IMAGE FORMING APPARATUS

Abstract

An image forming apparatus includes a photoconductor 8 which bears an image to be formed by exposure, a light emission part 600 which emits light for exposing the photoconductor 8 to the light, and a light quantity measuring part 700 which measures the quantity of the light emitted from the light emission part 600 and outputs a light quantity measuring signal. The light quantity measuring signal of the light quantity measuring part 700 is sent through an engine control part 42 to a controller 41, and the quantity of the light emitted from the light emission part 600 is controlled so that the light quantity measuring signal becomes a predetermined value. Here, a sign indicating inclination (change rate) of the light quantity measuring signal of the light quantity measuring part 700 for temperature is matched with a sign indicating inclination (change rate) of sensitivity of the photoconductor 8 for temperature.

Description

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a constitutional view of an image forming apparatus according to a first embodiment of the invention.

FIG. 2 is a diagram showing the constitution around a development station in the image forming apparatus according to the first embodiment of the invention.

FIG. 3 is a diagram showing the constitution of an exposure unit in the image forming apparatus according to the first embodiment of the invention.

FIGS. 4( a) and 4(b) are diagrams showing the detailed constitution of a glass substrate included in the exposure unit in the image forming apparatus according to the first embodiment of the invention.

FIG. 5 is a diagram showing a section of an organic electroluminescence element included in the exposure unit in the image forming apparatus according to the first embodiment of the invention and a section of structures around the organic electroluminescence element.

FIG. 6 is a diagram showing a top surface of the organic electroluminescence element included in the exposure unit in the image forming apparatus according to the first embodiment of the invention and a top surface of the structures around the organic electroluminescence element.

FIG. 7 is a diagram showing a top surface of the plural organic electroluminescence element included in the exposure unit in the image forming apparatus 1 according to the first embodiment of the invention and a top surface of the structures around the organic electroluminescence elements.

FIG. 8 is a block diagram showing the constitution of a processing circuit included in the exposure unit in the image forming apparatus according to the first embodiment of the invention.

FIG. 9 is a block diagram showing the constitution of a controller in the image forming apparatus according to the first embodiment of the invention.

FIG. 10 is an explanatory view showing contents of a light quantity correction data memory in the image forming apparatus according to the first embodiment of the invention.

FIG. 11 is a block diagram showing the constitution of an engine control part in the image forming apparatus according to the first embodiment of the invention.

FIG. 12 is a circuit diagram of the exposure unit in the image forming apparatus according to the first embodiment of the invention.

FIG. 13 is a diagram showing the constitution of an exposure unit in an image forming apparatus according to a second embodiment of the invention.

FIG. 14 is a block diagram showing the constitution of an engine control part in the image forming apparatus according to the second embodiment of the invention

FIG. 15 is a characteristic diagram showing one example of a relation between output current of a light receiving element formed of polysilicon and the temperature.

FIG. 16 is a sectional view showing the schematic constitution of the organic electroluminescence element used as a light source in the first embodiment.

FIG. 17 is a characteristic diagram showing an example of a relation between temperature and sensitivity of a photoconductor that is an image bearing body.

Claims

1. An image forming apparatus comprising: an image bearing body which bears an image to be formed by exposure;a light emission part which emits light for exposing the image bearing body to the light;a light quantity measuring part which measures the quantity of the light emitted by the light emission part and outputs a light quantity measuring signal; anda correction part which corrects the light quantity measuring signal so as to reduce a difference between a change rate of the image density of the image bearing body for temperature, and a change rate of the light quantity measuring signal of the light quantity measuring part for temperature.

2. An image forming apparatus comprising: an image bearing body which bears an image to be formed by exposure;a light emission part which emits light for exposing the image bearing body to the light;a light quantity measuring part which measures the quantity of the light emitted by the light emission part and outputs a light quantity measuring signal; anda light quantity control part which controls the quantity of the light emitted by the light emission part so that a value of the light quantity measuring signal outputted by the light quantity measuring part becomes a predetermined value,wherein the image bearing body and the light quantity measuring part are constituted so that temperature characteristics of them are offset by each other.

3. An image forming apparatus comprising: an image bearing body which bears an image to be formed by exposure;a light emission part which emits light for exposing the image bearing body to the light;a light quantity measuring part which measures the quantity of the light emitted by the light emission part and outputs a light quantity measuring signal; anda light quantity control part which controls the quantity of the light emitted by the light emission part so that a value of the light quantity measuring signal outputted by the light quantity measuring part becomes a predetermined value,wherein a sign indicating a change rate of the light quantity measuring signal of the light quantity measuring part for temperature coincides with a sign indicating a change rate of the density of a picture image formed by the image born by the image bearing body for temperature.

4. The image forming apparatus according to claim 2, wherein the light quantity measuring part includes a light receiving element which receives the light emitted by the light emission part and converts its light into an electric signal; and a sign indicating a change rate of the electric signal of the light receiving element for temperature coincides with a sign indicating a change rate of the density of a picture image formed by the image born by the image bearing body for temperature.

5. The image forming apparatus according to claim 2, wherein the light quantity measuring part includes a correction part which corrects a difference between temperature characteristic of the light quantity measuring part and temperature characteristic of the image bearing body; and between a change rate of the image density of the image bearing body for temperature, and a change rate of the light quantity measuring signal of the light quantity measuring part for temperature.

6. The image forming apparatus according to claim 1, wherein the light quantity measuring part includes a light receiving element which receives the light emitted by the light emission part and converts its light into an electric signal; and the correction part corrects the electric signal so as to reduce a difference between a change rate of the image density of the image bearing body for temperature, and a change rate of the electric signal of the light receiving element for temperature.

7. The image forming apparatus according to claim 6, wherein the correction part performs offset adjustment and level conversion of the electric signal.

8. The image forming apparatus according to claim 1, comprising a measuring part temperature control part which controls temperature of the light quantity measuring part.

9. The image forming apparatus according to claim 1, comprising an image bearing body temperature control part which controls temperature of the image bearing body.

10. The image forming apparatus according to claim 1, comprising a temperature difference reducing part which reduces a temperature difference between the image bearing body and the light quantity measuring part.

11. The image forming apparatus according to claim 10, including an exposure unit having at least the light emission part and the light quantity measuring part, wherein the temperature difference reducing part is formed by a protrusion part provided for the exposure unit.

12. The image forming apparatus according to claim 1, wherein the light emission part is formed of an organic electroluminescence element.

13. The image forming apparatus according to claim 12, wherein the area of a luminous area of the organic electroluminescence element is set to at least 25 m2 and at most 1000 m2 per pixel; and electric power applied to the organic electroluminescence element is set to at least 3.5 W/cm2 and at most 100 W/cm2 per pixel.