WO2011111310A1

WO2011111310A1 - Holder for display element

Info

Publication number: WO2011111310A1
Application number: PCT/JP2011/000897
Authority: WO
Inventors: 裕一大城
Original assignee: 住友電装株式会社
Priority date: 2010-03-08
Filing date: 2011-02-18
Publication date: 2011-09-15
Also published as: JP2011186103A

Abstract

A holder (40) for a display element, affixed to a circuit board (10) and holding an LCD element (20) on the circuit board (10) with the terminals (24) of the LCD terminal (20) respectively inserted in terminal holes (14). The holder (40) is provided with: element holding sections such as engagement claws (51) for holding the element body (22) of the LCD element (20); and a terminal guide section (52) located closer to the circuit board (10) than the element holding sections and guiding the terminals (24) of the LCD element (20) to the terminal holes (14). The terminal guide section (52) is provided with: guide holes (54) having a diameter which can, while maintaining the arrangement of the terminals (24), cause the terminals (24) to pass through the guide holes to the circuit board (10) side, the guide holes (54) comprising on the inlet side thereof lead-in sections for the terminals (24); and guide grooves (58) located closer to the element holding sections than the guide holes (54) and guiding the terminals (24) to the guide holes (54).

Description

Display element holder

The present invention relates to a display element holder for holding a display element such as an LCD (Liquid Crystal Display) or VFD (Vacuum Fluorescent Display) mounted on a printed circuit board.

Conventionally, a liquid crystal display unit in which an LCD element is mounted on a printed circuit board is known. For example, a so-called backlight-type liquid crystal display unit that includes a light emitter between an LCD element and a printed circuit board (hereinafter abbreviated as a substrate), and has improved visibility by projecting light from the back side of the LCD. It is used in many electrical devices. In this liquid crystal display unit, a display element holder (also called a lamp house) is fixed on a substrate, and the LCD element is mounted on the substrate while being held by the holder. A space is provided between the element main body of the LCD element and the substrate, and the light emitter is disposed in this space.

By the way, when assembling a liquid crystal display unit, it is necessary to assemble the LCD element on the substrate while inserting each terminal of the LCD element into a terminal hole (through hole) on the substrate. As the number of terminals increases, the number of terminals increases and the pitch decreases, and the terminal insertion operation tends to be difficult. Particularly, the LCD element used in the backlight type display unit as described above has a long terminal length because the element main body needs to be held at a position away from the substrate. Therefore, the LCD element is likely to be deformed in the terminals, and there are cases where the deformation of the terminals disturbs the terminal insertion work due to the deformation.

Patent Document 1 discloses a display element holder that is effective in solving such inconvenience. The holder disclosed in this document 1 holds an LCD element having a shape in which a plurality of terminals are arranged on both sides of a display surface on a substrate. The holder has a plurality of guide protrusions arranged on the side surface at a constant pitch corresponding to the terminal arrangement, and the LCD element is attached to the holder so that the terminal is interposed between the adjacent guide protrusions. The guide projections guide the terminals of the LCD element to the terminal holes when the guide protrusions are arranged close to the substrate side.

Japanese Utility Model Publication No. 6-22821

According to the display device holder of Patent Document 1, the terminals can be guided to the terminal holes while being positioned in the arrangement direction thereof. However, each terminal is almost free in the direction perpendicular to the arrangement direction thereof, and therefore, when adjacent terminals are displaced in a direction perpendicular to the terminal arrangement direction, the insertion of the terminal into the terminal hole is hindered. coming out. Therefore, there is still room for improvement in order to make the terminal insertion operation of the LCD element smoother.

As a means for solving such a problem, for example, a guide hole is provided in the display element holder, and each terminal is passed not only in the terminal arrangement direction but also in the direction orthogonal to this direction. The terminal is guided to the terminal hole on the board while positioning the terminal, and in this case, the diameter of the lead-in part of the terminal into each guide hole, that is, the end of the guide hole, so that the terminal can be smoothly inserted into each guide hole. It is conceivable to provide a portion that expands outward.

However, in the case of a display holder that holds display elements with a narrowed terminal arrangement, it is necessary to reduce the pitch of the guide holes, so a sufficient lead-in part that smoothly guides each terminal into the guide hole is secured. In this case, it is still difficult to insert the terminal into the guide hole, and improvement of the terminal insertion work cannot be expected.

