Gray scale monocomponent nonmagnetic development system

An arrangement for developing an electrostatic latent image, the arrangement comprising:

• a supply of monocomponent nonmagnetic developer comprising a mixture of a major proportion of image forming toner particles of selective particle size and triboelectrically chargeable to one polarity, and a corresponding minor proportion of generally transparent counterpart charging beads of substantially smaller particle size than the toner particles and triboelectrically chargeable to the opposite polarity;
• biasable developer means for carrying the mixture, for developing the latent image;
• conductive applying means adjacent the developer means for applying the mixture thereto;
• and
• voltage means arranged for applying to the developer means a bias voltage having an AC component selective for producing an alternating field for triboelectrically charging the mixture in bulk between the applying means and developer means substantially independently of friction contact of the mixture with any surfaces of the apparatus, and a DC component selective for producing an electric field for developing the latent image to a selective image density with the bulk charged mixture applied to the developer means.

An arrangement for developing an electrostatic latent image, the arrangement comprising:

• a photoconductor having a photosensitive surface for providing an electrostatic latent image;
• a supply of monocomponent nonmagnetic developer comprising a mixture of a major proportion of image forming toner particles of selective particle size and triboelectrically chargeable to one polarity, and a corresponding minor proportion of generally transparent counterpart charging beads of substantially smaller particle size than the toner particles and triboelectrically chargeable to the opposite polarity;
• electrically biasable developer means for carrying the mixture and arranged for developing the latent image on the photosensitive surface;
• electrically conductive applying means adjacent the developer means for applying the mixture thereto;
• voltage means arranged for applying to the developer means a bias voltage having an AC component selective for producing an alternating field for triboelectrically charging the mixture in bulk between the applying means and developer means substantially independently of friction contact of the mixture with any surfaces of the apparatus, and a DC component selective for producing an electric field for developing the latent image to a selective image density with the bulk charged mixture applied to the developer means;
• said voltage means being further arranged for applying a DC bias voltage to the applying means providing a gradient relative to the DC component of the bias voltage applied to the developer means, for driving the bulk charged mixture onto the developer means;
• and
• limiting means for selectively controlling the mass per unit area of the mixture applied to the developer means.

A method for triboelectrically charging in bulk a monocomponent nonmagnetic developer in apparatus having conductive applying means adjacent biasable developer means for carrying the developer for developing an electrostatic latent image on a photosensitive surface of a photoconductor, the method comprising the steps of:

• providing in feed contact with the applying means a supply of monocomponent nonmagnetic developer comprising a mixture of toner particles triboelectrically chargeable to one polarity and generally transparent counterpart charging beads triboelectrically chargeable to the opposite polarity;
• applying the mixture from the supply onto the developer means by the applying means;
• and
• simultaneously applying to the developer means a bias voltage having an AC component selective for producing an alternating field for triboelectrically charging the mixture in bulk between the applying means and developer means substantially independently of friction contact of the mixture with any surfaces of the apparatus, and a DC component selective for producing an electric field for developing the latent image to a selective image density with the bulk charged mixture applied to the developer means.

A method for triboelectrically charging in bulk a monocomponent nonmagnetic developer in apparatus having conductive applying means adjacent biasable developer means for carrying the developer for developing an electrostatic latent image on a photosensitive surface of a photoconductor, the method comprising the steps of:

• providing a supply of monocomponent nonmagnetic developer comprising a mixture of toner particles triboelectrically chargeable to one polarity and generally transparent counterpart charging beads triboelectrically chargeable to the opposite polarity;
• applying the mixture from the supply onto the developer means by the applying means;
• and
• simultaneously applying to the developer means a bias voltage having an AC component selective for producing an alternating field for triboelectrically charging the mixture in bulk between the applying means and developer means substantially independently of friction contact of the mixture with any surfaces of the apparatus, and a DC component selective for producing an electric field for developing the latent image to a selective image density with the bulk charged mixture applied to the developer means;
• and
• further comprising simultaneously applying a DC bias voltage to the applying means providing a gradient relative to the DC component of the bias voltage applied to the developer means, for driving the bulk charged mixture onto the developer means;
• and
• further comprising limiting the mass per unit area of the bulk charged mixture applied to the developer means by smoothing the mixture into a substantially uniform, selective thickness layer on the developer means;
• wherein the developer means comprises an exposed uncoated, resilient semiconductive layer onto which the bulk charged mixture is applied and which is in contact with the photosensitive surface of the photoconductor, and further comprising developing the latent image with the bulk charged mixture on the semiconductor layer.

A method for triboelectrically charging in bulk a monocomponent nonmagnetic developer in apparatus having conductive applying means adjacent biasable developer means for carrying the developer for developing an electrostatic latent image on a photosensitive surface of a photoconductor, the method comprising the steps of:

• providing a supply of monocomponent nonmagnetic developer comprising a mixture of toner particles triboelectrically chargeable to one polarity and generally transparent counterpart charging beads triboelectrically chargeable to the opposite polarity;
• applying the mixture from the supply onto the developer means by the applying means;
• and
• simultaneously applying to the developer means a bias voltage having an AC component selective for producing an alternating field for triboelectrically charging the mixture in bulk between the applying means and developer means substantially independently of friction contact of the mixture with any surfaces of the apparatus, and a DC component selective for producing an electric field for developing the latent image to a selective image density with the bulk charged mixture applied to the developer means;
• wherein the mixture comprises a major proportion of image forming toner particles of selective particle size and a corresponding minor proportion of charging beads of substantially smaller particle size than the toner particles.

