JP2005075545A - Printing apparatus and paper position detection method - Google Patents

Abstract

A printing apparatus and a paper position detection method capable of detecting a paper position more accurately than in the past are provided.
A printing apparatus that performs printing after transporting a sheet to a predetermined position is provided in the vicinity of the sheet transport path, detects a presence of the sheet, and detects a sheet transport speed. And detecting the position of the paper based on a history of paper speeds detected by the speed detection means before the detection time when the paper detection means detects the presence or absence of paper. Paper position detecting means.
[Selection] Figure 1

Description

  The present invention relates to a printing apparatus having a paper position detection function and a paper position detection method thereof, and more particularly, to a printing apparatus and a paper position detection method capable of performing highly accurate paper position detection.

  Some conventional printing apparatuses include a paper detection sensor including a photo interrupter in a paper conveyance path. The printing apparatus determines the presence or absence of paper based on an on / off signal from the paper detection sensor, thereby The paper position was detected. More specifically, the head of the paper, the setting of the override area, the determination of the paper size, and the like are executed by an on / off signal from the paper detection sensor.

  However, in such a paper detection sensor, the paper detection sensor actually starts from the time when the paper passes the position of the paper detection sensor and changes from the state where the paper is present at the position of the paper detection sensor to the state where there is no paper. It takes some time before the off signal (signal notifying that there is no paper) is issued. Similarly, it takes some time for the paper detection sensor to issue an ON signal (a signal indicating the presence of paper) from the time when the paper detection sensor changes from the state where there is no paper to the state where there is paper. . That is, there is a time lag between the actual change in the presence of paper at the sensor position and the on / off signal. Therefore, if it is determined that the leading edge or the trailing edge of the sheet is at the position of the sheet detection sensor when the on / off signal is issued, an error occurs in the sheet position detection.

Therefore, conventionally, it has been proposed to correct the detection position of the paper based on the speed of the paper when the on / off signal of the paper detection sensor is issued (see, for example, Patent Document 1 below). Specifically, since the time lag of the paper detection sensor is substantially constant depending on the on / off direction, the sheet moved between the time lags by multiplying the time lag by the speed of the sheet when the on / off signal is issued. When the on / off signal is output, it is determined that the paper has already moved by this distance from the position of the paper detection sensor, and the paper position is corrected.
JP 2003-72169 A

  However, the conventional position correction method described above can perform position correction almost accurately when the paper is always moving at a constant speed during the time lag of the paper detection sensor. In such a case, the sheet conveyance speed changes during the time lag, so that accurate position correction cannot be performed.

  Also, in recent years, the paper feed speed of printing apparatuses has been increased, that is, the distance that the paper moves within the same time has increased, and therefore more accurate paper position detection has been required. However, the conventional method is insufficient.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a printing apparatus and a paper position detection method capable of detecting a paper position more accurately than in the past.

  In order to achieve the above object, according to one aspect of the present invention, there is provided a printing apparatus that performs printing after transporting a sheet to a predetermined position, and detects the presence or absence of the sheet. Paper detecting means for detecting, paper speed detecting means for detecting the conveyance speed of the paper, and paper speed detected by the speed detecting means before the detection time when the paper detecting means detects the presence or absence of paper. And a paper position detecting means for detecting the position of the paper based on the history. Therefore, according to the present invention, it is possible to accurately detect the position of the sheet even when the conveyance speed of the sheet is changing.

Further, in the above-mentioned invention, the preferable aspect further includes storage means for storing the paper speed detected by the speed detection means at a predetermined frequency and holding the stored paper speed for a predetermined period, and detecting the paper position. The position detection of the sheet based on the sheet speed history by the means is performed by obtaining the amount of sheet movement during the predetermined period using the held sheet speed for the predetermined period.

In the above invention, another aspect further includes a storage unit that stores a sheet position obtained from the sheet speed detected by the speed detection unit at a predetermined frequency and holds the stored sheet position for a predetermined period. The sheet position detection based on the sheet speed history by the sheet position detecting means is performed by obtaining the amount of movement of the sheet during the predetermined period using the held sheet position for the predetermined period. .

  Furthermore, in the above invention, a preferable aspect is a lever-type sensor in which the paper detection unit includes a lever that moves according to a change in the presence or absence of the paper and a sensor that detects the presence or absence of the paper by the movement of the lever. It is characterized by that.

