Method and device for controlling toner density of an electrostatic printing apparatus employing toner

Claim 1

A method, of controlling a recording apparatus comprising : an image forming medium (1) for electrostatically forming a latent image thereon according to an image information to be recorded; developing means (2) for developing said latent image as a toner image on said image forming medium; cleaning means (4) for removing residual toner from said image forming medium after developing said toner image; a detector (3), comprising a light emitting means (3a) projecting a light spot onto a predetermined area on said image forming medium; and a light receiving means (3b) for receiving a light reflected from said light spot; and a control circuit (5) for controlling a light emision level of said light emitting means and measuring a level of the light received by said light receiving means, comprising the steps of : (1) enabling said image forming medium and said cleaning means while disabling an input of said image information and said developing means; (2) measuring a light emission level which keeps said received light level at a predetermined level, as a first light emission level; (3) measuring a light emission level which keeps said received light level at said predetermined level, as a second light emission level, after said developing means is enabled; (4) discriminating whether a difference between said first light emission level and said second light emission level is larger than a predetermined limit level; and (5) starting a recording procedure of said recording apparatus, whereby a deterioration of said image forming means and/or said toner is detected.

Claim 2

A method, of controlling a recording apparatus comprising : an image forming medium (1) for electrostatically forming a latent image thereon according to an image information to be recorded; developing means (2) for developing said latent image as a toner image on said image forming medium; cleaning means (4) for removing residual toner from said image forming medium after developing said toner image; a detector (3), comprising a light emitting means (3a) projecting a light spot onto a predetermined area on said image forming medium; and a light receiving means (3b) for receiving a light reflected from said light spot; and a control circuit (5) for controlling a light emision level of said light emitting means and measuring a level of the light received by said light receiving means, comprising the steps of : (1) enabling said image forming medium and said cleaning means while disabling an input of said image information and said developing means; (2) measuring a light emission level which keeps said received light level at a predetermined level, as a first light emission level; (3) measuring a light emission level which keeps said received light level at said predetermined level, as a second light emission level, after said developing means is enabled; (4) discriminating whether a difference between said first light emission level and said second light emission level is larger than a predetermined limit level; and (5) starting a recording procedure of said recording apparatus, whereby a deterioration of said image forming means and/or said toner is detected.

Claim 4

A method of controlling a recording apparatus comprising : an image forming medium (1) for electrostatically forming a latent image thereon according to an image information to be recorded; developing means (2) for developing said latent image as a toner image on said image forming medium; cleaning means (4) for removing residual toner from said image forming medium after developing said toner image; a detector (3), comprising a light emitting means (3a) for projecting a light spot onto a predetermined area on said image forming medium; and a light receiving means (3b) for receiving a light reflected from said light spot; and a control circuit for controlling a light emission level of said light emitting means and measuring a level of the light received by said light receiving means, comprising the steps of : (1) enabling said image forming medium and said cleaning means while disabling an input of said image information and said developing means; (2) measuring a light emission level which keeps said received light level at a predetermined level, as a first light emission level; and (3) discriminating whether said first light emission level is larger than a predetermined limit level, whereby a contamination of said detector is detected.

Claim 5

A method of controlling a recording apparatus comprising : an image forming medium (1) for electrostatically forming a latent image thereon according to an image information to be recorded; developing means (2) for developing said latent image as a toner image on said image forming medium; cleaning means (4) for removing residual toner from said image forming medium after developing said toner image; a detector (3), comprising a light emitting means (3a) for projecting a light spot onto a predetermined area on said image forming medium; and a light receiving means (3b) for receiving a light reflected from said light spot; and a control circuit for controlling a light emission level of said light emitting means and measuring a level of the light received by said light receiving means, comprising the steps of : (1) enabling said image forming medium and said cleaning means while disabling an input of said image information and said developing means; (2) measuring a light emission level which keeps said received light level at a predetermined level, as a first light emission level; and (3) discriminating whether said first light emission level is larger than a predetermined limit level, whereby a contamination of said detector is detected.

Claim 7

A method of controlling a recording apparatus comprising: an image forming medium (1) for electrostatically forming a latent image thereon according to an image information to be recorded; developing means (2) for developing said latent image as a toner image on said image forming medium; cleaning means (4) for removing reidual toner from said image forming medium after developing said toner image; a detector (3), comprising a light emitting means (3a) for projecting a light spot onto a predetermined area on said image forming medium, and a light receiving means (3b) for receiving a light reflected from said light spot, and toner mark generating means (10) for outputting a toner mark signal to said image information, said toner mark being produced outside a print area on a predetermined area on said image forming medium, said toner mark being detected by said detector; and a control circuit (5) comprising a feedback loop for controlling a light emission level of said light emitting means so as to keep a level of the light received by said light receiving means at a predetermined level, comprising the steps of : (1) forming said toner mark on said image forming medium; and (2) adjusting a location of said detector by observing a toner mark signal in the received light while said feedback loop is disabled and said light emission level is kept constant, whereby said adjusting operation is carried out correctly.

Claim 8

A method of controlling a recording apparatus comprising: an image forming medium (1) for electrostatically forming a latent image thereon according to an image information to be recorded; developing means (2) for developing said latent image as a toner image on said image forming medium; cleaning means (4) for removing reidual toner from said image forming medium after developing said toner image; a detector (3), comprising a light emitting means (3a) for projecting a light spot onto a predetermined area on said image forming medium, and a light receiving means (3b) for receiving a light reflected from said light spot, and toner mark generating means (10) for outputting a toner mark signal to said image information, said toner mark being produced outside a print area on a predetermined area on said image forming medium, said toner mark being detected by said detector; and a control circuit (5) comprising a feedback loop for controlling a light emission level of said light emitting means so as to keep a level of the light received by said light receiving means at a predetermined level, comprising the steps of : (1) forming said toner mark on said image forming medium; and (2) adjusting a location of said detector by observing a toner mark signal in the received light while said feedback loop is disabled and said light emission level is kept constant, whereby said adjusting operation is carried out correctly.

Claim 13

A method of controlling a recording apparatus comprising : an image forming medium (1) for electrostatically forming a latent image thereon according to an image information to be recorded; developing means (2) for developing said latent image as a toner image on said image forming medium; and a detector (3), comprising a light emitting means (3a) projecting a light spot onto a predetermined area on said image forming medium; and a light receiving means (3b) for receiving a light reflected from said light spot, comprising the steps of : (1) converting an analog value of said received light level into a digital value; (2) discriminating said digital received light level is equal or larger than a predetermined reference level; (3) increasing a light emission level when said digital received light level is discriminated to be smaller than said predetermined reference level; (4) repeating steps (2) and (3) until said digital received light level is discriminated to be equal to said predetermined reference level;

Claim 14

A method of controlling a recording apparatus comprising : an image forming medium (1) for electrostatically forming a latent image thereon according to an image information to be recorded; developing means (2) for developing said latent image as a toner image on said image forming medium; and a detector (3), comprising a light emitting means (3a) projecting a light spot onto a predetermined area on said image forming medium; and a light receiving means (3b) for receiving a light reflected from said light spot, comprising the steps of : (1) converting an analog value of said received light level into a digital value; (2) discriminating said digital received light level is equal or larger than a predetermined reference level; (3) increasing a light emission level when said digital received light level is discriminated to be smaller than said predetermined reference level; (4) repeating steps (2) and (3) until said digital received light level is discriminated to be equal to said predetermined reference level;