1. An image forming apparatus, comprising:
an image carrying member which is adapted to carry an electrostatic latent image;
a developer container which is adapted to contain a developer including a toner, a carrier for charging the toner, and opposite polarity particles to be charged opposite to a charge polarity of the toner;
a developer carrying member which is adapted to convey the developer supplied from the developer container;
a toner carrying member which is adapted to receive the toner from the developer on the developer carrying member and to convey the toner to a development position facing the image carrying member to develop the electrostatic latent image on the image carrying member; and
an electric field forming section which is adapted to form an electric field between the image carrying member and the toner carrying member, the electric field including a DC component overlapped with an AC component,
wherein the AC component of the electric field formed by the electric field forming section includes a trapezoidal wave.
2. The image forming apparatus of claim 1, wherein the trapezoidal wave includes a slope on a leading edge thereof.
3. The image forming apparatus of claim 1, wherein a number average particle diameter of the opposite polarity particles is from 100 to 1000 nm.
4. The developing apparatus of claim 1, further comprising:
a supplying mechanism which is adapted to supply the developer container with a toner to which opposite polarity particles are externally added.
5. An image forming apparatus, comprising:
an image carrying member which is adapted to carry an electrostatic latent image;
a developer container which is adapted to contain a developer including a toner, a carrier for charging the toner, and opposite polarity particles to be charged opposite to a charge polarity of the toner;
a developer carrying member which is adapted to convey the developer supplied from the developer container;
a toner carrying member which is adapted to receive the toner from the developer on the developer carrying member and to convey the toner to a development position facing the image carrying member to develop the electrostatic latent image on the image carrying member; and
an electric field forming section which is adapted to form an electric field between the image carrying member and the toner carrying member, the electric field including a DC component overlapped with an AC component,
wherein the AC component of the electric field formed by the electric field forming section includes a developing component which moves the toner to the image carrying member and a reverse-developing component which moves the toner to the toner carrying member, and a blank is formed within the reverse-developing component.
6. The image forming apparatus of claim 5, wherein the AC component includes a rectangular wave.
7. The image forming apparatus of claim 5, wherein the blank is formed at a timing from 0.1 to 0.2 ms after a leading edge of the reverse-developing component.
8. The image forming apparatus of claim 5, wherein a number average particle diameter of the opposite polarity particles is from 100 to 1000 nm.
9. The image forming apparatus of claim 5, further comprising:
a supplying mechanism which is adapted to supply the developer container with a toner to which opposite polarity particles are externally added.
10. A method for forming an image, the method comprising the steps of:
forming an electrostatic latent image on an image carrying member;
supplying a developer carrying member with a developer including a toner, a carrier for charging the toner, and opposite polarity particles to be charged opposite to a charge polarity of the toner;
transferring the toner from the developer carrying member onto the toner carrying member;
conveying the toner to a position facing the image carrying member by a movement of a surface of the toner carrying member, the opposite polarity particles being attached to the toner; and
forming an electric field including a DC component overlapped with an AC component between the image carrying member and the toner carrying member to develop the electrostatic latent image on the image carrying member with the toner on the toner carrying member, the AC component including a trapezoidal wave.
11. The method of claim 10, wherein the trapezoidal wave includes a slope on a leading edge thereof.
12. A method for forming an image, the method comprising the steps of:
forming an electrostatic latent image on an image carrying member;
supplying a developer carrying member with a developer including a toner, a carrier for charging the toner, and opposite polarity particles to be charged opposite to a charge polarity of the toner;
transferring the toner from the developer carrying member onto the toner carrying member;
conveying the toner to a position facing the image carrying member by a movement of a surface of the toner carrying member, the opposite polarity particles being attached to the toner; and
forming an electric field including a DC component overlapped with an AC component between the image carrying member and the toner carrying member to develop the electrostatic latent image on the image carrying member with the toner on the toner carrying member, the AC component including a developing component which moves the toner to the image carrying member and a reverse-developing component which moves the toner to the toner carrying member, and a blank being formed within the reverse-developing component.
