Recording-material type determination apparatus and method and image forming apparatus

Abstract

To provide a recording-material type determination apparatus and recording-material type determination method which can determine the type of recording material using simple calculations as well as to provide an image forming apparatus capable of obtaining stable image quality independent of the type of recording material using the apparatus and method. Based on data read by a read unit which reads surface images of recording material, a first calculation unit calculates the depth of irregularities in the surface of recording material and stores the results of calculation in a register A while a second calculation unit calculates the spacing of irregularities on the surface of the recording material and stores the results of calculation in a register B. Based on the values in the registers A and B, the type of recording material such as gloss paper, plain paper, rough paper or OHT is determined.

What is claimed is: 
     
       1. A recording-material type determination apparatus comprising:
 a light emit unit, adapted to illuminate a surface of recording material;   a read unit, adapted to read an illuminated region on the surface of the recording material as a video image;   a first calculation part adapted to calculate information about depth of irregularities in the surface of the recording material based on video information read by the read unit;   a second calculation part adapted to calculate information about spacing of irregularities on the surface of the recording material based on the video information read by the read unit; and   a determination part adapted to determine a type of recording material based on calculation results produced by the first calculation part and the second calculation part.   
     
     
       2. A recording-material type determination apparatus according to  claim 1 , wherein the read unit is an area sensor including a plurality of pixels. 
     
     
       3. A recording-material type determination apparatus according to  claim 1 , wherein the read unit outputs a video image of the surface of the recording material as digital values. 
     
     
       4. A recording-material type determination apparatus according to  claim 1 , wherein the first calculation part quantitatively determines the depth of irregularities in the surface of the recording material by extracting a maximum value of contrast difference among pixels in a specific pixel region, from video information picked up by the read unit. 
     
     
       5. A recording-material type determination apparatus according to  claim 1 , wherein the second calculation part quantitatively determines the spacing of irregularities on the surface of the recording material by binarizing video information about pixels in a specific pixel region in video information picked up by the read unit and counting edge numbers in a binarized image. 
     
     
       6. A recording-material type determination apparatus according to  claim 1 , comprising:
 a memory part adapted to prestore information about depth of irregularities and spacing of irregularities for each type of recording material,   wherein the determination part determines the type of recording material by comparing the calculation results produced by the first calculation part and the second calculation part with information stored in the memory unit.   
     
     
       7. A recording-material type determination apparatus according to  claim 1 , wherein the first calculation part and the second calculation part consist of a DSP. 
     
     
       8. A recording-material type determination apparatus according to  claim 1 , wherein the determination part determines that the recording material is plain paper. 
     
     
       9. A recording-material type determination apparatus according to  claim 1 , wherein the determination part distinguishes whether the recording material is glossy paper or plain paper. 
     
     
       10. A recording-material type determination apparatus according to  claim 1 , wherein the determination part distinguishes whether the recording material is rough paper or plain paper. 
     
     
       11. A recording-material type determination apparatus according to  claim 1 , wherein the determination part distinguishes whether the recording material is OHT or plain paper. 
     
     
       12. A recording-material type determination apparatus comprising:
 an input part adapted to input a video image of a surface of recording material;   a first calculation part adapted to calculate information about depth of irregularities in a surface of the recording material based on video information inputted in the input unit;   a second calculation part adapted to calculate information about spacing of irregularities on the surface of the recording material based on the video information inputted in the input unit; and   a determination part adapted to determine a type of recording material based on calculation results produced by the first calculation part and the second calculation part.   
     
     
       13. A recording-material type determination method comprising:
 a read step of reading a surface of recording material as a video image;   a first calculation step of calculating information about depth of irregularities in the surface of the recording material based on results of the read step;   a second calculation step of calculating information about spacing of irregularities on the surface of the recording material based on the results of the read step; and   a determination step of determining a type of recording material based on calculation results produced in the first calculation step and the second calculation step.   
     
     
       14. A recording-material type determination method according to  claim 13 , wherein, in the read step, an area sensor including a plurality of pixels is used. 
     
