Method and apparatus for aligning print

Abstract: A printing apparatus arranged to perform printing while a monochrome printing head and a color printing head are moved in a direction in which the two heads are moved, the printing apparatus being arranged to print a plurality of patterns in which the relative quantity of deviation of printing timings of the two heads is changed in a stepped manner to cause a user to select a pattern having the smallest quantity of deviation among the plural patterns. Then, the selected pattern is used as a central value when a plurality of patterns in which the relative quantity of deviation of the printing timings of the two heads is changed in a stepped manner are furthermore printed to cause the user to select a pattern having a smallest quantity of deviation from the plural patterns. The above-mentioned process is repeated as necessary. As a result, the operation which is performed by the user to adjust the printing position can simply and easily be performed. Control is performed in such a manner as to change color to be printed by the color printing head whenever an adjustment mode in which the relative quantity of deviation of the printing timing is adjusted is started.

Description: BACKGROUND OF THE INVENTION (1) Field of the Invention The present invention relates to a method of adjusting a printing position which is adaptable to a printing apparatus having, for example, a monochrome printing head and a color printing head and arranged to perform a printing operation in such a manner that the both printing heads are moved in the direction in which the both printing heads are disposed, a printing apparatus using the adjustment method and a recording medium on which a control program for performing the adjustment method is stored. (2) Description of the Related Art EP-A-0 589 718 describes a pen alignment method for use in ink-jet printers, the method involving user interaction with automatic pen alignment firmware to select the best alignment among a number of illustratively printed options to achieve semi-automatic inter-pen alignment. The method comprises printing of printing patterns for judging the horizontal alignment, after which the user enters the pattern showing the best alignment in his opinion in the horizontal direction. Then, a vertical alignment pattern is printed, after which the user enters the pattern showing the best alignment in his opinion in the vertical direction. Then, a confirmation pattern is printed. US-A-4 878 063 describes a multi-color printing apparatus and method that uses line patterns as a means for semi-automatic adjustment of color separation planes. A set of lines in one color having a specific adjustment width is printed, and below this set a second set of a different color and a different adjustment width is printed. A central line of this set is used as a base registration position. The user inputs the pattern corresponding to the line having the best alignment, such that if this selected line is different from the base registration position, then the printer can determine which adjustment to perform. Since a graphic process has relatively easily be performed because personal computers have been developed, a printing apparatus has been required which is capable of producing a high-quality output of a hard copy of a color image which is displayed on a display unit. To satisfy the above-mentioned requirement, printing apparatuses of a type having an ink jet printing head have been provided. The ink jet printing apparatuses of the foregoing type are able to perform a printing operation with a relatively low noise sound level. Moreover, the ink jet printing apparatuses are able to form a small dot at a high density. Therefore, the ink jet printing apparatuses of the foregoing type have been employed to perform a multiplicity of printing operations including color printing. The ink jet printing apparatus of the foregoing type incorporates an ink jet printing head arranged to be supplied with ink from an ink accommodating means and a paper feeding means for relatively moving recording paper with respect to the ink jet printing head. In response to a print command signal, an ink droplet is discharged to form a dot so that a printing operation is performed. The printing apparatus of the foregoing type has a common head holder (carriage) on which a monochrome printing head capable of discharging black ink and a color printing head capable of discharging, for example, yellow, cyan and magenta ink, are mounted. Thus, the printing apparatus of the foregoing type is able to perform a full color printing operation by changing the discharge ratio of ink in the foregoing colors as well as printing a text document using black ink. The carriage on which the monochrome printing head and the color printing head are mounted is pulled by a timing belt which is rotated by a motor for operating the carriage so as to perform a reciprocating motion in the direction of the printing lines. That is, both of the monochrome printing head and the color printing head are moved in the direction in which the two heads align so that the printing operation is performed. The above-mentioned serial-type printing apparatus has a structure that the monochrome printing head and the color printing head are disposed apart from each other. As a matter of course, printing cannot be performed at the same position of paper at the same timing. Therefore, ink discharge is performed in such a maker that timings of print signals arranged to be supplied to the two heads are shifted from each other. Thus, the printing position (the ink arrival position) of the monochrome printing head and the printing position of the color printing head are adjusted to coincide with each other in the direction in which the heads are moved. However, variations of the two assembled heads, change in the environmental temperature and vibrations cause the relative positions between the two heads to be deviated. As a result, the printing position of the monochrome printing head and that of the color printing head are deviated from each other in the direction in which the two heads are moved. As a result, the quality of the printed image deteriorates. To modify deviation in the printing position, a printing apparatus having a function capable of adjusting the printing position has been provided. Fig. 4 shows a method of adjusting the printing position employed by a printing apparatus having the conventional function of adjusting the printing position. The printing-position adjustment method is arranged in such a manner that timing data for delaying timing stored in a control unit of the printing apparatus is gradually changed. Thus, a plurality of patterns (in this case, twelve patterns (A) to (L)) in which the quantity of relative deviation in the printing timing between the monochrome printing head and the color printing head is changed in a stepped manner are simultaneously printed on one page of A4-size paper. In the pattern shown in Fig. 4, solid lines indicate results of printing operations performed by the monochrome printing head and dashed lines indicate results of printing operations performed by the color printing head. When the ink jet printing apparatus prints the foregoing patterns, upper half nozzles of nozzle lines on the ink discharge surface of the printing head composed of a plurality of nozzles of the monochrome head disposed in a direction perpendicular to the direction (the main scanning direction) in which the heads are disposed are used. On the other hand, lower half nozzles of the color head are used by the color head. As can be understood from the patterns (A) to (L), the printing positions (indicated by the dashed lines) of the color head with respect to the