CA1049770A - Method and apparatus for varying developer bandwidth - Google Patents
Method and apparatus for varying developer bandwidthInfo
- Publication number
- CA1049770A CA1049770A CA224,550A CA224550A CA1049770A CA 1049770 A CA1049770 A CA 1049770A CA 224550 A CA224550 A CA 224550A CA 1049770 A CA1049770 A CA 1049770A
- Authority
- CA
- Canada
- Prior art keywords
- developer
- image
- shunt
- magnetic
- magnetic member
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
- G03G15/08—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer
- G03G15/09—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer using magnetic brush
- G03G15/0921—Details concerning the magnetic brush roller structure, e.g. magnet configuration
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Magnetic Brush Developing In Electrophotography (AREA)
- Dry Development In Electrophotography (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An electrostatic copying machine is provided utilizing a magnetic brush development system. The magnetic brush presents a band of developer to a latent electrostatic image, the width of the developer band being changed in accordance with the size of copy paper used. This is effected by utilizing a variable length magnet inside a non-magnetic rotatable roller which carries de-veloper thereon. The length of the magnet is varied in accordance with the size of the copy paper used to accordingly change the length of the magnetic field emanating therefrom thereby effecting a corresponding change in the bandwidth of the developer trans-ported to the image. An alternate method for effecting the same result is to utilize a shunt which may be swung into a position surrounding one end of the magnet to prevent the magnet field emanating from that end of the magnet from being effective to attract developer to the roller thereby decreasing the developer bandwidth.
An electrostatic copying machine is provided utilizing a magnetic brush development system. The magnetic brush presents a band of developer to a latent electrostatic image, the width of the developer band being changed in accordance with the size of copy paper used. This is effected by utilizing a variable length magnet inside a non-magnetic rotatable roller which carries de-veloper thereon. The length of the magnet is varied in accordance with the size of the copy paper used to accordingly change the length of the magnetic field emanating therefrom thereby effecting a corresponding change in the bandwidth of the developer trans-ported to the image. An alternate method for effecting the same result is to utilize a shunt which may be swung into a position surrounding one end of the magnet to prevent the magnet field emanating from that end of the magnet from being effective to attract developer to the roller thereby decreasing the developer bandwidth.
Description
DESCRIPTION OF TH~ INVENTION
In an electrostatic copier system, it has been found that developer (carrier and toner particles) life is related to the function of the number of times the developeris cycled through the development system; the more times cycled, the shorter the life.
In known systems, it is the custom to present developer to a photoconductive sur~ace carrying a latent image over the same width regardless of the size of the final image ~esired.
For instance, developer may be presented to a surface carrying a latent image over a 14-inch bandwidth for copying an image onto either an 11 x 14-inch paper or an 8 1/2 x ll-inch paper.
The bandwidth coincides with the length of the paper as the paper is fed through the machine. For the latter size p~ er, developer is presented to a latent image over an extra 3-inch - 15 bandwidth and is, therefore, needlessly circulated with resultant shortening of developer life.
It is, therefore, an object of this invention in one of its aspects to stop needless circulation of excess developer and thus improve developer life.
It is an object of this invention in another of its aspects to limit developer presentation to a surface carrying a latent image over a bandwidth equal to the length of paper on which the developed image is to be transferred.
Furthermore, in some systems the photoconductive sur-face is developed beyond the borders of an original and copy sheet resulting in removal of excess toner particles from the areas of the surface which taxes the cleaning system.
It is, therefore, an object of the invention in another of its aspects to prevent needless cleaning of toner particles from a photoconductive surface.
In accordance with another aspect of this invention there is provided a method comprising effecting an electrostatic ~ - 2 -.
~049'770 latent image on a photoconductive surface, developing the latent image by contacting the photoconductive surface with developer of toner particles triboelectrically attached to carrier particles delivered to the surface from a developer sump, transferrin~the toner particles from the latent image to a copy medium of a given dimen-sion, effecting another electrostatic latent image on the same photoconductive surface, contacting the photo-conductive surface with developer from the same developer sump to develop another latent image with toner particles and transferring the toner particles from the other latent image to another copy medium of substantially different dimension than the first copy medium, the improvement comprising: contacting the photoconductive surface with developer over a bandwidth substantially equal to the dimension of the copy medium used.