The present invention has been made in view of such circumstances, and improves the assemblability of a display unit that is mounted on a substrate while a display element such as an LCD element is held by a display element holder. It is for the purpose.

In order to achieve this object, a display element holder according to the present invention is fixed to a substrate, and includes a device body having a display surface, and a plurality of elements extending in parallel to each other on the opposite side of the display surface from the device body. A display element holder for holding a display element provided with a terminal on the substrate in a state where the terminal is inserted into a terminal hole of the substrate, wherein the terminals are inserted at positions where the terminals are inserted into the terminal holes. An element holding portion for holding the element main body, and a terminal guide portion that is positioned closer to the substrate than the element holding portion and can guide the terminal to the terminal hole. A plurality of guide holes having a hole diameter into which the terminals can be inserted so that the terminals can be penetrated to the substrate side while maintaining their arrangement, and the element holding part side from these guide holes. Previous in position A plurality of guide wall portions that are arranged in parallel with each other in the direction in which the guide holes are arranged and that can guide each of the terminals to the guide holes, respectively, and an end portion of each guide hole on the element holding portion side is And a guide portion of the terminal having a shape in which the hole diameter increases from the substrate side toward the element holding portion side, and each guide wall portion includes a side wall portion that restrains the terminal from both sides in the arrangement direction thereof, and the side wall portions. A bottom wall portion that supports the terminal from one side in a direction orthogonal to the direction in which the guide holes are arranged, and has a shape that is open to the opposite side of the bottom wall portion, and the open side The terminal can be inserted between the side wall portions in a direction perpendicular to the axial direction of the terminal, and the inserted terminal can be guided to the guide hole.

According to this display element holder, by inserting each terminal of the display element into the guide hole of the terminal guide portion, the terminal of the display element is positioned in both the terminal arrangement direction and the direction orthogonal thereto. It is possible to guide to the terminal hole. In addition, the display element holder can guide the terminals to the guide holes while enclosing each terminal from three sides including both sides in the terminal arrangement direction on the front side (element holding part side) of the guide holes. As a result, each terminal is inserted into each guide wall in advance and then inserted into each guide hole while being guided along the guide wall. Each terminal can be smoothly inserted into each guide hole without providing a large guiding portion.

FIG. 1 is an exploded perspective view showing a display unit to which a display element holder according to the present invention is applied. FIG. 2 is a cross-sectional view showing a display unit (a state where only a display element holder is fixed on a printed circuit board). FIG. 3 is an enlarged perspective view showing the display element holder of FIG. 1. 4 is an enlarged perspective view showing a main part of the display element holder of FIG. FIG. 5 is a schematic cross-sectional view of the terminal guide portion.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 and 2 show a liquid crystal display unit to which a display element holder according to the present invention is applied. FIG. 1 is an exploded perspective view, and FIG. 2 is a sectional view (a sectional view in a partially exploded state). Each shows a liquid crystal display unit. This liquid crystal display unit is incorporated in an air conditioner operating device mounted on a vehicle, and displays the operation mode of the air conditioner, the temperature inside and outside the vehicle, and the time according to the operation of the air conditioner operating device.

This liquid crystal display unit is a so-called backlight type liquid crystal display unit, and diffuses the light projected from the light source to the LCD element 20 by the circuit board 10, the LCD (Liquid Crystal Display) element 20 that displays the operation mode and the like. A diffusion plate 30 and a display element holder 40 for holding the LCD element 20 and the diffusion plate 30 on a substrate are provided.

Although the circuit board 10 has a rectangular shape and is not shown in the drawing, a switch element for switching contacts in conjunction with the operation buttons of the air conditioner operating device is mounted on the surface thereof. The central portion in the longitudinal direction of the circuit board 10 is an assembly region of the LCD element 20 (part indicated by a two-dot chain line in FIG. 1), and the LCD element 20 is held by the display element holder 40 in this region. Implemented in. In this region, a plurality of LED elements 12 serving as light sources are further mounted. In the illustrated example, nine LED elements 12 are each mounted on the circuit board 10 in a state of being arranged in a line at regular intervals in the longitudinal direction of the board (the left-right direction in the figure).

