1. An image forming apparatus comprising:
an exposure unit including a plurality of light-emitting units that correspond to a respective plurality of pixels and a lens array optical system;
a photosensitive member exposed by the exposure unit; and
a correcting unit configured to estimate, from image data, an intensity of ghost light at a position of each pixel on the photosensitive member in the case where the photosensitive member is exposed by the exposure unit using the image data, and correct the image data based on the estimated intensity of the ghost light.
2. The image forming apparatus according to claim 1,
wherein the correcting unit holds information indicating a relationship between light from a light-emitting unit corresponding to a predetermined pixel that is different from a pixel of interest and ghost light produced at a position of the pixel of interest on the photosensitive member by the light, and is further configured to estimate the intensity of the ghost light at the position of each pixel on the photosensitive member based on the information.
3. The image forming apparatus according to claim 2,
wherein the correcting unit is further configured to use a tone value of each of one or more pixels in a predetermined positional relationship with the pixel of interest and the information to obtain the intensities of the ghost light produced at the position of the pixel of interest on the photosensitive member based on light from the light-emitting units corresponding to the one or more pixels, and estimate the intensity of the ghost light at the position of the pixel of interest as a sum of the obtained intensities of the ghost light.
4. The image forming apparatus according to claim 1,
wherein the correcting unit holds information indicating a relationship between light from a light-emitting unit corresponding to a predetermined pixel that is different from a pixel of interest and ghost light produced at a position of the pixel of interest on the photosensitive member by the light, and is further configured to estimate the intensity of the ghost light at the position of each pixel on the photosensitive member by obtaining the intensity of the ghost light at the position of each pixel on the photosensitive member based on the information, and by multiplying the obtained intensity of the ghost light at the position of each pixel by a coefficient greater than or equal to 0 and less than or equal to 1.
5. The image forming apparatus according to claim 1,
wherein the correcting unit is further configured to correct the image data by subtracting, from a tone value of each pixel in the image data, a value corresponding to the estimated intensity of the ghost light at a position of a corresponding pixel.
6. The image forming apparatus according to claim 1, further comprising:
a plurality of the correcting units connected in series,
wherein the second and subsequent correcting units take data output from the previous correcting unit as an input.
7. The image forming apparatus according to claim 6,
wherein of the plurality of correcting units, the correcting unit in the final stage is further configured to correct the image data by subtracting, from a tone value of each pixel in the image data, a value corresponding to the estimated intensity of the ghost light at a position of a corresponding pixel.
8. The image forming apparatus according to claim 1, further comprising:
an increase processing unit configured to increase a tone value of each pixel in the image data by a value obtained from the tone value and take the resulting value as data to be input to the correcting unit.
9. The image forming apparatus according to claim 8, further comprising:
a changing unit configured to change a developing bias based on an amount of increase in a maximum value or a minimum value for the tone value.
10. An image processing apparatus that supplies data for exposure performed by an exposure unit of an image forming apparatus that includes the exposure unit having a plurality of light-emitting units that correspond to a respective plurality of pixels and a lens array optical system, and a photosensitive member exposed by the exposure unit, the image processing apparatus comprising:
a correcting unit configured to estimate, from image data, an intensity of ghost light at a position of each pixel on the photosensitive member in the case where the photosensitive member is exposed by the exposure unit using the image data, and correct the image data based on the estimated intensity of the ghost light.
11. The image processing apparatus according to claim 10,
wherein the correcting unit holds information indicating a relationship between light from a light-emitting unit corresponding to a predetermined pixel that is different from a pixel of interest and ghost light produced at a position of the pixel of interest on the photosensitive member by the light, and is further configured to estimate the intensity of the ghost light at the position of each pixel on the photosensitive member based on the information.
12. A program product stored in a computer-readable storage medium that causes a computer to function as the image processing apparatus according to claim 10.
13. A computer-readable storage medium including a program that causes a computer to function as the image processing apparatus according to claim 10.
