JP2006091562A - Slide contact member and photoreceptor drum having the same in its inside, and drum cartridge for electrophotography provided with photoreceptor drum and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a slide contact member capable of permanently suppressing electric charge sounds which occur when directly bringing a contact charging member into contact with a photoreceptor drum and applying an AC voltage to charge the photoreceptor drum, even in a high-temperature environment, a photoreceptor drum having the slide contact member in its inside, a drum cartridge for electrophotography provided with the photoreceptor drum, and an image forming apparatus. <P>SOLUTION: The slide contact member is provided in the photoreceptor drum provided in the image forming apparatus including a charging device which is brought into contact with the photoreceptor drum to charge the photoreceptor drum and has a cylindrical shape having a slit and a constricted part formed extending in a longitudinal direction of the photoreceptor drum, and has a shape memory metal having a transformation temperature of 15 to 45°C installed in the constricted part. The photoreceptor drum has the slide member in its inside. The drum cartridge for the electrophotography and the image forming apparatus are provided with the photoreceptor drum. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic image forming apparatus such as an electrophotographic copying machine and a laser printer, and more particularly, to a slide which is a component of an image forming apparatus provided with a charging device that charges a photosensitive member in contact with the photosensitive member. The present invention relates to a contact member, a photosensitive drum, an electrophotographic drum cartridge, and an image forming apparatus.

Image forming devices that use electrophotographic technology, such as facsimiles, laser beam printers, and copiers, are becoming cheaper daily due to remarkable technological innovations in recent years, and are now used not only in offices but also in general home environments. Has been.
The image forming apparatus using the electrophotographic technology described here has at least a charging member, an image exposure system device, a developing device, and a transfer device, centering on a photosensitive member for electrophotography (hereinafter referred to as “photosensitive member”). Each of the devices operates in sequence to indicate a device that performs image formation.

The photoreceptor is first charged uniformly by the charging member, and then an image exposure system device is irradiated with light carrying the image information of the document, thereby forming an electrostatic latent image on the surface of the photoreceptor. Is developed with a developing device to obtain a toner image, and the transfer device is transferred to a non-transfer body to obtain a printed image.
When paying attention to the charging member, currently commonly used charging methods include a non-contact charging method typified by corona charging and a contact charging method typified by brush charging.

  In corona charging, since a high voltage is applied, a large amount of ozone is generated, and the influence of the ozone problem on the environment is regarded as a problem. However, since contact charging has a low applied voltage, generation of ozone is extremely low.

On the other hand, although the contact charging method can be used only with a DC voltage, it is desirable to perform the applied voltage with a DC voltage on which an AC voltage is superimposed because charging unevenness easily occurs.
However, when a DC voltage superimposed with an AC voltage is applied to the charging device, the applied voltage becomes higher due to the superimposed AC voltage, and the image quality is lower due to low-resistance contaminants such as ozone and nitrogen oxide than with DC voltage. In addition to the phenomenon of worsening, there is a problem of noise that a charging sound that is an unpleasant high frequency sound is generated.

This charging sound is hardly a problem when applied with a DC voltage, but in the case of an AC voltage, since it is an oscillating current, the photosensitive member is vibrated, and the vibration at this time is a continuous keen in the ear. Sounds like noise.
More details of the mechanism for generating the charged sound have already been shown (for example, see Patent Document 1).
Conventionally, various measures have been taken in order to reduce this charging noise. Broadly speaking, (1) weight type, (2) thick substrate type, (3) vibration damping type, (4) energy conversion type, etc. There is. Below, each typical thing is demonstrated with an example.

(1) Weight type In this method, a relatively high-density weight is disposed inside the photosensitive drum, and the weight of the photosensitive drum is increased to shift the resonance point and reduce the charging noise. In this method, an adhesive or the like is used to fix the weight inside the photosensitive drum. For this reason, if it cannot be reused and the selection of the adhesive is wrong, deterioration of the photoconductor drum cylindricity is caused. Furthermore, increasing the weight of the photosensitive drum is a very disadvantageous method against impact caused by dropping during transportation (see, for example, Patent Documents 2 to 6).
In addition, a method of avoiding adhesive fixing and holding a weight with an O-ring has been introduced, but in this case as well, the problem with drop deformation cannot be solved (see, for example, Patent Document 7).