In accordance with another aspect of this invention there is provided a copying machine comprising: a memberhaving ~ - 2a -'' ' ~' ' ' ' ' "" ~
" 1049770 ~ developable image thereon, a developer sump containing developer therein having magnetic properties, means for trans-porting a band of developer from said sump to the image for developing the same, means for selectively changing the width of the developer band, a copy paper supply receptacle, means for changing the size of said receptacle to accommodate various sizes of copy paper, said ~elective means being operably con-nected to said last named means to be controlled thereby.
In accordance with another aspect of this invention there is provided a copying machine comprising: a member having a developable image thereon, a developer sump containing developer therein having magnetic properties, means for trans-porting a bandwidth of the developer from said sump to the image for developing the same, said means comprising a rotatable non-magnetic member surrounding at least one magnetic member, said magnetic m~mber being so constructed to vary in length, and means to selectively increase or decrease the length of said magnetic member to effect a corresponding change in the magnetic field emanating therefrom thereby effecting a corres-ponding change in the bandwidth of the developer ~ransportedto the image.
In accordance with another aspect of this invention there is provided a copying machine comprising: a member having a developable image thereon; a developer sump containing a dev-; eloper therein having magnetic properties, means for transporting a band of developer from said sump ~o the image for developing the same, said means comprising a rotatable non-magnetic member surrounding at least one magnetic member; a shunt, said shunt being located adjacent one end of said magnetic member, means for moving said shunt into a position to surround one end of said magnetic member and for withdrawing said shunt from said position, said shunt being of a material to prevent the magnetic field emanating from the end of the magnetic member surrounded thereby - 2b ~
.
from being effective to attract developer to said non-magnetic member.
This invention will become apparent from the following description with reference to the drawing wherein:
Figure 1 is a schematic view of a copying apparatus;
Figure 2 is a view taken along section line 2-2 of Figure l;
Figure 3 (first sheet of drawings) is a view of a modification of the embodiment of Figures 1 and 2;
Figure 4 (first sheet of drawings) is a view taken along section line 4-4 of Figure 3;
Figure 5 is a top view of a copy paper receptacle adjuster; and Figure 6 is a partial view taken along section line 6-6 of Figure 5.
Referring to Figures 1 and 2, there is shown a drum 10 on which a photoconductive layer 12 is formed. Arranged about the drum 10 are a charging station A, an imaging station B, a development station C, an image transfer and fixing station D and a cleaning station E. All of the functions of these stations are well known in $he art. An electrostatic latent image may be formed on the layer 12 and developed with xerographic toner particles. The invention resides in the developing station to which particular attention is directed.
The development station comprises a developer sump 14 containing developer 16 therein. The developer is a mixture of toner particles and ferromagnetic carrier particles.
The toner particles are triboelectrically attached to the carrier particles. One side wall of the sump has a station-ary hub 18 affixed thereto which receives one end of a cylinderor roller 20 therein which is o~ non-magnetic material.
. .
A bearing race 22 is secured to the hub 18 to allow the cylinder 20 to rotate relative to the hub and sump. The other end of the cylinder 20 is operably secured to a motor (not shown) by a gear train (not shown) for driving the cylinder. A keeper mem-ber 24 of magnetic material is secured to the hub 18 and has se-cured thereto a developer pickup magnet 26, a development magnet 28 and a residual developer transport magnet 30, all of which are located within the confines of the cylinder 20. Attached to the keeper 24 is a guide portion 31 having an upper surface 32, a lower surface 34 and a side surface 36 surrounding the magnet 26 for purposes to be hereinafter described. The guide portion 31 is of a non-magnetic material and the magnets 26, 28 and 30 are permanent.
The magnet 26 is split into two sections, a stationary section 38 and a slidable section 40. Surfaces 42 and 44 of ; sections 38 and A0, respectively, are complementary to each other and slidably engage each other. A leaf spring 46 is secured-to the side wall 36 and engages the slidable section 40 to main-tain the section 40 in contact with the section 38. A flexible cable assembly is provided and comprises a tubular sheath 48, se-cured at one end to the hub 18 and at the other end to a portion 50 of the copier frame, and a flexible twisted wire 52 slidable within the sheath 48. The wire 52 is connected at one end to the slidable magnet section 40 and the other end has a knob 54 which may be manually engaged to slide the wire back and forth.
