JP4870629B2 - Printing device - Google Patents

Description

  The present invention relates to a print medium conveyance control technique in a printing apparatus that forms images, characters, and the like on a print medium.

  2. Description of the Related Art Conventionally, for example, there is a SIDM (Serial Impact Dot Matrix) printer as a printing apparatus that performs printing while controlling the conveyance of a print medium such as paper. In the printing apparatus, a plurality of paper detection sensors are provided on a table for setting paper. A technique has been developed in which the skew is detected when the paper is set obliquely or skewed, and the skew is corrected and printed (for example, see Patent Document 1).

  The sensor for detecting the skew includes a case where a light-emitting diode and a light-receiving transistor are arranged to face each other and a transmission type sensor that detects the presence of paper by blocking transmitted light by a paper passing between them, In some cases, a reflection type sensor that detects light reflected from a sheet by using a light receiving transistor on the same side may be used. In the latter reflection type sensor, the paper detection sensor is arranged on the table facing upward, and the reflected light from the back surface of the paper passing therethrough is detected.

  In the transmissive sensor, the light emitting diode and the light receiving transistor are arranged to face each other, so a space is required. However, since the reflective sensor only needs to be arranged in one direction, the space can be saved. Generally, the reflective sensor Is often used.

  When the paper is skewed and the skew of the paper is detected by the detection sensor, a skew removing roller (not shown) is rotated, the paper is abutted against the feed roller, the paper set obliquely is corrected horizontally, and then the print head Is moved, the sheet is pressed for sheet suction, the suction operation is started, and printing is performed.

If the skew is not corrected even after performing the skew correction operation, a paper set alarm is displayed after a retry operation.
JP 2005-187113 A

  However, in the above-described conventional printing apparatus, when printing on a sheet having a black belt preprinted on the front end portion of the sheet, when setting the sheet, the distance from the feed roller that contacts the sheet to the sheet detection sensor, and the sheet When the distance from the leading edge to the black belt preprint position is the same distance, the reflected light from the paper cannot be obtained, and it may be erroneously detected that there is no paper.

  For example, when the paper has a configuration as shown in FIG. 20 and the printing apparatus has a configuration as shown in FIG. 21, the distance from the leading edge of the paper 3 to the center of the black belt preprint 3x position on the back surface is 10 mm. Since the distance Ly from the paper detection sensor 2 to the feed roller 5 against which the paper 3 abuts when the paper is set on the paper is about 10 mm, when the paper 3 is abutted against the feed roller 5 and set, the black belt preprint portion on the back side 3x is located just on the paper detection sensor 2.

  In this case, when there is no black belt preprint portion 3x on the back surface, it is determined that there is a sheet by reflected light from the paper 3. However, when there is a black belt preprint portion 3x on the back surface, light is absorbed by this and the paper 3 It is judged that there is no paper.

  In the paper having the configuration shown in FIG. 20, there are 35 mm margins on the left and right edges of the black belt preprint portion 3x on the back side, and the distance Ls between the paper detection sensors is 48.5 mm as shown in FIG. Therefore, as the case where the left and right margins are located on the paper detection sensor 2, as shown in FIG. 22, when the paper detection sensors are located in the left and right margins as in the case (a), When the paper detection sensor is located only in one of the left and right margins as in (b), the paper detection sensor is not located in any of the left and right margins as in the case (c).

  In the case (a), the black belt preprint unit 3x on the back side erroneously detects that there is no paper by the paper detection sensors 2b to 2d, but the right and left paper detection sensors 2a and 2e detect the presence of two sheets. Therefore, it is determined that there is no skew, and the suction operation can be performed.

  However, in case (b), only the sheet detection sensor 2e detects the presence of the sheet, and the detection result is the same as when the sheet 3 is set obliquely as shown by the dashed line in FIG. Even if the operator has set it horizontally, it is determined that there is a skew, it is determined that the skew has been set to an extent that skew correction cannot be performed, a paper setting alarm is generated, and paper 3 is set again. There was a problem that had to be.

  In the case (c), the paper detection sensors 2b to 2e erroneously detect that there is no paper by the black belt preprint unit 3x on the back surface, so even if the operator sets the paper 3 correctly, the paper 3 There was also a problem that inhalation could not be started because it was determined that was removed.

The present invention employs the following configuration in order to solve the above-described problems. That is, a plurality of reflection type print medium detection sensors are arranged in a direction perpendicular to the print medium conveyance direction on the conveyance path in front of the print medium abutment position , and the print medium to be inserted based on the detection result of the print medium detection sensor the printing apparatus for detecting the set state of the print medium is a print medium having a black band region, the printing medium detecting sensor print medium chromatic when the printing medium detecting sensor has detected the first printing medium a first detection number that detected the Ri, skew performing skew determination of the first of the printing medium detecting sensor after a predetermined time has elapsed from the detection the second detection number to based have been the printing medium detected the presence of the print medium the determination means is provided, said skew determining means, when the second detection number is less than or equal to said first number of detected by one or more, the first detection number is given When the above detection number was possible to determine that there is no skew of the print medium.

According to the printing apparatus of the present invention, since it is configured as described above, it is possible to prevent erroneous detection of skew due to black band preprinting even on a sheet having a black band preprinted part on the back surface.