A method for triboelectrically charging in bulk a monocomponent nonmagnetic developer in apparatus having conductive applying means adjacent biasable developer means for carrying the developer for developing an electrostatic latent image on a photosensitive surface of a photoconductor, the method comprising the steps of:

• providing a supply of monocomponent nonmagnetic developer comprising a mixture of toner particles triboelectrically chargeable to one polarity and generally transparent counterpart charging beads triboelectrically chargeable to the opposite polarity;
• applying the mixture from the supply onto the developer means by the applying means;
• ad
• simultaneously applying to the developer means a bias voltage having an AC component selective for producing an alternating field for triboelectrically charging the mixture in bulk between the applying means and developer means substantially independently of friction contact of the mixture with any surfaces of the apparatus, and a DC component selective for producing an electric field for developing the latent image to a selective image density with the bulk charged mixture applied to the developer means;
• wherein the toner particles comprise a matrix of thermoplastic toner polymer containing a colorant and optionally a charge control agent, and the charging beads comprise an essentially transparent polymer having a glass transition temperature greater than 50.degree. C.

A method for developing an electrostatic latent image on a photosensitive surface of a photoconductor with a monocomponent nonmagnetic developer in apparatus having conductive applying means adjacent biasable developer means for carrying the developer for developing the latent image, the method comprising the steps of:

• providing in positive feed flow contact with the applying means a supply of monocomponent nonmagnetic developer comprising a mixture of a major proportion of image forming toner particles of selective particle size and triboelectrically chargeable to one polarity, and a corresponding minor proportion of generally transparent counterpart charging beads of substantially smaller particle size than the toner particles and triboelectrically chargeable to the opposite polarity;
• applying the mixture from the supply onto the developer means by the applying means;
• simultaneously applying to the developer means a bias voltage having an AC component selective for producing an alternating field for triboelectrically charging the mixture in bulk between the applying means and developer means substantially independently of friction contact of the mixture with any surfaces of the apparatus, and a DC component selective for producing an electric field for developing the latent image to a selective image density with the bulk charged mixture applied to the developer means;
• simultaneously applying a DC bias voltage to the applying means providing a gradient relative to the DC component of the bias voltage applied to the developer means, for driving the bulk charged mixture onto the developer means;
• limiting the mass per unit area of the bulk charged mixture applied to the developer means by smoothing the mixture into a substantially uniform, selective thickness layer on the developer means;
• and
• developing the latent image with the bulk charged mixture on the developer means.

A method for developing an electrostatic latent image on a photosensitive surface of a photoconductor with a monocomponent nonmagnetic developer in apparatus having conductive applying means adjacent biasable developer means for carrying the developer for developing the latent image, the method comprising the steps of:

• providing a supply of monocomponent nonmagnetic developer comprising a mixture of a major proportion of image forming toner particles of selective particle size and triboelectrically chargeable to one polarity, and a corresponding minor proportion of generally transparent counterpart charging beads of substantially smaller particle size than the toner particles and triboelectrically chargeable to the opposite polarity;
• applying the mixture from the supply onto the developer means by the applying means;
• simultaneously applying to the developer means a bias voltage having an AC component selective for producing an alternating field for triboelectrically charging the mixture in bulk between the applying means and developer means substantially independently of friction contact of the mixture with any surfaces of the apparatus, and a DC component selective for producing an electric field for developing the latent image to a selective image density with the bulk charged mixture applied to the developer means;
• simultaneously applying a DC bias voltage to the applying means providing a gradient relative to the DC component of the bias voltage applied to the developer means, for driving the bulk charged mixture onto the developer means;
• limiting the mass per unit area of the bulk charged mixture applied to the developer means by smoothing the mixture into a substantially uniform, selective thickness layer on the developer means;
• and
• developing the latent image with the bulk charged mixture on the developer means;
• wherein the mixture comprises, by weight, about 1-6 parts of charging beads per 100 parts of toner particles;
• and
• wherein the toner particles have an average size of about 8-15 microns and the charging beads have an average size of about 0.05-0.35 microns.

A method for developing an electrostatic latent image on a photosensitive surface of a photoconductor with a monocomponent nonmagnetic developer in apparatus having conductive applying means adjacent biasable developer means for carrying the developer for developing the latent image, the method comprising the steps of:

• providing a supply of monocomponent nonmagnetic developer comprising a mixture of a major proportion of image forming toner particles of selective particle size and triboelectrically chargeable to one polarity, and a corresponding minor proportion of generally transparent counterpart charging beads of substantially smaller particle size than the toner particles and triboelectrically chargeable to the opposite polarity;
• applying the mixture form the supply onto the developer means by the applying means;
• simultaneously applying to the developer means a bias voltage having an AC component selective for producing an alternating field for triboelectrically charging the mixture in bulk between the applying means and developer means substantially independently of friction contact of the mixture with any surfaces of the apparatus, and a DC component selective for producing an electric field for developing the latent image to a selective image density with the bulk charged mixture applied to the developer means;
• simultaneously applying a DC bias voltage to the applying means providing a gradient relative to the DC component of the bias voltage applied to the developer means, for driving the bulk charged mixture onto the developer means;
• limiting the mass per unit area of the bulk charged mixture applied to the developer means by smoothing the mixture into a substantially uniform, selective thickness layer on the developer means;
• and
• developing the latent image with the bulk charged mixture on the developer means;
• wherein the mixture comprises, by weight, about 1-6 parts of charging beads per 100 parts of toner particles;
• and
• wherein the toner particles comprise a matrix of thermoplastic toner polymer containing a colorant and optionally a charge control agent, and the charging beads comprise an essentially transparent polymer having a glass transition temperature greater than 50.degree. C.