Upon pushing the knob in, the wire 52 pushes the magnet section 40 inwards to the phantom position to shorten the effective magnetic field emanating from the magnet 26. These movements are guided by the guide surfaces 32 and 34. The leaf spring 46 ensures en-gagement of the section 40 with section 38. Upon pulling the knob ..
~049770 out, the wire 52 pulls the magnet section 40 back to the position as shown in Figure 2.
The split magnet has its applicability to copiers in the following manner: Assume the axial length "a" of fixed sec-tion 38 is 11 inches and the axial length "b" of movable section 40 is 3 inches and assume the combin~d axial length of the magnets 28 and 30 is 14 inches. With the section 40 in the full line position, shown in Figure 2, the total length of the magnet 26 is 14 inches. As the roller 20 rotates in the direction of the arrow "A", it will magnetically pick up developer material in the mag-netic field of magnet 26 across a 14-inch axial band and present a 14-inch band of developer to the photoconductive surface 12.
When the section 40 is in the phantom position, as shown in Figure
In an electrostatic copier system, it has been found that developer (carrier and toner particles) life is related to the function of the number of times the developeris cycled through the development system; the more times cycled, the shorter the life.
In known systems, it is the custom to present developer to a photoconductive sur~ace carrying a latent image over the same width regardless of the size of the final image ~esired.
For instance, developer may be presented to a surface carrying a latent image over a 14-inch bandwidth for copying an image onto either an 11 x 14-inch paper or an 8 1/2 x ll-inch paper.
The bandwidth coincides with the length of the paper as the paper is fed through the machine. For the latter size p~ er, developer is presented to a latent image over an extra 3-inch - 15 bandwidth and is, therefore, needlessly circulated with resultant shortening of developer life.
It is, therefore, an object of this invention in one of its aspects to stop needless circulation of excess developer and thus improve developer life.
It is an object of this invention in another of its aspects to limit developer presentation to a surface carrying a latent image over a bandwidth equal to the length of paper on which the developed image is to be transferred.
Furthermore, in some systems the photoconductive sur-face is developed beyond the borders of an original and copy sheet resulting in removal of excess toner particles from the areas of the surface which taxes the cleaning system.
It is, therefore, an object of the invention in another of its aspects to prevent needless cleaning of toner particles from a photoconductive surface.
In accordance with another aspect of this invention there is provided a method comprising effecting an electrostatic ~ - 2 -.
~049'770 latent image on a photoconductive surface, developing the latent image by contacting the photoconductive surface with developer of toner particles triboelectrically attached to carrier particles delivered to the surface from a developer sump, transferrin~the toner particles from the latent image to a copy medium of a given dimen-sion, effecting another electrostatic latent image on the same photoconductive surface, contacting the photo-conductive surface with developer from the same developer sump to develop another latent image with toner particles and transferring the toner particles from the other latent image to another copy medium of substantially different dimension than the first copy medium, the improvement comprising: contacting the photoconductive surface with developer over a bandwidth substantially equal to the dimension of the copy medium used.
In accordance with another aspect of this invention there is provided a copying machine comprising: a memberhaving ~ - 2a -'' ' ~' ' ' ' ' "" ~
" 1049770 ~ developable image thereon, a developer sump containing developer therein having magnetic properties, means for trans-porting a band of developer from said sump to the image for developing the same, means for selectively changing the width of the developer band, a copy paper supply receptacle, means for changing the size of said receptacle to accommodate various sizes of copy paper, said ~elective means being operably con-nected to said last named means to be controlled thereby.
In accordance with another aspect of this invention there is provided a copying machine comprising: a member having a developable image thereon, a developer sump containing developer therein having magnetic properties, means for trans-porting a bandwidth of the developer from said sump to the image for developing the same, said means comprising a rotatable non-magnetic member surrounding at least one magnetic member, said magnetic m~mber being so constructed to vary in length, and means to selectively increase or decrease the length of said magnetic member to effect a corresponding change in the magnetic field emanating therefrom thereby effecting a corres-ponding change in the bandwidth of the developer ~ransportedto the image.
