Claims
- 1. A developing method comprising the steps of forming a latent image and developing said latent image under an alternating electric field at a developing position with a developer containing magnetic carrier particles and toner particles, wherein an average particle size of the magnetic carrier particles is not less than 45 microns and not more than 75 microns, and wherein a particle size distribution of the magnetic carrier particles is such that the magnetic particles having a particle size not more than 45 microns is not more than 20% by weight, and the magnetic particles having a particle size of not less than 75 microns is not more than 30% by weight.
- 2. A method according to claim 1, wherein the magnetic carrier particles have an average particle size of not less than 50 microns and not more than 60 microns and have a particle size distribution wherein not more than 45 microns is not more than 15% by weight, and not less than 75 microns is not more than 20% by weight.
- 3. A method according to claim 1, wherein at a developing position where the developer carried on a developer carrying member is opposed to the latent image to be developed, an alternating electric field is applied, wherein the toner particles electrically charged to a polarity opposite to that of the magnetic carrier particles are transferred from a developer layer formed on the developer carrying member to develop the latent image.
- 4. A method according to claim 3, wherein the toner particles deposited on the surfaces of the magnetic carrier particles are also transferred to the latent image to develop it.
- 5. A developing method wherein a developing layer including a mixture of magnetic carrier particles and toner particles is carried on a rotatable developer carrying sleeve, in which magnetic field generating means is stationarily disposed, to a developing position where a latent image is developed by the toner particles, comprising:
- forming a substantially stationary layer containing the magnetic particles on the developer layer carried on the developer carrying member in a developer container for containing the magnetic carrier particles and the toner particles;
- forming, in the container, a toner particle supplying area upstream of the stationary layer with respect to movement of the developer carrying sleeve for supplying toner particles from the toner particle layer to the developer layer carried on the developer carrying sleeve; and allowing an upper portion of the stationary layer to change its thickness measured along a radial direction of the sleeve in accordance with a toner content in the developer layer to control the toner particle supply area thereby.
- 6. A developing method wherein a developer including a mixture of magnetic carrier particles and toner particles is carried on a rotatable developer carrying sleeve in which magnetic field generating means is stationarily disposed, to a developing position where a latent image is developed by the toner particles, comprising the steps of:
- forming a substantially stationary layer containing the magnetic particles on a layer of developer carried on the developer carrying sleeve in a developer container for containing the magnetic carrier particles and the toner particles;
- forming a toner particle layer on the stationary layer in the container;
- providing a toner particle supply area upstream of the stationary layer with respect to movement of the developer carrying sleeve, for supplying toner particles from the toner particle layer to the developer layer carried on the developer carrying sleeve in the container; and
- allowing the stationary layer to expand and contract along a path of the developer layer carried on the developer carrying sleeve in accordance with a toner content in the developer carried on the sleeve so as to control the toner particles supplying area.
- 7. A method according to claim 6, wherein the magnetic carrier particles contained in the developer container have an average particle size not less than 45 microns and not more than 75 microns, and wherein the magnetic carrier particles having particle sizes not more than 45 microns is not more than 20% by weight, and the magnetic carrier particles having particle sizes not less than 75 microns is not more than 30% by weight.
- 8. A method according to claim 7, wherein the carrier particle is coated with insulative resin material, and wherein the developer develops the latent image under application of an alternating electric field.
- 9. A method according to claim 8, wherein the magnetic carrier particles have a particle size distribution wherein not more than 45 microns is not more than 15% by weight, and not less than 75 microns is not more than 20% by weight.
- 10. A method according to claim 6, wherein a volumetric ratio which is a ratio of the total volume of the magnetic particles existing at the developing position to a volume of space defined by the surface of an electrostatic latent image bearing member bearing the latent image to be developed and the developer carrying member at the developing position, is 1.5-30%.
- 11. A method according to claims 5 or 6, wherein the substantially stationary layer moves in a direction of peripheral movement of the developer carrying sleeve at a speed not more than 1 mm/sec.
- 12. A method according to claims 5 or 6, wherein the stationary layer is defined at a downstream end with respect to peripheral movement of the sleeve by a surface of a limiting member, and is defined at a surface extending from the downstream side to an upstream side by another surface of the limiting member.
- 13. A method according to claims 5 or 6, wherein the developer develops the latent image under application of an alternating electric field.
- 14. A developing apparatus for developing a latent image, comprising:
- a developer container for containing a developer of a mixture of magnetic carrier particles and toner particles, said container including a regulating member for providing a regulated thickness of a developer layer;
- a rotatable developer carrying member of non-magnetic material for carrying the developer layer of toner particles and magnetic particles supplied by said developer container;
- a magnet stationarily disposed inside said developer carrying member, said magnet being provided with first and second magnetic poles having different magnetic polarities for forming a magnetic field extending substantially parallel with a surface of the developer carrying member in a developer supplying opening;
- a limiting member projected into said container, said limiting member having a surface for substantially stopping the developer moving by rotation of the developer carrying member;
- a projection member projecting into said container at a position upstream of said limiting member with respect to the movement direction of said developer carrying member, said projection member and said limiting member forming an angle .theta.1 seen from a center of said developer carrying member; and wherein positions where maximum magnetic flux densities of the first and second magnetic poles are formed are outside the angle .theta.1, and a substantially stationary layer containing magnetic particles extending from said regulating member is formed along the developer carrying member by the first and second magnetic poles and said limiting member to form in the container a variable toner taking area through which an amount of the toner is substantially taken into the developer layer carried on the developer carrying member upstream of the stationary layer with respect to peripheral movement of the developer carrying member, and wherein the size of the substantially stationary layer changes in accordance with the toner content of the developer carried on the developer carrying member to control the toner taking area.
