Patent Application
20110123203
The present application claims priority to and incorporates by reference the entire contents of Japanese Patent Application No. 2009-265695 filed in Japan on Nov. 20, 2009.
1. Field of the Invention
The present invention relates to a printing system that includes a first printer that forms an image on continuous-form printing paper and a second printer that receives the continuous-form printing paper fed from the first printer and forms an image on the continuous-form printing paper, and to a printing method.
2. Description of the Related Art
Conventionally, web printing systems (printing systems) have been proposed and brought into practical use as printing system that uses two printers to form images on both sides of elongated print paper (web) that has standard-compliant feed holes. An example of such a web printing system is disclosed in Japanese Patent No. 3680989.
In both lateral-side portions of the web W, standard-compliant feed holes (which engage with the conveying unit 1 and 5, and will be described later), for conveying the web W, are provided continually at regular intervals along the web conveying direction. The web conveying unit 1 is disposed upstream of a transfer device 4 in the web conveying direction, and the web conveying unit 5 is disposed downstream of the transfer device 4 in the web conveying direction. The web conveying units 1 and 5 convey the web W through a transfer region while applying a certain tension on the web W. A web-jam detecting sensor 2 is attached to the web conveying unit 1. The web-jam detecting sensor 2 is configured to detect a jam of the web W.
The web conveying units 1 and 5 convey the web W to a thermal fixing device. The thermal fixing device includes a pre-heating plate 6, a heating roller 7, and a pressure roller 8. The pre-heating plate 6 is a heating plate that preheats the web W so that fixation is performed reliably by the heating roller 7 and the pressure roller 8. A puller roller 9 conveys the web W having undergone fixation to discharge the web W to the outside of the printer through a shooter 10. A buffer mechanism 15 is provided to adjust slack in the web W. The buffer mechanism 15 is configured to be pivotable about its pivot center, which is an end of the buffer mechanism 15 on an upstream side relative to the feed direction of the web W.
In
The web-jam detectors 2a and 2b are configured to open and close in synchronization with the tractor doors 12. Accordingly, the web-jam detector 2b detects a web jam even when the web-jam detector 2b is prevented from receiving the sensor light 13 because one of the tractor doors 12 is open or because the tractor door 12 is lifted up by a jam of the web W.
In the web printing system configured as described above, the web-jam detecting sensor 2 detects a jam of the web W irrespective of operations of the first printer P1 and the second printer P2.
However, such an unfavorable situation as described below may occur in the conventional technique described above.
For instance, when printing operation pauses due to a trouble or the like or when printing operation is halted by an operator because of other circumstance, the web W is left as being loaded in the first printer P1 and the second printer P2 in a state where no printing is performed. Under such circumstances, the web W pausing in the thermal fixing device of the first printer P1 continues to be heated by the pre-heating plate 6 and the heating roller 7. Thus, as time passes, the moisture in the web W evaporates, and the web W partially and greatly shrinks and deforms due to heat.
When printing is resumed from such a state as described above, the web W that has the portion greatly deformed by heat shrinkage (hereinafter, “thermally shrunk portion”) is conveyed to the turnover device to be turned upside down and then fed into the second printer P2. When the thermally shrunk portion passes through the web conveying unit 1 of the second printer P2, the tractor door 12 may be lifted up due to the shape of the thermally shrunk portion, disadvantageously causing the web-jam detecting sensor 2 to detect a web jam in some cases.
It is an object of the present invention to at least partially solve the problems in the conventional technology.
According to an aspect of the present invention, a printing system includes: a first printer that forms an image on continuous-form printing paper; and a second printer that receives the continuous-form printing paper fed from the first printer and forms an image on the continuous-form printing paper, and the first printer includes: a pre-heating unit that preliminarily heats the continuous-form printing paper prior to fixation; and a fixing unit that fixes a not-yet-fixed image formed on the continuous-form printing paper onto the continuous-form printing paper, and the second printer includes: a jam detecting unit that detects a jam of the continuous-form printing paper at an upstream position where the second printer forms the image on the continuous-form printing paper; and a control unit that controls the jam detecting unit such that the jam detecting unit does not perform the jam detection for a period of time, over which a deformed portion of the continuous-form printing paper that has been at rest at the pre-heating unit of the first printer passes through the detection position of the jam detecting unit.