printing positions (indicated by the solid lines) of the monochrome head are, in a stepped manner, deviated in a rightward direction from the pattern (A) to the pattern (L). A user subjects the patterns (A) to (L) to comparisons to select a pattern having the smallest quantity of deviation. Then, a symbol corresponding to the selected pattern is input to the printing apparatus. Since the pattern (I) has the smallest quantity of deviation in this case, symbol (I) is input to the printing apparatus. When the symbol corresponding to the pattern is input to the printing apparatus, data corresponding to the symbol (which is I in this case), is written on a control unit of the printing apparatus (hereinafter also called as a "printer") so that adjustment of the printing position is completed. When the printing position is adjusted, color of ink for use to print the pattern by the color printing head is limited to a specific color (for example, cyan). The above-mentioned conventional method of adjusting the printing position of the printing apparatus is arranged in such a manner that a plurality of patterns are printed one time and an optimum pattern among the plural patterns is selected by a user. Therefore, if the range of the quantity of deviation which can be adjusted is enlarged or if the adjustment accuracy is improved (that is, if the quantity of change (the quantity of deviation) between patterns is reduced), there arises a problem in that an operation required for the user to perform selection becomes too complicated. The foregoing fact will specifically be described. In general, the quantity of change which can be determined visually by a human being is limited to 0.01 mm. If the quantity of change between patterns in the stepped manner is too large, a required adjustment cannot be performed. If the quantity of change is determined to be 0.1 mm and the number of patterns which can be printed on A4-size paper is assumed to be 15, the quantity of deviation which can be adjusted by the conventional printing-position adjustment method for the printing apparatus is 1.4 mm (the value is not 15 mm because of existence of a central value). However, the deviation of the printing position between the two heads occurring due to the foregoing change in the environmental temperature or the like is sometimes 1.4 mm or greater. When the range in which the printing position can be adjusted is enlarged to, for example, about 2.9 mm to overcome the above-mentioned problem, the conventional method of adjusting the printing position is required to simultaneously print thirty patterns. Since the above-mentioned patterns cannot be printed on one A4-size paper, the patterns are printed across a page boundary. Therefore, the user must subject the thirty patterns printed across the page boundary to comparisons to select one optimum pattern. Therefore, there arises a problem in that a complicated adjustment operation must be performed. On the other hand, printing apparatuses each of which is capable of forming an image having a higher resolution have recently been provided. An excessive influence of slight deviation in the printing position between the monochrome printing head and the color printing head exerts on the image quality of the above-mentioned printing apparatus. Therefore, more precise adjustment must be performed. That is, improvement in the adjustment accuracy (reduction of the quantity of change (the quantity of deviation) between patterns in the stepped manner) has been required. If the quantity of change is set to be 0.05 mm and the quantity of deviation which can be adjusted is made to be 1.4 mm (which is not 2.9 mm) to satisfy the above-mentioned requirement, the conventional printing-position adjustment method is required to print thirty patterns. Therefore, the thirty patterns are printed across the page boundary of A4-size paper. Similarly, the user must subject the thirty patterns printed across the page boundary to comparisons to select one optimum pattern. Therefore, there arises the same problem in that a complicated adjustment operation must be performed. Also in this case, a multiplicity of patterns of small quantities of change must simultaneously be subjected to comparisons. Therefore, a furthermore complicated adjustment operation must be performed. As described above, the conventional printing-position adjustment method is arranged in such a manner that a plurality of patterns are printed one time to cause a user to select one optimum pattern. Therefore, if the range of the quantity of deviation which can be adjusted is enlarged or if the adjustment accuracy is improved, the user cannot smoothly perform the selecting operation. The conventional printing-position adjustment method has the structure that the color for use to print the patterns by the color printing head is limited to a specific color. Therefore, only the ink of the specific color is consumed in a larger quantity as compared with ink of the other colors. If cyan ink is used to print the patterns by the color ink jet printing head, only the cyan ink is consumed in a larger quantity as compared with ink of the other colors. In general, an ink pack in which yellow, cyan and magenta ink is enclosed is mounted on a cartridge of color ink. If ink of a certain color is somewhat consumed, the cartridge must be changed. Therefore, if ink of a specific color is consumed, the cartridge must be changed though the other ink is remained in a considerably large quantity. It is disadvantage in terms of economy for the user. Since the cartridge in which other ink remains in a relatively large quantity must be discarded, disposal of the cartridge sometimes arises a problem. SUMMARY OF THE INVENTION In view of the foregoing, the object of the present invention is to provide a printing-position adjustment method capable of facilitating an operation for adjusting the printing position which is performed by a user, enlarging a range of a quantity of deviation of printing which can be adjusted and improving an adjustment accuracy, and to provide a printing apparatus adapted to the adjustment method and a recording medium on which a program for controlling adjustment of the printing position is stored. This object is achieved by the printing-position adjustement method of independent claim 1, the printing apparatus of independent claim 10, and the recording medium of independent claim 19. Advantageous embodiments are described in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing a printing apparatus according to the present invention and a structure in which a control program for performing the function for adjusting the printing position is installed from a recording medium on a printing apparatus; Fig. 2 is a diagram showing patterns printed by a printing-position adjustment method according to a first embodiment of the present invention; Fig. 3 is a diagram showing patterns printed by a printing-position adjustment method according to a second embodiment of the present invention; and Fig. 4 is a diagram showing patterns printed by a conventional printing-position adjustment method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will now be described. Fig. 1 is a diagram showing the structure of a printing apparatus according to the present invention and a structure for installing a control program for executing the printing-position adjustment function from a recording medium on the printing apparatus. Referring to Fig. 1, a drive mechanism 1 for the printing apparatus is provided. A monochrome printing head 2 and a color printing head 3 are secured to a carriage 4. The carriage 4 is joined in such a manner that the carriage 4 is, by a guide shaft 5 disposed in the horizontal direction, able to perform reciprocating motion in a direction