The LCD element 20 includes a plate-shaped element body 22 having a rectangular display surface 22a elongated in the same direction as the circuit board 10 and a plurality of terminals 24 provided at the center in the longitudinal direction of the element body 22. Each terminal 24 extends in a direction substantially orthogonal to the display surface 22a toward the side opposite to the display surface 22a, and is arranged in parallel to each other along one side of the element body 22.

The circuit board 10 is formed with a plurality of terminal holes 14 (through holes) of the same number as the terminals 24 arranged in a line in the longitudinal direction, and each terminal 24 of the LCD element 20 has these terminal holes. 14 and inserted into a circuit on the board. As a result, the LCD element 20 is mounted on the circuit board 10.

The diffusion plate 30 diffuses the light projected from the LED element 12. In this example, the diffusion plate 30 is made of a material such as milky white acrylic or polycarbonate, and has a rectangular plate shape elongated in the same direction as the circuit board 10. The diffusion plate 30 has a size substantially equal to that of the display surface 22a of the LCD element 20, and is superimposed on the back side of the element body 22 (the side opposite to the display surface 22a).

The display element holder 40 (hereinafter abbreviated as “holder 40”) includes the element body 22 and the diffusing plate 30 of the LCD element 20 in a state in which the circuit board 10 and the circuit board 10 are spaced apart from each other. Is to hold on.

The holder 40 is entirely made of a resin material. The holder 40 has an elongated rectangular parallelepiped shape in the same direction as the circuit board 10, and has an elongated recess 42 that opens in the direction orthogonal to the longitudinal direction (hereinafter referred to as the front-rear direction) and extends in the longitudinal direction. .

The end surface of the holder 40 opposite to the side where the concave portion 42 opens (hereinafter referred to as the front side) (hereinafter referred to as the rear side) is a fixing portion to the circuit board 10, and the four corners of the end surface are engaged. A pawl 44 is formed. On the other hand, the circuit board 10 is formed with locking holes 16 corresponding to the locking claws 44. That is, the holder 40 is fixed to the circuit board 10 by inserting the locking claws 44 into the locking holes 16 and engaging the circuit board 10 from the back side.

As shown in FIGS. 2 and 3, a plurality of openings 42a penetrating in the front-rear direction are formed in the inner bottom portion of the concave portion 42 at regular intervals in the longitudinal direction. These openings 42a correspond to the arrangement of the LED elements 12 on the circuit board 10. Therefore, in the state where the holder 40 is fixed to the circuit board 10 as described above, each LED element 12 is in the opening 42a. It is inserted and faces the inside of the recess 42.

The front end portion of the holder 40 is an element holding portion that holds the element body 22 of the LCD element 20 together with the diffusion plate 30 at a position where each terminal 24 is inserted into the terminal hole 14. The element holding unit includes a diffusion plate support 46 that supports the diffusion plate 30 from the rear side, and the element body 22 of the LCD element 20 at a position in front of the diffusion plate 30 supported by the diffusion plate support 46 thereafter. The element support part 48 supported from the side, the some surrounding wall part 50 fitted to the outer peripheral surface of the element main body 22, and a pair of latching claw 51 which latches the element main body 22 from the front side are provided. Although not shown, the diffusing plate support 46 includes a plurality of ribs for positioning the diffusing plate 30 in the longitudinal direction and the direction orthogonal thereto.

In the side portion (upper portion in FIGS. 1 and 2) of the holder 40 and in the middle portion in the longitudinal direction, each terminal 24 of the LCD element 20 is guided to the terminal hole 14 of the circuit board 10 when the unit is assembled. A terminal guide portion 52 is provided.

The terminal guide portion 52 has the same number of guide holes 54 as the terminals 24 of the LCD element 20 as shown in FIGS. These guide holes 54 are through-holes that allow the terminals 24 of the LCD element 20 to penetrate to the circuit board 10 side, and more specifically, are through-holes that penetrate in the front-rear direction (normal direction of the circuit board 10). It is formed in a state aligned in the longitudinal direction. These guide holes 54 have hole diameters that allow the terminals 24 to pass through to the circuit board 10 side while maintaining their arrangement, and in a state where the holder 40 is fixed to the circuit board 10, The circuit board 10 is provided so as to coincide with the terminal holes 14 of the circuit board 10. Accordingly, when each terminal 24 is inserted into the guide hole 54 from the front side of the holder, each terminal 24 is guided to the corresponding terminal hole 14. Each guide hole 54 has a rectangular cross section, and the outlet side (rear side) hole diameter (vertical and horizontal dimensions) is set to be approximately the same as or slightly larger than the terminal hole 14 of the circuit board 10. Yes.

