Image forming apparatus
View Patent ↗An image forming apparatus includes a plurality of image forming units. A first image forming unit includes a first image carrier, a first developer carrier that is applied with a first developing voltage, and a first layer-forming member that is applied with a first layer-forming voltage having the same polarity as polarity of the first developing voltage. The second image forming unit includes a second image carrier, a second developer carrier that is applied with a second developing voltage, and a second layer-forming member that is applied with a second layer-forming voltage having the same polarity as polarity of the second developing voltage. An absolute value of the first layer-forming voltage is smaller than an absolute value of the first developing voltage. An absolute value of the second layer-forming voltage is greater than an absolute value of the second developing voltage.
1. An image forming apparatus comprising a plurality of image forming units;
the plurality of image forming units including:
a first image forming unit that uses a first developer having first charging characteristics; and
a second image forming unit that uses a second developer having second charging characteristics differing from the first charging characteristics;
the first image forming unit including:
a first image carrier;
a first developer carrier that is applied with a first developing voltage and develops a latent image on the first image carrier with the first developer; and
a first layer-forming member that is applied with a first layer-forming voltage having the same polarity as polarity of the first developing voltage and is disposed to face the first developer carrier;
the second image forming unit including:
a second image carrier;
a second developer carrier that is applied with a second developing voltage and develops a latent image on the second image carrier with the second developer; and
a second layer-forming member that is applied with a second layer-forming voltage having the same polarity as polarity of the second developing voltage and is disposed to face the second developer carrier; wherein:
an absolute value of the first layer-forming voltage is smaller than an absolute value of the first developing voltage; and
an absolute value of the second layer-forming voltage is greater than an absolute value of the second developing voltage.
2. The image forming apparatus of claim 1 , wherein a difference between the absolute value of the second layer-forming voltage and the absolute value of the second developing voltage is greater than a difference between the absolute value of the first layer-forming voltage and the absolute value of the first developing voltage.
3. The image forming apparatus of claim 1 , wherein the absolute value of the second developing voltage is smaller than the absolute value of the first developing voltage.
4. The image forming apparatus of claim 1 , further comprising:
a first supply member that is disposed to face the first developer carrier, and is applied with a first supply voltage having the same polarity as the polarity of the first developing voltage to supply the first developer to the first developer carrier; and
a second supply member that is disposed to face the second developer carrier, is applied with a second supply voltage having the same polarity as the polarity of the second developing voltage, and supplies the second developer to the second developer carrier; wherein
| Vsb|−|Vdb|<|Vsw|−|Vdw|
is satisfied, where |Vsb| is an absolute value of the first supply voltage, |Vdb| is the absolute value of the first developing voltage, |Vsw| is an absolute value of the second supply voltage, and |Vdw| is the absolute value of the second developing voltage.
5. The image forming apparatus of claim 1 , wherein
0 [V]<(| Vbw|−|Vdw |) [V]≦400 [V]
is satisfied, where |Vbw| is the absolute value of the second layer-forming voltage, and |Vdw| is the absolute value of the second developing voltage.
6. The image forming apparatus of claim 1 , wherein an absolute value of a charge amount of the second developer that has passed between the second layer-forming member and the second developer carrier is smaller than an absolute value of a charge amount of the first developer that has passed between the first layer-forming member and the first developer carrier.
7. The image forming apparatus of claim 1 , wherein an absolute value |Q/M| of a charge amount Q/M [μC/g] of the second developer that has passed between the second layer-forming member and the second developer carrier satisfies:
5 [μC/g]≦| Q/M | [μC/g]≦10 [μC/g].
8. The image forming apparatus of claim 1 , wherein the second developer is negatively polarized.
9. The image forming apparatus of claim 1 , wherein the second developer is positively polarized.
10. The image forming apparatus of claim 1 , wherein the second developer includes a developer to which metal-containing colorant is added.