of lines which must be printed. A timing belt 9 is arranged between a drive pulley 7 joined to a drive shaft of the carriage-drive motor 6 and a follower pulley 8 disposed opposite to the drive pulley 7 in the axial direction of the guide shaft 5. Thus, the carriage 4 is, by the timing belt 9, able to perform reciprocating motion on the guide shaft 5 in the direction of the lines which must be printed, that is, the main scanning direction indicated with an arrow shown in Fig. 1. The monochrome printing head 2 and the color printing head 3 disposed in parallel on the carriage 4 print dots on printing paper P placed on a platen (not shown). That is, the monochrome printing head 2 and the color printing head 3 are structured in such a manner as to print data while moving in the direction in which the two heads 2 and 3 are disposed. The structure is arranged in such a manner that the monochrome printing head 2 and the color printing head 3 are supplied with black ink and color ink from an ink cartridge 10. Moreover, an ink-level-detecting portion 11 for detecting a remaining quantity of ink accommodated in the ink cartridge 10 is provided for the printing apparatus according to this embodiment. The ink cartridge 10 has a cartridge in which black ink is enclosed and a cartridge in which color ink is enclosed which are disposed individually. Moreover, the ink-level-detecting portion 11 is individually provided for each of the ink cartridges. The ink-level-detecting portion 11 corresponding to the cartridge in which color ink is enclosed is able to independently detect a remaining quantity of ink in each ink pack (for example, yellow, cyan and magenta). A portion 21 surrounded by a dashed line is a printer control unit for controlling the drive mechanism 1 and the like. The printer control unit 21 includes a printing control unit 25 serving as a printing control means having a monochrome head drive portion 22, a color head drive portion 23 and a motor drive portion 24 which are surrounded by a dashed line. The monochrome head drive portion 22 is supplied with an instruction issued from a central control unit 26 comprising a microprocessor so as to supply a print command signal to the monochrome printing head 2. The color head drive portion 23 receives an instruction issued from the central control unit 26 so as to supply a print command signal to the color printing head 3. The motor drive portion 24 receives an instruction issued from the central control unit 26 so as to supply a drive signal to the carriage-drive motor 6. An adjustment-pattern control unit 27 surrounded by a dashed line and serving as an adjustment-pattern control means is disposed in such a manner as to be capable of communicating data to and from the central control unit 26. The adjustment-pattern control unit 27 includes an adjustment-pattern storage portion 28, an adjustment-pattern generating portion 29 and an adjustment-repetition-number determination portion 30. In the adjustment-pattern storage portion 28, various delay pattern data items for realizing the printing-position adjustment mechanism are stored. The adjustment-pattern generating portion 29 makes an access to the adjustment-pattern storage portion 28 so as to generate various adjustment patterns in which the relative quantities of deviation of printing timings to be described are changed in a stepped manner in accordance with data of the delay patterns. The adjustment-repetition-number determination portion 30 administrates the number of repetitions of sequential input of patterns each having a small quantity of deviation among a plurality of patterns printed by the monochrome printing head 2 and the color printing head 3, the patterns having a small quantity of deviation being supplied from a pattern input means to be described later. The adjustment-pattern control unit 27 is structured in such a manner as to receive a command signal from a pattern selection portion 31. That is, the pattern selection portion 31 includes an administration table (not shown) for administrating color to be printed (ink which must be used) by the color printing head 3. Thus, selection is permitted from, for example, a first selection mode in which color to be printed (ink which must be used) by the color printing head 3 can be selected; a second selection mode in which color to be printed (ink which must be used) by the color printing head 3 is changed whenever the printing-position adjustment mode is started; a third selection mode in which color to be printed by the color head is changed whenever the plural patterns are printed after the printing-position adjustment mode has been started; and a fourth selection mode in which color to be printed by the color head is automatically selected in accordance with information of an ink level communicated from the ink-level-detecting portion as described later. Moreover, information of the ink level is communicated from the ink-level-detecting portion 11 to the ink-level-determination portion 32. The ink-level-determination portion 32 monitors the level of ink, in particular, color ink (for example, the levels of yellow, cyan and magenta). If the fourth selection mode is selected by the pattern selection portion 31, the ink-level-determination portion 32 issues a command to the ink selection portion 33 so that control is performed in such a manner that ink remaining in a large quantity among color ink is used. The central control unit 26 is arranged to communicate data to and from an operation control unit 34. The operation control unit 34 is structured in such a manner as to be capable of communicating data relating to operation and input to and from an operation panel 41 serving as a pattern input means. That is, the operation panel 41 incorporates a display unit 42 comprising, for example, an LCD, a start/completion button 43 for instructing to start/complete the printing-position adjustment operation, a cursor shift button 44 for shifting a cursor to any one of symbols (A, B, C, D and E) corresponding to patterns having small quantities of deviation and displayed on the display unit 42 in a printing-position adjustment mode to be described later and a selection button 45 for selecting the symbol corresponding to the position of the cursor. The central control unit 26 is structured in such a manner as to be capable of communicating data to and from an adjustment-timing-deviation-quantity storage portion 35 forming an adjustment-timing-deviation-quantity storage means and comprising a nonvolatile memory. In the adjustment-timing-deviation-quantity storage portion 35, data of the quantity of deviation of the printing timing in accordance with the pattern having a small quantity of deviation supplied from the operation panel 41 is stored. In synchronization with data of the quantity of deviation of the printing timing stored in the adjustment-timing-deviation-quantity storage portion 35, the printing timings of the monochrome printing head 2 and the color printing head 3 are adjusted when a usual printing operation is performed. On the other hand, a printer-side input/output portion 46 is connected to the central control unit 26 so that communication of data to and from a host computer to be described later is permitted. A lower half portion of Fig. 1 sectioned by an alternate long and short dash line shows the structure of the host computer 51. The host computer 51 includes a host-side central processing unit 52 comprising a microprocessor. The host-side central processing unit 52 is structured in such a manner as to be capable of communicating data to and from the central control unit 26 through a printer-side input/output portion 46 of the printer. A peripheral-unit-control portion 54 is connected to the host-side central processing unit 