1. An image forming apparatus comprising:
an image forming unit including image forming unit elements, wherein the image forming elements include,
an image carrier having a surface on which a latent image can be formed,
a charging unit configured to receive a charging voltage and to charge the surface of the image carrier, a developer carrier configured to receive a development voltage and to form a developer image by adhering a developer on the latent image formed on the image carrier, and
a developer supplier configured to receive a supply voltage and to supply the developer to the developer carrier,
a fixing unit configured to fix the transferred developer image formed on a medium which has been transferred from the image carrier to the medium;
a voltage setting unit operable, when an unoperated time period, which is a time period from an end of an image forming operation to a start of a subsequent image forming operation, is equal to or greater than a threshold, to set a post unoperated period image formation preparation voltage which is different from a normal image formation voltage, according to the unoperated time period; and
a post unoperated period image formation preparation processor operable to perform an idling operation to rotate the image carrier for a predetermined idling time while applying the post unoperated period image formation preparation voltage to a given one or more of the image forming elements, wherein the post unoperated period image formation preparation processor is configured to set different idling time periods based on different unoperated periods.
2. The image forming apparatus of claim 1, wherein the post unoperated period image formation preparation processor sets the predetermined idling time period longer as the unoperated period becomes longer.
3. The image forming apparatus of claim 2, wherein the post unoperated period image formation preparation processor sets the predetermined idling time period longer by setting an increased rotation number of the image carrier.
4. The image forming apparatus of claim 1, further comprising a timer measuring the unoperated time period.
5. The image forming apparatus of claim 1, further comprising
a post unoperated period image formation processor operable to operate, after the idling operation ends, image formation process while applying a post unoperated period image formation voltage, which is different from a normal image formation voltage and the post unoperated period image formation preparation voltage, to the given one or more of the image forming elements.
6. The image forming apparatus of claim 1, wherein
the given one or more image forming elements is the charging unit; and
the voltage setting unit sets the post unoperated period image formation preparation voltage for the charging voltage.
7. The image forming apparatus of claim 1, wherein
the given one or more image forming elements is the developer supplier; and
the voltage setting unit sets the post unoperated period image formation preparation voltage for the supply voltage.
8. The image forming apparatus of claim 1, wherein the voltage setting unit sets the absolute value of the post idle period image formation preparation voltage greater than the absolute value of a normal voltage set value.
9. The image forming apparatus of claim 8, wherein the voltage setting unit sets the post unoperated period image formation preparation voltage for the supply voltage larger in absolute value as the unoperated period becomes longer.
10. The image forming apparatus of claim 1, wherein the voltage setting unit is configured to set different image formation preparation voltages based on different unoperated periods.
11. An image forming apparatus comprising:
an image forming unit including image forming unit elements, wherein the image forming elements include,
an image carrier having a surface on which a latent image can be formed
a charging unit configured to receive a charging voltage and to charge the surface of the image carrier,
a developer carrier configured to receive a development voltage and to form a developer image by adhering a developer on the latent image formed on the image carrier, and
a developer supplier configured to receive a supply voltage and to supply the developer to the developer carrier,
a fixing unit configured to fix the transferred developer image formed on a medium which has been transferred from the image carrier to the medium;
a voltage setting unit operable, when an unoperated time period, which is a time period from an end of an image forming operation to a start of a subsequent image forming operation, is equal to or greater than a threshold, to set a post unoperated period image formation preparation voltage which is different from a normal image formation voltage, according to the unoperated time period;
a post unoperated period image formation preparation processor operable to perform an idling operation to rotate the image carrier for a predetermined idling time while applying the post unoperated period image formation preparation voltage to a given one or more of the image forming elements;
a fixing unit temperature detection unit operable to detect a temperature of the fixing unit; and
an unoperated period estimation processor operable to estimate the unoperated time period based on the temperature of the fixing unit.
12. An image forming apparatus comprising:
an exposure unit operable to emit light:
an image forming unit including image forming unit elements, wherein the image forming elements include,
an image carrier having a surface on which a latent image can be formed by the exposure unit,
a charging unit configured to receive a charging voltage and to charge the surface of the image carrier,
a developer carrier configured to receive a development voltage and to form a developer image by adhering a developer on the latent image formed on the image carrier, and
a developer supplier configured to receive a supply voltage and to supply the developer to the developer carrier,
a transfer unit configured to transfer the developer image from the image carrier to a medium,
a fixing unit configured to fix the transferred developer image onto the medium;
a voltage setting unit operable, when an unoperated time period, which is a time period from an end of an image forming operation to a start of a subsequent image forming operation, is equal to or greater than a threshold, to set a post unoperated period image formation preparation voltage which is different from a normal image formation voltage, according to the unoperated time period, wherein the voltage setting unit is configured to set different image formation preparation voltages based on different unoperated periods; and
a post unoperated period image formation preparation processor operable to perform an idling operation to operate the image forming unit for a predetermined idling time while applying the post unoperated period image formation preparation voltage to a given one or more of the image forming elements, without forming the latent image on the surface of the image carrier by the exposure unit.
