Image forming apparatus and image forming method

1. An image forming apparatus for performing an image forming process, comprising:

a brilliant image forming part that forms a brilliant toner image using a brilliant toner wherein the brilliant toner is used at a brilliant deposition amount (MS) for forming the brilliant toner image, the brilliant deposition amount being defined by a used weight of the brilliant toner per unit area,

a color image forming part that forms a color toner image using a color toner wherein the color toner is used at a color deposition amount (ML) for forming the color toner image, the color deposition amount being defined by a used weight of the color toner per unit area,

a transfer part that transfers the brilliant toner image and the color toner image to a medium, and

a controller that controls the brilliant deposition amount of the brilliant toner and the color deposition amount of the color toner on the medium, wherein

when the brilliant toner image is to be superimposed over the color toner image on the medium, the controller adjusts the brilliant deposition amount for the brilliant toner image in correspondence with a color type and the color deposition amount ML of the color toner that has been used for the color toner image.

2. The image forming apparatus according to claim 1 , wherein

the brilliant toner has a metallic pigment having flat-shape particles, and its aluminum element content measured by an energy dispersive fluorescent X-ray analyzer is 6.7% or higher and 17.2% or lower.

3. The image forming apparatus according to claim 1 , further comprising:

a density sensor that detects density of the brilliant toner image and the color toner image transferred onto the transfer part,

wherein the controller controls each of the brilliant deposition amount and the color deposition amount based on the detection by the density sensor.

4. An image forming apparatus for performing an image forming process, comprising:

a brilliant image forming part that forms a brilliant toner image using a brilliant toner wherein the brilliant toner is used at a brilliant deposition amount (MS) for forming the brilliant toner image, the brilliant deposition amount being defined by a used weight of the brilliant toner per unit area,

a color image forming part that forms a color toner image using a color toner wherein the color toner is used at a color deposition amount (ML) for forming the color toner image, the color deposition amount being defined by a used weight of the color toner per unit area,

a transfer part that transfers the brilliant toner image and the color toner image to a medium, and

a controller that controls the brilliant deposition amount of the brilliant toner and the color deposition amount of the color toner on the medium, wherein

in a case where the brilliant toner image is to be superimposed over the color toner image on the medium, the brilliant deposition amount MS is 0.03 mg/cm 2 or higher, and the color deposition amount ML is 0.04 mg/cm 2 or higher, the controller performs the image forming process to satisfy following equations (1) and (2):

1.17≤ ML/MS≤ 2.92  (1)

0.07≤ MS+ML≤ 0.72  (2).

5. The image forming apparatus according to claim 4 , wherein

in a case where the color tonner is a black toner of which the color type is black, the controller performs the image forming process to satisfy following equations (3) and (4):

1.27≤ ML/MS≤ 1.50  (3)

0.07≤ MS+ML≤ 0.69  (4).

6. The image forming apparatus according to claim 5 , wherein

the black toner has an optical density of about 1.4 if the color deposition amount ML is 0.40 mg/cm 2 or higher and 0.50 mg/cm 2 or lower.

7. The image forming apparatus according to claim 4 , wherein

in a case where the color tonner is a yellow toner of which the color type is yellow, the controller performs the image forming process to satisfy following equations (5) and (6):

1.17≤ ML/MS≤ 2.92  (5)

0.07≤ MS+ML< 0.47  (6).

8. The image forming apparatus according to claim 7 , wherein

the yellow toner has an optical density of about 1.4 if the color deposition amount ML is 0.40 mg/cm 2 or higher and 0.50 mg/cm 2 or lower.

9. The image forming apparatus according to claim 4 , wherein

in a case where the color tonner is a cyan toner of which the color type is cyan, the controller performs the image forming process to satisfy following equations (7) and (8):

1.18≤ ML/MS≤ 1.64  (7)

0.07≤ MS+ML≤ 0.72  (8)

10. The image forming apparatus according to claim 9 , wherein

the cyan toner has an optical density of about 1.4 if the color deposition amount ML is 0.40 mg/cm 2 or higher and 0.50 mg/cm 2 or lower.

11. The image forming apparatus according to claim 4 , wherein

in a case where the color tonner is a magenta toner of which the color type is magenta, the controller performs the image forming process to satisfy following equations (9) and (10):

1.32≤ ML/MS≤ 1.50  (9)

0.07≤ MS+ML≤ 0.69  (10).

12. The image forming apparatus according to claim 11 , wherein

the magenta toner has an optical density of about 1.4 if the color deposition amount ML is 0.45 mg/cm 2 or higher and 0.55 mg/cm 2 or lower.

13. The image forming apparatus according to claim 4 , wherein

the controller performs the image forming process to further satisfy following equations (11) and (12):

1.32≤ ML/MS≤ 1.50  (11)

0.07≤ MS+ML≤ 0.47  (12).

14. The image forming apparatus according to claim 4 , wherein

the color image forming part that forms the color toner image using two more color toners each of which is a different color type and has a predetermined deposition amount from the other color toners,

in the case where the brilliant toner image is to be superimposed over the color toner image on the medium, the controller considers only one of the three color toners and the color deposition amount of the one of the three color toners in order to satisfy the equations (1) and (2).

15. The image forming apparatus according to claim 4 , wherein

the color image forming part that forms the color toner image using two more color toners each of which is a different color type and has a predetermined deposition amount from the other color toners,

in the case where the brilliant toner image is to be superimposed over the color toner image on the medium, the controller considers all the three color toners and the color deposition amounts of the three color toners in order to satisfy the equations (1) and (2).

16. The image forming apparatus according to claim 4 , wherein

the brilliant image forming part is configured with

a photosensitive drum that has a photosensitive circumference,

a charging roller that evenly charges the photosensitive circumference,

a development roller that creates a latent image on the circumference of the photosensitive drum, and

a supply roller that supplies the tonner to develop the latent image with the tonner, a development roller,

the controller increases absolute values of bias voltages that are applied to the development roller and the supply roller in order to increase the brilliant deposition amount MS,

the controller decreases absolute values of bias voltages that are applied to the development roller and the supply roller in order to decrease the brilliant deposition amount MS.

17. The image forming apparatus according to claim 4 , wherein

the brilliant toner has a metallic pigment having flat-shape particles, and its aluminum element content measured by an energy dispersive fluorescent X-ray analyzer is 6.7% or higher and 17.2% or lower.

18. An image forming method for superimposing a brilliant toner image using a brilliant toner over a color toner image using a color toner on a medium, comprising:

an acquisition step that acquires a color type of the color toner and a color deposition amount (ML) that is defined by a used weight of the color toner per unit area, which has been used on the medium, and

a determination step that determines a brilliant deposition amount (MS) that is defined by a used weight of the brilliant toner per unit area, which is to be used on the medium in consideration of the color type of the color toner and the color deposition amount,

an adjustment step that adjusts an absolute value of bias voltage to be applied to form the brilliant toner image, and

a forming step that forms the brilliant toner image over the color toner image using the bias voltage, which is adjusted at the adjustment step, such that the brilliant deposition amount of the brilliant toner over the color toner either increases or decreases in correspondence with the bias voltage.

19. The image forming method according to claim 18 , wherein

in a case where the brilliant deposition amount MS is 0.03 mg/cm 2 or higher, and the color deposition amount ML is 0.04 mg/cm 2 or higher, the adjustment step executes to satisfy following equations:

1.17≤ ML/MS≤ 2.92,

0.07≤ MS+ML≤ 0.72.