     
       15. An image forming apparatus comprising:
 a conveying part adapted to convey recording material;   an image forming part which forms an image on the recording material conveyed by the conveyor;   a light emit unit, adapted to illuminate a surface of recording material;   a read unit, adapted to read an illuminated region on the surface of the recording material as a video image;   a first calculation part adapted to calculate information about depth of irregularities in the surface of the recording material based on video information read by the read unit;   a second calculation part adapted to calculate information about spacing of irregularities on the surface of the recording material based on the video information read by the read unit;   a determination part adapted to determine a type of recording material based on calculation results produced by the first calculation part and the second calculation part; and   a control part which controls image forming conditions of the image forming part based on the type of recording material determined by the determination part.   
     
     
       16. An image forming apparatus according to  claim 15 , wherein the image forming part comprises a developing part which develops a latent image on an image bearing member, a transferring part which transfers a visible image produced by the developing part to the recording material conveyed by the conveyor, and a fixing part which thermally fixes the visible image transferred to the recording material by the transferring part. 
     
     
       17. An image forming apparatus according to  claim 15 , wherein the image forming conditions controlled by the controller include at least one of developing conditions of the developing part, transfer conditions of the transferring part and fixing temperature for the fixing part.  
     
     
       18. An image forming apparatus according to  claim 15 , wherein an image forming condition controlled by the control part is speed at which the recording material passes through the fixing part. 
     
     
       19. A recording material type determination apparatus comprising:
 a sensor configured to read a surface image of a recording material, the surface image having pixels;   a calculation part configured to calculate difference information about irregularities in the surface of the recording material, wherein the calculation part generates a brightness difference between a bright portion and a dark portion in a pixel line of the surface image, and the difference information is obtained by using the brightness differences of plural pixel lines; and   a determination part configured to determine a type of the recording material based on the calculated difference information.   
     
     
       20. A recording material type determination apparatus according to claim 19,
 wherein the calculated difference information includes a contrast value that is calculated by the calculation part with brightness information of the pixels of the surface image.   
     
     
       21. A recording material type determination apparatus according to claim 19,
 wherein the sensor includes an area sensor that reads an area with a predetermined size of surface of the recording material as the surface image.   
     
     
       22. An image forming apparatus comprising:
 an image forming part configured to form an image on a recording material;   a sensor configured to read a surface image of a recording material, the surface image having pixels;   a calculation part configured to calculate difference information about irregularities in the surface of the recording material, wherein the calculation part generates a brightness difference between a bright portion and a dark portion in a pixel line of the surface image, and the difference information is obtained by using the brightness differences of plural pixel lines; and   a controller configured to control an image forming condition of the image forming part based on the calculated difference information about a depth of irregularities in the surface of the recording material.   
     
     
       23. An image forming apparatus according to claim 22, wherein the calculated difference information about the depth of irregularities in the surface of the recording material includes a contrast value that is calculated by the calculation part with the brightness information of the pixels of the surface image. 
     
     
       24. An image forming apparatus according to claim 22, wherein the sensor includes an area sensor that reads an area with a predetermined size of a surface of the recording material as the surface image. 
     
     
       25. An image forming apparatus according to claim 22, wherein the image forming part comprises an image bearing member, a developing part for developing an image on the image bearing member, a transferring part for transferring the image on the image bearing member to the recording material, a fixing part for fixing the image on the recording material, and
 wherein the image forming condition includes at least one of a developing condition of the developing part and a transferring condition of the transferring part and fixing condition of the fixing part and a transport speed of the recording material.   
     
     
       26. A recording material type determination method comprising:
 a read step of reading a surface image of a recording material, the surface image having pixels;   a calculation step of calculating difference information about irregularities in the surface of the recording material, wherein the calculation step includes a step of generating a brightness difference between a bright portion and a dark portion in a pixel line of the surface image and a step of using the brightness differences of plural pixel lines so that the difference information is obtained; and   a determination step of determining a type of the recording material based on the calculated difference information calculated in the calculation step.   
     
     
       27. A recording material type determination method according to claim 26,
 wherein the calculated difference information includes a contrast value that is calculated in the calculating step with the brightness information of the pixels of the surface image.   
     
     
       28. A recording material type determination apparatus comprising:
 a sensor configured to read a surface image of a recording material, the surface image having pixels;   a calculation part configured to calculate difference information about irregularities in the surface of the recording material, wherein the calculation part generates a brightness difference between a bright portion and a dark portion in a pixel line of the surface image, and the difference information is obtained by summing the brightness differences of plural pixel lines; and   a determination part configured to determine a type of the recording material based on the calculated difference information.   
     