In accordance with another aspect of this invention there is provided a copying machine comprising: a member having a developable image thereon; a developer sump containing a dev-; eloper therein having magnetic properties, means for transporting a band of developer from said sump ~o the image for developing the same, said means comprising a rotatable non-magnetic member surrounding at least one magnetic member; a shunt, said shunt being located adjacent one end of said magnetic member, means for moving said shunt into a position to surround one end of said magnetic member and for withdrawing said shunt from said position, said shunt being of a material to prevent the magnetic field emanating from the end of the magnetic member surrounded thereby - 2b ~
.
from being effective to attract developer to said non-magnetic member.
This invention will become apparent from the following description with reference to the drawing wherein:
Figure 1 is a schematic view of a copying apparatus;
Figure 2 is a view taken along section line 2-2 of Figure l;
Figure 3 (first sheet of drawings) is a view of a modification of the embodiment of Figures 1 and 2;
Figure 4 (first sheet of drawings) is a view taken along section line 4-4 of Figure 3;
Figure 5 is a top view of a copy paper receptacle adjuster; and Figure 6 is a partial view taken along section line 6-6 of Figure 5.
Referring to Figures 1 and 2, there is shown a drum 10 on which a photoconductive layer 12 is formed. Arranged about the drum 10 are a charging station A, an imaging station B, a development station C, an image transfer and fixing station D and a cleaning station E. All of the functions of these stations are well known in $he art. An electrostatic latent image may be formed on the layer 12 and developed with xerographic toner particles. The invention resides in the developing station to which particular attention is directed.
The development station comprises a developer sump 14 containing developer 16 therein. The developer is a mixture of toner particles and ferromagnetic carrier particles.
The toner particles are triboelectrically attached to the carrier particles. One side wall of the sump has a station-ary hub 18 affixed thereto which receives one end of a cylinderor roller 20 therein which is o~ non-magnetic material.
. .
A bearing race 22 is secured to the hub 18 to allow the cylinder 20 to rotate relative to the hub and sump. The other end of the cylinder 20 is operably secured to a motor (not shown) by a gear train (not shown) for driving the cylinder. A keeper mem-ber 24 of magnetic material is secured to the hub 18 and has se-cured thereto a developer pickup magnet 26, a development magnet 28 and a residual developer transport magnet 30, all of which are located within the confines of the cylinder 20. Attached to the keeper 24 is a guide portion 31 having an upper surface 32, a lower surface 34 and a side surface 36 surrounding the magnet 26 for purposes to be hereinafter described. The guide portion 31 is of a non-magnetic material and the magnets 26, 28 and 30 are permanent.
The magnet 26 is split into two sections, a stationary section 38 and a slidable section 40. Surfaces 42 and 44 of ; sections 38 and A0, respectively, are complementary to each other and slidably engage each other. A leaf spring 46 is secured-to the side wall 36 and engages the slidable section 40 to main-tain the section 40 in contact with the section 38. A flexible cable assembly is provided and comprises a tubular sheath 48, se-cured at one end to the hub 18 and at the other end to a portion 50 of the copier frame, and a flexible twisted wire 52 slidable within the sheath 48. The wire 52 is connected at one end to the slidable magnet section 40 and the other end has a knob 54 which may be manually engaged to slide the wire back and forth.
Upon pushing the knob in, the wire 52 pushes the magnet section 40 inwards to the phantom position to shorten the effective magnetic field emanating from the magnet 26. These movements are guided by the guide surfaces 32 and 34. The leaf spring 46 ensures en-gagement of the section 40 with section 38. Upon pulling the knob ..
~049770 out, the wire 52 pulls the magnet section 40 back to the position as shown in Figure 2.
The split magnet has its applicability to copiers in the following manner: Assume the axial length "a" of fixed sec-tion 38 is 11 inches and the axial length "b" of movable section 40 is 3 inches and assume the combin~d axial length of the magnets 28 and 30 is 14 inches. With the section 40 in the full line position, shown in Figure 2, the total length of the magnet 26 is 14 inches. As the roller 20 rotates in the direction of the arrow "A", it will magnetically pick up developer material in the mag-netic field of magnet 26 across a 14-inch axial band and present a 14-inch band of developer to the photoconductive surface 12.
When the section 40 is in the phantom position, as shown in Figure
2, the total length of the magnet 26 is 11 inches, thus decreasing the magnetic field emanating therefrom by 3 inches. As the roller 20 rotates in the direction of arrow "A", it will magnetically pick up developer material in the magnetic field of magnet 26 across an ll-inch axial band and present approximately an ll-inch band (allowing for slight spreading) of developer to the photoconductive surface 12. The magnet 40 may also be moved into positions inter-mediate the full line and phantom positions shown in Figure 2 wherein a developer band between 11 and 14 inches may be presented to the photoconductive surface 12.