According to another aspect of the present invention, a printing method to be performed in a printing system that includes a first printer that forms an image on continuous-form printing paper and a second printer that receives the continuous-form printing paper fed from the first printer and forms an image on the continuous-form printing paper, the first printer including: a pre-heating unit that preliminarily heats the continuous-form printing paper prior to fixation; and a fixing unit that performs the fixation by fixing a not-yet-fixed image onto the continuous-form printing paper, the printing method including: performing jam detection by detecting a jam of the continuous-form printing paper in the second printer at an upstream position where the second printer forms the image on the continuous-form printing paper; and performing control in the second printer such that the jam detection is not performed for a period of time, over which a deformed portion of the continuous-form printing paper that has been at rest at the pre-heating unit of the first printer passes through the detection position of the jam detecting unit.
The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings.
Exemplary embodiments of the present invention are described in detail below with reference to the accompanying drawings.
Basic configuration of a printing system according to an embodiment of the present invention is similar to the configuration of the conventional system illustrated in
Referring to
The web-jam-information receiving unit 21 determines whether a web jam has occurred during printing based on a detection signal fed from the web-jam detecting sensor 2. Upon web jam detection, the web-jam-information receiving unit 21 transmits web-jam information to the main control unit 22.
Upon receiving the web-jam information, the main control unit 22 recognizes that a web jam has occurred, stops printing, and transmits a notification of the web jam detection to the control device 20. Meanwhile, the main control unit 22 includes a timer 23 serving as a timepiece.
As described above, the web printing system includes the control device 20 (see
The control device 20 is configured to communicate with each of the main control units of the printers P1 and P2 and read information from each other. The control device 20 includes a touch panel 24 for displaying information for an operator and receiving information entered by an operator.
When the web printing system configured as described above is in a paused state, the web W continues to be heated by the pre-heating plate 6 and the heating roller 7 that partially greatly deform the web W. Hence, a thermally shrunk portion is formed on the web W.
Conveyance of the web W is resumed as the printing is resumed. During a period where the thermally shrunk portion formed on the web W by the printer P1 passes through the web conveying unit of the printer P2, the thermally shrunk portion may lift up the tractor door 12, which may cause the web-jam detecting sensor 2 to make false detection of a web jam.
To this end, in the present embodiment, false detection of a web jam resulting from detection of the thermally shrunk portion by the web-jam detecting sensor 2 is prevented from by not allowing the printer P2 to perform the web-jam detection operation for a period, over which the thermally shrunk portion passes through a detection position of the web-jam detecting sensor 2 of the printer P2.
Referring to
The length of L is a fixed value having been set so as to allow the printer P2 to print an image of an original or the like on a back side a page which corresponds to the front side on which the printer P1 has printed an image of an original or the like. The buffer mechanism 15 serving as an adjusting unit that allows slack in the web W and adjusts the slack to thereby keep the length L constant is disposed at a portion indicated with the caption “INTERMEDIATE FEED PATH” in
When resuming printing, the control device 20 transmits the length L between the transfer point of the printer P1 and the transfer point of the printer P2 of the web W loaded on the web feed path to the main control unit 22 of the printer P2 via the communication channel 25.
In the main control unit 22 of the printer P2, a distance X from the transfer point of the printer P1 to a leading end of the shooter 10 of the printer P1, a distance Y from the web-jam detecting sensor 2 of the printer P2 to the transfer point of the printer P2, and a distance K from a nip between the heating roller 7 and the pressure roller 8 of the printer P1 to the leading end of the shooter 10 of the printer P1 are stored in advance. The main control unit 22 calculates a timing (error mask timing) T, which is a period of time that elapses before the thermally shrunk portion reaches the web-jam detecting sensor 2 of the printer P2, from Equation (I):
T=S/Z=(L−X−Y+K)/Z (I)
where S is the distance from the nip between the heating roller 7 and the pressure roller 8 of the printer P1 to the web-jam detecting sensor 2 of the printer P2, and Z is print speed of the printers.