  Embodiments of the present invention will be described below with reference to the drawings. Elements common to the drawings are given the same reference numerals. The external configuration of the paper and the printing apparatus according to the first exemplary embodiment is the same as that described in the background art of FIG. 21, and thus detailed description thereof is omitted for simplification.

(Control system configuration)
As shown in FIG. 1, the configuration of the control system of the printing apparatus according to the first embodiment includes a sheet detection sensor 2 that detects whether or not the sheet 3 is set on the table 4, and a sheet detection sensor as a skew determination unit. 2 corrects the skew detection by the sheet detection unit 20 that detects the insertion and conveyance state of the sheet 3 based on the detection result 2 and the black band preprint unit 3x on the back side of the sheet 3 based on the detection result history of the sheet detection sensor 2. And a black belt detection correction unit 21.

  Then, a skew roller driving unit 12 that rotates a skew removing roller (not shown) and abuts the paper 3 against the feed roller 5 to correct the skew, and a head driving unit that drives a print head or carriage (not shown) in a direction perpendicular to the paper conveyance direction. 13, a suction conveyance unit 14 that performs suction and conveyance control of the sheet 3, and a control unit 10 that controls these.

(Operation)
With the above configuration, the printing apparatus according to the first exemplary embodiment operates as follows. This operation will be described in detail below with reference to the operation explanatory diagram of FIG. 2 and the time chart of FIG.

First, step ST1 is intended to indicate a state when the operator has started loading paper 3, the paper 3 at this time is not reached in any of the paper detection sensor 2a through 2g, the 2a through 2g Any paper detection sensor results in the detection of no paper.

  Then, when the operator pushes in the paper 3, the state as shown in step ST2 is established, the leading edge of the paper 3 is placed on the paper detection sensors 2b to 2e, and the paper detection sensor 2b to 2e changes from the absence of paper to the detection state of paper. To do.

  Further, when the paper 3 is pushed in, the state becomes as in step ST3, but the state of the paper detection sensors 2b to 2e is not changed.

  Further, when the paper 3 is pushed in, the state is as shown in step ST4. However, the black belt preprint portion 3x on the back surface of the paper 3 is placed on the paper detection sensors 2b to 2d, and the paper detection sensors 2b to 2d. Changes from the presence of paper to the no-paper detection state. At this time, since the sheet detection sensor 2e is applied to the right end margin of the black belt preprint portion 3x on the back surface, no change occurs in the sheet detection sensor 2e.

  Further, when the paper 3 is pushed in, the state becomes as shown in step ST5 and the front end of the paper 3 is in contact with the feed roller 5, but the state of the paper detection sensors 2b to 2e is not changed.

  As a result of the above, as shown in FIG. 3, the paper detection sensors (2a, 2f, 2g) are detected as being out of paper, and the paper detection sensors 2b to 2e are changed from no paper to paper in step ST2. In step ST4, the paper detection sensors 2b to 2d are switched from the presence of paper to the absence of paper, and the paper detection sensor (2e) detects the presence of paper as it is.

  The detection timing of these paper detection sensors (2a to 2g) may be set at an interval of about 20 ms from the operation speed of the operator.

  Next, the operation of correcting the erroneous detection of skew by the black band detection correction unit 21 will be described with reference to the operation flowchart of FIG.

  First, it is determined whether or not the detection result of the paper detection sensors (2a to 2g) is changed by the paper detection unit 20 (step S01). If there is a change, the detection of the paper detection sensors (2a to 2g) is detected. The result is read (step S02), and the detection result at this time is stored in the register Stp (step S03).

  Next, a predetermined time Tx from when the change of the sheet detection sensors (2a to 2g) is detected to when the sheet 3 starts to be sucked, that is, after the operator sets the sheet 3 on the table 4, the feed roller 5 is turned on. Waiting for the inhalation waiting time (for example, about 500 msec) until abutment (step S04).

  Then, after the suction waiting time Tx has elapsed, the detection results of the paper detection sensors (2a to 2g) are read (step S05), and the paper detection sensors (2a to 2g) at the position where the paper 3 hits the feed roller 5 are read. As a result, it is stored in the register Sed (step S06).

  Here, if the value of the register Sed is 0, that is, if the number of sensors that detected the presence of paper is 0, the paper 3 is once inserted up to the position of the paper detection sensors (2a to 2g) in step S01. Thereafter, it is determined that the paper has been removed, and the process returns to step S01 to wait for the paper 3 to be set again (steps S07 and S08).

  If the value of the register Sed, which is the number of sensors that detected the presence of paper, is other than 0 or 1, the control unit 10 issues a suction start request to the suction conveyance unit 14 (step S09), and the head drive unit 13 performs printing not shown. Move the head to the print position and print.

  On the other hand, if the value of the register Sed, which is the number of sensors that have detected the presence of paper after the elapse of the suction waiting time Tx in step S07, is 1, this is the number of sensors with paper when the paper detection sensor first changes. It is determined whether or not the value is 2 or more by referring to the value of the register Stp (step S10). If the value of the register Stp is 1 or less, the operator has set the paper 3 diagonally so that the skew cannot be corrected. Therefore, a set alarm is requested (step S11).

  On the other hand, when the value of the register Stp is 2 or more, the leading edge of the sheet 3 is detected by two or more sheet detection sensors. Therefore, the sheet 2 is set normally, but the sheet 3 is set after the suction waiting time Tx has elapsed. Is determined to be in a state where the black belt preprint unit 3x on the back surface of the paper is on the paper detection sensor 2, and the black belt detection correction unit 21 corrects the erroneous detection of the skew, and proceeds to step S09 to suck the paper 3 To start.