The length of a copy sheet usually corresponds to the axial length of a developed image carried by a photoconductive drum. For instance, the image may be over an ll-inch or a 14-inch axial length of the drum to be transferred to an ll-inch or a 14-inch length copy paper, respectively. Developer life is a function of circulation through the development system; the :
i~49770 more times cycled, the shorter the life. Thus, if developer is presented to the photoconductor 12 over a 14-inch bandwidth when an ll-inch image and copy sheet are used, a 3-inch bandwidth of developer is unnecessarily circulated resulting in shorter de-veloper life. However, if the length of the magnet 26 is decreased so the roller 20 will only pick up an ll-inch bandwidth of devel-oper which is then presented to the photoconductor, only the necessary amount of developer is presented to the photoconductor resulting in an increase in developer life. If a 13-inch length copy sheet is used, the section 40 may be moved inwards one inch from its position shown in Figure 2 by pushing the knob 54 accord-ingly. An indicator may be provided to guide an operator on how far to move the knob for various paper sizes. Obviously, various paper sizes may be designed for by changing the length of and the number of the stationary and movable sections of the pick-up magnet 26.
Referring to Figures 3 and 4, a modification of the embodiment of Figures 1 and 2 is shown. The same elements as in the previous embodiment are designated with the same refer-ence numeral with an "a" affixed thereto. In this embodiment, a shunt 100 is pivotally connected to the keeper member 24a. A
torsion spring 101 is wrapped around the pivot connection and urges the shunt in a clockwise direction to surround a permanent magnet 103. The flexible wire 52a is wrapped around a pulley 104 and connected at the other end to the shunt 100. The shunt may be approximately 3 inches in axial length and is of a material, such as thin gauge steel, to decrease the axial length of the magnetic field of the magnetic bar 103 by approximately 3 inches when the shunt is in the full line positions shown in Figure 3.
If a 14-inch copy paper is used, the knob 54a is pulled out to lift the shunt lOO into the phantom position shown in Figure 3 ;
~ ' '.. - - . . . .
whereby the axial length of the magnetic field of the magnetic bar 103 will extend the full length of the magnet, i. e., 14 inches. If an ll-inch copy paper is used, the knob 54a is pushed in which allows spring 101 to rotate the shunt 100 in a clockwise direction into the full line position shown in Figure
The length of a copy sheet usually corresponds to the axial length of a developed image carried by a photoconductive drum. For instance, the image may be over an ll-inch or a 14-inch axial length of the drum to be transferred to an ll-inch or a 14-inch length copy paper, respectively. Developer life is a function of circulation through the development system; the :
i~49770 more times cycled, the shorter the life. Thus, if developer is presented to the photoconductor 12 over a 14-inch bandwidth when an ll-inch image and copy sheet are used, a 3-inch bandwidth of developer is unnecessarily circulated resulting in shorter de-veloper life. However, if the length of the magnet 26 is decreased so the roller 20 will only pick up an ll-inch bandwidth of devel-oper which is then presented to the photoconductor, only the necessary amount of developer is presented to the photoconductor resulting in an increase in developer life. If a 13-inch length copy sheet is used, the section 40 may be moved inwards one inch from its position shown in Figure 2 by pushing the knob 54 accord-ingly. An indicator may be provided to guide an operator on how far to move the knob for various paper sizes. Obviously, various paper sizes may be designed for by changing the length of and the number of the stationary and movable sections of the pick-up magnet 26.
Referring to Figures 3 and 4, a modification of the embodiment of Figures 1 and 2 is shown. The same elements as in the previous embodiment are designated with the same refer-ence numeral with an "a" affixed thereto. In this embodiment, a shunt 100 is pivotally connected to the keeper member 24a. A
torsion spring 101 is wrapped around the pivot connection and urges the shunt in a clockwise direction to surround a permanent magnet 103. The flexible wire 52a is wrapped around a pulley 104 and connected at the other end to the shunt 100. The shunt may be approximately 3 inches in axial length and is of a material, such as thin gauge steel, to decrease the axial length of the magnetic field of the magnetic bar 103 by approximately 3 inches when the shunt is in the full line positions shown in Figure 3.