(2) Thick substrate type A method in which the thickness of the substrate other than the inlay portion is increased to increase the rigidity of the photosensitive drum, suppress vibrations, and reduce charging noise. It is unclear whether the effect is due to rigidity or the increase in mass, but if the base material is made thick, the mass also increases, resulting in the problem of drop deformation, which is a problem with the spindle type. In the case of this method, since the force concentrates particularly on the thin spigot portion, end deformation is likely to occur (see, for example, Patent Documents 8 and 9).

(3) Damping type A method in which metallic springs (coil springs, leaf springs, etc.) are loaded on the inner wall of the photosensitive drum, and the drum inner wall is pressed against the drum to suppress vibrations. As a result, charging noise is suppressed. It is. In the case of the coil spring type, since the pressing area is small, it is not very effective. In the case of a leaf spring or cylindrical spring, if a single metal is used as the material, the repulsive force is large. There is a problem that the roundness of the body drum is deteriorated (see, for example, Patent Documents 10 and 11).

In Patent Document 10, in the claims, a shape memory alloy is used as a material from the viewpoint of improving assemblability, but the same problem occurs when a shape memory alloy is used alone as a cylindrical spring.
Further, this problem is solved by coating a support having a spring function with a vibration absorber and a covering material. However, the assembly is troublesome and complicated at the time of reproduction (for example, Patent Document 12). reference).

(4) Energy conversion type For example, a cylindrical light resin sliding contact member that does not substantially increase the weight of the photosensitive drum having a slit and a constriction in the longitudinal direction is applied to the inner wall of the photosensitive drum with a predetermined friction. In this method, the sliding contact member moves in a small amount inside the photosensitive drum by the vibration energy from the charger, and the pressing force is preferably 0.5 kg · f or more and 12.5 kg · f or less. There has been proposed a method of reducing charging noise by converting and releasing vibration energy into thermal energy by rubbing (see, for example, Patent Document 13).

  This method is very excellent, and it is possible to obtain an effect with a simple structure without causing an excessive increase in mass. Examples of the material used for the sliding contact member include acrylic, ABS, polycarbonate with glass fiber, and hard rubber. ABS is often used because of ease of manufacturing. However, in this system, if the product is used or stored for a long time in a high temperature environment of 45 to 55 ° C., there may be a problem that the silencing function is reduced. This is because the constricted portion provided in order to improve the insertability into the photoreceptor is softened in a high temperature environment, and the outer diameter is adjusted so as to press against the inner wall surface of the drum with a predetermined frictional force. This is because it cannot be held.

  At this time, the pressing force by the inner wall surface of the drum, the gravity acting on the weight of the resin itself, and the like are factors that spur this undesirable restoring force. In such a symptom, not only the noise reduction effect is lowered, but in a severe case, the pressing force to the inner wall surface of the photosensitive drum is lost, and the inside of the photosensitive drum is easily moved. The flange that is bonded and fixed may be hit with a hammer from the inside, which may cause defects such as flange dropping. As means for solving this problem, control of the use environment temperature, use of a material having a high softening temperature, control of the thickness of the constricted portion, and the like can be considered. Although the air flow mechanism has already been devised to prevent excessive temperature rise in the actual machine for controlling the operating environment temperature, the heat accumulation due to the recent miniaturization is gradually surpassing the control range. In addition, the use under harsh conditions cannot be restricted due to customer needs.

  In a method using a material having a high softening temperature, for example, polyether ether ketone, polyphenylene sulfide, polyamidoimide, polyarylate, or the like called super engineering plastic, it is very difficult to control the outer diameter to obtain a predetermined pressing force. The manufacturing cost will be high. Further, when inserting into the photosensitive drum with the outer diameter narrowed with an excessive force, whitening occurs in the constricted portion that is weak in strength, and a predetermined pressing force cannot be obtained. The control of the neck thickness is in the direction of increasing the thickness, but also in this case, it is difficult to control the outer diameter to obtain a predetermined pressing force, and the problem of whitening of the neck occurs.

