JPH0723800Y2 - Corona charging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a corona charging device used in an electrophotographic copying machine or the like.

[Prior Art] Conventionally, in this type of corona charging device, a corotron wire is stretched between a pair of insulating blocks fixed to both ends of a discharge shield, and a high voltage is applied to the corotron wire. Corona discharge is generated to charge the photoconductor drum,
The toner image is transferred to a transfer sheet, the transfer sheet is separated from the photosensitive drum, and the like. In this corona charging device, it is possible to thin the corotron wire in order to reduce the amount of ozone generated by corona discharge and to eliminate the need for a filter for ozone removal, thereby simplifying the device. Has been done.

By the way, as a method of stretching the corotron wire in the corona charging device, there are the following methods.

(A) As shown in FIG. 25, the connection terminals 101 having the ring portions 101a are fixed to both ends of the corotron wire 100 by electric resistance welding or the like, and the connection terminals 101 on one end side are planted in the insulating block 102. In addition to being locked to the pin 103, the connection terminal 101 on the other end side is locked to the pin 106 implanted in the insulating block 105 via the coil spring 104.

(B) As shown in FIG. 26, the insulating block 107 is provided with a projection 108 protruding from the bottom surface, and a fitting hole 109 is provided at the upper end of the projection 108, and the fitting hole 109 is provided with a corotron wire 110. The pins 111 are fitted in a state where the pins are suspended. And
The corotron wire 110 is sandwiched between the pin 111 and the fitting hole 109, and the corotron wire 110 is stretched with an appropriate tension by the appropriate friction between the pin 111 and the fitting hole 109. .

(C) As shown in FIG. 27, small spherical stoppers 113, 113 are semi-attached to both ends of the corotron wire 112, and the stoppers 113 on one end side are two protruding from the insulating block 114. It is locked in the slit 116 formed by the protrusion 115 of the. In addition, a corotron wire 112 is stretched by locking a stopper 113 on the other end side with a slit 119 of a leaf spring 118 provided upright on an insulating block 117.

[Problems to be Solved by the Invention] However, the above-mentioned conventional technique has the following problems.

In the case of (a), it is possible to assemble when using a thick corotron wire 100 with a diameter of 60 μm or more, but when using a thin corotron wire 100 with a diameter of less than 60 μm, the corotron wire 100 can be connected. Connection terminals 1 fixed to both ends of the corotron wire 100 when welding to the terminal 101
When 01 is assembled to the insulating block 102 or 105, the corotron wire 100 easily breaks, and there is a problem that the assembly cost remarkably rises, such as part stoppage and work efficiency decrease. Further, the position where the Corotron wire 100 is stretched is apt to be displaced in the vertical direction and the horizontal direction,
There is a problem that the distance from the surface to be charged is not uniform.
This problem becomes more remarkable as the corotron wire 100 becomes thinner.

In the case of (b), since the corotron wire 110 is held by the pin 111 fitted in the fitting hole 109,
It is difficult to fit the pin 111 into the fitting hole 109, and if it is too loose, the Cotron wire 110 will fall out, and if it is too tight, the wire 110 will break, so it is not possible to attach a particularly thin wire 110 There was a problem. Further, the position where the corotron wire 110 is stretched is regulated in the vertical direction by the height of the protrusion 108, but in the horizontal direction, there is a positional deviation due to the fitted state of the pin 111 and the fitting hole 109. There was also a problem that it was likely to occur.

In the case of (c), when the corotron wire 112 becomes thin, it is difficult to attach the stopper 113 in half, and there is a problem that the wire 112 may be pulled out and the corotron wire 112 cannot be stretched. there were. In addition, even if the stopper 113 can be fixed to the wire 112 by a method other than half-fitting, the leaf spring
The variation of the spring multiplier of 118 is large, and Corotron Wire 1
There was a problem that the tension of 12 varied and the quality as a corona charging device was poor. Further, when one end of the corotron wire 112 is locked to the leaf spring 118, variation in the amount of deformation of the leaf spring 118 is likely to occur, and when variation occurs in the amount of deformation of the leaf spring 118, one end of the leaf spring 118 is There is also a problem in that the stretched position of the supported corotron wire 112 also varies, so that the corona discharge also varies.

