LOCATING METHOD OF AN OPTICAL SENSOR, AN ADJUSTMENT METHOD OF DOT PRINTING POSITION USING THE OPTICAL SENSOR, AND A PRINTING APPARATUS

• US 20030016263A1
• Filed: 10/25/1999
• Published: 01/23/2003
• Est. Priority Date: 10/27/1998
• Status: Active Grant

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: OTSUKA, NAOJI, TESHIGAWARA, MINORU, TAKAHASHI, KIICHIRO, CHIKUMA, TOSHIYUKI, IWASAKI, OSAMU, NISHIKORI, HITOSHI
• Granted Patent: US 6,547,360 B2
• Time in Patent Office: Days
• US Class Current: 347/19
• CPC Class Codes: B41J 19/145 Dot misalignment correction
• CPC Class Codes: B41J 2/125 Sensors, e.g. deflection sensors nozzle clogging detection for cleaning reasons B41J2/16579; detection for compensation for failed nozzles B41J2/2139
• CPC Class Codes: B41J 2/2135 Alignment of dots
• CPC Class Codes: B41J 29/393 Devices for controlling or analysing the entire machine ; Controlling or analysing mechanical parameters involving printing of test patterns

Abstract

There is provided a printing registration method for stably performing printing registration in bi-directional scanning by a print head in a printing apparatus or printing registration between a plurality of print heads with high accuracy. In complementary printing by the bi-directional scanning by the head, a plurality of patterns are printed while printing starting timings are shifted by predetermined quantities with respect to reference dots (dots formed by forward scanning). In the pattern, an area factor defined by the dots formed by the printing is varied according to the shifting. The plurality of patterns are optically read as an average density. The timing corresponding to a point where the read average density is highest can be determined as a printing registration condition. Furthermore, an optical sensor used for the reading is located at a position where an S/N ratio is stable with respect to fluctuations in distance from the object to be read, thus achieving stable reading.

Claims

1. An optical sensor locating method comprising the steps of:

providing a light-emitting portion for irradiating an object to be measured with light and a photosensing portion for sensing the light reflected on the object to be measured; and

locating the optical sensor at a position where a n output characteristic of the optical sensor is substantially stable with respect to factors of fluctuations at the time of measurement relatively to the object to be measured.

2. An optical sensor locating method as claimed in claim 1, wherein the factors of fluctuations include fluctuations in distance between the object to be measured and the optical sensor.

3. An optical sensor locating method as claimed in claim 2, wherein the center value of the fluctuations in distance is set at a value of a distance longer by a predetermined quantity than a distance where an S/N ratio as the output characteristic is maximum.

4. A printing registration method for processing for performing printing registration in a first printing and a second printing with respective to a printing apparatus for performing printing of an image by said first printing and said second printing with predetermined conditions of a dot forming position on a printing medium by using a printing head, said method comprising the steps of:

pattern-forming for controlling said printing head to form a plurality of patterns respectively having optical characteristics corresponding to a plurality of shifting amounts, said plurality of patterns being respectively formed corresponding to said plurality of shifting amounts of relative printing positions of said first printing and said second printing, said patterns being formed by said first printing and said second printing;

measuring respective optical characteristics of said plurality of the formed patterns by using an optical sensor providing a light-emitting portion for irradiating said pattern as an object to be measured with light and a photosensing portion for sensing the light reflected on the object to be measured;

said optical sensor being located at a position where an output characteristic of the optical sensor is substantially stable with respect to factors of fluctuations at the time of measurement relatively to the object to be measured; and

acquiring an adjustment value of a dot for ming position condition between said first printing and said second printing on the basis of respective optical characteristics of said plurality of patterns measured.

5. A printing registration method as claimed in claim 4, wherein the factors of fluctuations include fluctuations in distance between the object to be measured and the optical sensor.

6. A printing registration method as claimed in claim 5, wherein the center value of the fluctuations in distance is set at a value of a distance longer by a predetermined quantity than a distance where an S/N ratio as the output characteristic is maximum.

7. A printing registration method as claimed in claim 4, wherein said first printing and said second printing include at least one among a printing in a forward scan and in a reverse scan respectively upon performing printing by bi-directionally scanning said printing head with respect to said printing medium, a printing being a printing by a first printing head and a printing by a second printing head among a plurality of said printing heads respectively in a direction in which said first printing head and said second printing head are relatively scanned with respect to said printing medium, and a printing being a printing by a first printing head and a printing by a second printing head among a plurality of printing heads respectively, in a direction different from the direction which said first printing head and said second printing head are relatively scanned with respect to said printing medium.

8. A printing registration method as claimed in claim 4, wherein said adjustment value acquiring step derives said adjustment value by calculation employing continuous values on the basis of optical characteristics data obtained from said measuring step by using a linear approximation or a polynominal approximation.

9. A printing registration method as claimed in claim 4, wherein, in said pattern-forming step, the dots formed by said first printing and the dots formed by said second printing are arranged, and relative positional relationship of said dots is varied corresponding to said plurality of shifting amounts, and a ratio of said dots covering said printing medium is varied, thereby to form said plurality of patterns having optical characteristics corresponding to said shifting amounts.

