Color image forming apparatus and method of controlling same

Abstract

An image of stabilized tint is output even if a supplied transfer medium is changed to a transfer medium of a different surface gloss or type of paper. If the supplied transfer medium has changed, the tint of a corrective image formed on the transfer medium is sensed, a tint correction of an image forming portion is performed based upon result of sensing, and corrective data of the tint correction and information relating to the transfer medium is stored. If a change of the transfer medium is sensed subsequently, a determination is made as to whether the transfer medium is substantially the same transfer medium, based upon the stored information relating to the transfer medium. If the transfer medium is substantially the same, then image processing is executed based upon the stored corrective data.

1. A method of controlling an image forming apparatus for forming an image on a transfer medium, comprising:
 a determination step of determining that a characteristic of the transfer medium has changed;  
 an entering step for allowing an operator to enter whether or not a density sensing sequence is to be executed, based upon the determination of the change in the characteristic of the transfer medium;  
 a step of executing the density sensing sequence in a case where the fact that said sequence is to be executed has been entered, the density sensing sequence including a sensing step of forming an image, which is for sensing density, on the transfer medium, and sensing this density-sensing image on the transfer medium; and  
 a step of deciding image forming conditions of the image forming apparatus based upon a result of sensing density in the density sensing sequence.  
 
     
     
       2. The method according to  claim 1 , wherein said determination step includes determining the characteristic of the transfer medium using a sensor for sensing surface gloss of the transfer medium. 
     
     
       3. The method according to  claim 1 , wherein said determination step includes a step of determining that the characteristic of the transfer medium has changed by allowing a user to enter information relating to the characteristic of the transfer medium. 
     
     
       4. The method according to  claim 1 , further comprising:
 a step of storing the image forming conditions that have been decided; and  
 a correcting step of correcting image forming conditions based upon the stored image forming conditions corresponding to the determined characteristic of the transfer medium.  
 
     
     
       5. The method according to  claim 1 , wherein if the fact that the density sensing sequence is not to be executed has been entered, then the image forming conditions are corrected in said correcting step based upon the stored image forming conditions corresponding to the determined characteristic of the transfer medium. 
     
     
       6. The method according to  claim 1 , wherein the density sensing sequence includes a sensing step of forming the density-sensing image on the transfer medium and sensing tint of the density-sensing image using a sensor for sensing, on a per-color-component basis, density of the density-sensing image on the transfer medium. 
     
     
       7. The method according to  claim 1 , wherein the image forming conditions are data in a calibration table for converting image data. 
     
     
       8. A computer-readable recording medium on which is recorded, in executable form, a program for causing a computer to execute each step of the control method set forth in  claim 1 . 
     
     
       9. An image forming apparatus comprising:
 an image forming unit adapted to form an image on a transfer medium;  
 a sensor adapted to sense an image, which is for sensing density, formed by said image forming unit;  
 a control unit adapted to decide image forming conditions of said image forming unit based upon a result of sensing by said sensor;  
 a determination unit adapted to determine that a characteristic of the transfer medium has changed; and  
 input means for allowing an operator to enter whether or not a density sensing sequence is to be executed, based upon the determination of the change in the characteristic of the transfer medium;  
 said apparatus executing the density sensing sequence in a case where the fact that the sequence is to be executed has been entered, the density sensing sequence including forming the image, which is for sensing density, on the transfer medium, and sensing this density-sensing image on the transfer medium using said sensor.  
 
     
     
       10. The apparatus according to  claim 9 , further comprising a sensor adapted to sense surface gloss of the transfer medium;
 wherein said determination unit determines a change in the characteristic of the transfer medium based upon an output of said sensor.  
 
     
     
       11. The apparatus according to  claim 9 , wherein said input means is also for allowing an operator to enter information relating to the characteristic of the transfer medium,
 wherein said determination unit determines a change in the characteristic of the transfer medium based upon an output of said input unit.  
 
     
     
       12. The apparatus according to  claim 9 , further comprising a storage unit adapted to store the image forming conditions that have been decided,
 wherein said apparatus corrects the image forming conditions based upon the stored image forming conditions corresponding to the determined characteristic of the transfer medium.  
 
     
     
       13. The apparatus according to  claim 9 , wherein if the fact that the density sensing sequence is not to be executed has been entered, then said apparatus corrects the image forming conditions based upon the stored image forming conditions corresponding to the determined characteristic of the transfer medium. 
     
     
       14. The apparatus according to  claim 9 , wherein said sensor is capable of sensing tint of the density-sensing image by sensing, on a per-color-component basis, density of the density-sensing image on the transfer medium. 
     
     
       15. The apparatus according to  claim 9 , wherein the image forming conditions are data in a calibration table for convening image data. 
     
     
       16. A color image forming apparatus for forming a test pattern on a transfer medium and stabilizing tint based on a result of sensing the test pattern fixed on the transfer medium by a fixing unit, comprising:
   a sensing unit that automatically senses the test pattern fixed on the transfer medium, on the way of conveying path which the transfer medium is conveyed after an image is fixed on the transfer medium and before the transfer medium is discharged;        a color stabilization controller that executes a color stabilization control of obtaining corrective data, for correcting an image signal to stabilize tint, based on a result of sensing by the sensor;        a storage controller that controls a storage operation of the corrective data into a storage, wherein the corrective data according to each of a plurality of types of the transfer medium can be read from the storage;        an image forming unit that forms the image based on the corrective data stored in the storage; and        a recognition unit that recognizes a type of the transfer medium,        wherein the corrective data, which is able to read from the storage and according to each type of the transfer medium, is according to the controlling by the storage controller which controls the storage operation of the corrective data obtained by the color stabilization controller, so as to be able to form the image by the image forming unit based on the corrective data according to the type of the transfer medium recognized by the recognition unit from the plurality of types of the transfer medium, and        even if the color stabilization control is not executed again by the color stabilization controller, the corrective data according to the type of transfer medium recognized by the recognition unit from the plurality of types of transfer medium is read from the storage and the image is formed by the image forming unit.     
     