  In the above description of steps S02 to S04, the case where the front end of the paper 3 is inserted and set horizontally has been described as an example. However, the case where the paper 3 is set slightly obliquely or the front end of the paper is disturbed. In this case, the paper detection sensor (2b to 2d) detects the presence of paper from the absence of paper as shown by the broken line a in FIG. 3, and in consideration of this, the paper is detected at intervals of about 5 ms in step S02. It is preferable to read the output of the detection sensors (2b to 2d) several times and store the smoothed result in the register Stp.

(Operation of Modified Example of Embodiment 1)
In the above description, it has been described that the erroneous detection of the skew is prevented as in steps S07 to S11 by the values of the registers Stp and Sed. However, as shown in steps S27 to S31 of FIG. Detection may be prevented.

  That is, first, similarly to the operation of the first embodiment, when the detection results of the sheet detection sensors (2a to 2g) are changed in steps S21 to S26, the number is stored in the register Stp and pushed to the feed roller 5. As the contact position, the number of sensors with paper after the elapse of the suction waiting time Tx is stored in the register Sed (steps S21 to S26).

Then, it is determined whether or not the value of the register Sed, which is the number of sensors with paper at the feed roller abutting position, is equal to or larger than 1 with the value of the register Stp being the number of paper presence detected when the paper is set ( In step S27), if the condition is not met, it is determined that the sheet 3 without the black band preprint portion 3x on the back side is set slightly obliquely or removed , and then the register Sed is stored in the register Sed. It is determined whether or not it is 0 (step S28). If it is 0, after the paper 3 is set, the paper 3 is taken out and the process returns to step S21.

  On the other hand, when the value of the register Sed is smaller than the value of the register Stp, it is determined that there is a detection by the black band preprint unit 3x on the back surface, and the process proceeds to step S30, where it is determined whether the register Stp is equal to or greater than a predetermined value α. In the case above, the normal suction operation is started on the assumption that there is an erroneous detection by the black belt preprint unit 3x on the back surface.

  If the register Stp value is smaller than α in step S30, it is determined that the sheet 3 is set obliquely and a set alarm is requested (step S31).

  By doing as described above, even if the width of the black band preprint portion 3x on the back surface of the paper 3 in particular in the horizontal direction or the width of the margin changes, it is possible to prevent erroneous detection of skew.

(Effect of Example 1)
As described in detail above, according to the printing apparatus of the first embodiment, the black band detection correction unit that corrects erroneous detection of skew by the black band preprint unit on the back surface of the paper 3 from the history of detection results of the paper detection sensor. When the number of sheets detected at the abutting position on the feed roller is 1 and the number of sheets at the time of change of the sheet detection sensor is 2 or more, or the abutting on the feed roller The number of sheets detected at the position is 1 or more and less than the number of sheets when the sheet detection sensor is changed for the first time, and the number of sheets when the sheet detection sensor is changed is more than a predetermined number. Since it is judged that there is no skew and the suction operation is performed, even if the paper has a black belt preprint part on the back side, erroneous detection of skew due to the black belt preprint is prevented. Door can be.

(Control system configuration)
As shown in FIG. 6, the control system configuration of the printing apparatus 1 according to the second embodiment determines whether or not the sheet 3 having no margins has been extracted at the left and right ends of the black band preprint portion 3x once set. A sampling determination unit 22 is newly provided. Since other configurations are the same as those of the first embodiment, detailed description thereof is omitted.

(Operation)
With the above configuration, the printing apparatus 1 according to the second embodiment operates as follows. This operation will be described below in detail using the operation explanatory diagrams of FIGS. 7 and 9 and the data example of the history buffer of FIG.

  (When paper is pulled out during loading)

  First, the operation when the operator pulls out the sheet 3 before completing the setting of the sheet 3 will be described with reference to the operation explanatory diagram of FIG. 7 and the data example of the history buffer of FIG. First, as shown in FIG. 7, step ST11 shows a state when the operator starts to set the paper 3 in a state where the paper 3 rises to the left. At this time, the paper 3 is set to any of the paper detection sensors 2a to 2g. Therefore, any of the paper detection sensors 2a to 2g has a detection result of no paper, and the history buffer storage value is also in the no paper state of 00h.

  The history buffer storage values are “0” when there is no paper, “1” when there is paper, the least significant bit bit0 on the paper detection sensor 2a side, and the upper second bit bit6 on the paper detection sensor 2g. The most significant bit bit7 is represented in hexadecimal as “0”.

  Then, when the operator pushes the paper 3 in the direction of arrow A, the state is as shown in step ST12, the leading edge of the paper 3 is placed on the paper detection sensors (2b and 2c), and the paper detection sensors (2b and 2c) are out of paper. Since the state changes to the paper presence detection state and bit1 and bit2 become “1”, the history buffer storage value becomes 06h.

  Further, when the paper 3 is pushed in, a state as shown in step ST13 is established, the leading edge of the paper 3 is also applied to the paper detection sensor (2d), and the paper detection sensor (2d) is also changed to a paper presence detection state. Since bit3 is also "1" in addition to bit2, the history buffer storage value is 0Eh.

