JP6346732B2 - Printed circuit board fixing structure of display device - Google Patents

Description

  The present invention relates to a structure for fixing the printed circuit board of a display device in which a display element is disposed on the front surface of a case and a printed circuit board is disposed on the back surface.

  A display device in which a display element is disposed on the front surface of a case and a printed circuit board is disposed on the back surface is used for information display in in-vehicle equipment, industrial equipment, and the like. As a fixing structure, a structure in which a printed circuit board is fixed to a case together with a display element by a claw portion formed by bending a part of a side end of a sheet metal case cover covering the entire case inward, or a printed circuit board by a screw. The structure to fix to was adopted.

  However, the fixing structure requires additional parts such as a case cover and a screw, and also requires a process of bending the case cover to form a claw part and a process of inserting and screwing the screw, resulting in an increase in cost. There was a problem.

  Therefore, conventionally, a fixing structure as shown in FIG. 9 has been proposed and put into practical use.

  That is, FIG. 9 is a partial cross-sectional view of a display device showing a conventional printed circuit board fixing structure. In the illustrated display device 101, first and second locking claws having different cross-sectional shapes are provided on the back surface of the case 102. 104 and 105 are integrally projected downward. The printed circuit board 103 is fixed to the case 102 by being locked by the first and second locking claws 104 and 105 while being in close contact with the back surface of the case 102. Specifically, the printed circuit board 103 has both end portions inserted into the clearances of the first and second locking claws 104 and 105, and the back surface is locked by the first and second locking claws 104 and 105. As a result, the back surface of the case 102 is fixed.

  Further, regarding the fixing structure of the printed circuit board, Patent Document 1 proposes a configuration as shown in FIG.

  That is, FIG. 10 is a partial cross-sectional view showing the printed circuit board fixing structure proposed in Patent Document 1. The liquid crystal holder (case) 202 to which the printed circuit board 203 is fixed includes a multi-color molded thermoplastic resin member 202A. The substrate positioning boss 202a protrudes from the back surface of the thermoplastic resin member 202A, and a locking claw 202b is formed on the elastic member 202B.

  Thus, as shown in FIG. 10A, when the liquid crystal holder 202 is incorporated vertically downward (in the direction of arrow a) with respect to the printed circuit board 203, the substrate protruding from the thermoplastic resin member 202A of the liquid crystal holder 102. Since the positioning boss 202 a is inserted into the positioning hole 203 a of the printed board 203, the printed board 203 is positioned with respect to the liquid crystal holder 202. Further, when the locking claw 202b formed on the elastic member 202B of the liquid crystal holder 202 expands in the direction of arrow b in FIG. 10A due to elasticity, and when the locking claw 202b passes through the printed circuit board 203, FIG. As shown in b), the locking claw 202b returns to its original state and locks the side edge of the printed circuit board 203, so that the printed circuit board 203 is fixed to the liquid crystal holder 202.

JP 2001-264732 A

  Incidentally, in the conventional fixing structure shown in FIG. 9, the clearance H (for example, 1.2 mm) of the first and second locking claws 104 and 105 is set to be larger than the thickness d (for example, 1 mm) of the printed circuit board 102. (H> d). This is because when the case 102 is made of a resin that is difficult to plastically deform, such as polycarbonate, the clearance H of the first and second locking claws 104 and 105 is smaller than the thickness d of the printed circuit board 103 (H <d This is because the printed circuit board 103 cannot be inserted into the first and second locking claws 104 and 105.

  However, if the clearance H between the first and second locking claws 104 and 105 is larger than the thickness d of the printed circuit board 103 (H> d) as described above, the printed circuit board 103 is not sufficiently fixed, and the backlash is unstable. When the display device 101 is used in an environment in which vibration is likely to be applied, the case 102 and the printed circuit board 103 periodically repeat contact and separation, so that rattle noise that is periodic abnormal noise is generated. There's a problem. Such a problem also occurs in the fixing structure proposed in Patent Document 1.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a printed circuit board fixing structure of a display device that can securely fix the printed circuit board with a simple configuration without rattling.