     
       17. A color image forming apparatus for forming a test pattern on a transfer medium and stabilizing tint based on a result of sensing the test pattern fixed on the transfer medium by a fixing unit, comprising:
   a sensor that automatically senses the test pattern fixed on the transfer medium, on the way of conveying path which the transfer medium is conveyed after an image is fixed on the transfer medium before the transfer medium is discharged;        a color stabilization controller that executes a color stabilization control of obtaining corrective data, for correcting an image signal to stabilize tint based on a result of sensing by the sensor;        a storage that automatically stores the corrective data such that the corrective data can be specified in accordance with the type of transfer medium;        a recognition unit that recognizes a type of transfer medium; and        an image forming unit that forms the image using corrective data, which is specified in accordance with the type of transfer medium recognized by the recognition unit in a plurality of pieces of the corrective data stored in the storage.     
     
     
       18. The apparatus according to  claim 17 , wherein a patch of black and mixed- color patches of cyan, magenta and yellow are included in the test pattern, and a mixture ratio of cyan, magenta and yellow in the mixed - color patches is obtained by the color stabilization control such that tint of the mixed - color patches matches tint of the patch of black.   
     
     
       19. The apparatus according to  claim 17 , further comprising an update unit that updates the corrective data being readable from the storage by putting the sensor and the color stabilization controller in action. 
     
     
       20. The apparatus according to  claim 19 , wherein the update unit comprises a determination unit that determines whether or not to execute the update based on the change of use conditions of the color image forming apparatus. 
     
     
       21. The apparatus according to  claim 17 , further comprising an update unit that stores corrective data obtained by the color stabilization control such that the obtained corrective data can be specified in accordance with the type of changed transfer medium, by putting the sensor and the color stabilization controller in action, according to the recognition of the change of the type of transfer medium by the recognition unit. 
     
     
       22. A color stabilization control method of a color image forming apparatus for forming a test pattern on a transfer medium and stabilizing tint based on a result of sensing the test pattern fixed on the transfer medium by a fixing unit, comprising:
   a sensing step of automatically sensing the test pattern fixed on the transfer medium, on the way of conveying path which the transfer medium is conveyed after an image is fixed on the transfer medium and before the transfer medium is discharged;        a color stabilization control step of executing a color stabilization control of obtaining corrective data, for correcting an image signal to stabilize tint, based on the result of sensing in the sensing step;        a storage control step of controlling a storage operation of the corrective data into a memory, wherein the corrective data according to each of a plurality of types of the transfer medium can be read from the memory;        an image forming step of forming the image based on the corrective data stored in the memory; and        a recognition step of recognizing a type of the transfer medium,        wherein the corrective data, which is able to read from the memory according to each type of the transfer medium, is according to the controlling in the storage control step which controls the storage operation of the corrective data obtained in the color stabilization control step, so as to be able to form the image in the image forming step based on the corrective data according to the type of the transfer medium recognized in the recognition step from the plurality of types of the transfer medium, and        even if the color stabilization control is not executed again in the color stabilization control step, the corrective data according to the type of transfer medium recognized in the recognition step from the plurality of types of transfer medium is read from the memory and the image is formed in the image forming step.     
     
     
       23. A color stabilization control method of a color image forming apparatus for forming a test pattern on a transfer medium and stabilizing tint based on a result of sensing the test pattern fixed on the transfer medium by a fixing unit, comprising:
   a sensing step of automatically sensing the test pattern fixed on the transfer medium, on the way of conveying path which the transfer medium is conveyed after an image is fixed on the transfer medium before the transfer medium is discharged until an image is fixed and discharged on the transfer medium;        a color stabilization control step of executing a color stabilization control of obtaining corrective data, for correcting an image signal to stabilize tint based on the result of sensing in the sensing step;        a storing step of automatically storing the corrective data in a memory such that the corrective data can be specified in accordance with the type of transfer medium;        a recognition step of recognizing a type of transfer medium; and        an image forming step of forming the image using corrective data, which is specified in accordance with the type of transfer medium recognized in the recognition step in a plurality of pieces of the corrective data stored in the memory.     
     
     
       24. The method according to  claim 23 , wherein a patch of black and mixed- color patches of cyan, magenta and yellow are included in the test pattern, and a mixture ratio of cyan, magenta and yellow in the mixed - color patches is obtained by the color stabilization control such that tint of the mixed - color patches matches tint of the patch of black.   
     
     
       25. The method according to  claim 23 , further comprising an update step of updating the corrective data being readable from the memory by executing the sensing step and the color stabilization control step. 
     
     
       26. The method according to  claim 25 , wherein the update step comprises a determination step of determining whether or not to execute the update based on the change of use conditions of the color image forming apparatus. 
     
     
       27. The method according to  claim 23 , further comprising an update step of storing corrective data obtained by the color stabilization control such that the obtained corrective data can be specified in accordance with the type of changed transfer medium, by executing the sensing step and the color stabilization control step, according to the recognition of the change of the type of transfer medium in the recognition step.