In addition, because of the structure of the photosensitive drum, the sliding contact member is generally inserted into the photosensitive drum, and then the both ends of the drum are closed with flanges. The flange having a reduced diameter cannot exert its effect unless it is loaded on a new photosensitive drum after the photosensitive drum is destroyed and adjusted to an appropriate outer diameter again.
Japanese Patent Laid-Open No. 4-86682 JP-A-5-35167 JP-A-5-35048 JP-A-5-35166 JP-A-3-45981 JP-A-5-197321 JP 11-184308 A Japanese Patent Laid-Open No. 2000-091976 JP 2000-155500 A JP-A-5-142922 JP 2000-321929 A JP 2003-156972 A JP 2000-315036 A

  The present invention relates to a sliding contact member capable of permanently suppressing a charging sound generated when a contact charging member is directly contacted with a photosensitive drum and an AC voltage is applied to charge the photosensitive drum, even in a high temperature environment. The object is to provide a photosensitive drum provided therein, an electrophotographic drum cartridge including the photosensitive drum, and an image forming apparatus.

The above objects have been achieved by the present invention described below.
That is, the present invention
<1> A sliding contact member provided in an interior of a photosensitive drum provided in an image forming apparatus provided with a charging device of a type that comes into contact with the photosensitive drum and charges the photosensitive drum. It has a cylindrical shape in which a slit and a constriction extending in the longitudinal direction of the drum are formed, and further, a shape memory metal having a transformation temperature of 15 to 45 ° C. is provided around the constriction. It is a sliding contact member.

<2> The range in which the shape memory metal is installed is a range of 60 to 300 ° at the maximum and a range of 150 to 210 ° at the minimum when the slit portion is a reference (0 °). The sliding contact member according to <1>.
<3> A photosensitive drum comprising the sliding contact member according to <1> or <2> inside.

<4> An electrophotographic drum cartridge in which the photosensitive drum according to <3> is incorporated.
<5> An image forming apparatus including a photosensitive drum and a charging device that is charged by contacting the photosensitive drum, wherein the photosensitive drum is the photosensitive drum according to <3>. An image forming apparatus characterized by the above.

  The present invention relates to a sliding contact member capable of permanently suppressing a charging sound generated when a contact charging member is directly contacted with a photosensitive drum and an AC voltage is applied to charge the photosensitive drum, even in a high temperature environment. Can be provided, as well as an electrophotographic drum cartridge and an image forming apparatus including the photosensitive drum.

  The sliding contact member of the present invention is disposed inside a photosensitive drum provided in an image forming apparatus provided with a charging device that contacts a photosensitive drum (a drum-shaped photosensitive member) and charges the photosensitive drum. A sliding contact member provided, having a cylindrical shape in which a slit and a constricted portion extending in a longitudinal direction of the drum-shaped photoconductor are formed, and further, a transformation temperature is set to 15 to 45 ° C. around the constricted portion. The shape memory metal which has is installed, It is characterized by the above-mentioned.

  The sliding contact member of the present invention preferably includes a cylindrical resin in which a slit extending in the longitudinal direction of the photosensitive drum and a constricted portion are formed. The outer diameter of the resin is formed to be slightly larger than the inner diameter of the photosensitive drum, and since the slit and the constricted portion are formed, the resin is bent in a direction to reduce the diameter of the resin and the sliding contact member is moved to the photosensitive drum. Can be easily inserted, and assembling workability is improved. The slidable contact member inserted into the photosensitive drum presses the inner wall of the photosensitive drum so as to generate the desired frictional force as its diameter increases.

FIG. 1 is a longitudinal sectional view of a photosensitive drum in which a sliding contact member of the present invention is incorporated.
In FIG. 1, a sliding contact member 111 is inserted into a cylindrical photosensitive drum 11, and both ends of the photosensitive drum 11 are closed by flanges 112.