When the distance from the transfer point of the printer P1 to the nip between the heating roller 7 and the pressure roller 8 of the printer P1 is assigned to X in Equation (I), the need of taking the distance K into account is eliminated.
Meanwhile, the buffer mechanism 15 is provided to absorb the difference between a conveyance speed of the web W by the web conveying unit 5 and a conveyance speed of the web W by the heating roller 7 and the pressure roller 8. The buffer mechanism 15 keeps the tension placed on the web W constant by changing a pivot angle of the buffer mechanism 15. Accordingly, the distance X from the transfer point to the leading end of the shooter 10 varies because the amount of the slack in the web W on the feed path varies depending on operation of the buffer mechanism 15. The amount of the slack in the web W on the feed path is referred to as a buffer amount (adjustment amount), depending on which the distance X varies.
In contrast, the distance L is a fixed value as described above. This causes a necessity for making a change to the error mask timing T obtained from Equation (I) depending on the buffer amount. Hence, the distance X is desirably set to different value by displacing with the buffer amount.
The pivot angle of the buffer mechanism 15 is classified into a plurality of levels (e.g., five levels) and assumed as buffer positions. The buffer mechanism 15 of the printer P1 includes a position sensor unit, such as an angle sensor or an encoder, which measures the pivot angle thereof. A transmitting unit of the printer P1 transmits the pivot angle of the buffer mechanism 15 obtained by the position sensor unit to the control device 20.
The control device 20 receives the pivot angle from the printer P1 and transmits it to the printer P2. The main control unit 22 of the printer P2 receives the pivot angle from the control device 20 and determines a buffer amount associated with a buffer position of a pivot-angle level, into which the pivot angle is classified. The buffer amount is determined with reference to a reference distance X that is taken in a neutral state where the buffer mechanism 15 is pivoted by a neutral pivot angle, which is a median of pivot angles.
The printer P2 stores a buffer-amount table, which corresponds to an adjustment-amount table, which contains buffer amounts associated with pivot angles of the buffer mechanism 15 of the printer P1 with reference to a reference buffer position in a storage medium, such as memory. The reference buffer position is a buffer position in the neutral state where the buffer mechanism 15 is pivoted by the neutral pivot angle.
In
When printing pauses, the main control unit 22 obtains the buffer amount that corresponds to a pivot angle of the buffer mechanism 15 in this paused state by referring to the buffer-length table stored in the memory. The main control unit 22 performs addition or subtraction of the buffer amount to or from the reference distance X, thereby obtaining a corrected value of the distance X. The main control unit 22 sets this corrected value as a value to be assigned to X in Equation (I).
The main control unit 22 of the printer P2 calculates the error mask timing T from Equation (I) whereas the main control unit 22 of the printer P1 obtains information about the distance X for use in solving Equation (I). Therefore it is necessary to transfer the information about the distance X obtained by the main control unit 22 of the printer P1 to the main control unit 22 of the printer P2. This transfer may be preferably performed by the control device 20.
Assuming that the length of the thermally shrunk portion is approximately equal to Q, which is the distance from the pre-heating plate 6 to the heating roller 7 in the thermal fixing device, the main control unit 22 calculates M, which is a period of time for use in determining a web-jam-error masking period from Equation (II).
M=Q/Z (II)
The main control unit 22 of the printer P2 is thus capable of recognizing, respectively, the error mask timing T, which is the time from the resumption of printing to the thermally shrunk portion reaches the web-jam detecting sensor 2; and the web-jam-error masking period (period M), for which error detected in the web-jam detection is to be masked, and which is the period of time, over which the thermally shrunk portion passes through the web-jam detecting sensor 2 (period of time required for passage). Accordingly, the main control unit 22 is thus capable of setting a period of time, in which web-jam detection control is not performed, by causing the timer 23 to count (measure) elapsed time from start of printing, which is notified by the control device 20.