If a 14-inch copy paper is used, the knob 54a is pulled out to lift the shunt lOO into the phantom position shown in Figure 3 ;
~ ' '.. - - . . . .
whereby the axial length of the magnetic field of the magnetic bar 103 will extend the full length of the magnet, i. e., 14 inches. If an ll-inch copy paper is used, the knob 54a is pushed in which allows spring 101 to rotate the shunt 100 in a clockwise direction into the full line position shown in Figure
3.
Obviously, any number of shunts could be used and the length thereof could vary according to the results desired.
In the above embodiments, the magnetic bar section 40 and the shunt 100 have been shown as being selectlvely manually actuated. However, the cable 52 or 52a may be connected to a selector which adjusts a paper tray to the length of paper used.
In this manner, the axial magnetic field of the pick-up magnet 26 or 103 will be automatically adjusted to copy paper size when the paper tray is ad~usted. Figures 5 and 6 show an over-all view of such a selector and the wire 52 or 52a could be connected to a selector 200 depicted therein. For a detailed operation of the selector, reference is made to U. S. Patents 3,251,594 (J. W. Wagner), which discloses and describes a similar such selector 343.
While the pick-up magnet has been disclosed in a combined pick-up and development roller, the invention could be employed in a system using any number of rollers; the main fea~ure being to employ this invention in a roller prior to the developer being presented to the photoconductive surface. How-ever, it will be most advantageous to employ the invention in the initial developer pick-up roller.
:
_ 7 _ - .- . ~. . ~ . ~ . -
Obviously, any number of shunts could be used and the length thereof could vary according to the results desired.
In the above embodiments, the magnetic bar section 40 and the shunt 100 have been shown as being selectlvely manually actuated. However, the cable 52 or 52a may be connected to a selector which adjusts a paper tray to the length of paper used.
In this manner, the axial magnetic field of the pick-up magnet 26 or 103 will be automatically adjusted to copy paper size when the paper tray is ad~usted. Figures 5 and 6 show an over-all view of such a selector and the wire 52 or 52a could be connected to a selector 200 depicted therein. For a detailed operation of the selector, reference is made to U. S. Patents 3,251,594 (J. W. Wagner), which discloses and describes a similar such selector 343.
While the pick-up magnet has been disclosed in a combined pick-up and development roller, the invention could be employed in a system using any number of rollers; the main fea~ure being to employ this invention in a roller prior to the developer being presented to the photoconductive surface. How-ever, it will be most advantageous to employ the invention in the initial developer pick-up roller.
:
_ 7 _ - .- . ~. . ~ . ~ . -
Claims (7)
1. A method comprising effecting an electrostatic latent image on a photoconductive surface, developing the latent image by contacting the photoconductive surface with developer of toner particles triboelectrically attached to carrier particles delivered to the surface from a developer sump, transferring the toner particles from the latent image to a copy medium of a given dimension, effecting another electro-static latent image on the same photoconductive surface, con-tacting the photoconductive surface with developer from the same developer sump to develop another latent image with toner particles and transferring the toner particles from the other latent image to another copy medium of substantially different dimension than the first copy medium, the improvement comprising: contacting the photoconductive surface with devel-oper over a bandwidth substantially equal to the dimension of the copy medium used.
2. A copying machine comprising: a member having a developable image thereon, a developer sump containing developer therein having magnetic properties, means for trans-porting a band of developer from said sump to the image for developing the same, means for selectively changing the width of the developer band, a copy paper supply receptacle, means for changing the size of said receptacle to accommodate various sizes of copy paper, said selective means being operably con-nected to said last named means to be controlled thereby.
3. A copying machine comprising: a member having a developable image thereon, a developer sump containing developer therein having magnetic properties, means for trans-porting a bandwidth of the developer from said sump to the image for developing the same, said means comprising a rotatable non-magnetic member surrounding at least one magnetic member, said magnetic member being so constructed to vary in length, and means to selectively increase or decrease the length of said magnetic member to effect a corresponding change in the magnetic field emanating therefrom thereby effecting a corres-ponding change in the bandwidth of the developer transported to the image.
4. The structure as recited in Claim 3 further comprising a copy paper supply receptacle, means for changing the size of said receptacle to accommodate various sizes of copy paper, said selective means being operably connected to said last named means to be controlled thereby.
