Method and apparatus for producing a multi-colored image in an electrophotographic system

A method of producing a multi-colored image on a medium from image data in a liquid electrophotographic system, comprising the steps of:

• uniformly rotating a photoreceptor so that the following steps are performed in order;
• erasing any previously accumulated charge from said photoreceptor;
• uniformly charging said photoreceptor to a first predetermined charge level;
• first image-wise exposing said photoreceptor with radiation modulated in accordance with said image data for one of a plurality of colors in order to partially discharge said photoreceptor to produce an image-wise distribution of charges on said photoreceptor corresponding to said image data for said one of said plurality of colors;
• applying a first color liquid toner containing charged particles of said first color and transparent counter ions to said photoreceptor as a function of said image-wise distribution of charges on said photoreceptor to develop said photoreceptor and form a first color image, said photoreceptor recharging as a result of this step to a substantially uniform second predetermined charge level, said second predetermined charge level being lower than said first predetermined charge level but being sufficiently high to subsequently repel liquid toner in areas not subsequently further discharged;
• second image-wise exposing, without erasing previously accumulated charge on said photoreceptor subsequent to said first image-wise exposing step, said photoreceptor with radiation modulated in accordance with said image data for another of said plurality of colors in order to partially discharge said photoreceptor to produce an image-wise distribution of charges on a surface of said photoreceptor corresponding to said image data for said another of said plurality of colors in registration with said first color image;
• applying a second color liquid toner to said image-wise distribution of charges on said photoreceptor to form a second color image in registration with said first color image;
• transferring said first color image and said second color image together from said photoreceptor to said medium to form said multi-colored image.

A method of producing a multi-colored image on a medium from image data in a liquid electrophotographic system, comprising the steps of:

• rotating a photoreceptor so that the following steps are performed in a single pass;
• erasing any previously accumulated charge from said photoreceptor;
• charging said photoreceptor to a first predetermined charge level;
• first image-wise exposing said photoreceptor with radiation modulated in accordance with said image data for one of a plurality of colors in order to partially discharge said photoreceptor to produce an image-wise distribution of charges on said photoreceptor corresponding to said image data for said one of said plurality of colors;
• applying a first color liquid toner containing charged particles of said first color and transparent counter ions to said photoreceptor as a function of said image-wise distribution of charges on said photoreceptor to develop said photoreceptor and form a first color image, said photoreceptor recharging as a result of this step to a substantially uniform second charge level, said second charge level being lower than said first predetermined charge level but being sufficiently high to subsequently repel liquid toner to said photoreceptor in areas not subsequently further discharged;
• second image-wise exposing said photoreceptor with radiation modulated in accordance with said image data for a second of said plurality of colors in order to partially discharge said photoreceptor to produce an image-wise distribution of charges on a surface of said photoreceptor corresponding to said image data for said second of said plurality of colors in registration with said first color image;
• applying a second color liquid toner containing charged particles of said second color and transparent counter ions to said photoreceptor as a function of said image-wise distribution of charges on said photoreceptor in registration with said first color image, said photoreceptor recharging as a result of this step to a substantially uniform third charge level, said third charge level being lower than said second charge level but being sufficiently high to subsequently repel liquid toner in areas of said photoreceptor not subsequently further discharged;
• third image-wise exposing said photoreceptor with radiation modulated in accordance with said image data for a third of said plurality of colors in order to partially discharge said photoreceptor to produce an image-wise distribution of charges on a surface of said photoreceptor corresponding to said image data for said third of said plurality of colors in registration with said first color image and second color image;
• applying a third color liquid toner containing charged particles of said third color and transparent counter ions to said photoreceptor as a function of said image-wise distribution of charges on said photoreceptor to form a third color image in registration with said first color image and said second color image, said photoreceptor recharging as a result of this step to a substantially uniform fourth charge level, said fourth charge level being lower than said third charge level but being sufficiently high to subsequently repel liquid toner in areas of said photoreceptor not subsequently further discharged;
• fourth image-wise exposing said photoreceptor with radiation modulated in accordance with said image data for a fourth of said plurality of colors in order to partially discharge said photoreceptor to produce an image-wise distribution of charges on a surface of said photoreceptor corresponding to said image data for said fourth of said plurality of colors in registration with said first color image, second color image and said third color image;
• applying a fourth color liquid toner to said image-wise distribution of charges on said photoreceptor to form a fourth color image in registration with said first color image, said second color image and said third color image;
• transferring said first color image, said second color image, said third color image and said fourth color image together from said photoreceptor to said medium to form said multi-colored image.