  In order to achieve the above object, another aspect of the present invention provides a printing apparatus that performs printing after transporting a sheet to a predetermined position, and is provided in the vicinity of the sheet transport path to determine whether the sheet is present. When a paper position detection method in a printing apparatus comprising a paper detection means for detecting and a speed detection means for detecting the conveyance speed of the paper detects the presence or absence of paper when the paper detection means detects the presence or absence of paper, The position of the paper is detected based on the history of the paper speed detected by the speed detecting means.

  Further objects and features of the present invention will become apparent from the embodiments of the invention described below.

  Embodiments of the present invention will be described below with reference to the drawings. However, such an embodiment does not limit the technical scope of the present invention. In the drawings, the same or similar elements are denoted by the same reference numerals or reference symbols.

  FIG. 1 is a configuration diagram according to an embodiment of a printing apparatus to which the present invention is applied. The printing apparatus 1 shown in FIG. 1 is a printing apparatus according to the present embodiment, and includes a sheet detection unit and a speed detection unit in the conveyance path of the sheet 3, and accurately detects the position of the sheet using the sheet speed history. To go to.

The printing apparatus 1 has a configuration as shown in FIG. 1, and a thick line from the paper feeding device 11 to the discharge port 17 indicates a paper conveyance path, and position detection is performed on the paper on the conveyance path. .
First, the paper feeding device 11 is a device for storing the paper 3 before printing and supplying the paper 3 to the engine 15 as appropriate. The paper feeding device 13 is provided between the paper feeding device 11 and the engine 15. The paper feeding device 13 supplies the paper 3 supplied from the paper feeding device 11 to the engine 15. And the paper 3 is discharged when printing is completed. The paper feeding device 13 includes a paper feeding roller 131, a paper feeding motor (not shown), and the like.

  In the paper feeding device 13, specifically, the paper feeding motor is provided with an encoder 14 (speed detecting means) as a paper feeding speed detecting means for outputting a pulse signal having a period proportional to the rotational speed. ing. Based on the pulse signal output from the encoder 14, the control unit 18 described later calculates the rotation speed of the paper feed motor, that is, the paper speed.

  The paper detection sensor 12 (paper detection means) is a paper detection means for detecting the paper 3 on the transport path between the paper feeding device 11 and the paper feeding device 13. Although the detailed contents of the paper detection sensor 12 will be described later, it is a lever type sensor and outputs an on / off signal notifying of the presence or absence of the paper 3 at the sensor position based on the rotation of the lever 121 that hits the paper 3 on the conveyance path. .

  Next, the engine 15 is a portion that executes printing on the supplied paper 3 and includes a carriage 151 on which an ink cartridge and a print head are mounted, for example. The paper discharge device 16 includes a paper discharge roller, a paper discharge motor, and the like, and is a device for discharging the printed paper 3 from the discharge port 17.

  The control unit 18 (paper position detection means) includes a CPU 21, a ROM 19, a RAM 20 (storage means), and the like, and controls the printing apparatus 1. Specifically, it is connected to the host computer 2 via the interface device 22 and controls each mechanism according to the printer control language sent from the host computer 2 to actually perform the printing operation. The control performed by the control unit 18 includes control for detecting the position of the paper 3 based on the on / off signal sent from the paper detection sensor 12 and thereby instructing the paper 3 to be fed, cueing, and the like. In particular, the method for detecting the position of the paper 3 is characteristic. Each process performed by the control unit 18 is realized by the CPU 21 executing an application program stored in the ROM 19.

  FIG. 2 is a side view of the paper detection sensor 12. As shown in the drawing, the paper detection sensor 12 includes a lever 121 that rotates when the paper 3 conveyed from the paper supply device 11 hits, and an optical sensor 122 (sensor) that detects that the lever 121 has rotated. Consists of. The lever 121 rotates about a rotation shaft 124, and the optical sensor 122 is fixed to the substrate 123. The state a shown in FIG. 2, that is, the state where the lever 121 is standing up is a state where there is no paper 3 at the position of the paper detection sensor 12, and the state b shown in FIG. In this state, the paper 3 is present at the position of the paper detection sensor 12.

