1. A method of controlling a charge voltage, comprising the steps of:
superimposing an alternating-current voltage onto a direct-current voltage to form an application voltage;
applying the application voltage to charge a charge carrier via a charge-applying member;
changing the alternating-current voltage of the application voltage;
detecting an alternating current flowing through the charge carrier when the charge-applying member applies the application voltage to the charge carrier; and
determining a value of the alternating-current voltage of the application voltage based on at least two alternating currents detected by the alternating-current detector.
2. The method of claim 1, wherein the at least two alternating currents include first and second alternating currents detected by the detecting step when the applying step applies first and second alternating-current voltages, respectively, of the application voltage to the charge-applying member, wherein
the first and second alternating-current voltages are different from each other and each has a value at least double a discharge-start voltage that initiates an electrical discharge from the charge-applying member to the charge carrier.
3. The method of claim 1, further comprising the steps of:
detecting an ambient environmental including at least one of ambient temperature and humidity at a position close to the charge-applying member, wherein
the determining step includes determining the value of the alternating-current voltage of the application voltage based on the at least two alternating currents detected by the alternating-current detecting step when the ambient environmental detecting step detects a change in the ambient environment.
4. The method of claim 2, further comprising the steps of:
deriving relationships between the alternating-current voltage of the application voltage applied to the charge-applying member and the alternating current flowing through the charge carrier from a pair of the first alternating-current voltage and the first alternating current and another pair of the second alternating-current voltage and the second alternating current; and
substituting one of a plurality of predefined reference alternating currents capable of evenly charging the surface of the charge carrier into the relationships derived by the deriving step to obtain an appropriate value of the alternating-current voltage to be applied to the charge-applying member.
5. The method of claim 4, wherein the substituting step includes selecting one of the plurality of predetermined reference alternating currents based on a detection result of the ambient environment detecting step.
6. An image forming apparatus, comprising:
a charge carrier configured to carry a charge; and
a charging device configured to charge a surface of the charge carrier and including
a charge-applying device arranged at a position in parallel and facing the charge carrier,
a power controller configured to apply to the charge carrier an application voltage including a direct-current voltage and an alternating-current voltage superimposed onto the direct-current voltage,
an alternating-current detector configured to detect an alternating current flowing through the charge carrier when the charge-applying device applies the application voltage to the charge carrier, and
a voltage value controller configured to determine a value of the alternating-current voltage of the application voltage based on at least two alternating currents detected by the alternating-current detector.
7. The image forming apparatus of claim 6, wherein
the at least two alternating currents include first and second alternating currents detected when the power controller applies first and second alternating-current voltages, respectively, of the application voltage to the charge-applying device, and
the first and second alternating-current voltages are different from each other and each having a value at least double a discharge-start voltage that initiates an electrical discharge from the charge-applying device to the charge carrier.
8. The image forming apparatus of claim 6, wherein the charge carrier is further configured to carry an electrostatic image.
9. The image forming apparatus of claim 7, further comprising:
an AC voltage calculator configured to calculate the value of the alternating-current voltage of the application voltage based on the first and second alternating-current voltages, and first and second alternating currents, and a predefined reference alternating current capable of evenly charging the surface of the charge carrier.
10. The image forming apparatus of claim 9, further comprising:
an environment detector arranged at a position close to the charge-applying device and configured to detect at least one of ambient temperature and humidity; and
a reference AC adjuster configured to change the predefined reference alternating current in accordance with a detection result detected by the environment detector.
11. The image forming apparatus of claim 10, wherein the voltage value controller is configured to determine the alternating-current voltage value of the application voltage upon a detection of an environmental change through the environment detector.
12. The image-forming apparatus of claim 9, wherein the charging device further includes an identification memory chip storing the predefined reference alternating current.
13. The image forming apparatus of claim 6, further comprising:
an image density adjuster configured to adjust a density of an image after a determination of the alternating-current voltage value of the application voltage by the voltage value controller.