- 15. An apparatus according to claim 14, wherein the substantially stationary layer moves at a speed not more than 1 mm/sec when the peripheral speed of the developer carrying member is not less than 10 mm/sec.
- 16. An apparatus according to claim 15, wherein the stationary layer moves at a speed not more than 0.1 mm/sec.
- 17. An apparatus according to claim 14, wherein said limiting member is provided with a surface abutted to a surface of the stationary layer remote from said developer carrying member.
- 18. An apparatus according to claim 14, wherein the first magnetic pole is disposed downstream of the second magnetic pole with respect to peripheral movement of the developer carrying member and upsteam of a developer layer regulating portion of said regulating member, said apparatus further comprising means for forming an alternating electric field between said developer carrying member and a member for bearing a latent image to be developed.
- 19. An apparatus according to claim 18, wherein the toner particles electrically charged are supported on said developer carrying member and on the magnetic carrier particles at a developing zone where the development is effected, with those toner particles.
- 20. An apparatus according to claim 19, wherein said magnetic carrier particles are insulative, and wherein the magnetic carrier particles having particle sizes not more than 45 microns is not more than 20% by weight, and the magnetic carrier particles having particle sizes not less than 75 microns is not more than 30% by weight.
- 21. An apparatus according to claim 20, wherein not more than 45 microns is not more than 15% by weight, and not less than 75 microns is not more than 20% by weight.
- 22. An apparatus according to any one of claims 14-17 or 18-21, wherein said projection member is a magnetic member for forming a magnetic seal.
- 23. A developing apparatus for developing an electrostatic latent image on an electrostatic latent image bearing member, comprising:
- a developer container for containing a developer including toner particles and magnetic particles;
- a developer carrying member, opposite to the electrostatic latent image bearing member, for forming a developing position for supplying the toner particles to the latent image bearing member and for carrying the developer containing toner particles and magnetic carrier particles from said container to the developing position;
- first magnetic field generating means disposed across said developer carrying member from the latent image bearing member for generating a magnetic field to contact the magnetic particles to the latent image bearing member at the developing position;
- developer regulating means disposed upstream of the developing position with respect to movement of a surface of said developer carrying member and spaced apart from the surface of said developer carrying member for regulating the developer carried to the developing position;
- second magnetic field generating means disposed across said developer carrying member from said regulating member and upstream of said developer regulating member with respect to the movement of the developer carrying member; and
- alternating electric field generating means for forming an alternating electric field at the developing position to transfer at least the toner particles carried on said developer carrying member to the latent image bearing member;
- wherein the magnetic particles have an average particle size of 50-60 microns and have a particle size distribution wherein not more than 45 microns is not more than 20%, and not less than 75 microns is not more than 30% by weight.
- 24. An apparatus according to claim 23, wherein the particle size distribution is not more than 45 microns is not more than 15% by weight, and not less than 75 microns is not more than 20% by weight.
- 25. An apparatus according to claim 23, wherein said magnetic carrier particles are coated with insulative resin material, and wherein a magnetic flux density provided by said first magnetic field generating means on a surface of the developer carrying member is not less than 600 Gausses and not more than 900 Gausses.
- 26. A developing apparatus for developing a latent image with a developer containing a mixture of magnetic carrier particles and toner particles, comprising:
- a developer container, provided with an opening, for containing the developer;
- a rotatable developer carrying member disposed in the opening of said developer container for carrying the developer containing toner particles and magnetic carrier particles out of said container to a developing position where the latent image is developed with the developer;
- means for regulating a layer of the developer to be carried to the developing station on said developer carrying member, wherein said regulating means includes a non-magnetic regulating member and a magnetic member disposed upstream of the non-magnetic regulating member with respect to peripheral movement of said developer carrying member and stationary magnetic field generating means disposed across said developer carrying member from the non-magnetic regulating member, the non-magnetic regulating member and the magnetic member having ends disposed within influence of a magnetic field produced by the magnetic field generating means; and
- a limiting member disposed so as to be influenced by the magnetic field formed by said magnetic field generating means and upstream of said magnetic member with respect to peripheral movement of said developer carrying member and disposed opposed to a surface of said developer carrying member to form a substantially stationary layer containing magnetic carrier particles, wherein at a position upstream of the stationary layer with respect to movement direction of said developer carrying member, a supply region for supplying the toner to the developer layer supported on said developer carrying member is formed and wherein a size of the substantially stationary layer changes in accordance with the toner content in the developer carried on the developer carrying member to control the supply region.
- 27. An apparatus according to claim 26, wherein said non-magnetic regulating member, the magnetic member and the limiting member are connected in this order.
- 28. An apparatus according to claim 27, wherein said non-magnetic regulating member is closer to said developer carrying member than the magnetic member.
- 29. An apparatus according to claim 26, wherein said limiting member is spaced apart from the magnetic member to form a space for containing the developer by said developer carrying member, the limiting member and the magnetic member.
- 30. An apparatus according to claim 26, further comprising means for forming an alternating electric field.
Priority Claims (3)
Number |
Date |
Country |
Kind |
61-35458 |
Feb 1986 |
JPX |
|
61-147425 |
Jun 1986 |
JPX |
|
61-147428 |
Jun 1986 |
JPX |
|
Parent Case Info
This application is a continuation of application Ser. No. 015,929 filed Feb. 18, 1987, now abandoned.
US Referenced Citations (13)
Continuations (1)
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Number |
Date |
Country |
Parent |
15929 |
Feb 1987 |
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