  In the optical sensor 122, light passes through the position shown in FIG. A in the depth direction of the figure. Therefore, in the state a, the light is blocked by the lever 121, while in the state b. , The light is not blocked. The optical sensor 122 detects the rotation of the lever 121 and outputs the above-described on / off signal based on the change in the passage / blocking of the light. More specifically, in the state a, when the sheet 3 is conveyed and hits the lever 121, the lever 121 starts to rotate, and when it passes the position A, that is, moves by a distance B in the figure. Since the light is blocked from the blocked state, the optical sensor 122 outputs an ON signal indicating the presence of paper. On the other hand, in the state b, when the paper 3 passes the position of the paper detection sensor 12, the lever 121 starts to rotate and passes the position A, that is, moves by the distance C in the figure. The optical sensor 122 issues an off signal indicating that there is no paper because the light is passing from the light passing state.

  FIG. 3 is a diagram for explaining the time lag of the paper detection sensor 12. FIG. 3A shows a state immediately after the rear end of the paper 3 has passed the position of the paper detection sensor 12. At this time, the paper detection sensor 12 is already out of paper at the position of the paper detection sensor 12, but as described above, the lever 121 starts to rotate and moves to a position where the light of the optical sensor 122 is blocked. Since some time is required, the paper detection sensor 12 actually issues the OFF signal after the time point (a) in FIG.

  FIG. 3B shows a state at the time when the off signal is generated. Since the sheet 3 continues to move from the time point (a) to the time point (b), the sheet 3 The rear end is moved from the position of the paper detection sensor 12 toward the carriage 151 at the time point (b).

  In the example shown in FIG. 3, the position has moved from the X position to the Y position. Therefore, if the control unit 18 determines that the trailing edge of the paper 3 is at the position of the paper detection sensor 12 (X in the figure) when the off signal is issued, the position of the paper is erroneously detected. Become. Therefore, as described above, it is necessary to correct the detection position. In the example shown in FIG. 3, it is necessary to obtain the distance l that the sheet 3 has moved from the time point (a) to the time point (b) in the figure. . As a result, the correct position of the sheet 3 can be detected.

  Although the above description is for the case of detection of no paper, the same correction is required for the detection of paper presence. However, the time lag from the actual change in the presence or absence of paper at the position of the paper detection sensor 12 until the on / off signal is issued is detected from the difference in the movement distance (B and C) of the lever 121 shown in FIG. In this case, the correction is more important.

  The printing apparatus 1 is characterized by the sheet position detection method including the correction for the time lag described above, and the contents of the position detection will be described below. First, the control unit 18 of the printing apparatus 1 calculates the paper feeding (conveying) speed of the paper 3 based on the pulse signal of the encoder 14 at a constant interval while the paper feeding device 13 is being driven, and the value is stored in the RAM 20. Remember. The speed of the paper 3 to be stored may be the paper speed (ips) itself or the encoder cycle (usec). Further, the period for storing the paper speed is a predetermined period longer than at least the time lag of the paper detection sensor 12 immediately before. For example, if the time lag is 15 msec, the paper speed is stored every 1 msec, and at least the past 15 msec (15) values are stored in the RAM 20.

  FIG. 4 is a diagram showing an example of data stored in the RAM 20. In the example shown in the figure, first, the sheet speed at that time is stored at the position of A in the figure, and in this example, the encoder cycle “30 usec” is stored. After 1 msec, the encoder period “35 usec” at that time is stored in the next area of the RAM 20. Hereinafter, the encoder period is stored every 1 msec, and when the predetermined period elapses, that is, when a value is entered up to the area B in the figure, the next encoder period is held in the area A, and the previous value is Erased. Thereafter, the same storage process is repeated while the paper feeder 13 is being driven.

  If the sheet 3 moves on the conveyance path and the leading edge or the trailing edge of the sheet 3 passes the sheet detection sensor 12 while the processing described above is continued, as described above, a time lag after the passage of the sheet 3 elapses. Thereafter, an on signal or an off signal is issued from the paper detection sensor 12. Upon receipt of such a signal, the control unit 18 uses the paper speed (encoder cycle) stored in the RAM 20 for the past time lag (for example, 15 msec) from that point in time to the present ( The distance (for example, 1 shown in FIG. 3) that the sheet 3 has moved until the ON or OFF signal is received is calculated.

  More specifically, the stored paper speed corresponding to the past time lag from the time when the ON or OFF signal is received is multiplied by the stored speed and a predetermined interval (for example, 1 msec) storing the paper speed. The amount of movement of the paper 3 within each fixed interval (time) is calculated. Thereafter, the amount of movement of the sheet 3 during the time lag (for example, l shown in FIG. 3) is calculated by accumulating the calculated amounts of movement.