     
       29. A recording material type determination apparatus according to claim 28,
 wherein the sensor includes an area sensor that reads an area with a predetermined size of surface of the recording material as the surface image.   
     
     
       30. An image forming apparatus comprising:
 an image forming part configured to form an image on a recording material;   a sensor configured to read a surface image of the recording material, the surface image having pixels;   a calculation part configured to calculate difference information about irregularities in the surface of the recording material, wherein the calculation part generates a brightness difference between a bright portion and a dark portion in a pixel line of the surface image, and the difference information is obtained by summing the brightness differences of plural pixel lines; and   a controller configured to control an image forming condition of the image forming part based on the calculated information.   
     
     
       31. An image forming apparatus according to claim 30, wherein the sensor includes an area sensor that reads an area with a predetermined size of surface of the recording material as the surface image. 
     
     
       32. An image forming apparatus according to claim 30, wherein the image forming part comprises an image bearing member, a developing part for developing an image on the image bearing member, a transferring part for transferring the image on the image bearing member to the recording material, and a fixing part for fixing the image on the recording material, and
 wherein the image forming condition includes at least one of a developing condition of the developing part and a transferring condition of the transferring part and fixing condition of the fixing part and a transport speed of the recording material.   
     
     
       33. A recording material type determination method comprising:
 a read step of reading a surface image of a recording material, the surface image having pixels;   a calculation step of calculating difference information about irregularities in the surface of the recording material, wherein the calculation step includes a step of generating a brightness difference between a brightest portion and a darkest portion in a pixel line of the surface image and a step of summing the brightness differences of plural pixel lines so that the difference information is obtained; and   a determination step of determining a type of the recording material based on the difference information calculated by the calculation step.   
     
     
       34. A recording material type determination apparatus for determining a surface condition of a recording material, comprising:
 a sensor configured to read a surface image of the recording material, the surface image having pixels;   a calculation part configured to calculate information about a depth of irregularities in the surface of the recording material, wherein the calculation part generates a brightness difference between a brightest portion and a darkest portion in each pixel line among plural pixel lines of the surface image and the information is obtained by summing the brightness differences of the plural pixel lines; and   a determination part configured to determine a type of the recording material based on the calculated difference information.   
     
     
       35. A recording material type determination apparatus according to claim 34, wherein the sensor includes area sensor that reads an area with a predetermined size of surface of the recording material as the surface image. 
     
     
       36. An image forming apparatus comprising:
 an image forming part configured to form an image on a recording material;   a sensor configured to read a surface image of the recording material, the surface image having pixels;   a calculation part configured to calculate information about a depth of irregularities in the surface of the recording material, wherein the calculation part generates brightness differences between a brightest portion and a darkest portion in each pixel line among plural pixel lines of the surface image and the information is obtained by summing the brightness differences of the plural pixel lines; and   a controller configured to control an image forming condition of the image forming part based on the calculated difference information.   
     
     
       37. An image forming apparatus according to claim 36, wherein the sensor includes an area sensor that reads an area with a predetermined size of surface of the recording material as the surface image. 
     
     
       38. An image forming apparatus according to claim 36, wherein the image forming part comprises an image bearing member, a developing part for developing an image on the image bearing member, a transferring part for transferring the image on the image bearing member to the recording material, and a fixing part for fixing the image on the recording material, and
 wherein the image forming condition includes at least one of a developing condition of the developing part and a transferring condition of the transferring part and fixing condition of the fixing part and a transport speed of the recording material.   
     
     
       39. A recording material surface condition detection apparatus for determining a surface condition of a recording material, comprising:
 a sensor configured to read a surface image of the recording material, the surface image having pixels;   a calculation part configured to calculate information about a depth of irregularities in the surface of the recording material, the calculation part generates brightness differences between a brightest portion and a darkest portion in each pixel line among plural pixel lines of the surface image and the information is obtained by summing the brightness differences of the plural pixel lines; and   a detection part configured to detect a condition of the surface of the recording material based on the information calculated by the calculation part.   
     
     
       40. A recording material surface condition detection apparatus according to claim 39, wherein the calculated information includes a contrast value that is calculated by the calculation part with brightness information of the pixels of the surface image. 
     
     
       41. A recording material surface condition detection apparatus according to claim 39, wherein the sensor includes an area sensor that reads an area with a predetermined size of surface of the recording material as the surface image.