Image forming apparatus and image forming method
An image forming apparatus having a system speed of from 400 to 1,700 mm/sec, including a latent image bearer; an image developer developing the latent image with two-component developer including a toner and a carrier; a transferer, a toner concentration detector; a toner feeder; and a controller, wherein the toner comprises a release agent and a binder resin including a crystalline polyester resin and an amorphous resin, wherein a ratio (W/R) of a maximum rising peak height (W) of the crystalline polyester resin to a maximum rising peak height (R) of the amorphous resin, which are observed respective infrared absorption spectra when measured by an IR spectroscopy using a Fourier transform infrared spectroanalyzer, is from 0.22 to 0.55.
1. An image forming apparatus having a system speed of from 400 to 1,700 mm/sec, comprising:
a latent image bearer configured to bear a latent image;
an image developer configured to develop the latent image with a two-component developer comprising a toner and a carrier to form a toner image; and
a transferer configured to transfer the toner image onto a recording material,
wherein the image forming apparatus further comprises:
a toner concentration detector configured to detect a toner concentration of the two-component developer in the image developer;
a toner feeder configured to feed the toner into the image developer; and
a controller configured to control an amount of the toner fed by the toner feeder such that the toner concentration of the two-component developer in the image developer has a target toner concentration, and
wherein the toner comprises a release agent and a binder resin comprising a crystalline polyester resin and an amorphous resin, wherein a ratio (W/R) of a maximum rising peak height (W) of the crystalline polyester resin to a maximum rising peak height (R) of the amorphous resin, which are observed respective infrared absorption spectra when measured by an IR spectroscopy (a total reflection method) using a Fourier transform infrared spectroanalyzer, is from 0.22 to 0.55.
2. The image forming apparatus of claim 1 , wherein the crystalline polyester resin has a melting point of from 80 to 130° C. and a glass transition temperature of from 80 to 130° C.
3. The image forming apparatus of claim 1 , wherein the release agent comprises a wax having a melting point of from 70 to 150° C.
4. The image forming apparatus of claim 3 , wherein the wax is at least one member selected from the group consisting of carnauba waxes, polyolefin waxes and synthetic ester waxes.
5. An image forming method at a speed of 400 to 1,700 mm/sec, comprising:
developing a latent image on an image bearer by an image developer with a two-component developer comprising a toner and a carrier to form a toner image; and
transferring the toner image onto a recording material,
wherein the image forming method further comprises:
detecting a toner concentration of the two-component developer in the image developer;
feeding the toner into the image developer; and
controlling an amount of the toner fed by the toner feeder such that the toner concentration of the two-component developer in the image developer has a target toner concentration, and
wherein the toner comprises a release agent and a binder resin comprising a crystalline polyester resin and an amorphous resin, wherein a ratio (W/R) of a maximum rising peak height (W) of the crystalline polyester resin to a maximum rising peak height (R) of the amorphous resin, which are observed respective infrared absorption spectra when measured by an IR spectroscopy (a total reflection method) using a Fourier transform infrared spectroanalyzer, is from 0.22 to 0.55.