52. A known display unit 55, a keyboard 56 and a mouse 57 are connected to the peripheral-unit-control portion 54. On the other hand, an extemal-unit input/output portion 55 is connected to the host-side central processing unit 52. The host computer 51 is connected to a communication network 59 through the extemal-unit input/output portion 55. Moreover, communication of data to and from a server 60 on the network is permitted. Moreover, a reading unit 61 of a CD-ROM 62 is connected to the external-unit input/output portion 55. In the CD-ROM 62, a control program for causing the printing apparatus to perform the printing-position adjustment method is stored. The control program read by the reading unit 61 is loaded into a RAM or the like (not shown) of the central control unit 26 of the printer through the host computer 51. Thus, a printing-position adjustment operation to be described later is performed. Note that the control program for performing the printing-position adjustment may be stored in the server 60 on the network. In this case, a method is employed in which the control program is purchased from, for example, a provider for Internet. The operation of the printing apparatus having the above-mentioned structure will now be described together with the printing-position adjustment method to be described below. When the printing position is adjusted, the control program for performing the adjustment of the printing position is, by the reading unit 61, read from the CD-ROM 62 in which the control is stored. Then, the control program is loaded into the control unit 21 of the printer control unit 21 through the host computer 51 so that an environmental for performing the adjustment of the printing position is established. If the control program for performing the adjustment of the printing position is stored in the server 60 on the Intemet, the control program is purchased through the provider so that installation of the control program on the host computer 51 is permitted. When the start/completion button 43 provided for the operation panel 41 and arranged to start the operation for adjusting the printing position is operated, the adjustment is performed when the printer is delivered from the manufacturing plant or when the previous operation for adjusting the printing position has been performed. Thus, timing deviation data stored in the adjustment-timing-deviation-quantity storage portion 35 is read and supplied to the central control unit 26. When the central control unit 26 has received timing deviation data, the central control unit 26 makes an access to the adjustment-pattern control unit 27. Thus, the adjustment-pattern generating portion 29 generates data of first adjustment pattern in accordance with timing deviation data supplied from the adjustment-timing-deviation-quantity storage portion 35 and serving as a reference value. When data of the first adjustment pattern has been generated, the central control unit 26 supplies data of the adjustment pattern to the printing control unit 25. While the carriage is moved in response to a motor drive signal supplied from the motor drive portion 24, a plurality of patterns are printed in response to print signals supplied from the monochrome head drive portion 22 and the color head drive portion 23. If the first selection mode is attempted to be selected by the pattern selection portion 31, color ink selected manually is used to print the plural patterns. If the second selection mode is selected, different color ink is sequentially and cyclically used whenever the printing-position adjustment mode is started so that the plural patterns are printed. When the third selection mode has been selected, different color ink is sequentially and cyclically used to that the plural patterns are printed whenever the number of the operation for printing the pattern is increased from the first time and the second time. If the fourth selection mode is selected, color ink remaining in a largest quantity among the plural color ink is employed to print the plural patterns. If the color printing head is able to print six color images which are yellow, cyan, magenta, purple (mixed color of cyan and magenta), green (mixed color of cyan and yellow) and orange (mixed color of magenta and yellow), the program may be formed in such a manner that yellow is not used because visibility of yellow is unsatisfactory. <First Embodiment of Printing-Position Adjustment Method> Figs. 2 (I) to 2 (IV) show a first embodiment of the printing-position adjustment method according to the present invention. The printing-position adjustment method is arranged in such a manner that a plurality (five patterns (A) to (E)) of patterns, in which the relative quantity of deviation of the printing timings of the monochrome printing head 2 and the color printing head 3 is changed in a stepped manner, are simultaneously (in one operation) printed, as shown in Fig. 2 (I). In the illustrated patterns, solid lines indicate results of printing performed by the monochrome printing head and dashed lines indicate results of printing performed by the color printing head. The method of forming the above-mentioned patterns by an ink jet printer will now be described. The above-mentioned patterns can be formed by using upper half nozzles of a plurality of nozzles disposed on the ink discharge surface of the monochrome head in a direction perpendicular to a direction (main scanning direction A) in which the head is moved. The lower half nozzles are used by the color head. As can be understood from printed patterns (A) to (E) shown in Fig. 2 (I), the printing positions (indicated with dashed lines) of the color head with respect to the printing positions (indicated with solid lines) of the monochrome head are deviated to the right in a stepped manner in a direction from the pattern (A) to the pattern (E). Therefore, a user subjects the patterns (A) to (E) to comparisons to select a pattern having a smallest quantity of deviation, and then inputs a symbols (any one of A to E) corresponding to the selected pattern by using the operation panel 41. Since the pattern (E) has the smallest quantity of deviation in this case, the symbol (E) is supplied. The symbols A to E are displayed on the display unit 42 of the operation panel 41. When the cursor shift button 44 is sequentially depressed, the cursor is cyclically moved to the lower position of each of symbols A to E. When the selection button 45 is depressed in a state in which the cursor is moved to the symbol (E), a first pattern selection operation is completed. When the above-mentioned input operation is performed with the operation panel 41, the adjustment-repetition-number determination portion 30 increases the administrated number by "1". Then, a second operation for printing the pattern is performed. That is, as shown in Fig. 2 (II), the pattern corresponding to the supplied symbol, that is, the selected pattern (the pattern (E) shown in Fig. 2 (I)) is used as a central value (the pattern (C) shown in Fig. 2 (II)). Then, the adjustment-pattern generating portion 29 makes an access to the adjustment-pattern control unit 27 so as to generate the patterns (A) to (E), in which the relative quantity of deviation of the printing timings of the two heads is changed in a stepped manner. When the second adjustment pattern has been generated as described above, the central control unit 26 supplies data to be printed to the printing control unit 25 similarly to the first operation. Thus, second printing of the patterns is performed by the two heads 2 and 3. Then, the user subjects the printed patterns (A) to (E) to comparisons as shown in Fig. 2 (II) to select a pattern having the smallest quantity of deviation. Then, the user inputs a symbol corresponding to