In the example described above, the value of the distance X for use in calculating the timing T from Equation (I) has been determined based on the pivot angle of the buffer mechanism 15 in the printing-paused state; however, the timing T may alternatively be obtained by using a fixed value as the distance X. In this alternative configuration, a distance from the transfer point to the leading end of the shooter 10 in a state where the buffer amount of the buffer mechanism 15 is at its maximum is desirably used as the distance X in Equation (I). This allows the web-jam-error masking period to start prior to arrival of a leading end of the thermally shrunk portion at the web-jam detecting sensor 2 based on the time T irrespective of the pivot angle of the buffer mechanism 15.
In addition, the period M is desirably set to such a value that allows the web-jam-error masking period is set within a period the thermally shrunk portion passes through the web-jam detecting sensor 2 irrespective of buffer amount of the buffer mechanism 15. For instance, it is preferable to assign a sum of the distance of the difference between the minimum value and the maximum value of the buffer amount and the distance from the pre-heating plate 6 to the heating roller 7 to the distance Q in Equation (II).
Using fixed values as values of the timing T and the period M allows the main control unit 22 of the printer P2 to perform calculation by using the distances X, K, and Q calculated based on information about lengths of the feed paths and sizes of the units and the like of the printer P2 itself as the distances X, K, and Q of the printer P1 in Equations (I) and (II) because the printer P1 and the printer P2 are identical to each other in structure.
For a situation where the printer P1 and the printer P2 have different structures, for instance, a following configuration may be employed. The main control unit 22 of the printer P1 transmits the distances X, K, and Q of the printer P1 itself to the control device 20, and the control device 20 transmits the distances X, K, and Q to the main control unit 22 of the printer P2. This configuration allows the main control unit 22 of the printer P2 to obtain information about the distances X, K, and Q for use in solving Equations (I) and (II).
In the present embodiment, the buffer amount is obtained by accessing the buffer-amount table, in which the buffer positions and the buffer amounts are associated with each other, stored in the memory or the like in advance; however, a method for obtaining a buffer amount is not limited thereto. For instance, a configuration to be described below for dynamically calculating a buffer amount, which causes the distance X displace, based on the buffer position (pivot angle of the buffer mechanism 15) may be alternatively employed.
x1=B−A (III)
where A is the length of the buffer mechanism 15, and B is the distance from the pivot center of the buffer mechanism 15 to the pre-heating plate 6.
The transmitting unit of the printer P1 transmits: A which is the length of the buffer mechanism 15; B which is the distance from the pivot center of the buffer mechanism 15 to the pre-heating plate 6; and θ which is the pivot angle of the buffer mechanism 15 detected by the position sensor unit of the printer P1, to the control device 20. The control device 20 transfers A, B, and θ to the printer P2. The main control unit 22 of the printer P2 receives A, B, and θ from the control device 20.
In this situation, the main control unit 22 calculates x2, which is the distance from the distal end of the buffer mechanism 15 to the pre-heating plate 6, from Equation (IV).
x2=√(A2+B2−2AB cos θ) (IV)
The main control unit 22 uses Equations (III) and (IV), and the buffer mechanism 15 obtains the buffer amount Δx, which is a displacement of the web conveyance distance from the lower limit position using Equation (V).
Δx=x2−x1 (V)
The main control unit 22 adds the buffer amount Δx obtained from Equation (V) to the distance X.
The method described above allows dynamic calculation of a buffer amount to thereby adjust the distance X.
A web-jam detection control procedure performed by the printing system configured described above according to the present embodiment is described below.
Referring to
If the main control unit 22 detects a web jam (YES at Step S103), the main control unit 22 performs web-jam-error processing that includes transmitting a notification of occurrence of the web jam to the control device 20 and causing printing (web conveyance) to pause at Step S104.
