1. An image forming apparatus comprising:
image carriers, on whose surfaces electrostatic latent images are formed;
a plurality of development units which are provided in correspondence to different colors, which have developing-agent carriers that carry developing agents of corresponding colors, and which develop the electrostatic latent images on the surfaces of the image carriers through use of the developing agents by the developing-agent carriers; and
recovery units which are provided for the respective development units and which recover the developing agents adhering to the respective developing-agent carriers upon contact with the developing-agent carriers after the image carriers have been subjected to development,
wherein developing-agent images are sequentially formed on the image carriers by developing the electrostatic latent images by the respective development units, and the developing-agent images are transferred to a transfer-target material, thereby forming a multi-color image, and
recovery capabilities of the respective recovery units are determined such that the development unit which is last in sequence of formation of a developing-agent image is higher in recovery capability than at least the development unit which is first in sequence of formation of the developing-agent image, and such that recovery capability of one development unit is higher than recovery capability of another development unit which is immediately before the one development unit in sequence of formation of the developing-agent image.
2. The image forming apparatus according to claim 1, wherein recovery capabilities of the respective recovery unit are determined such that the development unit, which is second to last in sequence of formation of the developing-agent image, is higher in recovery capability than the development unit which is first in sequence of formation of the developing-agent image.
3. The image forming apparatus according to claim 1, wherein recovery capabilities of the respective recovery units are determined such that the development unit, which is last in sequence of formation of the developing-agent image, is higher in recovery capability than the development unit other than the development unit that is last in sequence.
4. The image forming apparatus according to claim 1, wherein recovery capabilities of the respective recovery units are determined such that the development unit, which is third to last in sequence of formation of the developing-agent image, is higher in recovery capability than the development unit which is first or second in sequence of formation of the developing-agent image.
5. The image forming apparatus according to claim 1, wherein each of the recovery units comprises a rotatable element which recovers the developing agent adhering to the developing-agent carrier when rotating while remaining in contact with the developing-agent carrier, and a circumferential speed of the rotatable element of the development unit whose recovery capability is to be improved is faster than that of the other development unit.
6. The image forming apparatus according to claim 5, wherein the rotatable element is a feeding roller which rotates while remaining in contact with the developing-agent carrier and supplies to the developing-agent carrier the developing agent stored in a developing-agent storage chamber of the development unit.
7. The image forming apparatus according to claim 1, wherein the respective recovery units are contact elements which recover the developing agents adhering to the developing-agent carriers by relative movement while remaining in contact with the respective developing-agent carriers, and hardness of the contact elements of the development unit whose recovery capability is to be improved is higher than that of the other development unit.
8. The image forming apparatus according to claim 1, wherein the respective recovery units are contact elements which recover the developing agents adhering to the developing-agent carriers by relative movement while remaining in contact with the respective developing-agent carriers, and a contact width between the contact element and the developing-agent carrier is wider in the development unit whose recovery capability is to be improved than that of other development unit.
9. The image forming apparatus according to claim 7, wherein the contact elements are feeding rollers which rotate while remaining in contact with the developing-agent carriers and feed to the developing-agent carriers developing agents in developing-agent storage chambers of the development units.
10. The image forming apparatus according to claim 1, wherein each of the recovery unit is a feeding roller which rotates while remaining in contact with the respective developing-agent carrier; which feeds to the developing-agent carrier the developing agent in a developing-agent storage chamber of the development unit; and which recovers the developing agent adhering to the developing-agent carrier; and
the image forming apparatus further comprises a development bias application unit for applying a development bias voltage to each of the developing-agent carriers, and a supply bias application unit for applying a supply bias voltage to each of the feeding rollers, wherein recovery capability of each of the development units is determined on the basis of the relationship between the supply bias voltage and the development bias voltage.
11. The image forming apparatus according to claim 1, further comprising:
an agitation member provided to each of the development units, for agitating the developing agent in a developing-agent storage chamber that stores the developing agent,
wherein agitation capabilities of the respective agitation members are determined such that the development unit which is last in sequence of formation of a developing-agent image is higher in agitation capability than at least the development unit which is first in sequence of formation of the developing-agent image and such that one development unit is higher in agitation capability than another development unit which is immediately before the one development unit in sequence of formation of the developing-agent image.
12. The image forming apparatus according to claim 1, wherein the development unit which is last in sequence of formation of the developing-agent image is configured such that the developing-agent carrier carries a black developing agent, and such that an electrostatic latent image is developed by the black developing agent.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An abnormality detection apparatus of an injection molding machine, comprising:
a drive unit that drivingly controls a servomotor to drive a moving part;
a physical quantity detection unit that detects a load applied to the servomotor or a speed, current or position error of the servomotor, as a physical quantity;
a storage unit that stores the detected physical quantity as a reference physical quantity in association with an elapsed time during which the moving part operates or an operating position of the moving part;
a physical quantity deviation calculation unit that successively compares the stored reference physical quantity and a current physical quantity with each other in association with the elapsed time during which the moving part operates or the operating position of the moving part, thereby determining a deviation of the physical quantity;
an absolute value calculation unit that calculates an absolute value of the determined deviation of the physical quantity;
an average calculation unit that calculates an average of the calculated absolute values of deviations of the physical quantities; and
a threshold calculation unit that calculates a threshold corresponding to the elapsed time during which the moving part operates or the operating position of the moving part, based on the calculated absolute value of the deviation of the physical quantity, such that the threshold increases as the calculated absolute value of the deviation of the physical quantity increases,
wherein abnormality is detected if the threshold calculated by the threshold calculation unit is exceeded by the deviation of the physical quantity determined by the physical quantity deviation calculation unit.