the selected pattern by using the operation panel 41. Since the quantity of deviation of the pattern (E) is smallest in this case, the symbol (E) is input. When the symbol (E) has been input by using the operation panel 41, the pattern corresponding to the supplied symbol, that is, the selected pattern (the pattern (E) shown in Fig. 2 (II)) is used as a central value (the pattern (C) shown in Fig. 2 (III)), as shown in Fig. 2 (III). Then, the adjustment-pattern generating portion 29 generates the patterns (A) to (E), in which the relative quantity of deviation of the printing timings of the two heads is changed in a stepped manner. When the third adjustment pattern has been generated, the central control unit 26 supplies data to be printed to the printing control unit 25, similarly to the previous operation. Thus, the two heads 2 and 3 prints third patterns. Then, the user subjects the printed patterns (A) to (E) to comparisons as shown in Fig. 2 (III) to select a pattern having the smallest quantity of deviation. Then, the user inputs a symbol corresponding to the selected pattern by using the operation panel 41 similarly to the previous operation. Since the quantity of deviation of the pattern (E) is smallest in this case, the symbol (E) is input. When the symbol (E) has been input by using the operation panel 41, the pattern corresponding to the supplied symbol, that is, the selected pattern (the pattern (E) shown in Fig. 2 (III)) is used as a central value (the pattern (C) shown in Fig. 2 (IV)), as shown in Fig. 2 (IV). Then, the adjustment-pattern generating portion 29 generates the patterns (A) to (E), in which the relative quantity of deviation of the printing timings of the two heads is changed in a stepped manner. When the fourth adjustment pattern has been generated, the central control unit 26 supplies data to be printed to the printing control unit 25, similarly to the previous operation. Thus, the two heads 2 and 3 prints fourth patterns. Then, the user subjects the printed patterns (A) to (E) to comparisons as shown in Fig. 2 (IV) to select a pattern having the smallest quantity of deviation. Then, the user inputs a symbol corresponding to the selected pattern by using the operation panel 41 similarly to the previous operation. Since the quantity of deviation of the pattern (C) is smallest in this case, the symbol (C) is input. Since the selected pattern (C) is in a state in which substantially no deviation exists, the user operates the start/completion button 43 of the operation panel 41. As a result, data of quantity of deviation of the printing timings corresponding to the symbol (the symbol (C) shown in Fig. 2 (IV)) corresponding to the selected pattern is written on the adjustment-timing-deviation-quantity storage portion 35. Thus, the operation for adjusting the printing position of the printer is completed. In the following and usual printing operation, the printing timings of the monochrome printing head 2 and the color printing head 3 are adjusted in accordance with data of the quantity of deviation of the printing timings stored in the adjustment-timing-deviation-quantity storage portion 35. This embodiment is characterized in that the color to be printed by the color printing head is changed whenever the above-mentioned adjustment mode is started when the second selection mode has been selected by the pattern selection portion 31. When printing-position adjustment is performed after the adjustment mode has been started in an initial stage of use of the printer, cyan is used. When the printing position is again adjusted subsequent to that, magenta is used. Thus, color is sequentially changed as cyan, magenta, purple, green, orange and cyan. As described above, the second selection mode is arranged in such a manner that the color to be printed by the color printing head is changed whenever the adjustment mode is started. When the third selection mode has been selected by the pattern selection portion 31, color which is used by the color printing head is changed whenever one printing operation is performed (for example, the patterns (A) to (E) have been printed) in the adjustment operation described with reference to Figs. 2 (I) to 2 (IV). That is, the number of times of the printing operations administrated by the adjustment-repetition-number determination portion 30 is used to sequentially change the color which is discharged from the color printing head. According to this embodiment having the structure that the color to be printed by the color printing head is changed whenever the adjustment is performed, the problem in that ink in a specific color is consumed in a larger quantity as compared with ink of the other colors can be prevented. Although the structure has been described in which the adjustment of the printing position is completed by performing four times of printing of the patterns (see Fig. 2 (IV)), a pattern substantially free from deviation sometimes appears at, for example, the second operation for printing the patterns (see Fig. 2 (II)) if the quantity of deviation of the printing positions of the two heads is relative small. In this case, the adjustment operation is completed when the second operation for printing the patterns has been completed. If the quantity of deviation of the printing positions of the two heads is relatively large, a pattern substantially free from deviation does not appear even after the fourth operation for printing the patterns (see Fig. 2 (IV)) have been performed. In this case, the foregoing operation is repeated and the adjustment operation is completed after a fifth or following operation for printing the patterns has been performed. If a specific color is used in the color printing operation as has been employed in the conventional method, the specific color ink is consumed in a larger quantity. The structure according to this embodiment is able to prevent the above-mentioned problem. As described above, the printing-position adjustment method according to this embodiment is arranged in such a manner that the pattern selected by a user is used as a central value. Moreover, a plurality of patterns in which the relative quantity of deviation of the printing timings of the two heads is changed in a stepped manner are printed. A pattern having a smallest quantity of deviation is, by the user, selected from the plural patterns. The above-mentioned process are repeated as necessary. Thus, the printing timings of the two heads can be adjusted. That is, the printing-position adjustment method according to this embodiment is arranged in such a manner that the patterns which must be printed simultaneously are printed at least in two times of operations. Moreover, plural patterns which are simultaneously printed at a second and following operations are in the form in which the pattern selected in the previous operation is used as the central value. As can be understood from Figs. 2 (I) to 2 (IV), the quantity of deviation of the plurality of the patterns which are printed simultaneously is sequentially reduced as the number of the printing operations increases. That is, the state of deviation is converged gradually. That is, the quantity of deviation in the pattern shown in Fig. 2 (II) is smaller than that in the pattern shown in Fig. 2 (I). The quantity of deviation in the pattern shown in Fig. 2 (III) is smaller than that of the pattern shown in Fig. 2 (II). The quantity of deviation in the pattern shown in Fig. 2 (IV) is smaller than that in the pattern shown in Fig. 2 (III). Since the patterns to be printed simultaneously are printed in at least two times of operations, the number of patterns required to be subjected to comparisons by a user in one operation can be reduced to at least half of the number required for the conventional