JP2006098854A - Image forming apparatus - Google Patents

Abstract

A developing roller that can be easily and effectively corrected for bending of a developing roller due to a contact force of a contact member while making a developing gap as small as possible to obtain high image quality.
In an image forming apparatus that performs non-contact jumping development, a contact position P1 of a supply roller 6 to a developing roller 5 is orthogonal to a straight line α that connects the center of a photoconductor 2 and the center of the developing roller 5. Further, it is arranged on the opposite side to the photoreceptor 2 with respect to a straight line β passing through the center of the developing roller 5. Further, the contact position P2 of the regulating blade 7 with respect to the developing roller 5 is arranged on the same side as the photosensitive member 2 with respect to the straight line β, that is, the side opposite to the contact position P1 of the supply roller 6 with respect to the developing roller 5. Thereby, the bending of the developing roller 5 by the supply roller 6 and the bending of the developing roller 5 by the regulating blade 7 cancel each other, and the bending of the developing roller 5 is suppressed.
[Selection] Figure 1

Description

  The present invention relates to the technical field of image forming apparatuses such as electrophotography, electrostatic copying machines, printers, facsimiles and the like, and in particular, non-contact jumping development system development having a predetermined development gap between an image carrier and a development roller. The present invention also relates to a technical field of an image forming apparatus in which a contact member such as a toner supply roller or a toner regulating member is pressed against a developing roller.

  Conventionally, many image forming apparatuses using a non-contact jumping development method are known as image forming apparatuses. In this non-contact jumping development method, a predetermined development gap is provided between a photosensitive member as an image carrier and a developing roller, and toner on the developing roller is jumped to the photosensitive member to electrostatic latent image on the photosensitive member. This is a method of developing. In this non-contact jumping development method, it is required to maintain a development gap between the photosensitive member and the development roller with high accuracy in order to perform good development.

  Therefore, conventionally, a spacer made of a roller having a larger radius than the developing roller is fitted to both ends of the developing roller as a developing gap adjusting member, and these rollers are brought into contact with the outer peripheral surface of the photosensitive member, whereby the photosensitive member and the developing roller are (See, for example, Patent Document 1).

  By the way, in such a conventional non-contact jumping development type image forming apparatus, a supply roller, a regulating blade, and the like are used to charge the toner or to form a uniform thin toner layer on the developing roller. The contact member is pressed. For this reason, since a bending moment acts on the developing roller by the contact force of these contact members, the central portion of the developing roller bends toward the photosensitive member, and the developing gap fluctuates to maintain a predetermined developing gap. Can not be. In order to fully exhibit the functions of the supply roller and the regulating blade, a force of about 1 kgf is required as a contact force of these contact members to the developing roller, so that the developing roller bends several tens of μm. If the predetermined development gap cannot be maintained as described above, not only a difference in density occurs between the both ends and the center of the photosensitive member, but also vibration due to deflection caused by the rotation of the developing roller. Occurs, resulting in a banding image, which makes it impossible to obtain a high-quality image.

  Therefore, in the image forming apparatus disclosed in Patent Document 1, the central portion of the developing roller or the central portion of the photosensitive member is formed in a concave shape or a convex shape so that, for example, the developing roller is attached to the photosensitive member by the contact force of the supply roller. A predetermined development gap can be maintained even if the film is bent in the direction.

  On the other hand, when a roller is used as the developing gap adjustment member, an appropriate developing gap is ensured between the developing roller and the photosensitive member by overlapping errors such as the coaxiality between the roller and the developing roller and the roundness of the roller. Difficult to do. In addition, in order to obtain high image quality in the non-contact jumping development method, it is necessary to narrow the development gap. However, since the roller has a certain thickness, the roller gap is formed very thin to narrow the development gap. Difficult to do.

Therefore, a sheet-like member is used as the developing gap adjusting member, and this sheet-like member is interposed between the outer peripheral surface of both ends of the developing roller and the outer peripheral surface of both ends of the photosensitive member, thereby providing a gap between the developing roller and the photosensitive member. It has been proposed that a proper development gap can be easily secured (see, for example, Patent Document 2). According to the image forming apparatus disclosed in Patent Document 2, it is possible to solve the problem in the case where a roller is used as the developing gap adjusting member.
JP-A-6-258933. Japanese Patent Laid-Open No. 5-27571.