An apparatus for producing a multi-colored image on a medium from image data in a liquid electrophotographic system, comprising:

• positioning means for movably positioning a photoreceptor in order that a given portion of said photoreceptor sequentially advances past a plurality of locations in a single pass;
• erasing means for erasing any previously accumulated charge from said photoreceptor;
• charging means for charging said photoreceptor to a predetermined charge level;
• first image-wise exposing means for exposing said photoreceptor with radiation modulated in accordance with said image data for one of a plurality of colors in order to partially discharge said photoreceptor to a first discharged level to produce an image-wise distribution of charges on said photoreceptor corresponding to said image data for said one of said plurality of colors;
• first application means for applying a first color liquid toner containing charged particles of said first color and transparent counter ions, using an electrode electrically biased to a voltage of between said predetermined charge level and said first discharged level, to said photoreceptor as a function of said image-wise distribution of charges on said photoreceptor to form a first color image, said photoreceptor recharging as a result of this step to a substantially uniform second predetermined charge level said second predetermined charge level being lower than said first predetermined charge level but being sufficiently high to subsequently repel liquid toner in areas not subsequently further discharged;
• second image-wise exposing means for exposing said photoreceptor with radiation modulated in accordance with said image data for another of said plurality of colors in order to partially discharge said photoreceptor to produce an image-wise distribution of charges on said photoreceptor corresponding to said image data for said another of said plurality of colors in registration with said first color image;
• said second image-wise exposing means occurring without erasing said photoreceptor subsequent to said first image-wise exposing of said photoreceptor;
• second application means for applying a second color liquid toner to said image-wise distribution of charges on said photoreceptor to form a second color image in registration with said first color image;
• transferring means for transferring said first color image and said second color image together from said photoreceptor to said medium to form said multi-colored image.

An apparatus for producing a multi-colored image on a medium from image data in a liquid electrophotographic system, comprising:

• rotating means for moving a photoreceptor sequentially past a number of locations in order;
• erasing means for erasing any previously accumulated charge from said photoreceptor;
• charging means for charging said photoreceptor to a first predetermined charge level;
• first image-wise exposing means for exposing said photoreceptor with radiation modulated in accordance with said image data for one of a plurality of colors in order to partially discharge said photoreceptor to produce an image-wise distribution of charges on said photoreceptor corresponding to said image data for said one of said plurality of colors;
• first application means for applying a first color liquid toner containing charged particles of said first color and transparent counter ions to said photoreceptor as a function of said image-wise distribution of charges on said photoreceptor to develop said photoreceptor and form a first color image, said photoreceptor recharging to a substantially uniform second predetermined charge level, said second predetermined charge level being lower than said first predetermined charge level but being sufficiently high to subsequently repel liquid toner in areas not subsequently further discharged;
• second image-wise exposing means for exposing said photoreceptor, without erasing previously accumulated charge on said photoreceptor subsequent to said first image-wise exposing, with radiation modulated in accordance with said image data for another of said plurality of colors in order to partially discharge said photoreceptor to produce an image-wise distribution of charges on a surface of said photoreceptor corresponding to said image data for said another of said plurality of colors in registration with said first color image;
• second application means for applying a second color liquid toner to said image-wise distribution of charges on said photoreceptor to form a second color image in registration with said first color image;
• transferring means for transferring said first color image and said second color image together from said photoreceptor to said medium to form said multi-colored image.

An apparatus for producing a multi-colored image on a medium from image data in a liquid electrophotographic system, comprising:

• rotating means for rotating a photoreceptor past a plurality of locations in a single pass;
• erasing means for erasing any previously accumulated charge from said photoreceptor;
• charging means for charging said photoreceptor to a first predetermined charge level;
• first image-wise exposing means for exposing said photoreceptor with radiation modulated in accordance with said image data for one of a plurality of colors in order to partially discharge said photoreceptor to produce an image-wise distribution of charges on said photoreceptor corresponding to said image data for said one of said plurality of colors;
• first application means for applying a first color liquid toner containing charged particles of said first color and transparent counter ions to said photoreceptor as a function of said image-wise distribution of charges on said photoreceptor to develop said photoreceptor and form a first color image, said photoreceptor recharging to a substantially uniform second charge level, said second charge level being lower than said first predetermined charge level but being sufficiently high to subsequently repel liquid toner to said photoreceptor in areas not subsequently further discharged;
• second image-wise exposing means for exposing said photoreceptor with radiation modulated in accordance with said image data for a second of said plurality of colors in order to partially discharge said photoreceptor to produce an image-wise distribution of charges on a surface of said photoreceptor corresponding to said image data for said second of said plurality of colors in registration with said first color image;
• second application means for applying a second color liquid toner containing charged particles of said second color and transparent counter ions to said photoreceptor as a function of said image-wise distribution of charges on said photoreceptor in registration with said first color image, said photoreceptor recharging to a substantially uniform third charge level, said third charge level being lower than said second charge level but being sufficiently high to subsequently repel liquid toner in areas of said photoreceptor not subsequently further discharged;
• third image-wise exposing means for exposing said photoreceptor with radiation modulated in accordance with said image data for a third of said plurality of colors in order to partially discharge said photoreceptor to produce an image-wise distribution of charges on a surface of said photoreceptor corresponding to said image data for said third of said plurality of colors in registration with said first color image and second color image;
• third application means for applying a third color liquid toner containing charged particles of said third color and transparent counter ions to said photoreceptor as a function of said image-wise distribution of charges on said photoreceptor to form a third color image in registration with said first color image and said second color image, said photoreceptor recharging to a substantially uniform fourth charge level, said fourth charge level being lower than said third charge level but being sufficiently high to subsequently repel liquid toner in areas of said photoreceptor not subsequently further discharged;
• fourth image-wise exposing means for exposing said photoreceptor with radiation modulated in accordance with said image data for a fourth of said plurality of colors in order to partially discharge said photoreceptor to produce an image-wise distribution of charges on a surface of said photoreceptor corresponding to said image data for said fourth of said plurality of colors in registration with said first color image, second color image and said third color image;
• fourth application means for applying a fourth color liquid toner to said image-wise distribution of charges on said photoreceptor to form a fourth color image in registration with said first color image, said second color image and said third color image;
• transferring means for transferring said first color image, said second color image, said third color image and said fourth color image together from said photoreceptor to said medium to form said multi-colored image.

A method of producing a multi-colored image on a medium from image data in a liquid electrophotographic system, comprising the steps of:

• charging said photoreceptor to a first predetermined charge level;
• first image-wise exposing said photoreceptor with radiation modulated in accordance with said image data for one of a plurality of colors in order to partially discharge said photoreceptor to produce an image-wise distribution of charges on said photoreceptor corresponding to said image data for said one of said plurality of colors;
• applying a first color liquid toner to said image-wise distribution of charges on said photoreceptor to develop said photoreceptor and form a first color image, said first color liquid toner containing charged particles of said first color and transparent counter ions, said photoreceptor recharging as a result of this step to a second predetermined charge level, said second predetermined charge level being lower than said first predetermined charge level but being sufficiently high to subsequently repel liquid toner in areas not subsequently further discharged;
• second image-wise exposing said photoreceptor with radiation modulated in accordance with said image data for another of said plurality of colors in order to partially discharge said photoreceptor to produce an image-wise distribution of charges on a surface of said photoreceptor corresponding to said image data for said another of said plurality of colors in registration with said first color image;
• applying a second color liquid toner to said image-wise distribution of charges on said photoreceptor to form a second color image in registration with said first color image;
• transferring said first color image and said second color image together from said photoreceptor to said medium to form said multi-colored image.

A method of producing a multi-colored image on a medium from image data in a liquid electrophotographic system, comprising the steps of:

• charging said photoreceptor to a first predetermined charge level;
• first image-wise exposing said photoreceptor with radiation modulated in accordance with said image data for one of a plurality of colors in order to partially discharge said photoreceptor to produce an image-wise distribution of charges on said photoreceptor corresponding to said image data for said one of said plurality of colors;
• applying a first color liquid toner to said image-wise distribution of charges on said photoreceptor to develop said photoreceptor and form a first color image, said first color liquid toner containing charged particles of said first color and transparent counter ions, said photoreceptor recharging as a result of this step to a second predetermined charge level, said second predetermined charge level being lower than said first predetermined charge level but being sufficiently high to subsequently repel liquid toner in areas not subsequently further discharged;
• second image-wise exposing said photoreceptor with radiation modulated in accordance with said image data for a second of said plurality of colors in order to partially discharge said photoreceptor to produce an image-wise distribution of charges on a surface of said photoreceptor corresponding to said image data for said second of said plurality of colors in registration with said first color image;
• applying a second color liquid toner to said image-wise distribution of charges on said photoreceptor to form a second color image in registration with said first color image;
• third image-wise exposing said photoreceptor with radiation modulated in accordance with said image data for a third of said plurality of colors in order to partially discharge said photoreceptor to produce an image-wise distribution of charges on a surface of said photoreceptor corresponding to said image data for said third of said plurality of colors in registration with said first color image and said second color image;
• applying a third color liquid toner to said image-wise distribution of charges on said photoreceptor to form a third color image in registration with said first color image and said second color image;
• fourth image-wise exposing said photoreceptor with radiation modulated in accordance with said image data for a fourth of said plurality of colors in order to partially discharge said photoreceptor to produce an image-wise distribution of charges on a surface of said photoreceptor corresponding to said image data for said fourth of said plurality of colors in registration with said first color image, said second color image and said third color image;
• applying a fourth color liquid toner to said image-wise distribution of charges on said photoreceptor to form a fourth color image in registration with said first color image, said second color image and said third color image;
• transferring said first color image, said second color image, said third color image and said fourth color image together from said photoreceptor to said medium to form said multi-colored image.