method. As a result, the selection operation which is performed by the user can be simplified and facilitated. That is, the user is required to subject five patterns in each operation in the above-mentioned embodiment. Since the quantity of deviation of the plural patterns in the stepped manner and which are simultaneously printed is converged as the number of times increases, the adjustment operation can efficiently be performed. Therefore, the adjustment operation which is performed by the user can easily be completed. Moreover, the range of the quantity of deviation which can be adjusted can be enlarged and the adjustment accuracy can be improved. Namely, the adjustment method according to this embodiment is arranged in such a manner that printing of a plurality of patterns and the selection operation which is performed by a user are simply repeated until the adjustment is completed (until a pattern substantially free from deviation appears). Therefore, even if the range of the quantity of deviation which can be adjusted is enlarged, the operation required for the user does not become excessively complicated. Therefore, even if the number of patterns is increased because the adjustment accuracy is improved, the adjustment can be performed in such a manner that printing of the plural patterns and the selection operation which is performed by the user are repeated. Therefore, the operation required for the user does not become excessively complicated. That is, the number of the patterns which must be subjected to comparisons by the user can be reduced when the user selects an optimum pattern. Therefore, the user is able to easily select an optimum pattern. Moreover, time and surfaces of paper required to perform one time of pattern printing operation can be reduced. Since the adjustment can sometimes be completed after the operation for printing the patterns have been performed two times, time required to complete the adjustment, the quantity of printing paper and consumption of ink can significantly be reduced as compared with the conventional method. <Second Embodiment of Printing-Position Adjustment Method> Figs. 3 (I) to 3 (IV) are diagrams showing a second embodiment of the printing-position adjustment method according to the present invention, in which states of printed patterns similarly to the above-mentioned embodiment are shown. This embodiment is characterized in that the relative quantity of deviation which is changed among the plurality of the patterns to be printed is reduced as compared with the relative quantity of deviation changed in the pattern printed in the previous printing operation. This embodiment has a structure that when a pattern except for an end pattern of the plural patterns is selected by a user, the relative quantity of deviation is reduced. The other structures are similar to those of the first embodiment. The structure according to this embodiment is arranged in such a manner that the adjustment-repetition-number determination portion 30 shown in Fig. 1 determines the number of repetition times to sequentially adjust the relative quantity of deviation. Moreover, the central control unit 26 determines a fact that a pattern of a plurality of patterns except for an end pattern has been selected by a user in accordance with a state of operation of the operation panel 41. When the printing-position adjustment method according to the second embodiment is performed, the operation of each block shown in Fig. 1 is similar to the structure according to the first embodiment. Therefore, description of the adjustment method will be performed about adjustment patterns shown in Fig. 3. The printing-position adjustment method according to the second embodiment will now be described. Initially, a plurality (which is five from (A) to (E)) of patterns, in which the relative quantity of deviation of the monochrome head and the color head is changed in a stepped manner, are simultaneously printed, as shown in Fig. 3 (I). In this case, the relative quantity of deviation (the pitch to be changed) in a stepped manner is determined to be, for example, 0.6 mm. Therefore, the distance from the printing position (indicated with solid lines) of the monochrome head to the printing position (indicated with dashed lines) of the color head is, as shown in Fig. 3 (I), made in such a manner that distance LB in the pattern (B) is shorter than distance LA in the pattern (A) by 0.6 mm. Similarly, the distance in the pattern (C) is shorter than that in the pattern (B) by 0.6 mm, the distance in the pattern (D) is shorter than that in the pattern (C) by 0.6 mm, and the distance in the pattern (E) is shorter than that in the pattern (D) by 0.6 mm. That is, the printing position (indicated with dashed lines) of the color head with respect to the printing position (indicated with solid lines) of the monochrome head is deviated to the right at pitches of 0.6 mm in a direction from the pattern (A) to the pattern (E). Therefore, a user subjects the patterns (A) to (E) to comparison to select a pattern having a smallest quantity of deviation, and then inputs a symbol corresponding to the selected pattern to the operation panel. Since the pattern (E) has a smallest quantity of deviation in this case, symbol (E) is input by using the operation panel. When the symbol (E) has been input by using the operation panel, the pattern corresponding to the supplied symbol, that is, the selected pattern (the pattern (E) shown in Fig. 2 (I)) is used as a central value (the pattern (C) shown in Fig. 3 (II)), as shown in Fig. 3 (II). Then, the patterns (A) to (E), in which the relative quantity of deviation of the printing timings of the two heads is changed in a stepped manner, are simultaneously printed. Also in this case, the relative quantity of deviation (the pitch which must be changed) in a stepped manner is determined to be 0.6 mm. Therefore, the printing position (indicated with the dashed lines) of the color head with respect to the printing position (indicated with the solid lines) of the monochrome head is deviated to the right at pitches of 0.6 mm in a direction from the pattern (A) to the pattern (E). Then, the user subjects the printed patterns (A) to (E) to comparisons as shown in Fig. 3 (II) to select a pattern having the smallest quantity of deviation. Then, the user inputs a symbol corresponding to the selected pattern by using the operation panel. Since the quantity of deviation in the pattern (C) and that in the pattern (D) are substantially the same and the quantity is smaller than quantity of deviation in the other patterns (A), (B) and (E) in this case, the symbol (C) or (D) is input by using the operation panel. In this embodiment, an assumption is made that the symbol (C) has been input by using the operation panel. When the symbol (C) has been input, the pattern corresponding to the supplied symbol, that is, the selected pattern (the pattern (C) shown in Fig. 2 (II)) is used as a central value (the pattern (C) shown in Fig. 3 (III)), as shown in Fig. 3 (III). In this state, the patterns (A) to (E) in which the relative quantity of deviation of the printing timings of the two heads is changed in a stepped manner are simultaneously printed Since the pattern (C) of the plurality of the patterns (A) to (E) shown in Fig. 3 (II) except for the end patterns (A) and (E) has been selected by the user in this case, the relative quantity of deviation is reduced to, for example, 03 mm. Therefore, the printing position (indicated with dashed lines) of the color head with respect to the printing position (indicated with solid lines) of the monochrome head is, in the case shown in Fig. 3 (III), deviated to the right at pitches of 03 mm in a direction from the pattern (A) to the pattern (E). Therefore, the