14. The image forming apparatus of claim 6, wherein the voltage value controller is configured to determine the alternating-current voltage value of the application voltage after a recovery from a jam of a recording sheet.
15. The image forming apparatus of claim 6, wherein
the charge-applying device is configured to rotate with the charge carrier,
the image forming apparatus includes a run detector configured to detect a travel distance of a surface of the charge-applying device by a rotation thereof, and
the voltage value controller is configured to determine the alternating-current voltage value of the application voltage when the travel distance of the surface of the charge-applying device reaches a predetermined value.
16. The image forming apparatus of claim 6, wherein the voltage value controller is configured to determine the alternating-current voltage value of the application voltage when a main power switch of the apparatus is turned on.
17. The image forming apparatus of claim 6, further comprising:
an instructing mechanism configured to generate an instruction, wherein
the voltage value controller is configured to determine the alternating-current voltage value of the application voltage in accordance with the instruction generated by the instructing mechanism.
18. The image forming apparatus of claim 6, further comprising:
a door arranged at a window accessible to the charging device and configured to be opened and closed when the charging device is replaced, wherein
the voltage value controller is configured to determine the alternating-current voltage value of the application voltage when the door is opened and closed.
19. The image-forming apparatus of claim 12, wherein the charge carrier and the charging device are assembled together in a process cartridge that is exchangeable as a whole, and the identification memory chip storing the predefined reference alternating current is mounted to the process cartridge, wherein
the AC voltage calculator is configured to calculate the alternating-current voltage of the application voltage based on the predefined reference alternating current stored in the identification memory chip.
20. A charging device, comprising:
a charge carrier configured to carry a charge; and
a charging device configured to charge a surface of the charge carrier and including
a charge-applying device arranged at a position in parallel and facing the charge carrier,
a power controller configured to apply to the charge carrier an application voltage including a direct-current voltage and an alternating-current voltage superimposed onto the direct-current voltage,
an alternating-current detector configured to detect an alternating current flowing through the charge carrier when the charge-applying device applies the application voltage to the charge carrier, and
a voltage value controller configured to determine an alternating-current voltage value of the application voltage based on at least two alternating currents detected by the alternating-current detector.
21. The charging device of claim 20, wherein the at least two alternating currents include first and second alternating currents detected when the power controller applies first and second alternating-current voltages, respectively, of the application voltage to the charge-applying device, wherein
the first and second alternating-current voltages are different from each other and each has a value at least double a discharge-start voltage that initiates an electrical discharge from the charge-applying device to the charge carrier when a direct-current voltage is singularly applied as the application voltage to the charge-applying device.
22. The charging device of claim 21, further comprising:
an AC voltage calculator configured to calculate the alternating-current voltage of the application voltage based on the first and second alternating-current voltages, and first and second alternating currents, and a predefined reference alternating current capable of evenly charging the surface of the charge carrier.
23. The charging device of claim 22, further comprising:
an environment detector arranged at a position close to the charge-applying device and configured to detect at least one of ambient temperature and humidity; and
a reference AC adjuster configured to change the predefined reference alternating current in accordance with a detection result detected by the environment detector.
24. The charging device of claim 23, wherein the voltage value controller is configured to determine the alternating-current voltage value of the application voltage upon a detection of an environmental change through the environment detector.
25. The charging device of claim 22, further comprising:
an identification memory chip storing the predefined reference alternating current.
26. A process cartridge which is exchangeably installed in an image forming apparatus, the process cartridge comprising:
a charge carrier configured to carry a charge; and
a charging device configured to charge a surface of the charge carrier and including
a charge-applying device arranged at a position in parallel and facing the charge carrier,
a power controller configured to apply to the charge carrier an application voltage including a direct-current voltage and an alternating-current voltage superimposed onto the direct-current voltage,
an alternating-current detector configured to detect an alternating current flowing through the charge carrier when the charge-applying device applies the application voltage to the charge carrier, and
a voltage value controller configured to determine an alternating-current voltage value of the application voltage based on at least two alternating currents detected by the alternating-current detector.