Further, as described above, when the corotron wire is thinned, the strength of the wire itself is significantly reduced. For example, in the case of a tungsten wire, the tensile strengths of diameters of 60, 30, and 20 μm are extremely low as the thickness becomes about 928, 227, and 96 grams. Therefore, if the corotron wire becomes thinner, it becomes difficult to assemble it manually,
In particular, it is almost difficult for a human to assemble a corotron wire having a diameter of 30 μm or less. Therefore, it may be possible to automate the work of stretching the corotron wire, but there is a problem in that none of the above (a), (b), and (c) stretching methods can support automation. is doing.

[Means for Solving the Problems] Therefore, the present invention was made in order to solve the problems of the above-described conventional technology, and the purpose thereof is to assemble even when the corotron wire is thinned. (EN) It is an object of the present invention to provide a corona charging device capable of accurately attaching the position of a corotron wire without breaking the wire and capable of being automatically assembled.

That is, the device according to the first aspect is a device base,
An insulating block fixed to each end of the device base and a holding member attached to the insulating block for holding the end of the corotron wire are provided. The holding member holds the end of the corotron wire. In a corona charging device in which a corotron wire is stretched between both insulating blocks, the insulating block is formed in a box shape with an open upper end, and the insulation formed in the box shape is The side wall of the block is provided with notches at front and rear positions of the corotron wire holding portion along the direction in which the corotron wire is stretched, and the corotron wire is positioned by the notches.

The invention according to claim 2 is the corona charging device according to claim 1, wherein the notch portion of the front portion is provided at a position higher than the corotron wire holding portion, and the rear portion. The notch portion is configured to be provided at a position lower than the corotron wire holding portion.

Further, as the holding member, for example, a leaf spring member is used, but the holding member is not limited to this and may be any member that can hold the corotron wire.

[Operation] In this invention, since the holding member is attached to the insulating block and the end of the corotron wire is held by this holding member, the end of the corotron wire is held by this holding member by direct welding or the like. Even if the corotron wire is thinned, it is possible to prevent the corotron wire from being cut during assembly. In addition, since the notch is provided inside the holding member of the insulating block, and the corotron wire is positioned by this notch, the corotron wire can be positioned more accurately than when the corotron wire is directly positioned by the holding member. You can
Further, since the holding and positioning of the corotron wire can be performed easily and reliably as described above, it is possible to cope with automatic assembly and the like.

[Embodiment] The present invention will be described below based on an illustrated embodiment.

FIG. 24 shows an electrophotographic copying machine to which the corona charging device according to the present invention can be applied. In the figure, reference numeral 1 denotes an original placing table glass on which an original not shown is placed. The original placed on the original placing table glass 1 is illuminated by a light source 2 and its reflected light image is composed of a mirror and a lens. It is projected onto the photosensitive drum 4 via the scanning optical system 3.
The surface of the photosensitive drum 4 is uniformly charged in advance by the charger 5 prior to the exposure of the image of the document.
After that, the image of the original is exposed to form an electrostatic latent image.
The electrostatic latent image formed on the photosensitive drum 4 is developed by the developing device 6. The developed image is sent from the paper feed cassette 7 by the paper feed roll 8 and is charged by the transfer charger 11 onto the transfer paper 10 which is conveyed by the registration roll 9 to the surface of the photosensitive drum 4 at a predetermined timing. Transcribed by The transfer sheet 10 on which the developed image is transferred is separated from the photosensitive drum 4 by the separation charger 12. Then, the toner image transferred by the fixing device 13 is fixed on the transfer paper 10, and the transfer paper 10 is discharged onto the tray 14. In the figure, 15 indicates a cleaner.

The corona charging device according to the present invention is used, for example, as the charging device 5, the transfer charging device 11 or the separation charging device 12.

FIG. 1 shows an embodiment of the corona charging device according to the present invention. In the figure, 16 is a corona charging device, and this corona charging device 16 comprises a shield member 17 as a device base, and insulating blocks 18 and 19 fixed to both ends of the shield member 17. The shield member 17
2 is formed in an elongated strip shape having the same plane shape as that of the corona charging device 16, as shown in FIG.
At both ends in the width direction of the shield member 17, a bent portion 20 bent in a U-shaped cross section is provided on one side, and the bent portion 20 is formed such that the width of the intermediate portion 20a is narrow. Both ends 20b, 20c are formed to have a wide width. Locking holes 21, 21, ... For snap-fitting the insulating blocks 18, 19 to the shield member 17 are formed in the both ends 20b, 20c.