user subjects the printed patterns (A) to (E) to comparisons as shown in Fig. 3 (III) to select a pattern having the smallest quantity of deviation. Then, the user inputs a symbol corresponding to the selected pattern by using the operation panel. Since the quantity of deviation in the pattern (D) is smallest, the symbol (D) is input by using the operation panel. When the symbol (D) has been input, the pattern corresponding to the supplied symbol, that is, the selected pattern (the pattern (D) shown in Fig. 3 (III)) is used as a central value (the pattern (C) shown in Fig. 3 (IV)), as shown in Fig. 3 (IV). In this state, the patterns (A) to (E) in which the relative quantity of deviation of the printing timings of the two heads is changed in a stepped manner are simultaneously printed. Since the pattern (D) of the plurality of the patterns (A) to (E) shown in Fig. 3 (III) except for the end patterns (A) and (E) has been selected by the user in this case, the relative quantity of deviation is reduced to, for example, 0.15 mm. Therefore, the printing position (indicated with dashed lines) of the color head with respect to the printing position (indicated with solid lines) of the monochrome head is, in the case shown in Fig. 3 (IV), deviated to the right at pitches of 0.15 mm in a direction from the pattern (A) to the pattern (E). Therefore, the user subjects the printed patterns (A) to (E) to comparisons as shown in Fig. 3 (IV) to select a pattern having the smallest quantity of deviation. Then, the user inputs a symbol corresponding to the selected pattern by using the operation panel. Since the quantity of deviation in the pattern (C) is smallest, the symbol (C) is input. Since the selected pattern (C) is substantially free from deviation, the user operates the start/completion button 43 similarly to the foregoing process and thus the adjustment operation is completed. Then, data of the quantity of deviation of the printing timing corresponding to the finally selected symbol (which is (C) shown in Fig. 3 (IV)), is written on the adjustment-timing-deviation-quantity storage portion 35. Thus, the operation for adjusting the printing position of the printer is completed. Then, the following and usual printing operation is performed in such a manner that the printing timings of the monochrome printing head 2 and the color printing head 3 are adjusted in accordance with data of the deviation of the printing timings stored in the adjustment-timing-deviation-quantity storage portion 35, similarly to the above-mentioned process. Although the adjustment can be completed in the above-mentioned case after the fourth operation for printing the patterns (see Fig. 3 (IV) has been performed, further repetition of the operation to furthermore reduce the relative deviation (for example, to 0.075 mm or furthermore reduced to 0.04 mm), further precise adjustment of the printing position can be performed. Also according to the second embodiment, selection of the second selection mode by the pattern selection portion 31 enables the color to be printed by the color printing head to be changed whenever the foregoing adjustment mode is started. When the third selection mode has been selected by the pattern selection portion 31, the color to be printed can be changed whenever one printing operation is performed (whenever, for example, the patterns (A) to (E) have been printed) in the adjustment operation described with reference to Figs. 3 (I) to 3 (IV). According to the above-mentioned embodiments, a problem in that only specific color ink is consumed as compared with ink in the other colors can be prevented. Although the invention has been described in its preferred form, it is understood that the present disclosure of the preferred form can be changed in the details of construction and in the combination and arrangement of parts without departing from the scope of the invention. For example, (1) Although the foregoing embodiments have the structure that the number of patterns to be printed in one printing operation is determined to be five, the number can arbitrarily be determined. It is preferable that the number is about 3 to about 15, more preferably about 4 to about 7. (2) The line segments which are printed as a result of one time of scanning operation are formed into dashed-line shapes because the intervals of nozzles of the color head according to the above-mentioned embodiments are relatively long. The shapes may be formed into solid lines when printing in one direction is repeated by feeding paper in a small quantity. (3) When the above-mentioned adjustment method is performed, the priority of color ink is determined in accordance with information about the remaining quantity of in supplied from the ink-level-detecting portion. However, another structure may be employed in which color ink to be used is changed whenever the adjustment is performed (whenever the adjustment mode is started) or whenever one printing operation is performed in one adjustment operation (for example, whenever the patterns (A) to (E) are printed). Thus, the necessity of using information about the remaining quantity which is supplied from the ink-level-detecting portion can be eliminated. Thus, the structure can be simplified.

Claims: A printing-position adjustment method for a printer including a first printing head (2) and a second printing head (3) which are arranged to perform a printing operation by moving in a direction aligning the printing heads (2, 3), the method comprising the step of (a) printing a set of patterns in which printing timings of the printing heads (2, 3) are changed by a relative quantity of deviation of printing timings in a stepped manner, so that a user is able to select a pattern having a smallest quantity of deviation among said set of patterns; characterized by further comprising the steps of: (b) making the selected pattern to be a central value; (c) printing another set of patterns based on the central value in which printing timings of the printing heads (2, 3) are changed by a relative quantity of deviation of printing timings in a stepped manner, so that a user is able to select another pattern having a smallest quantity of deviation among said another set of patterns; wherein the steps (b) and (c)are performed at least one time. The printing-position adjustment method according to claim 1, further including: (d) determining whether or not the steps (b) and (c) are performed again according to the selected pattern. The printing-position adjustment method according to claim 1 or 2, wherein the relative quantity of deviation which is changed in the set of patterns is made to be smaller than the relative quantity of deviation changed in the set of patterns printed previously. The printing-position adjustment method according to claim 3, wherein when a pattern of the set of patterns except for end patterns is selected by the user, the relative quantity of deviation is reduced. The printing-position adjustment method according to claim 1 or 2, wherein the first printing head (2) is a monochrome printing head (2) and the second printing head (3) is a color printing head (3). The printing-position adjustment method according to claim 5, wherein the color to be printed by the color printing head (3) is changed whenever the set of patterns is printed. The printing-position adjustment method according to claim 5, wherein the color to be printed by the color printing head (3) can be selected. The printing-position adjustment method according to claim 5, wherein the color to be printed by the color printing head (3) after an adjustment mode in which the relative quantity of deviation of the printing timings is adjusted has been started is changed whenever the adjustment mode is started. The printing-position