Image-forming method and image-forming apparatus using the same

1. An image-forming method, comprising:

pseudo-halftone-processing an input signal corresponding to image information to generate an output signal;

irradiating a radiation beam corresponding to the output signal onto the surface of a latent image-holding member to form a latent image;

developing the latent image with a developer including a toner containing a binder resin and a colorant to form a toner image on the surface of the latent image-holding member;

transferring the toner image onto a recording medium; and

fixing the toner image on the recording medium to form an image, wherein:

when a halftone image is formed as the image, the toner image formed on the surface of the latent image-holding member by the pseudo-halftone processing is composed of a plurality of toner aggregates scattered like dots on the surface of the latent image-holding member; the diameter of the radiation beam irradiated onto the surface of the latent image-holding member is 35 μm or more; the pseudo-halftone processing results in the toner aggregates, which have been transferred onto the recording medium, having uneven sizes; and the toner satisfies the following Formulae (1) and (2):

2.0×10 5 ≦G ′(60)≦4.0×10 6   Formula (1)

G ′(60)/ G ′(80)≦40  Formula (2)

wherein in Formulae (1) and (2), G′(60) represents the storage modulus (Pa) of the toner as determined under conditions of a temperature of 60° C., a vibration frequency of 6.28 rad/sec, and a distortion factor of 0.1%; and G′(80) represents the storage modulus (Pa) of the toner as determined under conditions of a temperature of 80° C., a vibration frequency of 6.28 rad/sec, and a distortion factor of 0.1%.

2. The image-forming method of claim 1 , wherein transferring the toner image further comprises transferring the toner image formed on the surface of the latent image-holding member onto the surface of an intermediate transfer member and transferring the toner image transferred on the surface of the intermediate transfer member to the surface of the recording medium.

3. The image-forming method of claim 1 , wherein the toner is prepared by:

adding a coagulant to a mixed dispersion liquid containing a first resin fine particle dispersion liquid containing first resin fine particles of a first binder resin having a volume average diameter of 1 μm or less and a colorant dispersion liquid containing colorant particles, and heating the resulting mixture to form a dispersion liquid containing core particles;

adding a second resin fine particle dispersion liquid containing second resin fine particles of a second binder resin having a volume average diameter of 1 μm or less to the dispersion liquid containing the core particles and adhering the second resin fine particles onto the surfaces of the core particles to form resin-adhered agglomerates; and

fusing the resin-adhered agglomerates.

4. The image-forming method of claim 1 , wherein the toner has a difference between the solubility parameter of a first binder resin (SPc) and that of a second binder resin (SPs), (ΔSP=|SPc−SPs|), of 0.2 to 0.6.

5. The image-forming method of claim 1 , wherein the toner further comprises a releasing agent.

6. The image-forming method of claim 1 , wherein the toner further comprises an external additive.

7. The image-forming method of claim 6 , wherein the external additive is metatitanic acid.

8. The image-forming method of claim 7 , wherein the metatitanic acid is hydrophobilized and has an electric resistance of 10 10 Ω·cm or more.

9. The image-forming method of claim 6 , wherein the amount of the external additive added is 0.3 to 3 parts by mass with respect to 100 parts by mass of toner particles.

10. A device for forming an image, comprising:

a latent image-holding member;

a pseudo-halftone processor for pseudo-halftone-processing an input signal corresponding to image information to generate an output signal;

a latent image-forming unit for irradiating a radiation beam corresponding to the output signal to form a latent image on the surface of the latent image-holding member;

a developing unit for developing the latent image with a developer including a toner containing a binder resin and a colorant to form a toner image on the surface of the latent image-holding member;

a transfer unit for transferring the toner image onto a recording medium; and

a fixing unit for fixing the toner image on the recording medium to form an image,

wherein the image is formed by the image-forming method according to claim 1 , and, when a halftone image is formed as the image, the toner image formed on the surface of the latent image-holding member by the pseudo-halftone processing is composed of a plurality of toner aggregates scattered like dots on the surface of the latent image-holding member.