  For example, if the fixed interval is 1 msec, the time lag is 15 msec, and the encoder is 1440 dpi, and if one of the encoder cycles stored in the past 15 msec is 80 usec, the amount of movement of the sheet 3 for 1 msec at that time Is 12.5 / 1440 inches (0.2 mm), and other movement amounts for the past 14 msec are calculated in the same manner, and the total of them is the movement amount of the sheet 3 during the time lag of 15 msec.

  The paper position detection method of the present invention is characterized in that the movement amount of the paper 3 between the time lags is obtained using the past speed history of the paper 3 before the detection signal in the paper detection sensor 12. The calculation method of the movement amount is merely an example, and the movement amount may be obtained by another method based on the past speed history. In the above-described example, the control unit 18 calculates the movement amount at regular intervals at the time of receiving the ON or OFF signal. However, the control unit 18 calculates the movement amount for each sheet speed (encoder cycle) in advance. The amount of movement for each predetermined interval may be obtained by referring to this table at the time of receiving the ON or OFF signal.

  As described above, when the movement amount (l) of the sheet 3 between the time lags is obtained, the control unit 18 thereby determines the leading edge of the sheet 3 at the time of receiving the ON or OFF signal from the sheet detection sensor 12. Alternatively, the position (at the rear end) is detected (understood), and based on the detected position of the sheet 3, an instruction to cue the sheet 3, a determination of the sheet size, an instruction to supply / discharge the sheet 3, etc. Specifically, the detection of the paper position is to determine that the leading edge or the trailing edge of the paper 3 is at a position advanced from the position of the paper detection sensor 12 by the amount of movement (l) between the obtained time lags. In other words, the position of the sheet 3 when receiving the ON or OFF signal from the paper detection sensor 12 is corrected from the position of the paper detection sensor 12 by the amount of movement (l).

  FIG. 5 is a diagram for explaining the effect of the paper position detection method in the printing apparatus 1. FIG. 5A is a diagram showing the detection timing of the presence or absence of paper in the paper detection sensor 12 and the speed of the paper feed roller 131 (speed of the paper 3) in time series. In the example of FIG. 5A, the trailing edge of the paper 3 passes the paper detection sensor 12 at the time t1, and then, after the time lag (T in the figure) has elapsed, at the time t2 in the figure, The paper detection sensor 12 transmits an off signal. Further, at time t1, the paper feed roller 131 does not pass much time since it is started, and the speed is increased.

  In such a case, in the conventional method described above, position correction is performed based on the speed v of the paper feed roller 131 at t2. Specifically, the amount of movement of the sheet 3 from t1 to t2 is calculated by multiplying the time lag T by the speed v. However, as shown in the figure, the paper feed roller 131 changes during the time lag T, and the amount of movement is not accurate in the above calculation method. On the other hand, in the method in the printing apparatus 1, as described above, the movement amount is calculated based on the speed at each point in time between the time lags T, so that the change in the speed of the paper feed roller 131 is reflected. It is possible to detect and correct the position close to the actual and with high accuracy.

  FIG. 5B is a diagram illustrating a change in the speed of the paper feed roller 131 (paper 3). The portion shown in (1) in the figure is when the speed is increased such as when the paper feed roller 131 is started, (2) in the figure is when the speed is almost constant, and (3) in the figure is the time of the paper feed roller 131. Each time the speed drops, such as when stopped, is shown. When the paper 3 passes the paper detection sensor 12 at the time of (1) in the figure, the movement amount of the paper 3 during the time lag T becomes the area of A1 (shaded portion) in the figure. In the method, the area is a rectangle obtained by multiplying the speed v1 and T at t2, and an error is clearly generated. However, in the method of the printing apparatus 1, as described above, the movement amount can be obtained with an area of almost A1, and position detection with high accuracy can be performed.

  Further, when the paper 3 passes the paper detection sensor 12 at the time of (2) in the figure, the actual movement amount A2 during the time lag T and the result by the conventional method (rectangle by v2 and T) are almost equal. Become. Further, when the paper 3 passes the paper detection sensor 12 at the time of (3) in the figure, the movement amount A3 between the time lags T is considerably different from the result by the conventional method (rectangle by v3 and T), and is almost the same. The accuracy of the printing apparatus 1 that can obtain A3 is higher. As described above, when the speed of the sheet 3 is changing, the effectiveness of the printing apparatus 1 using the past speed history is particularly remarkable.