At the inlet side (front side) end of each guide hole 54, a guide part 54a (taper part) for guiding the terminal 24 is formed. The guide portion 54a has a shape in which the hole diameter of the guide hole 54 increases from the rear side toward the front side, and in this example, a direction perpendicular to the arrangement direction of the guide holes 54 (the vertical direction in FIG. 2; Hereinafter, this direction is referred to as a vertical direction). That is, the guiding portion 54a has a shape that guides the terminal 24 only in the vertical direction.

The terminal guide portion 52 further has a plurality of guide grooves 58 for guiding each terminal 24 of the LCD element 20 to each guide hole 54 at a position in front of the guide hole 54. As shown in FIGS. 4 and 5, the guide grooves 58 extend in parallel with each other in the front-rear direction to restrain the terminals 24 from both sides in the arrangement direction, and the terminals between the side walls 58a. 24 having a bottom wall portion 58b that supports 24 from one side (lower side) in a direction orthogonal to the direction in which the guide holes 54 are arranged, and is open toward the opposite side (upper side) of the bottom wall portion 58b. have. As a result, each guide groove 58 allows the terminal 24 to be inserted from above in a direction perpendicular to the axial direction thereof, and the inserted terminal 24 can be guided to the guide hole 54. That is, in this example, the side wall portion 58a and the bottom wall portion 58b of each guide groove 58 correspond to the guide wall portion of the present invention.

In addition, the space | interval of the wall surfaces of the side wall part 58a of each guide groove 58 is formed so that it may reduce toward those from the front end side toward the bottom wall part 58b side. The wall surfaces of the side wall portions 58a and the bottom wall portion 58b of the guide groove 58 and the inner peripheral surface of the guide hole 54 are continuous. In particular, the inner bottom surface (the bottom wall portion 58b) of each guide groove 58 is As shown in FIG. 2, the inclined surface is inclined downward from the rear side toward the front side (so that the front side is further away from the central axis of the guide hole 54 than the rear side).

The LCD element 20 and the diffusion plate 30 are held by the holder 40 as follows. First, the diffusing plate 30 is supported on the diffusing plate support 46 in a state where the diffusing plate 30 is positioned by a rib (not shown). Next, the element main body 22 of the LCD element 20 is fitted inside the peripheral wall portion 50 from the front side of the diffusion plate 30, and the element main body 22 is overlaid on the diffusion plate 30. The element main body 22 is locked with respect to the holder 40 by 51 engaging. Thereby, the LCD element 20 and the diffusion plate 30 are integrally held by the holder 40 in a state where they are overlapped with each other.

When the LCD element 20 is held by the holder 40 in this way, each terminal 24 of the LCD element 20 is inserted into each terminal hole 14 of the circuit board 10. The terminals 24 are respectively inserted into the respective guide grooves 58 from the upper side in front of the guide holes 54 in the terminal guide portions 52, and the respective terminals 24 are inserted into the guide holes 54 along the guide grooves 58 in this state. In this way, each terminal 24 is inserted into each terminal hole 14 of the circuit board 10 through the guide hole 54. Each terminal 24 is soldered to a circuit on the circuit board 10 to mount the LCD element 20 on the circuit board 10.

As described above, the holder 40 of the present invention includes the terminal guide portion 52 having the guide hole 54. When the unit is assembled, the terminals 24 of the LCD element 20 are inserted into the guide holes 54, respectively. Each terminal 24 can be guided to the terminal hole 14 of the circuit board 10 while being positioned in both the arrangement direction and the direction orthogonal thereto. Therefore, each terminal 24 is more securely connected to the terminal hole 14 as compared with the conventional holder in which the terminals are positioned only in the arrangement direction thereof and guided to the terminal holes in a substantially free state in the direction orthogonal thereto. The liquid crystal display unit can be assembled and improved.