This shield member 17 is arranged on the side of the photoconductor drum 4 of the corona charging device 16, and the shield member 17
Also serves as a grid electrode. That is, the grid electrode 22 is formed on the flat plate portion 17a of the shield member in a region excluding both ends in the longitudinal direction and both ends in the width direction by etching or the like.
Are formed. In the figure, reference numeral 23 indicates a handle integrally provided on the shield member 17 for mounting the corona charging device on the main body of the copying machine.

Further, both insulating blocks 18 and 19 fixed to both ends of the shield member 17 have basically the same structure as shown in FIGS. 3 to 6, and here, one insulating block is used. The block 18 will be described. As shown in FIGS. 3 and 4, the insulating block 18 is formed of a synthetic resin or the like into a rectangular parallelepiped box shape having an open upper end. The insulating block 18 is provided with protrusions 25, 25 ... For snap-fitting into the engaging holes 21, 21, ... Of the shield member on the outer surfaces of the widthwise side walls 24, 24. Also, the side walls 24, 24
As shown in FIG. 7, projections 27, 27 for snap-fitting the corona charging device 16 to the shield member 26 provided on the main body of the copying machine are provided at the inner end in the longitudinal direction of the outer surface. Side wall 2 provided with these protrusions 27, 27
The outer surfaces 24a and 24a of the reference numerals 4 and 24 slightly project outward from the other portions.

Inside the insulating block 18, an intermediate partition wall 28 is provided on the inner side in the longitudinal direction, and the partition wall 28 is
As shown in FIG. 4, the upper end side is tapered so that it has a thin wall. Further, inside the insulating block 18, slits 29, 29 for fitting and fixing a leaf spring member 41, which will be described later, are formed at the central portion in the longitudinal direction thereof and at a position continuous with the side walls 24, 24. There is. This slit 29, 29
Is formed by a pair of protrusions 31, 31 rising from the bottom wall 30 along the side walls 24, 24.
As shown in FIG. 4, 31a and 31a are inclined toward the inner side to facilitate the fitting of the leaf spring member 41 into the slits 29 and 29. Further, inside the insulating block 18, at the center in the width direction and on the outer end side of the slits 29, 29, a pedestal 32 having a planar rectangular shape is provided so as to project, and at the upper end of the pedestal 32,
The hole 32a is bored. When the corotron wire W is welded to the leaf spring member 41, the hole 33 presses the leaf spring member 41 onto the pedestal 32 by the head of the welding machine, and makes the leaf spring member 41 convex downward. It is for deforming so as to position the welding position of the leaf spring member 41. In the figure, R indicates a reinforcing rib.

Further, as shown in FIG. 8, V-grooves 35, 36, 37 for positioning the corotron wire W at the time of assembling the device are formed in the longitudinal side walls 33, 34 and the partition wall 28 of the insulating block 18.
Are formed. These V-grooves 35, 36, 37 are located at the center of the insulating block 18 in the width direction and are linearly arranged along the longitudinal direction thereof. As shown in FIG. 4, the tips of the V-grooves 36 and 37 are set so that the V-groove 36 is higher than the V-groove 37. The tip of the V-groove 35 is slightly lower than the V-groove 36 so that the corotron wire W does not come into contact with the V-groove 35 when the corotron wire W is stretched. Further, the pedestal 32 is set at an intermediate height between the V grooves 36 and 37, as shown in FIG. Moreover, the upper end of the pedestal 32 and the tip of the V groove 37 are located on the same straight line L inclined so that the V groove 35 side becomes higher, and an extension line L ′ of the straight line is slightly smaller than the upper end of the V groove 36. It is set to be low. By doing so, the corotron wire W comes to come on the plate spring member 41 positioned on the pedestal 32.

Although the insulating block 18 is formed of synthetic resin or the like, the V groove 36 has an important function of positioning the corotron wire W during assembly, and therefore, the edge of the V groove 36 has a tenth position.
As shown in the figure, chamfering is performed in an arc shape. Also,
When the insulating block 18 is formed, the V groove 36 is formed so that burrs or the like are not attached to the edges of the V groove 36 and the corotron wire W sliding on the V groove 36 is not caught by the burrs or the like. The mold parting line PL for the mold is set so as to come to a position lower than the end edge of the V groove 36, as shown in FIG.