13. The image forming apparatus of claim 12, wherein the post unoperated period image formation preparation processor sets the predetermined idling time period longer as the unoperated time period becomes longer.
14. The image forming apparatus of claim 13, wherein the post unoperated period image formation preparation processor sets the predetermined idling time period longer by setting an increased rotation number of the image carrier.
15. The image forming apparatus of claim 12, further comprising
a timer measuring the unoperated time period.
16. The image forming apparatus of claim 12, further comprising
a fixing unit temperature detection unit operable to detect a temperature of the fixing unit; and
an unoperated period estimation processor operable to estimate the unoperated time period based on the temperature of the fixing unit.
17. The image forming apparatus of claim 12, further comprising
a post unoperated period image formation processor operable to operate, after the idling operation ends, image formation process while applying a post unoperated period image formation voltage, which is different from a normal image formation voltage and the post unoperated period image formation preparation voltage, to the given one or more of the image forming elements.
18. The image forming apparatus of claim 12, wherein
the given one or more image forming elements is the charging unit; and
the voltage setting unit sets the post unoperated period image formation preparation voltage for the charging voltage.
19. The image forming apparatus of claim 12, wherein
the given one or more image forming elements is the developer supplier; and
the voltage setting unit sets the post unoperated period image formation preparation voltage for the supply voltage.
20. The image forming apparatus of claim 12, wherein the voltage setting unit sets the absolute value of the post idle period image formation preparation voltage greater than the absolute value of a normal voltage set value.
21. The image forming apparatus of claim 20, wherein the voltage setting unit sets the post unoperated period image formation preparation voltage for the supply voltage larger in absolute value as the unoperated period becomes longer.
22. The image forming apparatus of claim 12, wherein the post unoperated period image formation preparation processor is configured to set different idling time periods based on different unoperated periods.
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. A display apparatus, comprising:
a light-emitting unit that includes a plurality of light-emitting devices of which emission colors are different from one another;
a display unit configured to display an image on a screen by modulating light from the light-emitting unit based on image data;
a first determination unit configured to determine, in a region of the screen that corresponds to the light-emitting unit, whether a ratio of a total number of first type pixels of which chroma level is less than a first chroma level, with respect to a total number of pixels in the region, is a first ratio or more;
a second determination unit configured to determine, in the region, whether a ratio of a total number of second type pixels of which chroma level is a second chroma level or more, with respect to the total number of pixels in the region, is a second ratio or more, when the determination result of the first determination unit is affirmative; and
a control unit configured to increase emission brightness of a target device, which is at least one of the plurality of light-emitting devices, based on the determination result of the second determination unit.
2. The display apparatus according to claim 1, further comprising:
a determination unit configured to determine an increase rate of emission brightness of each of the plurality of light-emitting devices based on the image data; and
a correction unit configured to correct an increase rate of the emission brightness of the target device to a greater value as the number of the second type pixels of which chroma level for the emission color of the target device is the second chroma level or more is greater, wherein
the control unit controls the emission brightness of the target device to be a value generated by correcting a predetermined reference value with the increase rate after the correction by the correction unit.
3. The display apparatus according to claim 2, further comprising:
a limiting unit configured to limit the increase rate after correction by the correction unit so that the emission brightness of the target device does not exceed an upper limit value, wherein
the control unit controls the emission brightness of the target device to be a value generated by correcting the predetermined reference value with the increase rate after limiting the increase rate by the limiting unit.
4. The display apparatus according to claim 3, further comprising:
a setting unit configured to set an upper limit value of the increase rate determined by the determination unit, wherein
the limiting unit limits the increase rate after the correction by the correction unit to a value not greater than B1B2 where B1 denotes an upper limit value of the emission brightness, and B2 denotes a value generated by correcting the predetermined reference value with the upper limit value that is set by the setting unit.
5. The display apparatus according to claim 4, further comprising:
a gradation number setting unit configured to set a lower limit value of a gradation number of the image data, wherein
the setting unit sets, as the upper limit value of the increase rate, a value that is smaller as the lower limit value set by the gradation number setting unit is greater.
6. The display apparatus according to claim 1, further comprising:
an image correction unit configured to correct the image data according to emission brightness of each of the plurality of light-emitting devices, wherein
the display unit modulates the light from the light-emitting unit based on the image data after the correction by the image correction unit.
7. The display apparatus according to claim 6, wherein
the color of the light emitted from the light-emitting unit is changed by increasing the emission brightness of the target device, and
the image correction unit corrects the image data so that a color gamut of the image displayed on the screen is expanded in a direction where the color of the light emitted from the light-emitting unit changes.
8. The display apparatus according to claim 6, wherein
the image data is image data in which a brightness gradation of a high brightness region is compressed, and the image correction unit increases a brightness value of the high brightness region of the image data.
