EP0647889A1
Expired / Lapsed
EP
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Electrophotographic recording apparatus
Assignee: Oki Electric Industry Co Ltd
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Filing: 1994-10-06
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Granted: —
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Expires: 2014-10-06
Abstract
Abstract An electrophotographic recording apparatus comprises a photosensitive drum (11), a transfer roller (13), a high voltage power supply circuit (48) for applying a transfer voltage to the transfer roller (13) and a CPU (21) for controlling the entire apparatus. The high voltage power supply circuit (48) supplies an output voltage (Vo) corresponding to a control signal issued from the CPU (21) as the transfer voltage to the transfer roller (13). At this time, the high voltage power supply circuit (48) sends a current detection signal to the CPU (21) to inform the same of an output current (I) which flows to the transfer roller (13). On the other hand, the CPU (21) outputs a control signal to the high voltage power supply circuit (48), the control signal corresponding to said current detection signal output from the high voltage power supply circuit (48). As a result, even if the output current (I) is varied depending on the kind of the print medium (15) and the resistance of the transfer roller (13), it is possible to generate the output voltage (Vo) in accordance with the varied output current (I).
Inventors
- 👤 Chihiro C/O Oki Electric Industry Co. Ltd Komori
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 00:03
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/14; G03G15/16; G03G15/1665; G03G15/167; G03G15/1675
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
145 words
In an electrophotographic recording apparatus including a photosensitive drum and a transfer roller confronting said photosensitive drum, said electrophotographic recording apparatus further comprising: a high voltage power supply circuit for applying a transfer voltage to said transfer roller; a control circuit for receiving information of said electrophotographic recording apparatus including information of an output current value of said high voltage power supply circuit and controlling a voltage value output from said high voltage power supply circuit; wherein said control circuit calculates a value corresponding to a voltage value to be applied to said transfer roller based on a value which is varied in correspondence with a resistance value of said transfer roller and a resistance value of a print medium and outputs a control signal for controlling said voltage value which is supplied by said high pressure power supply circuit based on the calculated value.
Claim 2
Dependent Claim
84 words
An electrophotographic recording apparatus according to Claim 1, wherein said control circuit further receives an output of a medium sensor and calculates a width of said print medium based on an output of said medium sensor and calculates a value which is varied in response to said resistance value of said transfer roller and said resistance value of said print medium and a value corresponding to said voltage value to be applied to said transfer roller based on the width of said print medium.
Claim 3
Dependent Claim
69 words
An electrophotographic recording apparatus according to Claim 1, wherein said control circuit receives a set value of an operation panel and calculates a value which is varied corresponding to the resistance value of said transfer roller and the resistance value of said medium and also calculates a value corresponding to said voltage value to be applied to said transfer roller based on the set value of said operation panel.
Claim 4
Dependent Claim
50 words
An electrophotographic recording apparatus according to Claim 1, wherein said electrophotographic recording apparatus includes a memory device which stores therein information for operating said control circuit, and wherein said control circuit reads a formula for calculating said value from said memory device and calculates said value based on said formula.
Claim 5
Dependent Claim
46 words
An electrophotographic recording apparatus according to Claim 1, wherein said electrophotographic recording apparatus includes a memory device which stores therein information for operating said control circuit, and wherein said control circuit calculates said value referring to a calculation table which is stored in said memory device.
Claim 6
Dependent Claim
53 words
An electrophotographic recording apparatus according to Claim 1, wherein said control circuit includes a pulse width modulation signal generator for outputting said control signal to said high voltage power supply circuit so as to control a voltage of said high voltage power supply circuit based on a pulse width of said control signal.
Claim 7
Dependent Claim
106 words
An electrophotographic recording apparatus according to Claim 6, wherein said high voltage power supply circuit comprises: a transformer composed of a first coil having a first number of turns and a second coil having a second number of turns which is greater than said first number of turns; a switching element for receiving an output signal of said pulse width modulation signal generator and for controlling current to be supplied to said first coil; a smoothing circuit connected to said second coil; and a first detection terminal for outputting a voltage value in response to a current value supplied from said high voltage power supply circuit.
Claim 8
Dependent Claim
39 words
An electrophotographic recording apparatus according to Claim 7, wherein said high voltage power supply circuit further includes a second detection terminal for outputting a voltage value corresponding to said voltage value supplied from said high voltage power supply circuit.
Claim 9
Dependent Claim
229 words
In a method of transferring toner image in an electrophotographic recording apparatus which includes a photosensitive drum and a transfer roller confronting the photosensitive drum, said method comprising: a step of measuring a resistance value of said transfer roller before a print medium is introduced into said electrophotographic recording apparatus; a step of inserting said print medium between said photosensitive drum and said transfer roller; a step of detecting a first current value at a first time immediately after said print medium is inserted between said photosensitive drum and said transfer roller and a variation of said first current value which is varied during a very short period of time close to said first time while a constant voltage is applied to said transfer roller; a step of detecting a second current value at a second time before the variation of said current comes to an end after said first time and a variation of said second current value which is varied during a very short period of time close to said second time; a step of calculating a resistance value Rm of said print medium using a calculation formula: Rm = {(B2/B2)-1}/{(A2/A1)-(B2/V0)}; and a step of applying a voltage value to said transfer roller, said voltage value corresponding to a combined resistance of the resistance value of said transfer roller and the resistance value of said print medium.
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