  When the operator starts to pull out the paper 3 in the direction of arrow B from this state, the state becomes as shown in step ST14, the leading edge of the paper 3 comes off from the paper detection sensor (2d), and the paper detection sensor (2d) enters the paper-out detection state. Since bit3 changes to “0”, the history buffer storage value becomes 06h.

  If the operator further pulls out the paper 3 from this state, the state becomes as shown in step ST15, the leading edge of the paper 3 comes off from the paper detection sensors (2b and 2c), and the paper detection sensors (2b and 2c) detect no paper. Since the state changes and bit1 and bit2 become “0”, the history buffer storage value becomes 00h.

(When paper cannot be removed)
Next, the case where the operator sets the paper 3 and does not remove it will be described with reference to the operation explanatory diagram of FIG. 9 and the data example of the history buffer of FIG.

  When the operator sets the paper 3 in a state where the left shoulder is raised and pushes it in the direction of the arrow A, the paper detection sensors (2b and 2c) change from the state without paper to the state with paper, and bit1 and bit2 become "1". The history buffer stored value is 06h, and further, when pushed in the direction of arrow A, the paper detection sensor (2d) also changes to the paper present state, bit3 becomes "1", and the history buffer stored value becomes 0Eh. (Step ST11 to Step ST13).

  When the operator further presses the paper 3 from the state of step ST13, the state of step ST14f is entered, and the black belt preprint portion 3x on the back surface is placed on the paper detection sensors (2b and 2c), and the paper detection sensors (2b and 2c). ) Changes from the paper presence detection state to the paper absence detection state, and the paper detection sensor (2d) remains in the paper presence detection state, so that bit1 and bit2 are “0”, and the history buffer storage value is 08h.

  When the operator further presses the paper 3, the state of step ST15f is entered, the black belt preprint portion 3x on the back surface is also applied to the paper detection sensor (2d), and the paper detection sensor (2d) is changed from the paper presence detection state to the paper. The state changes to the absence detection state, bit3 is also set to “0”, and the history buffer storage value is 00h.

  As described above, when the operator pulled out the paper 3, compared with the case where the paper 3 was not removed, the history buffer stored value was 06h in step ST14 when the paper 3 was not picked up. In this case, the history buffer storage value is 08h in step ST14f. The values stored in the history buffer in the other steps are the same.

(Sampling judgment process)
Next, an operation of determining whether or not the sheet 3 has been extracted in the middle of setting by the extraction determination unit 22 will be described with reference to an operation flowchart of FIG.

  First, the paper detection unit 20 determines whether any of the detection results of the paper detection sensors (2a to 2g) has changed (step S41), and if there has been a change, the paper detection sensors (2a to 2g). ) Is read (step S42), and the changed detection result is stored in the register Stp (step S43).

  The state of the paper detection sensors (2a to 2g) is read (step S44) and stored in the history buffer (step S45).

  Here, it is determined whether or not a predetermined time Tx from when the suction waiting time, that is, the change of the paper detection sensors (2a to 2g) is detected until the suction of the paper 3 is started (step S46). If the inhalation waiting time Tx has not elapsed, it is determined whether the sensor detection timing time has elapsed (step S47). When the sensor detection timing time has elapsed, the process returns to step S44, and steps S45 and S46 are performed. Repeat the operation.

  Then, after the suction waiting time Tx elapses, that is, the result of the paper detection sensors (2a to 2g) at the position where the paper 3 is abutted against the feed roller 5 is stored in the register Sed (steps S48 and S49).

  If the number of sensors in the register Sed is zero, that is, if all the sensor states after the inhalation waiting time Tx have elapsed (steps S50 and S51), the history buffer stored in step S45 is stored. A value is searched (step S52).

  Then, the sampling determination unit 22 searches for the maximum value stored in the history buffer and determines whether the same sensor state exists at the front and back positions. If the same sensor state exists, the paper detection sensor (2a The sheet 3 is inserted up to the position of ~ 2g). Thereafter, it is determined that the sheet 3 has been removed, and the process returns to step S41 to wait for the sheet 3 to be set again (step S53).

  On the other hand, if the same sensor state does not exist before and after the maximum value stored in the history buffer, the paper 3 is pushed in without being removed, and the black belt preprint portion 3x on the back surface is placed on the paper detection sensor 2. It is determined that there is, and a suction start request is made to the suction conveyance unit 14 (step S54), and the print head (not shown) is moved to the print position by the head drive unit 13 to perform printing.

  Further, when the value of the register Sed is 1, that is, when the number of sensors that detect the presence of the sheet 3 in the state where the sheet 3 hits the feed roller 5 is 1, whether the value is 2 or more with reference to the value of the register Stp. Determination is made (step S55), and if the value of the register Stp is 1 or less, it is determined that the sheet 3 is set obliquely to an extent that skew correction cannot be performed, and a set alarm is requested (step S56).

  On the other hand, when the value of the register Stp is 2 or more, that is, when the number of sensors that first detected the presence of the sheet is 2 or more, the sheet 3 having the black belt preprint portion 3x on the back side is inclined so that skew correction is possible. It is determined that this is the case, and inhalation is started.

  That is, when the leading edge of the paper 3 is detected by the paper detection sensors (2a to 2g), the number of sensors that detect the presence of the paper is two or more, so the paper 3 is set normally and the inhalation waiting time Tx has elapsed. Later, it is determined that the black belt preprint unit 3x on the back surface of the paper 3 is placed on the paper detection sensor 2, and the black belt detection correction unit 21 corrects the erroneous detection of skew, and proceeds to step S54. Start inhaling.