In order to achieve the above object, the invention according to claim 1 is a structure for fixing the printed circuit board of a display device in which a display element is disposed on the front surface of the case and a printed circuit board is disposed on the back surface.
Protruding a first locking claw and a second locking claw having different cross-sectional shapes on the back surface of the case,
The first locking claw is provided with a protrusion protruding from a portion facing the back surface of the printed circuit board, and a clearance between the first locking claw and the back surface of the case is determined by the thickness of the printed circuit board. And setting the clearance between the protrusion and the back surface of the case smaller than the thickness of the printed circuit board,
The first said projection protruding from the engaging pawl is backside point contact or line contact of the printed circuit board, one end of the printed circuit board engaged by the first locking claw,
The second locking claw is provided with a first rib-like protrusion protruding along a thickness direction of the printed circuit board at a portion facing the side surface of the printed circuit board. Set the clearance with the back of the case larger than the thickness of the printed circuit board,
The first rib-shaped protrusion is brought into contact with a side end surface of the printed circuit board , and the other end of the printed circuit board is locked by the second locking claw.

According to a second aspect of the present invention, in the first aspect of the present invention, a second part of the outer surface of the case opposite to the surface on which the first rib-like protrusion of the second locking claw protrudes is provided. The rib-shaped projections are provided so as to project, and the height of the second rib-shaped projections is set to be equal to or less than the height of the second locking claws .

According to a third aspect of the present invention, in the second aspect of the present invention, the protrusion projecting from the first locking claw is hemispherical, conical, polygonal pyramid or semicylindrical, and the second The first or second rib-like projections protruding from the locking claws are formed into a quadrangular prism shape, a semi-cylindrical shape, or a triangular prism shape .

  According to the first aspect of the present invention, the first and second locking claws are provided with a clearance larger than the thickness of the printed board so that the printed board can be easily inserted into the first and second locking claws of the case. Even so, the protrusion protruding from the first locking claw contacts the printed circuit board and presses the printed circuit board against the back surface of the case. In addition, the first rib-like projections protruding from the second locking claw abuts against the side end surface of the printed circuit board and presses the printed circuit board toward the first locking claw side. As a result, the printed circuit board can be securely fixed to the case with a simple structure without increasing the number of parts and the number of assembly steps, and the occurrence of rattle noise due to vibration can be prevented.

  According to the second aspect of the present invention, when the case is covered with the case cover, the second rib-like protrusions protruding from the second locking claws press a part of the case toward the printed circuit board. The printed circuit board is more securely fixed to the case.

  According to the third aspect of the present invention, since the protrusion protruding from the first locking claw is brought into point contact or line contact with the back surface of the printed circuit board, the printed circuit board is inserted into the first locking claw. The resistance is suppressed to a low level and the assembly of the printed circuit board is enhanced, and the load applied to the first locking claw is reduced to prevent the first locking claw from being damaged.

It is a fragmentary sectional view of a display apparatus provided with the printed circuit board fixation structure concerning the present invention. It is the A section enlarged detail drawing of FIG. FIG. 3 is a sectional view taken along line B-B in FIG. 2. It is a perspective view of the 1st latching claw protrudingly provided by the case of the display device. (A), (b) is a figure similar to FIG. 3 which shows another form of this invention. FIG. 2 is an enlarged detail view of a C part in FIG. 1. It is a figure which shows the 2nd latching claw protrudingly provided by the case of the display apparatus, Comprising: (a) is a side view, (b) is a perspective view. It is a back view of a display apparatus provided with the printed circuit board fixing structure which concerns on this invention. It is a fragmentary sectional view of a display apparatus provided with the conventional printed circuit board fixing structure. It is a fragmentary sectional view which shows the printed circuit board fixing structure proposed in patent document 1.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  1 is a partial cross-sectional view of a display device having a printed circuit board fixing structure according to the present invention, FIG. 2 is an enlarged detail view of part A in FIG. 1, FIG. 3 is a cross-sectional view along line BB in FIG. FIG. 5A and FIG. 5B are views similar to FIG. 3 showing another embodiment of the present invention, and FIG. 6 is an enlarged detail of a portion C in FIG. FIGS. 7A and 7B are diagrams showing a second locking claw protruding from the case of the display device, wherein FIG. 7A is a side view, FIG. 7B is a perspective view, and FIG. 8 is a printed circuit board fixing according to the present invention. It is a back view of a display apparatus provided with a structure.