10. A printing registration method as claimed in claim 4, wherein said printing head is a head for performing printing by ejecting the ink.

11. A printing registration method as claimed in claim 10, wherein said printing head has heating elements for generating thermal energy to make the ink to film-boil, as an energy used for ejecting the ink.

13. A printing apparatus as claimed in claim 12, wherein the factors of fluctuations include fluctuations in distance between the object to be measured and the optical sensor.

14. A printing apparatus as claimed in claim 13, wherein the center value of the fluctuations in distance is set at a value of a distance longer by a predetermined quantity than a distance where an S/N ratio as the output characteristic is maximum.

16. A printing apparatus as claimed in claim 15, wherein the factors of fluctuations include fluctuations in distance between the object to be measured and the optical sensor.

17. A printing apparatus as claimed in claim 16, wherein the center value of the fluctuations in distance is set at a value of a distance longer by a predetermined quantity than a distance where an S/N ratio as the output characteristic is maximum.

18. A printing apparatus as claimed in claim 15, wherein said first printing and said second printing include at least one among a printing in a forward scan and in a reverse scan respectively upon performing printing by bi-directionally scanning said printing head with respect to said printing medium, a printing being a printing by a first printing head and a printing by a second printing head among a plurality of said printing heads respectively in a direction in which said first printing head and said second printing head are relatively scanned with respect to said printing medium, and a printing being a printing by a first printing head and a printing by a second printing head among a plurality of printing heads respectively, in a direction different from the direction which said first printing head and said second printing head are relatively scanned with respect to said printing medium.

19. A printing apparatus as claimed in claim 15, wherein said adjustment value acquiring means derives said adjustment value by calculation employing continuous values on the basis of optical characteristics data obtained from said measuring means by using a linear approximation or a polynominal approximation.

20. A printing apparatus as claimed in claim 15, wherein, in the pattern forming by said pattern-forming means, the dots formed by said first printing and the dots formed by said second printing are arranged, and relative positional relationship of said dots is varied corresponding to said plurality of shifting amounts, and a ratio of said dots covering said printing medium is varied, thereby to form said plurality of patterns having optical characteristics corresponding to said shifting amounts.

21. A printing apparatus as claimed in claim 15, wherein said printing head is a head for performing printing by ejecting the ink.

22. A printing apparatus as claimed in claim 21, wherein said printing head has heating elements for generating thermal energy to make the ink to film-boil, as an energy used for ejecting the ink.

12. A printing apparatus for performing printing of an image on a printing medium by using a printing head, comprising:

means for measuring by using an optical sensor providing a light-emitting portion for irradiating an object to be measured with light and a photosensing portion for sensing the light reflected on the object to be measured; and

means for supporting said optical on a position where an output characteristic of the optical sensor is substantially stable with respect to factors of fluctuations at the time of measurement relatively to the object to be measured.

15. A printing apparatus for performing printing of an image by a first printing and a second printing with predetermined conditions of a dot forming position on a printing medium by using a printing head, comprising:

pattern-forming means for controlling said printing head to form a plurality of patterns respectively having optical characteristics corresponding to a plurality of shifting amounts, said plurality of patterns being respectively formed corresponding to said plurality of shifting amounts of relative printing positions of said first printing and said second printing, said patterns being formed by said first printing and said second printing;

means for measuring respective optical characteristics of said plurality of the formed patterns by using an optical sensor providing a light-emitting portion for irradiating said pattern as an object to be measured with light and a photosensing portion for sensing the light reflected on the object to be measured;

said optical sensor being located at a position where an output characteristic of the optical sensor is substantially stable with respect to factors of fluctuations at the time of measurement relatively to the object to be measured; and

means for acquiring an adjustment value of a dot forming position condition between said first printing and said second printing on the basis of respective optical characteristics of said plurality of patterns measured.

23. A printing system provided with a printing apparatus for performing printing of an image by a first printing and a second printing with predetermined conditions of a dot forming position on a printing medium by using a printing head, and a host apparatus for supplying an image data to said printing apparatus, comprising:

pattern-forming means for controlling said printing head to form a plurality of patterns respectively having optical characteristics corresponding to a plurality of shifting amounts, said plurality of patterns being respectively formed corresponding to said plurality of shifting amounts of relative printing positions of said first printing and said second printing, said patterns being formed by said first printing and said second printing;

means for measuring respective optical characteristics of said plurality of the formed patterns by using an optical sensor providing a light-emitting portion for irradiating said pattern as an object to be measured with light and a photosensing portion for sensing the light reflected on the object to be measured;

said optical sensor being located at a position where an output characteristic of the optical sensor is substantially stable with respect to factors of fluctuations at the time of measurement relatively to the object to be measured; and

means for acquiring an adjustment value of a dot forming position condition between said first printing and said second printing on the basis of respective optical characteristics of said plurality of patterns measured.