The V groove 36 has a role of keeping the gap between the corotron wire W and the surface of the photosensitive drum 4 at a predetermined value in a state where the corona discharge device 16 is attached to the main body of the copying machine. Also,
The V groove 36 and the V groove 37 connect the corotron wire to the leaf spring member 41.
It is for positioning at the welding position of. The V groove 37 for positioning the rear end side of the corotron wire W does not necessarily have to be provided in the insulating block 18, and may be provided in a jig or the like for welding the corotron wire W to the leaf spring member 41.

Further, the structure of the other insulating block 19 is as shown in FIGS.
As shown in the figure, it is basically the same as the insulating block 18, and the same portions are denoted by the same reference numerals and detailed description thereof will be omitted. The side wall 33 of this insulating block 19 is an insulating block.
It has the same structure and operation as the 18 partition walls. Further, in the insulating block 18, while the pedestal 32 is located outside the slit 29 in the longitudinal direction, the insulating block 19
In the above, the pedestal 32 is provided inside the slit 29 in the longitudinal direction, and the leaf spring member 41 is attached so as to face the same direction as the leaf spring member 41 of the insulating block 18 as shown in FIG. The insulating block 19 is also provided with a socket 38 for applying a high voltage to the corotron wire W. This socket 38 has an electrode plate 39, and the tip 39a of this electrode plate is in pressure contact with a part of a leaf spring member 41 mounted on the insulating block 19, and the corotron wire is inserted through the leaf spring member 41. A high voltage is applied to W.

A leaf spring member 41 is fitted and fixed inside the insulating blocks 18 and 19, and the leaf spring member 41 is integrally formed by bending a thin metal plate having a spring property such as SUS. Has been formed. The leaf spring member 41 is shown in FIG.
As shown in FIG. 12, a mounting portion 42 formed in a substantially concave shape on the front side.
The mounting portion 42 is formed by connecting the mounting plates 43, 43 at both ends with a connecting plate 44. As shown in FIG. 12 (c), the protrusions 45 are provided on the mounting plates 43, 43.
Are formed so as to project laterally.
The mounting plates 43, 43 of the leaf spring member 41 to the insulating block 1
When fitted in the slits 29, 29 of 8, 19, the plate spring members 41, 41 are elastically deformed so that the leaf spring members 41, 41 are insulated.
It is for fixing in place.

Further, as shown in FIG. 12 (C), a spring portion 46 having a substantially L-shaped side surface is continuously provided on one side at the lower end of the connecting plate 44, and a bent portion 47 of this spring portion has an arc shape. It is bent into a spring to give it elasticity. Further, in order to improve the spring property of the spring portion 46, it is preferable that the rolling direction of the plate material forming the plate spring member 41 is aligned with the longitudinal direction of the spring portion 46.

A holding portion 48 for holding the corotron wire W is continuously provided at the upper end of the spring portion 46. This holding portion 48 is
Two holding plates 49 and 50 having a rectangular shape in a plane are integrally formed via a hinge 51, and the holding plate 50 is set to be slightly smaller than the holding plate 49. The hinge 51 is provided at a position orthogonal to the stretching direction of the corotron wire W. Further, the holding plate 49 is arranged horizontally, whereas the holding plate 50 is arranged in a state of being inclined by 45 degrees.
The holding plate 49, as shown in FIG.
It is located right above the cradle 23 of 8 and 19,
The gap G between the two is set to, for example, about 0.2 to 0.5 mm.
Then, as described later, the holding plate holds the corotron wire W.
The upper holding plate 50 is hinged 51
In order to fix the corotron wire W to the holding part 48 of the leaf spring member 41 by welding from above the holding plate 50 in a state in which the corotron wire W is clamped by both holding plates 49 and 50. It has become.