  In the display device 1 according to the present embodiment, a display element (not shown) is disposed on the front surface of the case 2 and the printed circuit board 3 is disposed on the back surface, and the printed circuit board 3 has a fixing structure according to the present invention. The case 2 is fixed to the back surface. As the display element, a liquid crystal display element, an organic LED element, a fluorescent display tube or the like is used, and the printed circuit board 3 incorporates a display element drive circuit, a control circuit, an electronic component such as an LED, and the like.

  Here, the fixing structure of the printed circuit board 3 according to the present invention will be described.

  The case 2 is made of polycarbonate that is not easily plastically deformed. As shown in FIG. 1, the back surface of the case 2 has a first locking claw 4 and a second locking claw 5 having different cross-sectional shapes. It protrudes integrally downward. The printed circuit board 3 is fixed to the case 2 by being locked to both ends by the first and second locking claws 4 and 5 while being in close contact with the back surface of the case 2. A recess 2a for avoiding interference with an electronic component (not shown) such as an LED mounted on the printed circuit board 3 is formed on a part of the back surface.

  By the way, a clearance H is formed in the first and second locking claws 4, 5 protruding from the back surface of the case 2, and insertion of the printed circuit board 3 into these locking claws 4, 5 is possible. In order to make it possible, the clearance H is set larger than the thickness d of the printed circuit board 2 (H> d). In the present embodiment, the clearance H of the first and second locking claws 4 and 5 is set to 1.2 mm, and the thickness d of the printed circuit board 2 is set to 1 mm.

Thus, in the present embodiment, as shown in FIGS. 2 to 4, a hemispherical protrusion 4 a is integrated at the center in the width direction of the surface of the first locking claw 4 that faces the back surface of the printed circuit board 3. Projected to Here, the clearance H ′ (see FIGS. 2 and 3) between the protrusion 4a and the back surface of the case 2 is set to be smaller than the thickness d of the printed circuit board 3 (H ′ <d). Therefore, a magnitude relationship of H>d> H ′ is established between the clearances H and H ′ of the first locking claws 4 and the thickness d of the printed circuit board 3. In this embodiment, H ′ is set to 0.9 mm (crushing margin of the protrusion 4a: 0.1 mm), but H ′ satisfies d−0.3 mm ≦ H ′ ≦ d−0.1 mm. It is preferable to set the range (crushing margin of the protrusion 4a: 0.1 mm to 0.3 mm). In the present embodiment, one hemispherical protrusion 4a is provided on the first locking claw 4, but for example, as shown in FIG. 5 (a), two (or more) hemispherical protrusions are provided. The protrusion 4a may be protruded, or as shown in FIG. 5B, a cone-shaped protrusion 4a other than a hemisphere (or a polygonal pyramid such as a quadrangular pyramid or a semi-cylindrical shape) may be provided.

  On the other hand, as shown in FIGS. 6 and 7, the first rib-like protrusion 5a of the quadrangular prism is integrated along the vertical direction at a portion of the second locking claw 5 facing the side end surface of the printed circuit board 3. Projected to In addition, the first rib-shaped protrusion 5a and a part of the outer surface of the case 2 (the lower end) opposite to the surface on which the first rib-shaped protrusion 5a of the second locking claw 5 protrudes are provided. A similar quadrangular prism-like second rib-like projection 5b is integrally projected along the vertical direction. In addition, although the dimension of the 2nd latching claw 5 in this Embodiment is shown in FIG. 7, as shown in the figure, the width and height of the 1st rib-shaped protrusion 5a are set to 0.2 mm, The length of the second rib-like protrusion 5b is set to 2 mm, and the width and height are set to 0.3 mm. In the present embodiment, the first and second rib-like protrusions 5a and 5b are formed in a quadrangular prism shape, but these shapes may be a semi-cylindrical shape, a triangular prism shape, or the like.