  In the above description of the embodiment, the left-up shoulder paper set has been described as shown in FIGS. 7 and 9. However, the same applies to the right-up paper set, and the maximum value stored in the history buffer is the same. Whether or not the sampling is performed can be determined by whether or not the same sensor state exists before and after.

  Further, in the above description of the embodiment, it has been described that whether or not the same sensor state exists before and after the maximum value of the history buffer stored value is determined as to whether or not to extract, the paper is determined from the history buffer stored value. A position where the number of detected sensors is maximized may be searched, and it may be determined whether or not the extraction is performed depending on whether or not the same sensor state exists at the positions before and after that.

  Further, the operations in steps S50, S51, and S55 may be determined based on the predetermined value α as in S27, S28, and S30 as described in the modification of the first embodiment. .

(Effect of Example 2)
As described in detail above, according to the printing apparatus of the second embodiment, in addition to the configuration of the first embodiment, paper is extracted depending on whether or not the same sensor state exists before and after the position where the maximum value is detected in the history. In addition to the effects of the first embodiment, the sampling determination unit that determines whether or not the sheet has been removed can be accurately determined whether or not the sheet has been extracted without being affected by the black belt preprint unit on the back side of the sheet. Can do.

(Control system configuration)
The configuration of the control system of the printing apparatus 1 according to the third embodiment is a configuration in which a first head centering reference position correction unit 23 is newly provided in the configuration of the second embodiment, as shown in FIG. In general, the head centering operation is an operation of determining the print head writing position by detecting the left and right edges of the paper with a sensor attached to the print head or carriage after the paper is sucked. In the example, the operation for holding the paper edge curl with the print head before inhaling the paper is called a head centering operation.

  The first head centering reference position correction unit 23 is provided to solve the problem that the reference position for performing the head centering operation is not an appropriate position due to the influence of the black belt preprint unit 3x on the back surface.

  That is, for example, when the paper 3 having the back black band preprint portion 3x as shown in FIG. 2 is set and printed, the leftmost paper detection is detected immediately before inhalation (step ST5). When the position of the detected paper detection sensor is the reference position for head centering, the paper detection sensors 2b to 2d are detected as no paper by the black belt preprint unit 3x on the back surface, and only the paper detection sensor 2e detects the presence of paper by the right margin. Therefore, the position of the sheet detection sensor 2e becomes the position of the sheet detection sensor that has detected the presence of the leftmost sheet, and the head centering reference position is erroneous.

  In order to solve this problem, the first head centering reference position correction unit 23 according to the third embodiment uses the detection result stored in the register Stp when the sensor is changed first and the register after a predetermined time Tx has elapsed. The OR of the detection result stored in Sed is taken, and the position of the paper detection sensor 2 corresponding to the leftmost end of the detection result is determined as the reference position of the head center rig. Since other configurations are the same as those of the second embodiment, detailed description thereof is omitted for the sake of brevity.

(Operation)
With the above configuration, the printing apparatus according to the third embodiment operates as follows. This operation will be described below with reference to an example of the history buffer data in FIG. 13 and the logical OR of the sensor result in FIG. 14, taking as an example the case where a sheet is inserted as shown in FIG. 2 described in the first embodiment. .

  First, when the paper as shown in FIG. 2 is set and inserted, the detection result of the paper detection sensor is obtained for each step as shown in FIG. Then, the detection result when the sensor is changed first is stored in the register Stp. In this example, since the paper detection sensors (2b to 2e) have paper, the value of the register Stp is 1Eh (step ST2).

  Then, after the suction waiting time Tx has elapsed, when the operator detects and inserts the paper 3 to the position of the feed roller 5, only the paper detection sensor (2e) has the paper, and the value of the register Sed is 10h (step ST5).

  Then, in the first head centering reference position correction unit 23, the register Stp value as the result of the sheet detection sensor when the sensor is changed first, and the sheet after the elapse of the suction waiting time Tx (immediately before the start of suction). A logical OR with the register Sed value, which is the result of the detection sensor, is obtained and stored in the register Sor. In this example, since the register Stp value is 1Eh and the register Sed value is 10h, the value of the register Sor is 1Eh.

  Then, from the bit 0 of the least significant bit of the register Sor (that is, the detection result of the leftmost paper detection sensor 2a), the bit whose bit information is 1 in order of bit1, bit2, and bit3 is detected, and the bit is detected as the paper. It is determined that the position of the paper detection sensor corresponds to the left end position.

  In this example, since bit1 (paper detection sensor 2b) is a paper detection sensor that first becomes 1, the position of the paper detection sensor (2b) is determined as the reference position of the head centering position.

  Next, the operation of the third embodiment will be described in detail with reference to the operation flowchart of FIG. First, when there is a change in the detection results of the paper detection sensors (2a to 2g) in the paper detection unit 20, the detection results of the paper detection sensors (2a to 2g) are read, and the detection results at the time of the change are stored in the register Stp. Store (steps S61 to S63).

  Then, the state of the paper detection sensors (2a to 2g) is read and stored in the history buffer (steps S64 and S65).

  Here, it is determined whether or not the suction waiting time Tx from the time when the suction waiting time, that is, the change of the paper detection sensors (2a to 2g) is detected to the time when the suction of the paper 3 is started has elapsed (step S66). If the inhalation waiting time Tx has not elapsed, it is determined whether the sensor detection timing has elapsed (step S67). If the sensor detection timing has elapsed, the operations of steps S64 and S65 are repeated.