11. The image forming apparatus of claim 1 , wherein the second developer is a white color developer.
12. The image forming apparatus of claim 1 , wherein the second developer includes a developer containing a metal oxide, wherein any of a titanium oxide, an aluminum oxide, a barium sulfate, and a zinc oxide is contained as the metal oxide.
13. The image forming apparatus of claim 1 , wherein the second developer is a metallic-color developer.
14. The image forming apparatus of claim 13 , wherein the metallic-color developer contains any of aluminum, silver, and a fluorescent pigment.
15. The image forming apparatus of claim 1 , wherein the absolute value of the second layer-forming voltage is greater than the absolute value of the first layer-forming voltage during image forming operation.
16. An image forming apparatus comprising:
a plurality of image forming units;
the plurality of image forming units including:
a first image forming unit that uses a first developer having first charging characteristics; and
a second image forming unit including a second developer differing from the first developer in color;
the first image forming unit including:
a first image carrier;
a first developer carrier that is applied with a first developing voltage and develops a latent image on the first image carrier with the first developer; and
a first layer-forming member that is applied with a first layer-forming voltage having the same polarity as polarity of the first developing voltage and is disposed to face the first developer carrier;
the second image forming unit including:
a second image carrier;
a second developer carrier that is applied with a second developing voltage and develops a latent image on the second image carrier with the second developer; and
a second layer-forming member that is applied with a second layer-forming voltage having the same polarity as polarity of the second developing voltage and is disposed to face the second developer carrier;
wherein an absolute value of the first layer-forming voltage is smaller than an absolute value of the first developing voltage, and
an absolute value of the second layer-forming voltage is greater than an absolute value of the second developing voltage.
17. The image forming apparatus of claim 16 , wherein a difference between the absolute value of the second layer-forming voltage and the absolute value of the second developing voltage is greater than a difference between the absolute value of the first layer-forming voltage and the absolute value of the first developing voltage.
18. The image forming apparatus of claim 16 , wherein the absolute value of the second developing voltage is smaller than the absolute value of the first developing voltage.
19. The image forming apparatus of claim 16 , further comprising:
a first supply member that is disposed to face the first developer carrier, and is applied with a first supply voltage having the same polarity as the polarity of the first developing voltage to supply the first developer to the first developer carrier; and
a second supply member that is disposed to face the second developer carrier, is applied with a second supply voltage having the same polarity as the polarity of the second developing voltage, and supplies the second developer to the second developer carrier; wherein
| Vsb|−|Vdb|<|Vsw|−|Vdw|
is satisfied, where |Vsb| is an absolute value of the first supply voltage, |Vdb| is the absolute value of the first developing voltage, |Vsw| is an absolute value of the second supply voltage, and |Vdw| is the absolute value of the second developing voltage.
20. The image forming apparatus of claim 16 , wherein
0 [V]<( |Vbw|−|Vdw |) [V]≦400 [V]
is satisfied, where |Vbw| is the absolute value of the second layer-forming voltage, and |Vdw| is the absolute value of the second developing voltage.
21. The image forming apparatus of claim 16 , wherein the second developer is a spot color developer.
22. The image forming apparatus of claim 21 , wherein the spot color developer is a white color developer.
23. The image forming apparatus of claim 21 , wherein the spot color developer is a metallic color developer.
24. The image forming apparatus of claim 16 , wherein the second developer includes a developer to which metal-containing colorant is added.
25. The image forming apparatus of claim 16 , wherein the second developer includes a developer containing a metal oxide.
26. The image forming apparatus of claim 25 , wherein the metal oxide includes any of a titanium oxide, an aluminum oxide, a barium sulfate, and a zinc oxide.
27. The image forming apparatus of claim 24 , wherein the metal-containing colorant contains any of aluminum, silver, and a fluorescent pigment.
28. The image forming apparatus of claim 16 , wherein the absolute value of the second layer-forming voltage is greater than the absolute value of the first layer-forming voltage during image forming operation.