adjustment method according to claim 5, wherein the color to be printed by the color printing head (3) is automatically selected in accordance with information of an ink level communicated from an ink-level-detecting portion (11). A printing apparatus having a first printing head (2) and a second printing head (3) which are arranged to perform a printing operation by moving in a direction aligning the printing heads (2, 3), the printing apparatus further comprising: printing control means (25) for printing a set of patterns in which printing timings of the printing heads (2, 3) are changed by a relative quantity of deviation of printing timings in a stepped manner, so that a user is able to select a pattern having a smallest quantity of deviation among said set of patterns; characterized by further comprising pattern selecting means (41; 45) for selecting a pattern among the set of patterns; adjustment-pattern control means (27) for issuing a command to the printing control means (25) to print another set of patterns in which printing timings of the printing heads are changed by a relative quantity of deviation of printing timings in a stepped manner by making the selected pattern provided from the pattern selecting means (41, 45) to be a central value, so that a user is able to select another pattern having a smallest quantity of deviation among said another set of patterns; and means (35) for storing the quantity of deviation of printing timings in accordance with the selected pattern. The printing apparatus according to claim 10, wherein the adjustment-pattern control means (27) performs control in such a manner that a relative quantity of deviation which is changed in a set of patterns which is printed next is made to be smaller than a relative quantity of deviation changed in the set of patterns printed previously. The printing apparatus according to claim 11, wherein the adjustment-pattern control means (27) performs control in such a manner as to reduce the relative quantity of deviation which is changed in a set of patterns to be printed next when a pattern of the set of patterns printed previously except for end patterns has been supplied by the pattern selecting means. The printing apparatus according to claim 10, wherein the first printing head (2) is a monochrome printing head (2) and the second printing head (3) is a color printing head (3). The printing apparatus according to claim 13, wherein the adjustment-pattern control means (27) is adapted for performing control such that color to be printed by the color printing head (3) is changed whenever the set of patterns is printed. The printing apparatus according to claim 13, wherein the adjustment-pattern control means (27) is adapted for performing control to change color to be printed by the color printing head (3) after an adjustment mode in which the relative quantity of deviation of the printing timings is adjusted has been started whenever the adjustment mode is started. A printing apparatus according to any one of claims 10 to 15, further comprising a host computer (51) for receiving a control program for adjusting the printing position which is performed by the printing apparatus. A printing apparatus according to claim 16, wherein the host computer (51) is structured to receive the control program through a communication network (59). A printing apparatus according to claim 16, wherein the host computer (51) is structured to receive the control program from a recording medium (62) which can be read through a reading unit (61). A read-enabled recording medium (62) in which a control program is stored which adjusts a printing position of a printing apparatus having a first printing head (2) and a second printing head (3) and arranged to perform printing while the two heads (2, 3) are moved in a direction in which the two heads (2, 3) align, the recording medium (62) comprising a control program for causing the printing apparatus to perform the step of causing printing control means (25) to print a set of patterns in which the relative quantity of deviation of printing timings of the two heads (2, 3) is changed in a stepped manner, so that a user is able to select a pattern having a smallest quantity of deviation among said set of patterns; characterized in that the control program causes the printing apparatus to perform the further steps of: obtaining from pattern selecting means (41; 45) a selected pattern among the set of the printed patterns; causing adjustment-pattern control means (27) to issue a command to the printing control means (25) to print another set of patterns in which printing timings of the printing heads are changed by a relative quantity of deviation of printing timings in a stepped manner by making the selected pattern provided from the pattern selecting means (41, 45) to be a central value, so that a user is able to select another pattern having a smallest quantity of deviation among said another set of patterns; and causing means (35) for storing a quantity of deviation of printing timings to store data of a quantity of deviation of printing timings in accordance with the selected pattern. A read-enabled recording medium (62) according to claim 19, wherein the program stored on the read-enabled recording medium (62) causes the adjustment-pattern control means (27) to perform control to make the relative quantity of deviation in a set of patterns which is printed next to be smaller than the relative quantity of deviation in the set of patterns printed previously. A read-enabled recording medium (62) according to claim 20, wherein the program stored on the read-enabled recording medium (62) causes the adjustment-pattern control means (27) to perform control such that the relative quantity of deviation in a set of patterns to be printed next is made to be smaller when a pattern of the set of patterns printed previously except for end patterns have been selected by the pattern selecting means (41; 45). A read-enabled recording medium according to claim 19, wherein the first printing head (2) is a monochrome printing head (2) and the second printing head (3) is a color printing head (3). A read-enabled recording medium (62) according to claim 22, wherein the control program causes the printing apparatus to perform the further step of causing the adjustment-pattern control means (27) to performing control in such a manner that color to be printed by the color printing head (3) is changed whenever the set of patterns is printed. A read-enabled recording medium (62) according to claim 22, wherein the control program causes the printing apparatus to perform the further step of causing the adjustment-pattern control means (27) to performing control to change color to be printed by the color printing head (3) after an adjustment mode in which the relative quantity of deviation of the printing timings is adjusted has been started whenever the adjustment mode is started. A recording medium (62) according to any one of claims 19 to 24, wherein the read-enabled recording medium (62) is a CD-ROM (62). A printing-position adjustment method according to any one of Claims 1 to 4, or a printing apparatus according to any one of Claims 10 to 12 and Claims 16 to 18 or a recording medium (62) according to any one of Claims 19 to 21 and Claim 25 on which the program for controlling the printing position is stored, wherein the first printing head (2) and the second printing head (3) are a monochrome printing head (2) and a color printing head (3).

Inventors: IGARASHI HITOSHI, MURAKAMI KENJIRO, SESHIMO TATSUYA, UCHIYAMA YUKIHIRO, IGARASHI, HITOSHI, MURAKAMI, KENJIRO, SESHIMO, TATSUYA, UCHIYAMA, YUKIHIRO
Applicants: SEIKO EPSON CORP, SEIKO EPSON CORPORATION
Application year: 1998
Main classification: G06K15
IPC codes: B41J2