  By the way, in the image forming apparatus disclosed in Patent Document 1 described above, it is necessary to form the central portion of the developing roller or the central portion of the photoreceptor in a concave shape or a convex shape. In that case, on the outer peripheral surface of the developing roller or the photoreceptor, the depth of the recess or the height of the protrusion at the center with respect to both end portions is extremely small, such as several tens of μm, corresponding to several tens of μm of the deflection amount of the developing roller. A concave curved surface or a convex curved surface is formed. Thus, for example, when the central portion of the developing roller is to be formed in a concave shape or a convex shape, there is the following problem, that is, the width of the normal developing roller is several tens of centimeters, and this is expressed in μm units. And tens of thousands of μm. For this reason, an extremely small concave surface or convex surface of several tens of μm must be processed on a member having an extremely long length of several tens of thousands of μm. The cost will be very high. In addition, it is extremely difficult to process the outer peripheral surface of the developing roller over the entire surface to have the same surface roughness and the same electric resistance by processing. Such a problem also occurs when the central portion of the photoreceptor is formed in a concave shape or a convex shape.

  Further, Patent Document 2 does not disclose or suggest that the predetermined developing gap cannot be maintained because the developing roller is bent toward the photosensitive member by the contact force of a contact member such as a supply roller or a regulating blade. However, even in the image forming apparatus disclosed in Patent Document 2, when the contact member presses the developing roller, the central portion of the developing roller bends toward the photosensitive member, and the development gap varies. In particular, when the development gap is reduced by using a sheet-like spacer as in Patent Document 2, the variation rate of the development gap increases due to such bending of the development roller. In particular, in the case of a development gap of 100 μm or less, the development gap fluctuation rate reaches several tens of percent. For this reason, the influence on the image quality of the development gap fluctuation due to the deflection of the developing roller is increased.

  Therefore, the image forming apparatus disclosed in Patent Document 2 is also required to suppress the fluctuation of the development gap. However, as disclosed in Patent Document 1 described above, the central portion of the developing roller disclosed in Patent Document 2 or photosensitive When the central part of the body is formed in a concave shape or a convex shape, the above-described problem occurs.

  The present invention has been made in view of such circumstances, and an object of the present invention is to bend the developing roller due to the contact force of the contact member while making the development gap as small as possible to obtain high image quality. It is an object to provide an inexpensive image forming apparatus that can easily and effectively correct the above.

  In order to solve the above-mentioned problems, the invention of claim 1 is characterized in that an image carrier and a toner conveying surface are provided to face the image carrier with a predetermined development gap therebetween, and the image carrier is provided with toner. In the image forming apparatus for performing non-contact jumping development, the pressure contact position of the two contact members with respect to the development roller is at least provided with a development roller that conveys the toner and two contact members that are in pressure contact with the development roller. It is characterized in that they are arranged on opposite sides with respect to a straight line orthogonal to a straight line connecting the center of the image carrier and the center of the developing roller and passing through the center of the developing roller.

  According to a second aspect of the present invention, there is provided an image carrier, a developing roller that is provided so that a toner conveyance surface faces the image carrier with a predetermined development gap, and conveys toner to the image carrier; In an image forming apparatus that includes at least two contact members that are in pressure contact with the developing roller and performs non-contact jumping development, a position where the two contact members are in contact with the developing roller is a center of the image carrier. Arranged on the straight line passing through the center of the developing roller and perpendicular to the straight line connecting the center of the developing roller and opposite to each other with respect to the straight line connecting the center of the image carrier and the center of the developing roller. It is characterized by that.

  Further, according to a third aspect of the invention, the two contact members are brought into pressure contact with the developing roller to supply toner to the developing roller, and are brought into pressure contact with the developing roller and conveyed to the image carrier. It is a regulating member that regulates toner on the developing roller.

  Further, the invention according to claim 4 is that the sheet-like spacers are fixed to the outer peripheral surfaces of both end portions of the developing roller, and the spacers are pressed against the outer peripheral surface of the image carrier, thereby The developing gap is formed between the developing roller and the peripheral speed of the image carrier and the peripheral speed of the spacer are set to be the same or substantially the same.

  According to the image forming apparatus of the first, third, and fourth aspects of the present invention configured as described above, the position where the two contact members such as the supply roller and the regulating member are in contact with the developing roller is defined as the center of the image carrier. With respect to a straight line that is orthogonal to the straight line connecting the center of the developing roller and that passes through the center of the developing roller, they are arranged on opposite sides, so that the developing roller is bent by the pressure contact of one contact member and the pressure contact of the other contact member The bending of the developing roller can be made to act in the direction of canceling each other. Therefore, the bending of the developing roller due to the pressure contact between the two contact members can be suppressed. As a result, fluctuations in the development gap between the image carrier and the developing roller due to the pressure contact of these contact members can be suppressed and corrected. In particular, when the development gap is set small for the purpose of improving the image quality, the influence on the image quality due to the fluctuation of the development gap can be effectively suppressed.

