illumination device according to any one of claims 1 to 5 ,
LCD panel,
A light guide member disposed behind the liquid crystal panel and guiding light emitted from the light source to the liquid crystal panel to transmit and illuminate the liquid crystal panel ;
The liquid crystal display device , wherein the upper case houses the liquid crystal panel and the light guide member.

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