5. A copying machine comprising: a member having a developable image thereon; a developer sump containing developer therein having magnetic properties, means for transporting a band of developer from said sump to the image for developing the same, said means comprising a rotatable non-magnetic member surrounding at least one magnetic member; a shunt, said shunt being located adjacent one end of said magnetic member, means for moving said shunt into a position to surround one end of said magnetic member and for withdrawing said shunt from said position, said shunt being of a material to prevent the magnetic field ema-nating from the end of the magnetic member surrounded thereby from being effective to attract developer to said non-magnetic member.
6. The structure as recited in Claim 5 wherein said magnetic member is supported by a stationary support member, and means for pivotably connecting said shunt to said support member.
7. The structure as recited in Claim 5 further comprising a copy paper supply receptacle, means for changing the size of said receptacle to accommodate various sizes of copy paper, said means for moving said shunt being operably connected to said last named means to be controlled thereby.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US464864A US3893414A (en) | 1974-04-29 | 1974-04-29 | Method and apparatus for varying developer bandwidth |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1049770A true CA1049770A (en) | 1979-03-06 |
Family
ID=23845559
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA224,550A Expired CA1049770A (en) | 1974-04-29 | 1975-04-10 | Method and apparatus for varying developer bandwidth |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US3893414A (en) |
| JP (1) | JPS50147720A (en) |
| CA (1) | CA1049770A (en) |
| DE (1) | DE2516433A1 (en) |
| GB (1) | GB1498830A (en) |
| NL (1) | NL7504311A (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4095883A (en) * | 1976-02-02 | 1978-06-20 | Xerox Corporation | Magnetic mixing apparatus and process |
| JPS52153448A (en) * | 1976-06-16 | 1977-12-20 | Fuji Xerox Co Ltd | Magnetic brush developing device |
| DE2725109C2 (en) * | 1977-06-03 | 1985-12-05 | Magnetfabrik Bonn Gmbh Vorm. Gewerkschaft Windhorst, 5300 Bonn | Magnetic roller for electrographic developing and / or duplicating devices |
| WO1978000006A1 (en) * | 1977-06-03 | 1978-12-07 | Battelle Memorial Institute | Method and apparatus for making a compiled copy |
| JPS5468633U (en) * | 1977-10-17 | 1979-05-16 | ||
| US4178095A (en) * | 1978-04-10 | 1979-12-11 | International Business Machines Corporation | Abnormally low reflectance photoconductor sensing system |
| US4183657A (en) * | 1978-04-10 | 1980-01-15 | International Business Machines Corporation | Dynamic reference for an image quality control system |
| US4179213A (en) * | 1978-04-10 | 1979-12-18 | International Business Machines Corporation | Vector pinning in an electrophotographic machine |
| DE3585743D1 (en) * | 1984-01-30 | 1992-05-07 | Konishiroku Photo Ind | METHOD FOR GENERATING IMAGES. |
| JP7030443B2 (en) * | 2017-08-07 | 2022-03-07 | キヤノン株式会社 | Image forming device and its control method |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3040704A (en) * | 1957-04-16 | 1962-06-26 | Rca Corp | Apparatus for developing electrostatic printing |
| DE7025426U (en) * | 1969-07-08 | 1970-12-10 | Minolta Camera Kk | DRY DEVELOPMENT DEVICE IN ELECTRONIC PHOTOGRAPHY. |
| JPS511939B2 (en) * | 1973-08-07 | 1976-01-21 |
-
1974
- 1974-04-29 US US464864A patent/US3893414A/en not_active Expired - Lifetime
-
1975
- 1975-04-10 NL NL7504311A patent/NL7504311A/en unknown
- 1975-04-10 CA CA224,550A patent/CA1049770A/en not_active Expired
- 1975-04-15 DE DE19752516433 patent/DE2516433A1/en active Pending
- 1975-04-22 JP JP50049065A patent/JPS50147720A/ja active Pending
- 1975-04-24 GB GB17036/75A patent/GB1498830A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS50147720A (en) | 1975-11-27 |
| US3893414A (en) | 1975-07-08 |
| GB1498830A (en) | 1978-01-25 |
| NL7504311A (en) | 1975-06-30 |
| DE2516433A1 (en) | 1975-11-06 |
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