  Thus, the printed circuit board 3 is locked by inserting one end portion thereof into the clearance H of the first locking claw 4 of the case 2, but the printed circuit board 3 of the first locking claw 4. A protrusion 4 a is provided on the surface opposite to the back surface of the substrate, and a clearance H ′ (clearance between the protrusion 4 a and the back surface of the case 2) H ′ is smaller than the thickness d of the printed circuit board 3. Since it is set (H ′ <d), when the printed circuit board 3 is inserted into the first locking claw 4, the protrusion 4a is plastically deformed and crushed (in this embodiment, crushed allowance: 0.1 mm)) . For this reason, the protrusion 4a protruding from the first locking claw 4 contacts the back surface of the printed circuit board 3 and presses the printed circuit board 3 against the back surface of the case 2, and one end portion of the printed circuit board 3 is the first portion. It is locked by the locking claw 4 and is securely fixed to the back surface of the case 2 without rattling. In the present embodiment, since the shape of the protrusion 4 a of the first locking claw 4 is hemispherical, the protrusion 4 a is in point contact with the back surface of the printed circuit board 3. For this reason, the resistance when inserting one end of the printed circuit board 3 into the first locking claw 4 is suppressed to be small, and the insertion of the printed circuit board 3 into the first locking claw 4 can be performed easily and easily. In addition to facilitating the attaching operation, the load applied to the first locking claw 4 when the printed circuit board 3 is inserted is suppressed to be small, and the breakage of the first locking claw 4 is prevented. Even when the shape of the protrusion 4a is a cone, a triangular pyramid, etc., the protrusion 4a is in point contact with the back surface of the printed circuit board 3, and when the shape of the protrusion 4a is a semi-cylindrical shape, the protrusion 4a is printed. Since line contact is made with the back surface of the substrate 3, resistance when one end portion of the printed circuit board 3 is inserted into the first locking claw 4 can be kept small.

  Next, when the other end of the printed circuit board 3 is pressed against the case 2 side (upper side in FIG. 6), the second locking claw 5 of the case 2 spreads outward (to the left in FIG. 6). 3 can pass through the second locking claw 5, and when the other end of the printed circuit board 3 passes through the second locking claw 5, the second locking claw 5 is elastically moved. In order to return to the original state, as shown in FIG. 6, the other end portion of the printed circuit board 3 is locked to the second locking claw 5 and fixed to the back surface of the case 2. At this time, the first rib-like protrusion 5a protruding from the second locking claw 5 abuts on the side end surface of the printed circuit board 3, and the printed circuit board 3 is moved to the first locking claw 4 side (in FIG. 6). Since the pressure is applied to the right side, backlash in a direction parallel to the surface of the printed circuit board 3 (left and right direction in FIG. 1) is suppressed.

As described above, in the present embodiment, the protrusion 4 a is protruded from the first locking claw 4 protruding from the case 2, and the first rib-shaped protrusion 5 a is protruded from the second locking claw 5. Since the printed circuit board 3 can be securely fixed to the case 2 with a simple structure that is simply provided, there is no increase in the number of parts and the number of assembly steps. As a result of securely fixing the printed circuit board 3 to the case 2 without rattling, even if the display device 1 is used in an environment that is susceptible to vibration, rattle noise caused by the rattling of the printed circuit board 3 can be prevented. Occurrence is prevented. In addition, although the vibration test was done with respect to the display apparatus 1 shown in FIG. 1 and the conventional display apparatus 101 shown in FIG. 9 according to the present embodiment, the test was performed by an electrodynamic vibration test apparatus manufactured by IMV; -120-06 is used to scan a sinusoidal vibration at a vibration frequency of 10 to 200 Hz and acceleration of about 42 m / s ² (4.4 G) in 20 minutes in two directions perpendicular to the thickness direction and in-plane. For 4 hours in the thickness direction and 2 hours in each of the two in-plane directions. As a result of the test, rattle noise was generated in the conventional display device 101 shown in FIG. 9, and no rattle noise was generated in the display device 1 according to the present embodiment shown in FIG.