In addition, the holder 40 includes only guide portions 54a for guiding the terminals 24 in the vertical directions (directions orthogonal to the alignment direction of the guide holes 54) in the guide holes 54, and the terminals are arranged in the alignment direction of the guide holes 54. This is omitted for the guiding portion for guiding 24, and instead a guide groove 58 is provided on the front side (element holding portion side) of each guide hole 54, so that each terminal 24 can be connected from both sides in the arrangement direction. It is configured to guide to the guide hole 54 while restraining. Therefore, while each terminal 24 can be smoothly inserted into the guide hole 54, each guide hole 54 can be narrowed by a pitch because there is no guide portion for guiding the terminal 24 in the direction in which the guide holes 54 are arranged. it can. That is, there is an advantage that it is possible to meet the demand for narrowing the pitch of the terminal arrangement of the LCD element 20 while ensuring the operability of inserting the terminals 24 into the respective guide holes 54.

In particular, each guide groove 58 of the terminal guide portion 52 has a shape in which the distance between the wall surfaces of the side wall portions 58a is reduced from the front end side toward the bottom wall portion 58b side as described above. The terminals 24 can be easily inserted into the guide grooves 58 while being able to guide the guide holes 54 while appropriately positioning them in the arrangement direction thereof. Further, since each guide groove 58 has a continuous wall surface of the side wall portion 58 a and the bottom wall portion 58 b and the inner peripheral surface of the guide hole 54, each terminal 24 is smoothly inserted into the guide hole 54 along the guide groove 58. Can be guided to. In addition, since the inner bottom surface (bottom wall portion 58b) of each guide groove 58 is a slanted surface, the inner bottom surface of each guide groove 58 and each guide hole 54 are easy to see, and the terminal 24 to each guide groove 58 is visible. And insertion of each terminal 24 into each guide hole 54 is easy. Accordingly, the terminal insertion work into the terminal hole 14 as described above can be performed very smoothly.

The liquid crystal display unit described above is an example of an embodiment of a display unit to which the display element holder according to the present invention is applied, and includes a specific configuration of the display element holder and a specific configuration of the liquid crystal display unit. Can be appropriately changed without departing from the scope of the present invention.

For example, in the display element holder 40 of this embodiment, as described above, each guide hole 54 is provided with a guiding portion for guiding the terminal 24 only in a direction orthogonal to the alignment direction. In the case where it is allowed in relation to the arrangement pitch of 24, a guiding portion for guiding the terminal 24 in the arrangement direction of the terminals 24 may be provided.

In the embodiment, the display element holder for holding the LCD element has been described as an application example of the present invention. However, the display element holder may hold other display elements such as VFD (Vacuum Fluorescent Display) on the substrate. The display element holder of the invention is applicable.

The present invention described above is summarized as follows.

That is, the display element holder according to the present invention includes an element body fixed to a substrate and having a display surface, and a display element including a plurality of terminals extending in parallel to each other on the opposite side of the display surface from the element body. Is a holder for a display element that is held on the substrate in a state of being inserted into the terminal hole of the substrate, and an element holding portion that holds the element body at a position where each of the terminals is inserted into the terminal hole; And a terminal guide part that is located on the substrate side of the element holding part and capable of guiding the terminal into the terminal hole. The terminal guide part maintains the arrangement of the terminals. However, a plurality of guide holes having a hole diameter into which the terminal can be inserted so as to be able to penetrate to the substrate side, and in the arrangement direction of the guide holes at positions closer to the element holding part than these guide holes To each other A plurality of guide walls that are arranged in a row and capable of guiding each of the terminals to the guide hole, and the end of the guide hole on the element holding part side holds the element from the substrate side. Each guide wall portion includes a side wall portion that constrains the terminals from both sides in the arrangement direction thereof, and the terminal portion between the side wall portions. A bottom wall portion that is supported from one side in a direction orthogonal to the direction in which the guide holes are arranged, and has a shape that is open to the opposite side of the bottom wall portion, and from the open side, the terminal is in the axial direction It can be inserted between the side wall portions in a direction perpendicular to each other and has a shape capable of guiding the inserted terminal into the guide hole.