According to the image forming apparatus of the second, third and fourth aspects of the present invention, for example, the positions of the two contact members such as the supply roller and the regulating member, which are in contact with the developing roller, are set between the center of the image carrier and the developing roller. Since the two contact members are arranged on a straight line passing through the center of the developing roller and perpendicular to the straight line connecting the center, the contact force of the two contact members to the developing roller has a component force in the direction toward the image carrier. You can avoid it. In addition, since the contact positions of the two contact members to the developing roller are arranged on opposite sides with respect to a straight line connecting the center of the image carrier and the center of the developing roller, each of the developing rollers by the two contact members is arranged. The contact forces can be made to oppose each other so as to cancel the deflection of the developing roller due to these contact forces. Therefore, it is possible to more effectively suppress the fluctuation of the developing gap between the image carrier and the developing roller due to the contact member.
In particular, when the development gap is set small for the purpose of improving the image quality, the influence on the image quality due to the fluctuation of the development gap can be more effectively suppressed.

  Furthermore, in any of the image forming apparatuses according to claims 1 to 4, as disclosed in the above-mentioned Patent Document 1, the central portion of the developing roller or the central portion of the image carrier is formed in a concave shape or a convex shape. This eliminates the need for special processing that requires high precision on the developing roller or the image carrier, thereby reducing the cost of the developing roller and making the outer peripheral surface of the developing roller the entire surface thereof. In addition, the same surface roughness and the same electric resistance can be easily obtained. In particular, since no special processing is required, a conventional developing roller can be used as it is.

  In particular, according to the invention of claim 4, since the sheet-like spacer is used as a member for adjusting the developing gap between the image carrier and the developing roller, the surface of the spacer that contacts the image carrier is relatively wide. It can be made into a plane of width. Therefore, the deflection of the developing roller itself can be easily corrected, and the tolerance of the developing gap is determined by the thickness of the spacer, so that the accuracy of the developing gap can be improved. In addition, since the peripheral speed of the image carrier and the peripheral speed of the spacer on the developing roller are set to be the same or substantially the same, the friction between the pressure contact portion between the image carrier and the spacer on the developing roller is reduced to generate heat. As well as development gap fluctuation due to frictional vibration. In this way, a small development gap of 100 μm or less can be formed especially in the non-contact development of non-magnetic one-component toner, but with respect to such a small development gap, there is a decrease of several tens of percent with respect to the variation rate of the development gap. Thus, the influence on the image quality due to the change in the development gap can be most effectively suppressed.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view schematically showing an example of an embodiment of an image forming apparatus according to the present invention. FIG. 2 is an image carrier, a developing roller, a supply roller, and a regulating blade in the example shown in FIG. It is a figure which shows typically arrangement | positioning relationship.

  As shown in FIG. 1, the image forming apparatus 1 of this example includes a photoconductor 2 that is an image carrier and a developing device 3. The developing device 3 includes a case 4, a developing roller 5 that conveys the toner T to the photosensitive member 2, a supply roller 6 that is pressed against the developing roller 5 to supply the toner T, and a pressure roller that contacts the developing roller 5, and is conveyed to the photosensitive member 2. A regulating blade 7 that regulates the toner T, a toner stirring and conveying member 8 that agitates and conveys the toner T, a toner receiving member 9 that receives the toner T conveyed by the toner agitating and conveying member 8 and guides it toward the supply roller 6; An upper seal 10 is provided for preventing toner leakage while contacting the developing roller 5 in the direction of collecting the toner T remaining after development. The developing roller 5, the supply roller 6, the regulating blade 7, the toner stirring and conveying member 8, and the toner receiving member 9 are all disposed in the case 4.

  Sheet-like spacers 11 are fixed to the toner non-conveying surfaces at both ends of the developing roller 5, respectively. As shown in FIG. 2, these spacers 11 are pressed against the image non-carrying surface of the photoreceptor 2, so that the toner carrying surface of the developing roller 5 and the image carrying surface of the photoreceptor 2 facing the toner carrying surface are provided. In the meantime, a predetermined development gap g is formed.