  By the way, when the case 2 of the display device 1 shown in FIG. 1 is covered with a case cover (not shown), the second rib-like protrusion 5 b protruding from the second locking claw 5 prints a part of the case 2. The printed circuit board 3 is more securely fixed to the case 2 because it is pressed toward the substrate 3 side.

  In the present embodiment, the second locking claw 5 is pushed into the inside of the case 2 by pressing the second rib-shaped protrusion 5b against a case cover (not shown), and the second locking claw 5 The stress may concentrate in the direction in which the tip of the substrate pushes up the printed circuit board 3. For this reason, the fixing of the printed board 3 in the vertical direction of the drawing by the tip end portion of the second locking claw 5 can be made stronger. In order to obtain this action more effectively, it is preferable that the second rib-like protrusion 5 b is not more than the height of the second locking claw 5.

  Here, FIG. 8 shows the state of the back surface of the display device 1 according to the present embodiment (fixed state of the printed circuit board 3). When the printed circuit board 3 is a rectangular flat plate as shown in FIG. The pawl 4 and the second latching pawl 5 are preferably arranged in two each at two locations on the long side of the printed circuit board 3. The number of the first locking claws 4 and the second locking claws 5 does not necessarily have to be the same, but is more preferably the same.

DESCRIPTION OF SYMBOLS 1 Display apparatus 2 Case 2a Case recessed part 3 Printed circuit board 4 1st latching claw 4a 1st latching claw protrusion 5 2nd latching claw 5a 1st rib-like projection of 2nd latching claw 5b Second rib-like protrusion of the second locking claw d Printed board thickness H Clearance of the first locking claw H ′ Clearance of the protrusion of the first locking claw

Claims (3)

The printed circuit board fixing structure of the display device, wherein the display device is arranged on the front surface of the case and the printed circuit board is arranged on the back surface,
Protruding a first locking claw and a second locking claw having different cross-sectional shapes on the back surface of the case,
The first locking claw is provided with a protrusion protruding from a portion facing the back surface of the printed circuit board, and a clearance between the first locking claw and the back surface of the case is determined by the thickness of the printed circuit board. And setting the clearance between the protrusion and the back surface of the case smaller than the thickness of the printed circuit board,
The first said projection protruding from the engaging pawl is backside point contact or line contact of the printed circuit board, one end of the printed circuit board engaged by the first locking claw,
The second locking claw is provided with a first rib-like protrusion protruding along a thickness direction of the printed circuit board at a portion facing the side surface of the printed circuit board. Set the clearance with the back of the case larger than the thickness of the printed circuit board,
A printed circuit board fixing structure for a display device, wherein the first rib-shaped protrusion is brought into contact with a side end surface of the printed circuit board , and the other end of the printed circuit board is locked by the second locking claw.
A second rib-shaped projection is provided on a part of the outer surface of the case opposite to the surface on which the first rib-shaped projection of the second locking claw is projected, and the second rib-shaped projection is formed. The printed circuit board fixing structure for a display device according to claim 1 , wherein the height is set to be equal to or lower than the height of the second locking claw . The first or second rib protruding from the second locking claw, wherein the protrusion protruding from the first locking claw has a hemispherical shape, a conical shape, a polygonal pyramid shape, or a semi-cylindrical shape. 3. The printed circuit board fixing structure for a display device according to claim 2 , wherein the projection is a quadrangular prism shape, a semi-cylindrical shape, or a triangular prism shape .

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