  Then, after the suction waiting time Tx elapses, the detection result of the paper detection sensors (2a to 2g) is read (step S68), and the result of the paper detection sensor (2a to 2g) at the position where the paper 3 is abutted against the feed roller 5 is read. Is stored in the register Sed (step S69).

  Here, when the value of the register Sed is 1, that is, when the number of sensors that detect the presence of paper at the position where the paper 3 is abutted against the feed roller 5 is 1 (step S70), the value of the register Stp is referred to. Then, it is determined whether or not it is 2 or more (step S78).

  If the value of the register Stp is 2 or more, that is, the number of sensors that first detected the presence of paper is 2 or more, when the leading edge of the paper 3 is detected by the paper detection sensor 2, the number of sensors that detected the presence of paper is 2 or more. Therefore, it is determined that the paper 3 is set normally, and the black belt preprint portion 3x on the back surface of the paper 3 is placed on the paper detection sensor 2 after the suction waiting time Tx has elapsed, and a suction start request is issued. Prior to this, the first head centering reference position correction unit performs the following sensor information determination process to determine the correct head center rig position reference.

  That is, the bit information of the register Stp and the bit information of the register Sed are logically ORed and stored in the register Sor (step S74). In the example of FIG. 2, as described above, since the result of the logical OR is 1Eh, 1Eh is stored in the register Sor.

  Then, the first bit in which the bit information is 0 to 1 is searched from the lowest bit 0 of 1Eh which is the register Sor value (step S75). The leftmost paper detection sensor 2 is determined from the search result, and the position of the paper detection sensor 2 is used as a reference for the head centering position (step S76).

  Then, based on the head centering reference position obtained in the sensor information determination process, the print head is centered, and a suction start request is sent to the suction transport unit 14 (step S77).

  On the other hand, when the value of the register Stp is 1 or less, it is a case where the sheet 3 is set obliquely to such an extent that the operator cannot correct the skew. Therefore, it is determined that the skew cannot be corrected, and a set alarm is requested (step S79).

  If the number of sensors in the register Sed is 0, that is, if the number of sensors that detect the presence of paper at the position where the paper 3 is abutted against the feed roller 5 is 0, the data is stored in step S65. A history buffer stored value is searched (steps S70 to S72).

  If the same sensor state appears before and after the maximum value stored in the history buffer in the extraction determination unit 22, it is determined that the paper 3 has been once inserted up to the paper detection sensor 2, but then has been extracted. The process returns to S61 and waits for the sheet 3 to be inserted.

  On the other hand, if the same sensor state does not appear before and after the maximum value stored in the history buffer, it is determined that the black belt preprint unit 3x on the back surface is on the paper detection sensor 2, and the sensor information described above is used. After performing the determination process and the centering of the head (steps S74 to S76), a suction start request is made to the suction conveyance unit 14 (step S77).

  In addition, when the value of the register Sed is other than 0 or 1, that is, when the number of sensors that detect the presence of the sheet is other than 0 or 1, it is a normal sheet without the black belt preprint 3x on the back surface, and thus the above-described case. After performing the sensor information determination process and performing the centering of the head (steps S74 to S76), a suction start request is sent to the suction conveyance unit 14 (step S77).

  In the above description, the first bit where the bit information is 0 to 1 is searched from the lowest bit 0 of the register Sor value, and the position of the paper detection sensor 2 corresponding to the bit is used as the reference of the head centering position. As described above, a bit whose bit information further changes to 0 is searched, and the position of the sheet detection sensor 2 corresponding to the bit is set as the right end position of the sheet, and the center position of the sheet is calculated from the position information. However, the head centering position may be used.

(Effect of Example 3)
As described above in detail, according to the printing apparatus of the third embodiment, the logical sum of the detection result of the paper detection sensor that detects the leading edge of the paper and the detection result of the paper detection sensor after a predetermined time has elapsed is obtained. Since the first head centering reference position correction unit that determines the leftmost sensor based on the logical sum is provided, erroneous detection of the reference position of the head centering is prevented even in the paper having the black belt preprint part on the back surface. be able to.

(Control system configuration)
As shown in FIG. 16, the control system of the printing apparatus 1 according to the fourth embodiment has a second head centering reference position correction unit 24 instead of the first head centering reference position correction unit 23 according to the third embodiment. The configuration is provided. The second head centering reference position correcting unit 24 performs the horizontal direction from the time when the paper leading edge is first detected by the paper detection sensor 2 to the time when the suction waiting time Tx elapses and hits the feed roller 5. This is provided to solve the problem that the reference position of the head centering is not appropriate when the paper 3 is inserted while being shifted.

  That is, the second head centering reference position correcting unit 24 detects the position of the sheet detection sensor when the sheet 3 is abutted against the feed roller 5 in the left or right region from the center of the sheet setting possible range. In the case of the paper detection sensor in the right region, correction is performed so that the paper detection sensor located approximately left by the paper width from the position of the paper detection sensor is set as the reference position for head centering. is there. Since other configurations are the same as those of the third embodiment, detailed description thereof is omitted.

(Operation)
With the above configuration, the printing apparatus 1 according to the fourth exemplary embodiment operates as follows. This operation will be described in detail below with reference to the operation explanatory diagram of FIG. 17, the operation flowchart of FIG. 18, and the paper set range explanatory diagram of FIG.