  The developing gap g is adjusted to a desired size by appropriately selecting the thickness of the spacer 11. As a result, the developing device 3 performs non-magnetic one-component developer non-contact jumping development using the toner T which is a non-magnetic one-component developer. In this case, the image forming apparatus 1 of this example is set so that the photosensitive member 2 rotates clockwise in FIG. 1 and the developing roller 5 and the supply roller 6 both rotate counterclockwise. The peripheral speed of the photosensitive member 2 and the peripheral speed of the spacers 11 and 12 on the developing roller 5 are set to be the same or substantially the same.

For the developing roller 5, a metal roller such as iron having extremely small stress shrinkage and heat shrinkage is used, and an elastic spacer is used for the spacer 11 fixed on the metal roller. As an elastic body used for the spacer, a plastic or rubber such as fluororesin, polyester, polyolefin, polyimide, epoxy, acetate, silicone, acrylic, rubber, etc. can be used, and in that case, an insulator is preferable. And as the spacer 11 which consists of such an elastic body, an adhesive tape may be sufficient and a seamless heat-shrinkable tube may be sufficient.
In addition, an elastic roller made of an elastic body can be used as the developing roller 5, and in this case, a material that has a very small stress contraction or thermal contraction such as metal or ceramics is used as a spacer fixed to the elastic roller. preferable.

  The contact position P <b> 1 of the supply roller 6 with the developing roller 5 is perpendicular to a straight line α connecting the center of the photosensitive member 2 and the center of the developing roller 5, and with respect to the straight line β passing through the center of the developing roller 5. Located on the opposite side. Further, the contact position P2 of the regulating blade 7 with the developing roller 5 is arranged on the same side as the photoreceptor 2 with respect to the straight line β, that is, on the opposite side to the contact position P1 of the supply roller 6.

  In the image forming apparatus 1 of this example configured as described above, the supply roller 6 is arranged such that the contact position P1 between the supply roller 6 and the developing roller 5 is opposite to the photoreceptor 2 with respect to the straight line β. Accordingly, the contact force of the supply roller 6 against the developing roller 5 has a component force in the direction toward the photosensitive member 2, so that the central portion of the developing roller 5 bends in a direction approaching the photosensitive member 2. On the other hand, the regulating blade 7 is arranged so that the contact position P2 between the regulating blade 7 and the developing roller 5 is on the same side as the photosensitive member 2 with respect to the straight line β. Since the contact force has a component force in a direction away from the photoconductor 2, the central portion of the developing roller 5 bends in a direction away from the photoconductor 2.

  Therefore, the bending of the developing roller 5 due to the pressure contact of the supply roller 6 and the bending of the developing roller 5 due to the regulating blade 7 act in a mutually canceling direction, and the two contact members of the feeding roller 6 and the regulating blade 7 The bending of the developing roller 5 due to the pressure contact is suppressed. Thereby, the fluctuation | variation of the development gap g between the photoreceptor 2 and the developing roller 5 due to the pressure contact of these contact members can be suppressed and corrected. In particular, when the development gap g is set small for the purpose of improving the image quality, the influence on the image quality due to the fluctuation of the development gap g can be effectively suppressed.

  Further, as disclosed in the aforementioned Patent Document 1, it is not necessary to form the central portion of the developing roller 5 or the central portion of the photosensitive member 2 in a concave shape or a convex shape. On the other hand, it becomes unnecessary to perform special processing that requires high accuracy, and the cost of the developing roller 5 or the photosensitive member 2 can be reduced, and the outer peripheral surface of the developing roller 5 or the photosensitive member 2 is covered over the entire surface. The same surface roughness and the same electrical resistance can be easily achieved. In particular, since no special processing is required, a conventional one can be used as it is as the developing roller 5 or the photoreceptor 2.

  Further, since the sheet-like spacer 11 is used as a member for adjusting the developing gap g between the photosensitive member 2 and the developing roller 5, the surface of the spacer 11 that contacts the photosensitive member 2 has a relatively wide width. Therefore, it is possible to easily correct the deflection of the developing roller 5 itself, and since the tolerance of the developing gap g is determined by the thickness of the spacer, the accuracy of the developing gap g can be improved.

  Further, since the peripheral speed of the photosensitive member 2 and the peripheral speed of the spacer 11 on the developing roller 5 are set to be the same or substantially the same, the friction of the pressure contact portion between the photosensitive member 2 and the spacer 11 on the developing roller 5 is reduced. It is possible to suppress heat generation and reduce development gap fluctuation due to frictional vibration.