2. The abnormality detection apparatus of an injection molding machine according to claim 1, further comprising a storage unit that stores the calculated average of the absolute values of the deviations in association with the elapsed time during which the moving part operates or the operating position of the moving part, wherein
the average calculation unit calculates the average of the absolute values of deviations of the physical quantities according to the following equation,
R(n, x)=|E(n, x)|n+R(n\u22121, x)\xd7(n\u22121)n
where n is the number of cycles performed since the start of threshold calculation, x is an elapsed time or position of a moving part, R(n, x) is the average of the absolute values of deviations at x for first to n-th cycles, and E(n, x) is the deviation at x in the n-th cycle, in association with the elapsed time during which the moving part operates or the operating position of the moving part, and
the threshold calculation unit calculates the threshold according to the following equation,
L(n, x)=\u03b1\xd7\u03b2R(n, x)+\u03b2
where L(n, x) is a threshold at x in the n-th cycle and \u03b1 and \u03b2 are coefficients (\u03b1>0).
3. The abnormality detection apparatus of an injection molding machine according to claim 1, further comprising a storage unit that stores the calculated threshold in association with the elapsed time during which the moving part operates or the operating position of the moving part, wherein
the threshold calculation unit calculates the threshold according to the following equation
L(n, x)=|E(n, x)|\xd7\u03b1n+{L(n\u22121, x)\u2212\u03b2}\xd7(n\u22121)n+\u03b2,
where n is the number of cycles performed since the start of threshold calculation, x is an elapsed time or position of a moving part, E(n, x) is a deviation at x in the n-th cycle, L(n, x) is a threshold at x in the n-th cycle, and \u03b1 and \u03b2 are coefficients (\u03b1>0).
4. An abnormality detection apparatus of an injection molding machine, comprising:
a drive unit that drivingly controls a servomotor to drive a moving part;
a physical quantity detection unit that detects a load applied to the servomotor or a speed, current or position error of the servomotor, as a physical quantity;
a calculation unit that calculates an average of the physical quantities within a predetermined number of cycles in association with an elapsed time during which the moving part operates or an operating position of the moving part;
a storage unit that stores the calculated average of the physical quantities;
a physical quantity deviation calculation unit that successively compares the stored average of the physical quantities and a current physical quantity in association with the elapsed time during which the moving part operates or the operating position of the moving part, thereby determining a deviation of the physical quantity;
an absolute value calculation unit that calculates an absolute value of the determined deviation of the physical quantity;
an average calculation unit that calculates an average of the calculated absolute values of deviations of the physical quantities; and
a threshold calculation unit that calculates a threshold corresponding to the elapsed time during which the moving part operates or the operating position of the moving part, based on the calculated absolute value of the deviation of the physical quantity, such that the threshold increases as the calculated absolute value of the deviation of the physical quantity increases,
wherein abnormality is detected if the threshold calculated by the threshold calculation unit is exceeded by the deviation of the physical quantity determined by the physical quantity deviation calculation unit.
5. The abnormality detection apparatus of an injection molding machine according to claim 4, further comprising a storage unit that stores the calculated average of the absolute values of the deviations in association with the elapsed time during which the moving part operates or the operating position of the moving part, wherein
the average calculation unit calculates the average of the absolute values of deviations of the physical quantities according to the following equation,
R(n, x)=|E(n, x)|n+R(n\u22121, x)\xd7(n\u22121)n
where n is the number of cycles performed since the start of threshold calculation, x is an elapsed time or position of a moving part, R(n, x) is the average of the absolute values of deviations at x for first to n-th cycles, and E(n, x) is the deviation at x in the n-th cycle, in association with the elapsed time during which the moving part operates or the operating position of the moving part, and
the threshold calculation unit calculates the threshold according to the following equation,
L(n, x)=\u03b1\xd7R(n, x)+\u03b2
where L(n, x) is a threshold at x in the n-th cycle and \u03b1 and \u03b2 are coefficients (\u03b1>0).
6. The abnormality detection apparatus of an injection molding machine according to claim 4, further comprising a storage unit that stores the calculated threshold in association with the elapsed time during which the moving part operates or the operating position of the moving part, wherein
the threshold calculation unit calculates the threshold according to the following equation
L(n, x)=|E(n, x)|\xd7\u03b1n+{L(n\u22121, x)\u2212\u03b2}\xd7(n\u22121)n+\u03b2,
where n is the number of cycles performed since the start of threshold calculation, x is an elapsed time or position of a moving part, E(n, x) is a deviation at x in the n-th cycle, L(n, x) is a threshold at x in the n-th cycle, and \u03b1 and \u03b2 are coefficients (\u03b1>0).