Image forming apparatus, image forming method, and computer program product for causing a computer to execute the method

Abstract

An image forming apparatus includes: an image carrier; a toner image forming unit that forms a toner image on the image carrier; a transfer unit that transfers the toner image on the image carrier to a transfer target having ridges and valleys on a surface thereof; an adjusting unit that adjusts a ratio of A/B, where A is a transfer ratio [%] from the image carrier to a valley portion of the transfer target while B is a transfer ratio [%] from the image carrier to a ridge portion of the transfer target, based on an adjustment input by a user; and a control unit that controls a transfer condition of the transfer unit based on the ratio of A/B adjusted by the adjusting unit.

What is claimed is: 
     
       1. An image forming apparatus, comprising:
 an image carrier; 
 a transfer unit roller that transfers a toner image on the image carrier to a sheet; 
 a transfer bias application unit power source that applies, to the transfer unit roller, a transfer bias in which an alternating-current component is superimposed on a direct-current component; 
 an adjusting unitinput device hardware that adjusts a level of the alternating-current component and a level of the direct-current componenta user operates only when a predetermined kind of the sheet having ridges and valleys on a surface thereof is selected to input a ratio between a selectable image density in a valley portion of the sheet and a selectable image density in a ridge portion of the sheet; and 
 aprocessing circuitry configured to adjust a level of the alternating-current component and a level of the direct-current component based on the ratio between the selectable image density in the valley portion of the sheet and the selectable image density in the ridge portion of the sheet that is input by the input device hardware, and to control unit that controls the transfer bias application unit power source to apply the transfer bias based on according to the level of the alternating-current component and the level of the direct-current component that is adjusted based on the ratio between the selectable image density in the valley portion of the sheet and the selectable image density in the ridge portion of the sheet that is input by the adjusting unit input device hardware, 
 wherein a value of the level of the alternating-current component increases and a value of the level of the direct-current component decreases as the ratio between the selectable image density in the valley portion of the sheet and the selectable image density in the ridge portion of the sheet that is input by the input device hardware increases, the value of the level of the alternating-current component being greater than zero when the ratio between the selectable image density in the valley portion of the sheet and the selectable image density in the ridge portion of the sheet that is input by the input device hardware is greater than or equal to 1. 
 
     
     
       2. The image forming apparatus according to  claim 1 , further comprising a selection unit that selects a wherein the input device hardware allows selection of the predetermined kind of the sheet, wherein the adjusting unit allows to adjust the level of the alternating-current component and the level of the direct-current component and the input device hardware allows input of the ratio only when the sheet selected by the selection unit input device hardware is a predetermined sheet. 
     
     
       3. The image forming apparatus according to  claim 2 , wherein the predetermined sheet is a sheet having ridges and valleys on a surface thereof. 
     
     
       4. The image forming apparatus according to  claim 2 , wherein, when the sheet selected by the selection unit input device hardware is a sheet other than the predetermined sheet, the control unit controls processing circuitry is configured to control the transfer bias application unit power source to apply the transfer bias having only the direct-current component. 
     
     
       5. The image forming apparatus according to  claim 2 , wherein the selection unit input device hardware includes an operation panel. 
     
     
       6. The image forming apparatus according to  claim 1 , wherein the adjusting unit input device hardware includes an operation panel. 
     
     
       7. The image forming apparatus according to  claim 1 , wherein the image carrier is an intermediate transfer belt. 
     
     
       8. The image forming apparatus according to  claim 1 , wherein the transfer unit includes further comprising a transfer member configured conveyor to contact with the image carrier via the sheet so that the transfer roller transfers the toner image on the image carrier to the sheet. 
     
     
       9. The image forming apparatus according to  claim 8 , wherein the transfer member conveyor is a transfer conveying belt. 
     