  Thus, in the non-contact development of the non-magnetic one-component toner, the development gap g is formed using the sheet-like spacer 11 to which the developing roller 5 is fixed, and the peripheral speed of the photosensitive member 2 and the peripheral speed of the spacer 11 are formed. Can be formed at a constant speed, and a small development gap g of 100 μm or less can be formed. Thus, according to the image forming apparatus 1 of this example, with respect to such a small development gap g, it is possible to reduce the variation rate of the development gap by several tens of percent, and the influence on the image quality due to the variation of the development gap g. Can be suppressed most effectively.

  Further, the developing roller 5 is formed of an elastic body and a metal spacer 11 is fixed on the elastic body, or the developing roller 5 is formed of a metal roller and an elastic spacer 11 is formed on the metal roller. Since they are fixed, even if the developing roller 5 is bent or shaken as described above, it is possible to alleviate the generated vibration and make it difficult to generate a banding image.

  In particular, it is preferable to use a heat shrinkable tube as the spacer 11. Since this heat-shrinkable tube is seamless and elastic, it can sufficiently exhibit the above-described effects and is suitable as a developing gap adjusting member, and can be fixed to the developing roller 5 relatively easily.

FIG. 3 is a diagram showing another example of the embodiment of the image forming apparatus of the present invention. Note that the same reference numerals are given to the same components as those in the above-described example, and a detailed description thereof will be omitted.
In the example shown in FIG. 1, the supply roller 5 and the regulating blade 7 are arranged on the opposite sides with respect to the straight line β. However, in the image forming apparatus 1 of this example, as shown in FIG. The contact position P1 to the developing roller 5 is arranged on the straight line β, and the contact position P2 of the regulating blade 7 to the developing roller 5 is on the straight line β and the supply roller 5 contacts the developing roller 5. It arrange | positions on the opposite side regarding the position P1 and the straight line (alpha).
Other configurations of the image forming apparatus 1 of this example are the same as the example shown in FIG.

In the image forming apparatus 1 of this example configured as described above, the supply roller 6 has a contact position P1 between the supply roller 6 and the developing roller 5 on the straight line β, and the regulating blade 7 and the developing roller. 5 is also arranged on the straight line β, so that the contact force of the supply roller 6 and the regulating blade 7 to the developing roller 5 has no component force in the direction toward the photosensitive member 2. . In addition, since the contact position P1 of the supply roller 6 to the developing roller 5 and the contact position P2 of the regulating blade 7 to the development roller 5 are arranged on the opposite sides with respect to the straight line α, the development roller by the supply roller 6 The abutting force 5 and the abutting force of the developing roller 5 by the regulating blade 7 oppose each other and act to cancel the bending of the developing roller 5 due to these abutting forces. Therefore, the fluctuation of the developing gap g between the photosensitive member 2 and the developing roller 5 due to the contact member is further effectively suppressed.
Other functions and effects of the image forming apparatus 1 of this example are the same as those of the example shown in FIG.

Next, examples and comparative examples of the present invention will be described.
Example 1
In Example 1, the image forming apparatus 1 shown in FIG. 1 was used. At this time, the developing roller 5 was an iron metal roller having a diameter of 18 mm and a length of 290 mm. Note that the spacer was not fixed to the metal roller because only the deflection of the developing roller 5 due to the contact force of the supply roller 6 and the regulating blade 7 to the developing roller 5 was measured. Further, the contact force of the supply roller 6 and the regulating blade 7 to the developing roller 5 was set to 2 kgf. The deflection of the developing roller 5 measured at this time was 5 μm in terms of the difference between both end portions and the central portion.

(Example 2)
In Example 2, the image forming apparatus 1 shown in FIG. 3 was used. At this time, the developing roller 5 was an iron metal roller having a diameter of 18 mm and a length of 290 mm. In addition, the spacer was not fixed to the metal roller like Example 1. Further, the contact force of the supply roller 6 and the regulating blade 7 to the developing roller 5 was set to 2 kgf. The deflection of the developing roller 5 measured at this time was 2 μm in terms of the difference between both end portions and the central portion.