  FIG. 17 is a diagram showing the transition of the paper when the paper 3 having the black belt preprint portion 3x on the back surface is pushed in while being slid (obliquely moved). First, step ST21 is a state when the paper 3 is set.

  Step ST22 is a state in which the leading edge of the sheet is placed on the sheet detection sensors 2a to 2d during the sheet setting process. From this state, the operator further pushes the paper while moving it in the upper right direction.

  Then, as in step ST23, the sheet 3 is placed on the sheet detection sensor 2e in addition to the sheet detection sensors 2a to 2d. Further, since the sheet 3 is moved obliquely, the left end of the sheet 3 is coming off the sheet detection sensor 2a. From this state, the operator further pushes in the paper while moving it obliquely.

  Then, as in step ST24, the operator hits the sheet up to the position of the feed roller 5, and the sheet is physically placed on the sheet detection sensors 2b to 2e. The left end of the sheet 3 is separated from the sheet detection sensor 2a. At this time, since there is the black belt preprint unit 3x on the back surface, the sheet detection sensor detected as having a sheet is only 2e.

  In this case, when the processing by the first head centering reference position correcting unit 23 of the third embodiment is performed, the detection result (0Fh) is stored in the register Stp in step ST22, and the detection result (1Eh) is registered in step ST24. Since it is stored in Sed, the result of logical OR is 1Fh, and the paper detection sensor 2b is supposed to be the reference, but the paper detection sensor 2a becomes the reference of the head centering position and does not become an appropriate position.

  The operation of the second head centering reference position correction unit 24 provided to solve this problem will be described in detail with reference to the operation explanatory diagram of FIG. 19 according to the operation flowchart of FIG. In this example, as shown in FIG. 19, the paper width is 203 mm, the black belt width is 133 mm, the margin length is 35 mm, and the paper detection sensor interval is 48.5 mm. Will be described.

  First, in the case of the paper set between case A and case B in FIG. 19, since the two sensors, paper detection sensors 2b and 2e, detect the presence of paper, the process moves to step S86 according to the determination in step S80 in FIG. Then, the same head centering reference position correction as that in the third embodiment is performed, and the position of the leftmost paper detection sensor that detects the presence of paper, that is, the paper detection sensor 2b, is determined as the reference position for head centering.

  Similarly, in the case of the paper set between case C and case D in FIG. 19, since the two sensors, the paper detection sensors 2a and 2e, detect the presence of paper, the process moves to step S86 according to the determination in step S80, and is executed. Head centering reference position correction similar to that in Example 3 is performed, and the position of the leftmost paper detection sensor that detects the presence of paper, that is, the paper detection sensor 2a, is determined as the reference position for head centering.

  In the case of a paper set such as Case B 2 between Case B and Case C, only the paper detection sensor 2e is detected as having paper, so if the number of paper detection sensors is 1, step S81 is performed. In Steps S81 and S82, it is determined whether or not the presence of paper has been detected at the left or right margin position of the black belt preprint portion 3x.

  Here, the paper detection sensors 2d, 2e, 2f, and 2g that can detect the presence of paper in the right edge margin of the black belt preprint unit 3x are the paper detection sensors 2d, 2e, 2f, and 2g. Cannot be detected.

  Therefore, if the number of paper detection sensors is 1 and the paper detection is one of the paper detection sensors 2a, 2b, and 2c, it is detected at the left margin of the black belt preprint unit 3x. In step 85, the position of the paper detection sensor is determined as a reference position for head centering.

  On the other hand, if the number of paper presence sensors is 1 and the paper presence detection is one of the paper detection sensors 2e, 2f, and 2g, it is determined that the detection has been made at the right end margin 3b of the black belt preprint unit 3x. it can. In this case, a paper detection sensor corresponding to the leftmost end is estimated by calculation described below, and the position of the paper detection sensor is determined as a reference position for head centering (steps S83 and S84).

  That is, since the length L + C including the black belt preprint portion (width C) and the left end margin (width L) of the black belt preprint portion is 168 mm, 48.5 mm which is the distance ΔLs between the sensors is n ( It is multiplied by an integer) and compared with the L + C length of 168 mm.

  Then, the minimum value of n that satisfies L + C <48.5 × n is obtained, and the number of the detection sensor that detects the sheet presence state in the right end margin 3b (in this case, the sheet detection sensor 2e is the fifth from the left). On the basis of the information, the sheet detection sensor to be obtained that is applied to the leftmost end is obtained.

  In this example, when n = 3, 48.5 × n = 145.5 mm, when n = 4, 48.5 × n = 194 mm, and when n = 5, 48.5 × n = 242.5 mm. The minimum value n satisfying L + C = 168 mm <48.5 × n is “4”.

  Since the sensor number at which the sheet presence state is detected at the right end 3b of the black belt preprint unit 3x is 5 as described above, the leftmost sheet detection sensor on the left end is 5- (n-1) = 2. Thus, the second sheet detection sensor 2b from the left is estimated.

  By the way, when the number of paper presence sensors is 1 and the paper detection sensor that detects the presence of paper is 2d, the paper is set to the leftmost end of the paper setting possible range and the paper is set to the rightmost end. In this case, there is a possibility of detection in both the left end margin 3a and the right end margin 3b of the black belt preprint portion 3x.