FIG. 2 is a diagram showing an example of the shape of the sliding contact member viewed in the direction of the arrow XX shown in FIG.
The sliding contact member 111 shown in FIG. 2 is cylindrical and has a slit 111a extending in the longitudinal direction, and a constricted portion 111b extending in the longitudinal direction is formed on the opposite side of the slit 111a. It is formed to be easily bent in the radial direction. The sliding contact member 111 can be formed of a resin such as acrylic, ABS, or glass-containing polycarbonate. In addition, the sliding contact member 111 may be formed of a metal such as stainless steel or hard rubber. The sliding contact member 111 has an outer diameter dimension, a surface roughness, etc. in advance so as to come into contact with the inner wall of the photosensitive drum 11 with a predetermined frictional force when arranged in the photosensitive drum 11. It has been established.

  Further, the sliding member 111 shown in FIG. 2 is provided with a shape memory metal 111c having a transformation temperature of 15 to 45 ° C. around the constricted portion 111b.

  The sliding contact member 111 of the present invention has the effect of reducing the charging noise due to the formation of the slit 111a and the constricted portion 111b. However, the shape memory metal 111c is further installed in a high temperature environment. Undesirable restoring force generated when used for a long period of time can be prevented, the sound deadening effect can be maintained semipermanently, and reuse can be facilitated.

  The method of installing the shape memory metal 111c includes a method of attaching to the inner wall of the sliding contact member, a method of embedding in the sliding contact member from the inner wall of the sliding contact member toward the outer wall, and the like. Although it is not particularly limited, for example, when the shape memory metal is exposed on the outer wall of the sliding contact member, for example, when the shape memory metal is attached to the outer wall of the sliding contact member, the adhesive force is changed to the shape. If the restoring force of the memory metal is smaller, the shape memory resin not only separates from the outer wall of the sliding contact member, but also exerts an excessive pressing force on the inner wall of the photosensitive drum, resulting in deterioration of the roundness of the photosensitive drum. May end up.

  The range in which the shape memory metal 111c is installed is a range of 60 to 300 ° at the maximum when the slit 111a positioned opposite to the constricted portion 111b is set as a reference (0 °), with the constricted portion 111b as the center. It is preferably in the range of 150-210 ° at the minimum, more preferably in the range of 90-270 ° at the maximum, and in the range of 135-225 ° at the minimum. When the range in which the shape memory metal 111c is installed is larger than the range of 60 to 300 °, the obtained image may be deteriorated. On the other hand, if it is smaller than the range of 150 to 210 °, the effect of maintaining the silencing effect may not be obtained even when left in a high sound environment.

In the present invention, the angle with respect to the slit 111a refers to an angle with the center of the slit 111a as 0 ° as shown in FIG. For example, 60 to 300 ° indicates the region shown in FIG.
In the present invention, the constricted portion 111b refers to a portion that enters the inner side of the other portion on the outer peripheral surface of the cylindrical sliding contact member 111.
Furthermore, although the shape memory metal 111c may be continuously installed in the longitudinal direction, it may be intermittently installed in the longitudinal direction as shown in FIG.

  Here, the shape memory metal 111c used in the present invention is a shape memory effect in which even if a large deformation that cannot be restored by a general metal material is applied, the shape memory metal 111c is restored to its original shape only by heating above the transformation temperature of the alloy. A titanium-nickel alloy is generally used as a metal (alloy) having a shape memory, and a copper-zinc-nickel alloy, nickel-aluminum has a shape memory effect. Ten or more types of shape memory alloys such as alloys have been confirmed. The shape memory effect means that a sample of a certain shape is rapidly cooled from a temperature higher than the critical temperature to form a low-pitched (martensite) phase, and when this is deformed and then heated again, when the critical temperature is exceeded, reverse transformation occurs at the same time. The phenomenon that the shape also recovers. The shape memory effect is caused by this martensitic transformation, and the temperature at which this martensitic transformation occurs is called the transformation temperature. The transformation temperature can be adjusted to about -20 to 100 ° C by adjusting the titanium-nickel mixing ratio or adding a small amount of cobalt or copper, but the actual transformation has a range of 10 to 30 ° C. Deformation also occurs gradually over a certain temperature range.