9. The display apparatus according to claim 1, wherein
the light-emitting unit is provided in plurality,
for each of the light-emitting units, the first determination unit determines, in a region corresponding to the light-emitting unit, whether a ratio of a total number of first type pixels with respect to a total number of pixels in the region, is the first ratio or more, and
the second determination unit determines, in a region corresponding to the light-emitting unit for which the determination result of the first determination unit is affirmative, whether a ratio of a total number of second type pixels with respect to a total number of pixels in the region, is the second ratio or more.
10. The display apparatus according to claim 1, wherein
the second determination unit performs determination for each of the light-emitting devices, using a pixel of which chroma level for the emission color of the light-emitting device is the second chroma level or more, as the second type pixel, and
the control unit increases emission brightness of the light-emitting device for which the determination result of the second determination unit is affirmative.
11. The display apparatus according to claim 1, wherein
the first type pixel is a pixel for which the difference between the emission color of each of the plurality of light-emitting devices and a color of the pixel is a first threshold or greater, and
the second type pixel is a pixel for which the difference between the emission color of any of the plurality of light-emitting devices and a color of the pixel is a second threshold or less.
12. A method for controlling a display apparatus which has:
a light-emitting unit that includes a plurality of light-emitting devices of which emission colors are different from one another; and
a display unit configured to display an image on a screen by modulating light from the light-emitting unit based on image data, the method comprising:
a first determination step of determining, in a region of the screen that corresponds to the light-emitting unit, whether a ratio of a total number of first type pixels of which chroma level is less than a first chroma level, with respect to a total number of pixels in the region, is a first ratio or more;
a second determination step of determining, in the region, whether a ratio of a total number of second type pixels of which chroma level is a second chroma level or more, with respect to the total number of pixels in the region, is a second ratio or more, when the determination result in the first determination step is affirmative; and
a control step of increasing emission brightness of a target device, which is at least one of the plurality of light-emitting devices based on the determination result in the second determination step.
13. The method according to claim 12, further comprising:
a determination step of determining an increase rate of emission brightness of each of the plurality of light-emitting devices based on the image data; and
a correction step of correcting an increase rate of the emission brightness of the target device to a greater value as the number of the second type pixels of which chroma level for the emission color of the target device is the second chroma level or more is greater, wherein
in the control step, the emission brightness of the target device is controlled to be a value generated by correcting a predetermined reference value with the increase rate after the correction in the correction step.
14. The method according to claim 13, further comprising:
a limiting step of limiting the increase rate after correction in the correction step so that the emission brightness of the target device does not exceed an upper limit value, wherein
in the control step, the emission brightness of the target device is controlled to be a value generated by correcting the predetermined reference value with the increase rate after limiting the increase rate in the limiting step.
15. The method according to claim 14, further comprising:
a setting step of setting an upper limit value of the increase rate determined in the determination step, wherein
in the limiting step, the increase rate after the correction in the correction step is limited to a value not greater than B1B2 where B1 denotes an upper limit value of the emission brightness, and B2 denotes a value generated by correcting the predetermined reference value with the upper limit value that is set in the setting step.
16. The method according to claim 15, further comprising:
a gradation number setting step of setting a lower limit value of a gradation number of the image data, wherein
in the setting step, a value, that is smaller as the lower limit value set in the gradation number setting step is greater, is set as the upper limit value of the increase rate.
17. The method according to claim 12, further comprising:
an image correction step of correcting the image data according to emission brightness of each of the plurality of light-emitting devices, wherein
the display unit modulates the light from the light-emitting unit based on the image data after the correction in the image correction step.
18. The method according to claim 17, wherein
the color of the light emitted from the light-emitting unit is changed by increasing the emission brightness of the target device, and
in the image correction step, the image data is corrected so that a color gamut of the image displayed on the screen is expanded in a direction where the color of the light emitted from the light-emitting unit changes.
19. The method according to claim 17, wherein
the image data is image data in which a brightness gradation of a high brightness region is compressed, and in the image correction step, a brightness value of the high brightness region of the image data is increased.
20. The method according to claim 12, wherein
the light-emitting unit is provided in plurality,
in the first determination step, for each of the light-emitting units, it is determined that, in a region corresponding to the light-emitting unit, whether a ratio of a total number of first type pixels with respect to a total number of pixels in the region, is the first ratio or more, and
in the second determination step, it is determined that, in a region corresponding to the light-emitting unit for which the determination result in the first determination step is affirmative, whether a ratio of a total number of second type pixels with respect to a total number of pixels in the region, is the second ratio or more.
21. The method according to claim 12, wherein
in the second determination step, for each of the light-emitting devices, determination is performed using a pixel of which chroma level for the emission color of the light-emitting device is the second chroma level or more, as the second type pixel, and
in the control step, emission brightness of the light-emitting device for which the determination result in the second determination step is affirmative is increased.
22. The method according to claim 12, wherein
the first type pixel is a pixel for which the difference between the emission color of each of the plurality of light-emitting devices and a color of the pixel is a first threshold or greater, and
the second type pixel is a pixel for which the difference between the emission color of any of the plurality of light-emitting devices and a color of the pixel is a second threshold or less.