  In this case, although not shown in the drawing, the detection result of the presence of paper when the paper detection sensor is changed first is referred to, that is, the register Stp, and it is determined whether it is set to the leftmost side or the rightmost side. To do. For example, if the paper detection result when the paper detection sensor first changes is any of 2a to 2c, it is determined that the paper is first set to the leftmost side, and the paper detection result is If any one of 2e to 2g, it is initially determined that the sensor is set to the rightmost end side, and the sensor position as a reference for the head centering position is determined.

  In the above description, the paper size, the length of the black belt preprint unit, the interval between the paper detection sensors, the arrangement position, and the like have been described by way of examples. However, when printing on various types of paper, The same can be applied.

  In the above description, the head centering position reference is determined based on the left side. However, the right side may be determined as a reference.

(Effect of Example 4)
As described above in detail, according to the printing apparatus of the fourth embodiment, the sheet detection sensor that is detected as having a sheet when the sheet is abutted against the feed roller is in the region on the right side of the center of the sheet setting possible range. In the case of the paper detection sensor, a second head centering reference position correction unit is provided that corrects the position of the paper detection sensor that is located approximately the paper width to the left of the position of the paper detection sensor as the head centering reference position. Therefore, even when a paper having a black belt preprint on the back side of the paper is set by sliding, the head centering reference position can be set to an appropriate position.

  As described above, the present invention can be widely used in printing apparatuses that form images, characters, and the like on a print medium.

FIG. 3 is a configuration diagram of a control system of the printing apparatus according to the first embodiment. FIG. 6 is an operation explanatory diagram of the printing apparatus according to the first embodiment. FIG. 3 is a time chart of the printing apparatus according to the first exemplary embodiment. FIG. 5 is an operation flowchart of the printing apparatus according to the first embodiment. FIG. 10 is an operation flowchart of a modification of the first embodiment. FIG. 6 is a configuration diagram of a control system of a printing apparatus according to a second embodiment. FIG. 9 is an operation explanatory diagram of the printing apparatus according to the second embodiment. 6 is a data example of a history buffer of the printing apparatus according to the second embodiment. FIG. 9 is an operation explanatory diagram of the printing apparatus according to the second embodiment. 6 is a data example of a history buffer of the printing apparatus according to the second embodiment. FIG. 10 is an operation flowchart of the printing apparatus according to the second embodiment. FIG. 10 is a configuration diagram of a control system of a printing apparatus according to a third embodiment. 10 is a data example of a history buffer of the printing apparatus according to the third embodiment. FIG. 10 is an explanatory diagram of an OR operation process of sensor detection results of the printing apparatus according to the third embodiment. FIG. 10 is an operation flowchart of the printing apparatus according to the third embodiment. FIG. 10 is a configuration diagram of a control system of a printing apparatus according to a fourth embodiment. FIG. 10 is an operation explanatory diagram of the printing apparatus according to the fourth embodiment. FIG. 10 is an operation flowchart of the printing apparatus according to the fourth embodiment. FIG. 10 is an explanatory diagram of a sheet setting range of Embodiment 4. It is a figure explaining the structure of a paper. It is a figure (top view of a printing apparatus) explaining the attachment position of each sensor. It is operation | movement explanatory drawing of the conventional printing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printing apparatus 2 (2a-2g) Paper detection sensor 3 Paper 3a Left end margin 3b Right end margin 3x Black belt preprint part 4 Table 5 Feed roller 20 Paper detection part 21 Black belt detection correction part 22 Extraction determination part 23 1st head Centering reference position correction unit 24 Second head centering reference position correction unit

Claims (5)

A plurality of reflective print medium detection sensors are arranged in a direction perpendicular to the print medium conveyance direction on the conveyance path in front of the print medium abutment position, and a set of print media to be inserted based on the detection result of the print medium detection sensor In the printing device that detects the state,
The print medium is a print medium having a black belt region,
A first detection number of the printing medium detecting sensor the printing medium detecting sensor when detecting that there is first print medium has detected the Ri print medium Yes, the print medium detecting sensor from said first detected after the predetermined time has elapsed a skew determining means for performing a skew determination of the printing medium provided based on the second detection number that detected the presence print medium,
The skew determination means is configured such that when the second detection number is 1 or more and less than or equal to the first detection number, and the first detection number is greater than or equal to a predetermined detection number, A printing apparatus characterized by determining that there is no skew . The printing apparatus according to claim 1, wherein the predetermined number of detection is two . The detection result for each state in which the detection result of the print medium detection sensor changes is stored, and if the same detection result exists before and after the state in which the number of detections with the print medium is maximum, printing is performed. The printing apparatus according to claim 1, further comprising a sampling determination unit that determines that the medium has been extracted . The head centering reference position is corrected based on the logical sum of the first detection result when the print medium detection sensor first detects the presence of the print medium and the second detection result after a predetermined time has elapsed since the first detection. first head centering reference position correcting means according to claim 1 Symbol placement of the printing apparatus, characterized in that a to. When the second detection number is one and the print medium detection sensor is in a region opposite to the reference position side of the head centering from the center of the print medium settable range. Is a second head centering reference for correcting so that the position of the print medium detection sensor located in the direction of the reference position of the head centering is approximately the print medium width from the position of the print medium detection sensor. position correcting unit according to claim 1 Symbol placement of the printing apparatus, characterized in that a.

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