     
       10. An image forming apparatus, comprising:
 an image carrier; 
 a transfer unit roller that transfers a toner image on the image carrier to a sheet having ridges and valleys on a surface thereof; 
 a transfer bias application unit power source that applies, to the transfer unit roller, a transfer bias in which an alternating-current component is superimposed on a direct-current component; 
 an adjusting unitinput device hardware that adjusts a level of the alternating-current component and a level of the direct-current componenta user operates only when a predetermined kind of the sheet having ridges and valleys on a surface thereof is selected to input a ratio between a selectable image density in a valley portion of the sheet and a selectable image density in a ridge portion of the sheet; and 
 aprocessing circuitry configured to adjust a level of the alternating-current component and a level of the direct-current component based on the ratio between the selectable image density in the valley portion of the sheet and the selectable image density in the ridge portion of the sheet that is input by the input device hardware, and to control unit that controls the transfer bias applied to the transfer unit based on roller according to the level of the alternating-current component and the level of the direct-current component that is adjusted based on the ratio between the selectable image density in the valley portion of the sheet and the selectable image density in the ridge portion of the sheet that is input by the adjusting unit input device hardware, 
 wherein a value of the level of the alternating-current component increases and a value of the level of the direct-current component decreases as the ratio between the selectable image density in the valley portion of the sheet and the selectable image density in the ridge portion of the sheet that is input by the input device hardware increases, the value of the level of the alternating-current component being greater than zero when the ratio between the selectable image density in the valley portion of the sheet and the selectable image density in the ridge portion of the sheet that is input by the input device hardware is greater than or equal to 1. 
 
     
     
       11. An image forming apparatus, comprising:
 an image carrier; 
 a transfer unit roller that transfers a toner image on the image carrier to a sheet; 
 a transfer bias application unit power source that applies a transfer bias to the transfer unit roller; 
 a selecting unitinput device hardware that a user operates only when a predetermined kind of the sheet having ridges and valleys on a surface thereof is selected to select the transfer bias from any one of a first direct-current voltage and a superimposed voltage in which an alternating-current voltage is superimposed on a second direct-current voltageinput a a ratio between a selectable image density in a valley portion of the sheet and a selectable image density in a ridge portion of the sheet; and 
 aprocessing circuitry configured to select the transfer bias from any one of a first direct-current voltage and a superimposed voltage in which an alternating-current voltage is superimposed on a second direct-current voltage based on the ratio between the selectable image density in the valley portion of the sheet and the selectable image density in the ridge portion of the sheet that is input by the input device hardware, and to control unit that controls the transfer bias applied to the transfer unit roller according to the transfer bias that is selected based on a selection result of the selecting unit ratio between the selectable image density in the valley portion of the sheet and the selectable image density in the ridge portion of the sheet that is input by the input device hardware, 
 wherein a level of the first direct-current voltage is greater than a level of the second direct-current voltage, and 
 wherein a value of the level of the alternating-current voltage increases and a value of the level of the direct-current voltage decreases as the ratio between the selectable image density in the valley portion of the sheet and the selectable image density in the ridge portion of the sheet that is input by the input device hardware increases, the value of the level of the alternating-current voltage being greater than zero when the ratio between the selectable image density in the valley portion of the sheet and the selectable image density in the ridge portion of the sheet that is input by the input device hardware is greater than or equal to 1. 
 
     
     
       12. The image forming apparatus according to  claim 11 , wherein the transfer unit includes further comprising a transfer member conveyor that forms a transfer nip between the image carrier and the transfer member conveyor, and wherein the toner image on the image carrier is transferred to the sheet at the transfer nip. 
     
     
       13. The image forming apparatus according to  claim 12 , wherein the transfer member conveyor is a transfer conveying belt. 
     