According to this display element holder, each terminal of the display element is inserted into the guide hole of the terminal guide portion, whereby each terminal is guided to the terminal hole of the substrate while being positioned in both the terminal alignment direction and the direction orthogonal thereto. be able to. Therefore, regarding the assembly of the display unit mounted on the substrate while the display element is held by the display element holder, in particular, the terminal insertion work into the terminal hole on the substrate can be performed more smoothly and appropriately. As a result, the assembly workability of the display unit is improved. In addition, a guide wall portion is provided on the front side of the guide hole (element holding portion side) so that each terminal can be guided to the guide hole while being surrounded from three sides including both sides of the terminal arrangement direction. Is inserted in each guide wall portion in advance and then guided along these guide wall portions, so that each guide hole can be inserted into each guide hole. The terminal can be smoothly inserted into each guide hole.

In the display element holder, the wall surfaces of the side wall portion and the bottom wall portion and the inner peripheral surface of the guide hole may be continuous. According to this configuration, since each terminal of the display element can be guided along the continuous wall surface from the guide wall portion to the guide hole, each terminal can be more smoothly inserted into the guide hole.

Further, in the display element holder described above, the distance between the wall surfaces of the side wall portions of each guide wall portion may be formed so as to decrease from the tip side toward the bottom wall side. According to this configuration, it is possible to easily insert the terminals into the guide wall portions, and when guiding the terminals into the guide holes, the terminals are properly positioned in the alignment direction while being positioned in the guide holes. It is possible to guide.

In the display element holder described above, the bottom wall portion of each guide wall portion is formed from the guide hole side so that the element holding portion side is further away from the center axis of the guide hole than the guide hole side. It may be inclined toward the element holding part. According to this configuration, the bottom wall portion and the guide hole of each guide wall portion can be easily seen, and each terminal can be more smoothly inserted into the guide hole.

In the above display element holder, each guide hole may have a hole diameter that expands only in a direction orthogonal to the alignment direction of the guide holes. Good. In short, the lead-in portion has a structure for guiding the terminal only in the direction orthogonal to the direction in which the guide holes are arranged. According to this structure, it becomes a structure which can respond easily by narrowing each guide hole pitch.

As described above, the display element holder according to the present invention is useful for a display unit in which a display element such as an LCD (Liquid Crystal Display) or a VFD (Vacuum Fluorescent Display) is mounted on a substrate. Suitable for improving productivity.

Claims

An element main body fixed to the substrate and having a display surface and a display element having a plurality of terminals extending in parallel to each other on the opposite side of the display surface from the element main body, the terminals are respectively inserted into terminal holes of the substrate A display element holder for holding the substrate on the substrate,
An element holding portion for holding the element body at a position where each of the terminals is inserted into the terminal hole;
It is located on the substrate side with respect to this element holding part, and comprises a terminal guide part capable of guiding the terminal to the terminal hole,
The terminal guide portion includes a plurality of guide holes having a hole diameter into which the terminals can be inserted so that the terminals can be penetrated to the substrate side while maintaining the arrangement of the terminals. A plurality of guide wall portions arranged in parallel with each other in the direction of arrangement of the guide holes at a position on the element holding portion side and capable of guiding each of the terminals to the guide holes, respectively;
The end portion of each guide hole on the element holding portion side has a lead-in portion for a terminal having a shape in which the hole diameter increases from the substrate side toward the element holding portion side,
Each of the guide wall portions includes a side wall portion that restrains the terminal from both sides in the arrangement direction thereof, and a bottom wall portion that supports the terminal from one side in a direction orthogonal to the arrangement direction of the guide holes between the side wall portions. And the terminal can be inserted between the side walls in the direction perpendicular to the axial direction from the open side, and the shape is open to the side opposite to the bottom wall. A display element holder having a shape capable of guiding the inserted terminal into the guide hole.
In the display element holder according to claim 1,
The display element holder, wherein the wall surfaces of the side wall portion and the bottom wall portion and the inner peripheral surface of the guide hole are continuous.
In the display element holder according to claim 1 or 2,
A display element holder, wherein the distance between the wall surfaces of the side wall portions of each guide wall portion decreases from the tip side toward the bottom wall side.
In the display element holder according to claim 1 or 2,
The bottom wall portion of each guide wall portion is inclined from the guide hole side toward the element holding portion side so that the element holding portion side is further away from the central axis of the guide hole than the guide hole side. A display element holder.
In the display element holder according to claim 1 or 2,
The display element holder according to claim 1, wherein each of the guide holes has a hole diameter that expands only in a direction orthogonal to an arrangement direction of the guide holes.