  In the sliding contact member of the present invention, it is essential that the transformation temperature is in the range of 15 to 45 ° C. and is in the range of 35 to 45 ° C. for the purpose of suppressing softening of the constricted portion at 45 to 55 ° C. preferable.

The drum cartridge for electrophotography of the present invention is characterized by incorporating the above-described photosensitive drum of the present invention.
An image forming apparatus according to the present invention includes the above-described photosensitive drum according to the present invention and a charging device that is charged by contacting the photosensitive drum. The image forming apparatus of the present invention may include the photosensitive drum of the present invention.

The image forming apparatus of the present invention will be described with reference to FIG. FIG. 5 is a schematic configuration diagram illustrating an example of an image forming apparatus including a contact charging type charging device.
The image forming apparatus shown in FIG. 5 includes a photosensitive drum 11, a charging roll 121 rotatably supported around an axis parallel to the axis of the photosensitive drum 11, and a charging roll 121 from a voltage application power source (not shown). A charging device 12 that contacts and charges the photosensitive drum 11 having a leaf spring electrode 122 that applies a predetermined voltage (DC voltage + AC voltage) and a cleaning pad 123; a developing device 14 that includes a developing roll 141; A transfer device 15, a cleaner 16, and a transfer roll 151 are provided.

  In the image formation by the image forming apparatus shown in FIG. 5, the photosensitive drum 11 rotates in the direction of the arrow A shown in the figure, and the photosensitive drum 11 is uniformly contact-charged by the charging device 12. The charging device 12 includes a charging roll 121 that is rotatably supported around an axis parallel to the axis of the photosensitive drum 11, and the charging roll 121 is a photosensitive member by a pressure spring (not shown). The drum 11 is pressed and urged to come into linear contact with the photosensitive drum 11, and is rotated in the direction of arrow B following the rotation of the photosensitive drum 11. A predetermined voltage (DC voltage + AC voltage) from a voltage application power source (not shown) is applied to the charging roll 121 via a plate spring-like electrode 122, whereby the surface of the photosensitive drum 11 is applied. It is charged to the required potential. Further, the surface of the charging roll 121 is cleaned by the cleaning pad 123.

  An image is recorded by a laser beam 13 in an area charged by the charging device 12 of the photosensitive drum 11 to form an electrostatic latent image, and the electrostatic latent image is rotated by the developing device 14 in the direction of arrow C. The toner image is developed by the toner conveyed by the developing roller 141, and the toner image is transferred to the transfer roller 151 constituting the transfer device 15. Thereafter, the toner image transferred to the transfer roller 151 is transferred onto a sheet (not shown). Is done. On the other hand, the photoreceptor roll 11 is cleaned by the cleaner 16 for the next image formation.

Hereinafter, the present invention will be specifically described by way of examples.
(Example 1-1)
An ABS plastic cylindrical pipe with an outer diameter of φ28mm, wall thickness of 4mm, and length of 100mm is processed with a slit width of 3mm, a constriction thickness of 0.7mm, and a constriction width of 2mm. However, on the inner surface side of the sliding contact member whose outer diameter is expanded to φ28.5 mm so as to obtain a predetermined pressing force by heating the constricted portion, the slit portion is set as a reference (0 °) and is 150 ° to 210 °. A shape memory metal (KIOKALLOY: manufactured by Daido Steel Co., Ltd.) having a transformation temperature of 20 ° C. and a plate thickness of 1 mm was installed in the range. Here, a method of attaching with a resin adhesive was used as the installation method. One sliding contact member thus obtained was inserted into the center of the photoconductor drum of φ30 × L404 × t1.0 mm, and both sides were closed with flanges for our laser beam printer DocuCenterColor f450, and the photoconductor drum Was made.

(Example 1-2)
In Example 1-1, except that the installation range of the shape memory metal was changed to a range of 60 ° to 300 ° when the slit portion was the reference (0 °), the same as in Example 1-1. A photoreceptor drum was produced.