13. The method of claim 12, wherein the AC component includes a rectangular wave.
14. The method of claim 12, wherein the blank is formed at a timing from 0.1 to 0.2 ms after a leading edge of the reverse-developing component.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for improving handover performance in a cellular wireless communication system, said cellular wireless communication system employing a handover procedure in which a handover preparation for a mobile station is initiated if a channel quality value between a source cell for said mobile station and said mobile station is less than a channel quality threshold value; said method comprising:
tuning said channel quality threshold value based on one or more handover performance criteria used in said cellular wireless communication system.
2. The method according to claim 1, wherein said channel quality threshold value is increased if a handover failure rate HOError is higher than a handover failure rate target HOErrorTarget times a first constant k1.
3. The method according to claim 2, wherein said first constant k1 is equal to or larger than 1.
4. The method according to claim 1, wherein said channel quality threshold value is decreased if a handover failure rate HOError is less than a handover failure rate target HOErrorTarget times a second constant k2.
5. The method according to claim 4, wherein said second constant k2 is less than or equal to 1.
6. The method according to claim 4, wherein said second constant k2 is less than or equal to said first constant k1.
7. The method according to claim 4, wherein said channel quality threshold value is decreased if the condition in claim 4 is fulfilled and if a handover ping pong rate HOpp is higher than a handover ping pong rate target HOPPTarget.
8. The method according to claim 1, wherein said channel quality value is a downlink SINR value SINRDL between said source cell and said mobile station, and said channel quality threshold value is a downlink SINR threshold value SINRTr between said source cell and said mobile station.
9. The method according to claim 8, wherein said downlink SINR value SINRDL is estimated by using at least one of CQI reports, RSRP reported measurements and RSRQ reported measurements.
10. The method according to claim 1, wherein said channel quality value is an uplink SINR value SINRUL between said source cell and said mobile station.
11. The method according to claim 1, wherein said mobile station periodically transmits measurement reports including measurements on reference signals transmitted from one or more candidate target cells, said measurement reports being used for selecting a target cell;
said method further comprising:
tuning a periodicity for said periodically transmit measurement reports based on said one or more handover performance criteria.
12. The method according to claim 11, wherein said periodically transmitted measurement reports are triggered if a reference signal measurement of a candidate target cell is greater than a reference signal measurement of said source cell by at least a threshold handover offset value; and said method further comprises:
tuning said threshold handover offset value based on said one or more handover performance criteria.
13. The method according to claim 11, wherein said tuning further involves considering a signaling load generated by said mobile station when tuning said periodicity andor said threshold handover offset value.
14. A computer-readable medium, for improving handover performance in a cellular wireless communication system, said cellular wireless communication system employing a handover procedure in which a handover preparation for a mobile station is initiated if a channel quality value between a source cell for said mobile station and said mobile station is less than a channel quality threshold value, comprising computer program code, which, when executed by a computer unit, will cause the computer unit to tune said channel quality threshold value based on one or more handover performance criteria used in said cellular wireless communication system.
15. A device for improving handover performance in a cellular wireless communication system, said cellular wireless communication system employing a handover procedure in which a handover preparation for a mobile station is initiated if a channel quality value between a source cell for said mobile station and said mobile station is less than a channel quality threshold value; wherein said device being arranged to tune said channel quality threshold value based on one or more handover performance criteria used in said cellular wireless communication system.
16. The device according to claim 15, wherein said device is configured to increase said channel quality threshold value if a handover failure rate HOError is higher than a handover failure rate target HOErrorTarget times a first constant k1.
17. The device according to claim 15, wherein said device is configured to decrease said channel quality threshold value if a handover failure rate HOError is less than a handover failure rate target HOErrorTarget times a second constant k2.
18. The device according to claim 15, wherein said channel quality value is a downlink SINR value SINRDL between said source cell and said mobile station, and said channel quality threshold value is a downlink SINR threshold value SINRTr between said source cell and said mobile station.
19. The device according to claim 15, wherein said channel quality value is an uplink SINR value SINRUL between said source cell and said mobile station.