By the way, the corona charging device according to this embodiment is assembled as follows. First, at both ends of the shield member 17, as shown in FIG. 13, locking holes provided at both ends thereof.
The insulating blocks 18 and 19 are fixed by snap-fitting the projections 25 and 25 of the insulating blocks 18 and 19 onto the insulating blocks 18 and 19. Next, slits 29 of both insulating blocks 18 and 19,
29, the leaf spring members 41, 41 are fitted and fixed in the same direction as shown in FIGS. 3 and 5. Then, the corotron wire wound around the reel 70 is stretched from the outside of the one insulating block 18 toward the other insulating block 19. At that time, connect the corotron wire W to the V groove 3 of the insulating blocks 18 and 19.
Instead of aligning with the deepest part of 5, 36, 37, as shown in FIG.
Approximately 2 mm, it should be placed at a position shifted to the right in the figure. In this state, the insulating blocks 18 and 19 are raised relative to the corotron wire W. By doing so, the corotron wire W descends along the inclined surfaces 36a, 37a of the V grooves 36, 37 and is positioned at the deepest predetermined position of the V grooves 36, 37. In this state, the Corotron wire W is
As shown in FIG. 16, the leaf spring member 41 is automatically positioned at the center of the holding plate 49. At that time, Corotron Wire W
Since the initial state is displaced from the deepest part of the V-grooves 36 and 37, when the insulating blocks 18 and 19 are relatively raised, the corotron wire W holds the holding plate of the leaf spring member 41.
You never get caught in 50.

Next, the corotron wire W positioned on the holding portions 48 of the insulating blocks 18 and 19 is clamped by bending the upper holding plate 50. The bending of the holding plate 50 is performed by welding the YA for welding the corotron wire W as shown in FIG.
This is performed by the processing head 52 of the G laser. That is, the processing head 52, as shown in FIG. 18, is connected to the optical fiber 53 for guiding the laser light to the base end,
Lens the laser light emitted from this optical fiber 53
The light is focused by 54 and is irradiated onto the workpiece from the tip of the conical nozzle 55. Therefore, when the corotron wire W is welded to the holding portion 48, the nozzle 55 of the processing head 52 is
By pressing the holding plate 50 with
Is bent, and the corotron wire W is sandwiched between the holding plate 49 and the holding plate 50 as shown in FIG. Then, laser light is emitted from a nozzle 55 provided at the tip of the processing head 52 to melt the holding plate 49 and the holding plate 50 as shown in FIG.
Fixes together with 9 and 50.

Then, the other end of the corotron wire W is pulled with a constant tension F. Then, the leaf spring member 41 of the insulating block 18 is
As shown in FIG. 21, the spring portion 46 is elastically deformed, and a constant tension F is applied to the corotron wire W. At this time, the other end of the corotron wire W is connected to the V groove on one end of the insulating block 19.
36 to the V groove 37 on the other end side are fitted and positioned. In this state, similarly to the above, the holding plate 50 of the leaf spring member 41 is
Is bent by the nozzle 55 of the processing head 52, and the corotron wire W is welded by a laser beam while being sandwiched between the holding plates 49 and 50 to fix the corotron wire W to the holding portion 48. In this state, the spring portion 46 of the leaf spring member 41 is in elastic contact with the pedestal 32 of the insulating block 19 and is not elastically deformed. Finally, the extra corotron wire W protruding from the leaf spring member 41 is cut. By doing so, the corotron wire W is stretched with a constant tension F between the insulating blocks 18 and 19, as shown in FIG.

Thus, the leaf spring member 41 is attached to the insulating blocks 18 and 19, and the corotron wire W is attached to the holding portion 48 of the leaf spring member 41.
Since the end of the wire is held directly by welding, even if the corotron wire W is thinned, it is necessary to weld the corotron wire W at one end to the connection terminal and attach this connection terminal to the insulating block. Since it is not present, it is possible to prevent the corotron wire W from being cut during assembly. In addition, the side walls on the inner end side of the insulating blocks 18 and 19 have Vs at 33 and 33.
Since the grooves 36, 36 are provided and the V-grooves 36, 36 are used to position the corotron wire W, the corotron wire W can be positioned more accurately than when the corotron wire W is directly positioned by a connecting member. it can. Further, as described above, since the holding and positioning of the corotron wire W can be performed easily and reliably, it is possible to cope with automatic assembly and the like.