 In the above-described embodiment, as illustrated in FIG. 4, the sheet speed is stored while the sheet feeding device 13 is being driven. However, the position of the sheet 3 may be stored instead of the sheet speed. Good.

  Specifically, at a fixed interval (for example, 1 msec interval), the amount of movement of the paper 3 within the predetermined interval is calculated from the speed of the paper feeding device 13 (paper 3) at that time, and stored one time before. The movement amount is added to the current position to obtain the current position, and the position is held in the RAM 20. When the signal from the paper detection sensor 12 is received, the movement amount of the paper 3 between the time lags is obtained from the position stored immediately before it and the position stored before the time lag. Specifically, the amount of movement is obtained by taking the difference between the position stored immediately before and the position stored before the time lag. Note that the position to be stored is relatively used and does not need to have a special meaning as an absolute value.

  As described above, by using the printing apparatus 1 according to this embodiment, the detection of the paper position based on the on / off signal from the paper detection sensor 12 is performed on the paper 3 before the detection by the paper detection sensor 12. This is done based on the speed history. Therefore, even when the speed of the paper 3 changes during the time lag from the actual passage of the paper 3 to the detection by the paper detection sensor 12, the amount of movement of the paper 3 during the time lag can be accurately grasped. It is possible to detect the paper position with higher accuracy than in the past.

  In the above embodiment, the paper detection sensor 12 is a lever type sensor. However, the present invention can be applied even if it is not a lever type sensor as long as the paper detection sensor has a time lag as described above. it can.

  The protection scope of the present invention is not limited to the above-described embodiment, but covers the invention described in the claims and equivalents thereof.

1 is a configuration diagram according to an embodiment of a printing apparatus to which the present invention is applied. 3 is a side view of the paper detection sensor 12. FIG. It is a figure for demonstrating the time lag of the paper detection sensor. 4 is a diagram illustrating an example of data stored in a RAM 20. FIG. FIG. 5 is a diagram for explaining an effect of a paper position detection method in the printing apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Printing device, 2 Host computer, 3 Paper, 11 Paper feeding device, 12 Paper detection sensor (paper detection means), 13 Paper feeding device, 14 Encoder (speed detection means), 15 Engine, 16 Paper discharge device, 17 Outlet , 18 control unit (paper position detection means), 19 ROM, 20 RAM (storage means), 21 CPU, 22 interface device, 121 lever, 122 optical sensor (sensor), 123 substrate, 124 rotating shaft, 131 paper feed Roller, 151 carriage

Claims (5)

In a printing apparatus that performs printing after transporting paper to a predetermined position,
A paper detection means provided in the vicinity of the paper conveyance path for detecting the presence or absence of the paper;
Speed detecting means for detecting the conveying speed of the paper;
A paper position detecting means for detecting the position of the paper based on a history of paper speeds detected by the speed detecting means before the detection time when the paper detecting means detects the presence or absence of paper; A printing apparatus comprising the printing apparatus. In claim 1, further comprising:
Storage means for storing the paper speed detected by the speed detection means at a predetermined frequency, and holding the stored paper speed for a predetermined period;
The paper position detection based on the paper speed history by the paper position detecting means
The printing apparatus is characterized in that it is performed by obtaining the amount of movement of the sheet during the predetermined period using the held sheet speed for the predetermined period. In claim 1, further comprising:
Storage means for storing the paper position obtained from the paper speed detected by the speed detection means at a predetermined frequency, and holding the stored paper position for a predetermined period;
The paper position detection based on the paper speed history by the paper position detecting means
The printing apparatus is characterized in that it is performed by obtaining the amount of movement of the paper in the predetermined period using the held paper position of the predetermined period. In any one of Claim 1 thru | or 3,
The printing apparatus according to claim 1, wherein the paper detection unit is a lever sensor that includes a lever that moves according to a change in the presence or absence of the paper and a sensor that detects the presence or absence of the paper by the movement of the lever. A printing apparatus that performs printing after transporting a sheet to a predetermined position, the sheet detecting unit being provided in the vicinity of the sheet transport path for detecting the presence or absence of the sheet, and speed detection for detecting the sheet transport speed A paper position detection method in a printing apparatus comprising:
When the paper detection means detects the presence or absence of paper, the paper position is detected based on a history of paper speeds detected by the speed detection means before the time of the detection. Position detection method.

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