(Example 2-1)
A photoconductor drum was produced in the same manner as in Example 1-1 except that the shape memory metal in Example 1-1 was changed to a shape memory metal having a transformation temperature of 40 ° C. and a plate thickness of 1 mm.

(Example 2-2)
In Example 2-1, the installation range of the shape memory metal was changed to a range of 60 ° to 300 ° when the slit portion was set as a reference (0 °), and was the same as Example 1-1. A photoreceptor drum was produced.

(Comparative Example 1)
A photoconductor drum was produced in the same manner as in Example 1-1 except that the shape memory metal in Example 1-1 was changed to a shape memory metal having a transformation temperature of 10 ° C. and a plate thickness of 1 mm.

(Comparative Example 2)
A photoconductor drum was produced in the same manner as in Example 1-1 except that the shape memory metal in Example 1-1 was changed to a shape memory metal having a transformation temperature of 50 ° C. and a plate thickness of 1 mm.

(Comparative Example 3)
In Example 1-1, a photosensitive drum was produced in the same manner as in Example 1-1 except that no shape memory metal was installed.

  The obtained photosensitive drum is set in a laser beam printer DocuCentreColor f450 manufactured by Fuji Xerox Co., Ltd., printed with an image quality of 50% halftone, and the presence or absence of density unevenness synchronized with the circumferential direction of the photosensitive drum. Sensory evaluation of the charging sound was performed. Next, the same photosensitive drum was stored for 24 hours in an environment of 50 ° C./RH 80%, and after acclimatizing to room temperature, the same evaluation was performed. The results are shown in Table 1. The presence / absence of density unevenness and the sensory evaluation are as follows.

(Existence of uneven density)
○: Density unevenness does not occur.
X: Density unevenness occurred.

(Charging sound)
○: Quiet, high-frequency sound called keen is not generated.
X: An annoying high-frequency sound called “Kean” was generated.

  From Table 1, the photosensitive drum satisfying the conditions of the present invention can reduce charged sound without causing deterioration of roundness to the extent that image quality is impaired even when stored for 24 hours in a 50 ° C./RH 80% environment. It can be seen that the image quality without density unevenness can be obtained.

It is sectional drawing of the longitudinal direction of the photoreceptor drum in which the sliding contact member of this invention was integrated. It is the figure which showed an example of the shape of the sliding contact member seen in the arrow XX direction shown in FIG. It is explanatory drawing for demonstrating the angle on the basis of the slit 111a. It is explanatory drawing for demonstrating the case where the shape memory metal 111c is not continuously installed in the longitudinal direction. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus including a contact charging type charging device.

Explanation of symbols

11 ... photosensitive drum,
12 ... Charging device,
13 ... Laser beam,
14 ... Developing device,
15 ... Transfer device,
16 ... cleaner,
111 ... sliding contact member,
111a ... slit,
111b ... Constriction part,
111c ... shape memory metal,
121... Charging roll,
122... Plate spring-like electrode,
123 ... cleaning pad,
141... Development roll,
151: Transfer roll

Claims (5)

A sliding contact member provided inside a photoconductor provided in an image forming apparatus provided with a charging device of a type for contacting the photoconductor drum and charging the photoconductor drum,
It has a cylindrical shape in which a slit and a constricted portion extending in the longitudinal direction of the photosensitive drum are formed, and a shape memory metal having a transformation temperature of 15 to 45 ° C. is installed around the constricted portion. A slidable contact member.   The range in which the shape memory metal is installed is a range of 60 to 300 ° at the maximum and a range of 150 to 210 ° at the minimum when the slit portion is a reference (0 °). Item 2. The sliding contact member according to Item 1.   A photosensitive drum comprising the sliding contact member according to claim 1 inside.   An electrophotographic drum cartridge comprising the photosensitive drum according to claim 3 incorporated therein. An image forming apparatus including a photosensitive drum and a charging device that is charged by contacting the photosensitive drum,
The image forming apparatus according to claim 3, wherein the photosensitive drum is a photosensitive drum according to claim 3.

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