FIG. 23 shows another embodiment of the present invention, in which the same parts as those in the above embodiment are designated by the same reference numerals, and in this embodiment, the shape of the notch and the leaf spring member The shape is different from the above embodiment. That is, the cutout is
Instead of the V-shaped groove as in the above-mentioned embodiment, it is constituted by the step 60 provided on the side walls 33, 34 of the insulating blocks 18, 19. Corotron wire W has a low step 60a
First, the corotron wire W is brought into contact with the rising wall 60b of the step to be positioned by being first pressed against the step 60 and then slid to the step 60 side. Further, in the leaf spring member 41, as shown in FIG. 23, the spring portion 46 is formed in a linear shape, and the tip end of the spring portion 46 is deformed in the direction of the arrow so as to exhibit the spring property. ing. The leaf spring member 41 has an insulating block 18, which is attached to a base end of a spring portion 46 by an attachment portion 42 having an L-shaped cross section.
Mounted on 19. The horizontal mounting plate 43 of the mounting portion 42 is
As shown in FIG. 23, the protrusion 62 protruding from the bottom wall 30 of the insulating block is inserted into the hole 61, and the tip portion of the protrusion 62 is melted to be attached to the insulating blocks 18 and 19. ing. Even in the case of such a configuration, tension can be applied to the corotron wire W as in the above-described embodiment, and the other leaf spring member 41 is deformed by abutting the spring portion 46 on the pedestal 32. Can be prevented. The rest of the configuration and operation are the same as those of the above-described embodiment, so the description thereof will be omitted.

[Effects of the Invention] The present invention has the above-described configuration and operation. Even if the corotron wire is thinned, the wire will not be broken during assembly and the position of the corotron wire can be accurately attached. It is also possible to support automatic assembly.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the corona charging device according to the present invention, and FIGS. 2 (a), (b), and (c) are plan views, front views, enlarged side views, and FIG. 3 is a plan view of the insulating block, FIG. 4 is a sectional view taken along line IV-IV of FIG. 3, FIG. 5 is a plan view showing the other insulating block, and FIG.
FIG. 7 is a sectional view taken along the line VI-VI in FIG. 7, FIG. 7 is a perspective view showing a state in which the corona charging device is mounted on the main body of the copying machine, FIG. 8 is a sectional view of an essential part of the insulating block, and FIG. 9 is a V groove and a cradle. 10 is a perspective view showing the shape of the V groove, FIG. 11 is a perspective view showing a leaf spring member, and FIGS. 12 (a) and 12 (b) are
(C) is a plan view of the leaf spring member, a front view, and a sectional view taken along the line XII-XII of FIG. 12 (b). FIG. 13 is a perspective view showing an assembled state of the corona charging device, FIGS. 14 and 15. Figure is a side view and a cross-sectional view showing a corotron wire attachment state, FIG. 16 is a perspective view of the same, FIG. 17 is a side view showing a corotron wire fixed state, and FIG. 18 is a schematic view showing a machining head. FIG. 19 is a sectional view showing a state in which a corotron wire is welded to a leaf spring member, FIG. 20 is a perspective view showing a state in which a corotron wire is welded to the leaf spring member, and FIGS. 21 and 22 are assembled. FIG. 23 is a perspective view showing a corona charging device according to another embodiment of the present invention, and FIG. 24 is an electrophotographic copy to which the corona charging device according to the present invention can be applied. Fig. 25, Fig. 26, Fig. 26 and Fig. 27 show different machines of the conventional corona charging device. Each perspective view of the cross-sectional views and perspective views. [Explanation of symbols] 17 …… Shield member 18, 19 …… Insulation block 35, 36, 37 …… V groove 41 …… Leaf spring member W …… Wire

Claims (2)

[Scope of utility model registration request] 1. A device base, an insulating block fixed to both ends of the device base, and a holding member attached to the insulating block for holding an end portion of a corotron wire. In the corona charging device which holds the end of the corotron wire in, and stretches the corotron wire between both insulating blocks, the insulating block is formed in a box shape with an open upper end,
On the side wall of the box-shaped insulating block, cutouts are provided in front and rear positions of the corotron wire holding portion along the stretching direction of the corotron wire, and the corotron wire is positioned by the cutouts. A corona charging device characterized in that 2. The corona charging device according to claim 1, wherein the front notch is provided at a position higher than the corotron wire holding portion, and the rear notch is provided with the corotron wire. A corona charging device characterized in that it is provided at a position lower than the holding portion.