(Comparative Example 1)
In Comparative Example 1, the image forming apparatus 1 shown in FIG. 4 was used. In the example shown in FIG. 1, the supply roller 5 and the regulating blade 7 are arranged on the opposite sides with respect to the straight line β. On the other hand, as shown in FIG. 4, the image forming apparatus 1 used in Comparative Example 1 is used. , The supply roller 5 and the regulating blade 7 are arranged on the opposite side of the photoreceptor 2 and on the same side with respect to the straight line β. The other configuration of the image forming apparatus 1 shown in FIG. 4 is the same as the example shown in FIG.
As the developing roller 5, an iron metal roller having a diameter of 18 mm and a length of 290 mm was used. In addition, the spacer was not fixed to the metal roller like Example 1. Further, the contact force of the supply roller 6 and the regulating blade 7 to the developing roller 5 was set to 2 kgf. The deflection of the developing roller 5 measured at this time was 30 μm in terms of the difference between both end portions and the central portion.

  From the results of Examples 1 and 2 and Comparative Example 1 described above, when the supply roller 5 and the regulating blade 7 are arranged on the opposite side of the photoreceptor 2 and on the same side with respect to the straight line β, the supply roller 6 and the regulation blade 7 are regulated. Although the deflection of the developing roller 5 due to the pressure contact of the blade 7 to the developing roller 5 can be effectively suppressed and cannot be corrected, the supply roller 5 and the regulating blade 7 are arranged on the opposite sides with respect to the straight line β as in the present invention. In this case, it was confirmed that the deflection of the developing roller 5 due to the pressure contact of the supply roller 6 and the regulating blade 7 to the developing roller 5 can be effectively suppressed and corrected. In particular, it was confirmed that when the supply roller 5 and the regulating blade 7 are arranged on the straight line β so that the contact forces face each other, the deflection of the developing roller 5 can be further effectively suppressed and corrected. .

  The image forming apparatus according to the present invention is a non-contact jumping developing type developing having a predetermined developing gap between an image carrier and a developing roller in an image forming apparatus such as an electrophotography, an electrostatic copying machine, a printer, and a facsimile. In addition, it can be suitably used for an image forming apparatus in which a contact member such as a toner supply roller or a toner regulating member is pressed against the developing roller.

1 is a cross-sectional view schematically showing an example of an embodiment of an image forming apparatus according to the present invention. In the example shown in FIG. 1, it is a figure which shows typically the arrangement | positioning relationship of an image carrier, a developing roller, a supply roller, and a control blade. It is a cross-sectional view schematically showing another example of the embodiment of the image forming apparatus according to the present invention. It is a cross-sectional view which shows typically the image forming apparatus used for the comparative example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Photoconductor (image carrier), 3 ... Developing device, 4 ... Case, 5 ... Developing roller, 6 ... Supply roller, 7 ... Restricting blade, 11 ... Spacer, [alpha] ... Center of photoconductor A straight line connecting the center of the developing roller, β: a straight line orthogonal to the straight line α and passing through the center of the developing roller

Claims (4)

An image carrier, a developing roller provided with a toner conveyance surface facing the image carrier with a predetermined development gap therebetween, and a roller for conveying the toner to the image carrier; In an image forming apparatus that includes at least two contact members and performs non-contact jumping development,
The two contact members are pressed against the developing roller at positions opposite to each other with respect to a straight line that is perpendicular to a straight line connecting the center of the image carrier and the center of the developing roller and passes through the center of the developing roller. An image forming apparatus. An image carrier, a developing roller provided with a toner conveyance surface facing the image carrier with a predetermined development gap therebetween, and a roller for conveying the toner to the image carrier; In an image forming apparatus that includes at least two contact members and performs non-contact jumping development,
The pressure contact position of the two contact members to the developing roller is orthogonal to a straight line connecting the center of the image carrier and the center of the developing roller, and is on a straight line passing through the center of the developing roller, and the image carrier. An image forming apparatus, wherein the image forming apparatus is disposed on opposite sides with respect to a straight line connecting the center of the body and the center of the developing roller. The two contact members are a roller that is pressed against the developing roller and supplies toner to the developing roller, and a regulation that regulates the toner on the developing roller that is pressed against the developing roller and conveyed to the image carrier. The image forming apparatus according to claim 1, wherein the image forming apparatus is a member. The sheet-like spacers are fixed to the outer peripheral surfaces of both ends of the developing roller, and the developer is pressed against the outer peripheral surface of the image carrier, whereby the development is performed between the image carrier and the developing roller. The image according to any one of claims 1 to 3, wherein a gap is formed, and a peripheral speed of the image carrier and a peripheral speed of the spacer are arranged to be the same or substantially the same. Forming equipment.

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