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. Device for controlling a JFET power electronic switch (15) of the normally ON type, the control device comprising a main gate control circuit (30) powered by a main power source (11) for driving the gate (G) of the JFET switch (15), characterized in that the control device comprises:
a protection switching device (41,51) that is switchable between two positions,
an auxiliary control circuit (40,50) driving the protection switching device (41,51),
an auxiliary power source (25) which is supplied by the said main power source, whose positive terminal is connected to the source (S) of the JFET switch (15) and whose negative terminal is connected to the gate of the JFET switch (15) bypassing said main gate control circuit (30) in one of the two positions of the protection switching device (41,51).
2. Control device according to claim 1, characterized in that the JFET power electronic switch (15) is made of silicon carbide.
3. Control device according to claim 1, characterized in that the auxiliary power source is an auxiliary capacitor (25) connected to the main power source through a charging diode (26).
4. Control device according to claim 1, characterized in that the protection switching device comprises an electromagnetic switch having a contact (41) mobile between two positions by the action of a control solenoid (43) of the auxiliary control auxiliary control circuit (40), the said mobile contact (41) being switchable between a first position in which the gate (G) of the JFET switch (15) is connected to the main gate control circuit (30) and a second position in which the gate (G) of the JFET switch (15) is connected to the negative terminal of the auxiliary power source (25).
5. Control device according to claim 4, characterized in that, in the absence of power to the control solenoid (43), the mobile contact (41) of the electromagnetic switch is held in the second position.
6. Control device according to claim 5, characterized in that the auxiliary control circuit (40) comprises a device (45) for detecting a minimum threshold in the voltage from the main power source, below which the control solenoid (43) of the electromagnetic switch is not powered.
7. Control device according to claim 6, characterized in that it also comprises a device (35) for detecting a short-circuit in the JFET switch (15).
8. Control device according to either of claims 6 and 7, characterized in that the electromagnetic switch additionally comprises a second contact (42) mobile between the said two positions by the action of the said control solenoid (43), the second mobile contact (42) being configured in such a manner that the auxiliary power source (25) is disconnected from the main power source in the second position.
9. Control device according to one of claims 4 to 8, characterized in that the electromagnetic switch is a switch of the MEMS type.
10. Control device according to claim 1, characterized in that the protection switching device comprises a first electronic switch (51) which is placed between the gate (G) of the JFET switch (15) and the negative terminal of the auxiliary power source (25), and which is driven by the auxiliary control circuit (50) between a first non-conducting state in which the gate (G) of the JFET switch (15) is not connected to the negative terminal of the auxiliary power source (25) and a second conducting state in which the gate (G) of the JFET switch (15) is connected to the negative terminal of the auxiliary power source (25).
11. Control device according to claim 10, characterized in that in the absence of a control signal coming from the auxiliary control circuit (50), the first electronic switch (51) is positioned in the second conducting state.
12. Control device according to claim 11, characterized in that the auxiliary control circuit (50) comprises a device (55) for detecting a minimum threshold in the voltage from the main power source, below which the auxiliary control circuit (50) does not generate the control signal for the first electronic switch (51).
13. Control device according to claim 12, characterized in that it also comprises a device (35) for detecting a short-circuit of the JFET switch (15).
14. Control device according to one of claims 10 to 13, characterized in that the first electronic switch (51) is a MOSFET transistor.
15. Control device according to claim 14, characterized in that the switching device comprises a second electronic switch (52) of the MOSFET transistor type, configured in such a manner as to disconnect the auxiliary power source (25) from the main power source when the first electronic switch (51) is positioned in the second conducting state.
16. Speed controller comprising an inverter stage (0) having several JFET power electronic switches (15a, 15b) of the normally ON type for supplying a variable voltage to an electrical load (M), such as an electric motor, characterized in that the controller comprises a control device according to one of the preceding claims for each of the said power electronic switches.