An apparatus for producing a multi-colored image on a medium from image data in a liquid electrophotographic system, comprising:

• charging means for charging said photoreceptor to a first predetermined charge level;
• first image-wise exposing means for exposing said photoreceptor with radiation modulated in accordance with said image data for one of a plurality of colors in order to partially discharge said photoreceptor to produce an image-wise distribution of charges on said photoreceptor corresponding to said image data for said one of said plurality of colors;
• first application means for applying a first color liquid toner containing charged particles of said first color and transparent counter ions to said photoreceptor as a function of said image-wise distribution of charges on said photoreceptor to develop said photoreceptor and form a first color image, said photoreceptor recharging to a substantially uniform second predetermined charge level, said second predetermined charge level being lower than said first predetermined charge level but being sufficiently high to subsequently repel liquid toner in areas not subsequently further discharged;
• second image-wise exposing means for exposing said with radiation modulated in accordance with said image data for another of said plurality of colors in order to partially discharge said photoreceptor to produce an image-wise distribution of charges on a surface of said photoreceptor corresponding to said image data for said another of said plurality of colors in registration with said first color image;
• second application means for applying a second color liquid toner to said image-wise distribution of charges on said photoreceptor to form a second color image in registration with said first color image;
• and
• transferring means for transferring said first color image and said second color image together from said photoreceptor to said medium to form said multi-colored image.

An apparatus for producing a multi-colored image on a medium from image data in a liquid electrophotographic system, comprising:

• charging means for charging said photoreceptor to a first predetermined charge level;
• first image-wise exposing means for exposing said photoreceptor with radiation modulated in accordance with said image data for one of a plurality of colors in order to partially discharge said photoreceptor to produce an image-wise distribution of charges on said photoreceptor corresponding to said image data for said one of said plurality of colors;
• first application means for applying a first color liquid toner containing charged particles of said first color and transparent counter ions to said photoreceptor as a function of said image-wise distribution of charges on said photoreceptor to develop said photoreceptor and form a first color image, said photoreceptor recharging to a substantially uniform second predetermined charge level, said second predetermined charge level being lower than said first predetermined charge level but being sufficiently high to subsequently repel liquid toner in areas not subsequently further discharged;
• second image-wise exposing means for exposing said with radiation modulated in accordance with said image data for a second of said plurality of colors in order to partially discharge said photoreceptor to produce an image-wise distribution of charges on a surface of said photoreceptor corresponding to said image data for said second of said plurality of colors in registration with said first color image;
• second application means for applying a second color liquid toner containing charged particles of said second color and transparent counter ions to said image-wise distribution of charges on said photoreceptor to develop said photoreceptor and form a second color image, said photoreceptor recharging to a third predetermined charge level, said third predetermined charge level being lower than said second predetermined charge level but being sufficiently high to subsequently repel liquid toner in areas not subsequently further discharged;
• third image-wise exposing means for exposing said with radiation modulated in accordance with said image data for a third of said plurality of colors in order to partially discharge said photoreceptor to produce an image-wise distribution of charges on a surface of said photoreceptor corresponding to said image data for said third of said plurality of colors in registration with said first color image and said second color image;
• third application means for applying a third color liquid toner containing charged particles of said third color and transparent counter ions to said image-wise distribution of charges on said photoreceptor to develop said photoreceptor and form a third color image, said photoreceptor recharging to a fourth predetermined charge level, said fourth predetermined charge level being lower than said third predetermined charge level but being sufficiently high to subsequently repel liquid toner in areas not subsequently further discharged;
• fourth image-wise exposing means for exposing said with radiation modulated in accordance with said image data for a fourth of said plurality of colors in order to partially discharge said photoreceptor to produce an image-wise distribution of charges on a surface of said photoreceptor corresponding to said image data for said fourth of said plurality of colors in registration with said first color image, said second color image and said third color image;
• fourth application means for applying a fourth color liquid toner to said image-wise distribution of charges on said photoreceptor to form a fourth color image in registration with said first color image, said second color image and said third color image;
• and
• transferring means for transferring said first color image, said second color image, said third color image and said fourth color image together from said photoreceptor to said medium to form said multi-colored image.