In the procedure illustrated in
Referring to
The main control unit 22 monitors whether the error mask timing T calculated in advance (see Equation (I)) has elapsed at Step S203. If the time T has elapsed (YES at Step S203), it is indicated that a thermally shrunk portion has reached the web-jam detecting sensor 2. Accordingly, the main control unit 22 sets the printer to be the web-jam-error masking period at Step S204. Subsequently, the main control unit 22 monitors whether the period M, which is the web-jam-error masking period calculated in advance, has elapsed at Step S205. If the web-jam-error masking period M has elapsed (YES at Step S205), the main control unit 22 cancels the web-jam-error masking period setting (Step S206).
In the present embodiment, the web-jam-error masking period is determined by causing the timer 23 to count the period M calculated in advance based on the error mask timing T. However, the web-jam-error masking period may be determined by other method, example of which includes a method of defining the web-jam-error masking period by counting the number of printed pages.
Referring to
In this case, the main control unit 22 calculates the error mask timing T1 of the thermally shrunk portion formed at first from Equation (VI):
T1=T−Tp (VI)
where Tp is a period of time (in other words, print duration) that has elapsed from resumption of the printing until the printing pauses again.
If calculated value of the time T1 is equal to or greater than one, the main control unit 22 stores the value in a storage device 26.
The main control unit 22 counts, when printing is resumed for the second time, each of the error mask timing T (see Equation (I)) and the error mask timing T1 related to arrival of the thermally shrunk portion at the printer P2. When the time has elapsed, the main control unit 22 sets the printer to enter a web-jam-error masking period of the period M to thereby mask the web-jam detection for each of the thermally shrunk portions. This allows masking of an error resulting from detection of a web jam to be started at each of points in time where the thermally shrunk portions individually reach the web-jam detecting sensor 2, thereby allowing appropriate web-jam detection.
In the example described above, it is assumed that there are two thermally shrunk portions on the web. However, the main control unit 22 is adaptable to a situation where there are three or more thermally shrunk portions by calculating, for each of the thermally shrunk portions, time that is to elapse before the thermally shrunk portion reaches the web-jam detecting sensor 2 of the printer P2 by performing similar calculation to that according to Equation (VI) and storing results of the calculation in the storage device 26.
In a case when the printing pauses in the middle of a web-jam-error masking period of the web-jam detecting sensor 2. The main control unit 22 stops a process that corresponds to the web-jam-error masking period. When resuming the printing, it is possible to deal with the above described situation by resuming the operations that correspond to the paused web-jam-error masking period.
According to the embodiment described above, the web printing system free from false detection of a web jam in the printer P2 even when printing is resumed from a paused state can be provided. Prevention against false detection of a web jam that may be caused by a thermally shrunk portion that has been at rest at the pre-heating plate 6 of the printer P1 may be achieved. Prevention against false detection that may be caused due to a plurality of thermally shrunk portions may also be achieved.
In the embodiment discussed above, the printer P1 forms an image on the first surface of the web W while the printer P2 forms an image on the second surface of the web W; however, the present invention is similarly applicable to a configuration where the printer P2 additionally forms an image of the first surface of the web W as well.
In the embodiment described above, the standard-compliant feed holes H are created in both lateral-side portions of the web W so that the web W is conveyed by the web conveying units 1 and 5; however, the present invention is similarly applicable to a configuration where the holes H are not created in both lateral-side portions of the web W.
In the embodiment described above, the printer P1 and the printer P2 are identical to each other in structure; however, the present invention is similarly applicable to a configuration where the printer P1 and the printer P2 have different structures.
The embodiments and modifications described above may be combined appropriately without departing from the scope of the present invention. In the embodiments described above, printing paper is used as the web; however, the present invention is similarly applicable to a configuration where a thermally deformable print medium, such as film, is used as the web.
The present invention is applicable to any printing system that includes a first printer that forms an image on elongated print medium by performing image forming process that involves thermal fixing and a second printer that receives the print medium with the image printed thereon fed from the first printer and forms an image on the print medium that is conveyed at the same conveyance speed as that in the first printer irrespective of image forming process and structure of the second printer.
Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-265695 | Nov 2009 | JP | national |