27. The charging device of claim 26, wherein the at least two alternating currents include first and second alternating currents detected when the power controller applies first and second alternating-current voltages, respectively, of the application voltage to the charge-applying device,
wherein the first and second alternating-current voltages are different from each other and each of them has a value at least double a discharge-start voltage that initiates an electrical discharge from the charge-applying device to the charge carrier when a direct-current voltage is singularly applied as the application voltage to the charge-applying device.
28. The process cartridge of claim 26, further comprising:
an identification memory chip storing a predefined reference alternating current.
29. An image forming apparatus, comprising:
means for applying an application voltage including a direct-current voltage and an alternating-current voltage superimposed onto the direct-current voltage, to a charge-applying device to charge a charge carrier;
means for changing the alternating-current voltage of the application voltage;
means for detecting an alternating current flowing through the charge carrier when the charge-applying device applies the application voltage to the charge carrier; and
means for determining a value of the alternating-current voltage of the application voltage based on at least two alternating currents detected by the alternating-current detector.
30. The image forming apparatus of claim 28, wherein the at least two alternating currents include first and second alternating currents detected by the detecting step when the applying step applies first and second alternating-current voltages, respectively, of the application voltage to the charge-applying device, wherein
the first and second alternating-current voltages are different from each other and each of them has a value at least double a discharge-start voltage that initiates an electrical discharge from the charge-applying device to the charge carrier when a direct-current voltage is singularly applied as the application voltage to the charge-applying device.
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. Method of producing 2,4-dihydroxybutyric acid (2,4-DHB) comprising:
a first step of transforming malate into 4-phospho-malate using a malate kinase having the full-length amino acid sequence selected from the group of amino acid sequences set forth in SEQ ID NOS: 9, 12, 14, 16, 20, 22, 24, 26, 39, 41, 43, and 45,
a second step of transforming 4-phospho-malate into malate-4-semialdehyde using a malate semialdehyde dehydrogenase having the full-length amino acid sequence selected from the group of amino acid sequences set forth in SEQ ID NOS: 54, 56, 58, 60, 62, 64, 66, 68, and 231, and
a third step of transforming malate-4-semialdehyde into 2,4-DHB using a DHB dehydrogenase having the full-length amino acid sequence selected from the group of amino acid sequences set forth in SEQ ID NOS: 74, 76, 81, 225, and 227.
2. The method of claim 1 wherein the malate semialdehyde dehydrogenase is represented by SEQ ID NO: 68.
3. A process of producing 2,4-DHB, comprising: cultivating a host microorganism that expresses:
a malate kinase having the full-length amino acid sequence selected from the group of amino acid sequences set forth in SEQ ID NOS: 9, 12, 14, 16, 20, 22, 24, 26, 39, 41, 43 and 45,
a malate semialdehyde dehydrogenase having the full-length amino acid sequence selected from the group of amino acid sequences set forth in SEQ ID NOS: 54, 56, 58, 60, 62, 64, 66, 68, and 231, and
a DHB dehydrogenase having the full-length amino acid sequence selected from the group of amino acid sequences set forth in SEQ ID NOS: 74, 76, 81, 225, and 227.
4. The process of claim 3, wherein the host organism is cultivated in a medium where malate, pyruvate, succinate, or fumarate is added.
5. The process of claim 4, wherein the culture medium further comprises another carbon source.
6. A method of producing 4-phospho-malate comprising:
transforming malate into 4-phospho-malate using a malate kinase having the full-length amino acid sequence selected from the group of amino acid sequences set forth in SEQ ID NOS: 12, 14, 16, 20, 22, 24, 26, 39, 41, 43, and 45.
7. A method of producing malate-4-semialdehyde comprising:
transforming 4-phospho-malate into malate-4-semialdehyde using a malate semialdehyde dehydrogenase having the full-length amino acid sequence selected from the group of amino acid sequences set forth in SEQ ID NOS: 54, 56, 58, 60, 62, 64, 66, 68, and 231.