     
       14. The image forming apparatus according to  claim 11 , wherein the image carrier is an intermediate transfer belt. 
     
     
       15. An image forming apparatus, comprising:
 an image carrier; 
 a transfer unit roller that transfers a toner image on the image carrier to a sheet; 
 a transfer bias application unit power source that applies a transfer bias to the transfer unit roller; 
 a selecting unit to select the transfer bias from any one of a first direct current and a superimposed current in which an alternating current is superimposed on a second direct-current voltageinput device hardware that a user operates only when a predetermined kind of the sheet having ridges and valleys on a surface thereof is selected to input a ratio between a selectable image density in a valley portion of the sheet and a selectable image density in a ridge portion of the sheet; and 
 aprocessing circuitry configured to select the transfer bias from any one of a first direct current and a superimposed current in which an alternating current is superimposed on a second direct current based on the ratio between the selectable image density in the valley portion of the sheet and the selectable image density in the ridge portion of the sheet that is input by the input device hardware, and to control unit that controls the transfer bias applied to the transfer unit roller according to the transfer bias that is selected based on a selection result of the selecting unit ratio between the selectable image density in the valley portion of the sheet and the selectable image density in the ridge portion of the sheet that is input by the input device hardware, 
 wherein a level of the first direct current is greater than a level of the second direct current, and 
 wherein a value of a level of the alternating current increases and a value of a level of the direct current decreases as the ratio between the selectable image density in the valley portion of the sheet and the selectable image density in the ridge portion of the sheet that is input by the input device hardware increases, the value of the level of the alternating current being greater than zero when the ratio between the selectable image density in the valley portion of the sheet and the selectable image density in the ridge portion of the sheet that is input by the input device hardware is greater than or equal to 1. 
 
     
     
       16. The image forming apparatus according to  claim 15 , wherein the transfer unit includes further comprising a transfer member conveyor that forms a transfer nip between the image carrier and the transfer member conveyor, and wherein the toner image on the image carrier is transferred to the sheet at the transfer nip. 
     
     
       17. The image forming apparatus according to  claim 16 , wherein the transfer member conveyor is a transfer conveying belt. 
     
     
       18. The image forming apparatus according to  claim 15 , wherein the image carrier is an intermediate transfer belt. 
     
     
       19. An image transferring apparatus, comprising:
 a belt-shaped image carrier including an elastic layer;   a transfer roller to transfer a toner image on the image carrier to a sheet;   a power source to apply, to the transfer roller, a transfer bias in which an alternating-current component is superimposed on a direct-current component; and   input device hardware that a user operates only when a predetermined kind of the sheet having ridges and valleys on a surface thereof is selected to input a selection of a ratio between a selectable image density in a valley portion of the sheet and a selectable image density in a ridge portion of the sheet, and the transfer bias is adjusted based on the ratio between the selectable image density in the valley portion of the sheet and the selectable image density in the ridge portion of the sheet that is input by the input device hardware,   wherein a value of a level of the alternating-current component increases and a value of a level of the direct-current component decreases as the ratio between the selectable image density in the valley portion of the sheet and the selectable image density in the ridge portion of the sheet that is input by the input device hardware increases, the value of the level of the alternating-current component being greater than zero when the ratio between the selectable image density in the valley portion of the sheet and the selectable image density in the ridge portion of the sheet that is input by the input device hardware is greater than or equal to 1.   
     
     
       20. The image transferring apparatus according to claim 19, wherein the image carrier includes a resin layer on which the elastic layer is formed. 
     
     
       21. The image transferring apparatus according to claim 20, wherein the image carrier includes a coated layer formed on the elastic layer. 
     
     
       22. The image transferring apparatus according to claim 21, wherein the coated layer contains fluorine components. 
     
     
       23. The image transferring apparatus according to claim 19, further comprising:
 processing circuitry configured to adjust the transfer bias based on the ratio between the selectable image density in the valley portion of the sheet and the selectable image density in the ridge portion of the sheet that is input by the input device hardware, and to control the power source to apply the transfer bias according to the transfer bias that is adjusted based on the ratio between the selectable image density in the valley portion of the sheet and the selectable image density in the ridge portion of the sheet that is input by the input device hardware, wherein   the processing circuitry is configured to adjust a level of the direct-current component.   
     
     
       24. The image transferring apparatus according to claim 23, wherein the processing circuitry is configured to adjust the transfer bias such that a level of the alternating-current component increases as the level of the direct-current component decreases. 
     
     
       25. The image transferring apparatus according to claim 23, wherein the input device hardware includes an operation panel. 
     
     
       26. The image transferring apparatus according to claim 19, wherein
 the input device hardware allows selection of the predetermined kind of the sheet, and   when the sheet selected by the input device hardware is a sheet other than the predetermined sheet, the power source applies the transfer bias having only the direct-current component.