JP3891239B2 - Printing apparatus, control method therefor, and information recording medium - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a printing apparatus (printer), a control method for the printing apparatus, and an information recording medium on which a program for controlling the printing apparatus is recorded, and in particular, a printing apparatus that feeds paper with a plurality of rollers, Printing device that discharges the paper and prevents paper jam when a paper having a shorter depth (paper feeding direction) than the path to the roller is inserted into the printing device, and a control method for the printing device The present invention also relates to an information recording medium on which a program for controlling the printing apparatus is recorded.
[0002]
[Prior art]
Conventionally, printing in which a BOF (BottomOfForm) sensor, a first roller, a TOF (TopOfForm) sensor, a stopper, a second roller, and a print head are arranged along a paper feed path. An information recording medium on which an apparatus, a control method for the printing apparatus, and a program for controlling the printing apparatus are recorded has been proposed.
[0003]
In such a printing device, the paper feed path is arranged on a flat surface, a flatbed (FlatBed) type printer in which the paper is fed linearly, the paper feed path is curved, and the paper is fed in a curved line. There is a CurlBed type printer that can reduce the area.
[0004]
In particular, in a curled bed type printer, the paper feed path is curved, and therefore at least two rollers for feeding paper are required before and after the curved portion. For this reason, the first roller and the second roller are prepared as described above.
[0005]
In such a printing apparatus, the sheet is initially fed by the first roller, and when the front end of the sheet reaches the second roller, the sheet is fed by both the first roller and the second roller, and the rear end of the sheet reaches the first roller. Then, the sheet is fed by the second roller. That is, the delivery of the paper feeding role is performed.
[0006]
The time point at which the first roller and the second roller are driven or stopped is determined based on the feed amount of the first roller such as when the TOF sensor or BOF sensor detects the front edge or the rear edge of the paper.
[0007]
Since accuracy is required for paper feeding, a stepping motor is often used as a driving source for the first roller and the second roller. In the stepping motor, the rotation amount can be controlled in units of a predetermined angle (this is referred to as “step”). Therefore, the sheet feed amount of the first roller and the second roller can be obtained by multiplying the number of steps by a predetermined constant (proportional to the radius of the roller).
[0008]
Each of the first roller and the second roller has two cylindrical paper friction portions, and opens and closes between them, and the paper friction portion is rotated after the paper is sandwiched between the paper friction portions and closed. To feed the paper.
[0009]
A process at the time of inserting a sheet in a conventional printing apparatus will be described.
[0010]
Initially, the stopper closes the paper feed path.
[0011]
When the user inserts a sheet into the printing apparatus, the front end of the sheet collides with the stopper, and the stopper prevents further insertion.
[0012]
A TOF sensor disposed near the stopper detects the passage of the front edge of the paper, and the first roller pinches the paper.
[0013]
Until the TOF sensor detects that the front edge of the paper has passed in the opposite direction, the first roller rotates in the opposite direction to the paper feeding direction and performs the cueing process of the paper.
[0014]
After performing the cueing process of the paper, it is possible to detect where the front edge of the current paper is in the paper feed path based on the distance between the TOF sensor and the first roller and the rotation amount of the first roller.
[0015]
[Problems to be solved by the invention]
However, such a conventional printing apparatus has the following problems.
[0016]
In other words, when the length of the paper (in the direction along the paper feed path) is short, the front edge of the paper does not reach the second roller even if the rear edge of the paper reaches the first roller. The delivery of the paper feeding role with the two rollers is not performed smoothly. Therefore, there has been a problem that the paper is jammed between the first roller and the second roller.
[0017]
Further, if the paper is jammed between the first roller and the second roller, the paper cannot be taken out even if the first roller or the second roller is driven. Therefore, when a paper jam occurs, the problem arises that the printing apparatus must be disassembled and taken out.
[0018]
For this reason, printing is performed on various sizes of paper depending on the application of the printing device. Therefore, the only measure is to measure the size of the paper in advance and prevent paper jams. There has been a problem of increasing the number of people.
[0019]
The present invention has been made to solve these problems, and is a printing apparatus that feeds a sheet with a plurality of rollers, and a sheet whose depth is shorter than the path between the rollers is the printing apparatus. It is an object of the present invention to provide a printing apparatus that discharges the paper sheet to prevent paper jamming when inserted into the printer, a control method for the printing apparatus, and an information recording medium that records a program for controlling the printing apparatus.
[0020]
[Means for Solving the Problems]
Inventions for achieving the above object are the following inventions.
[0021]
A first invention is a printing apparatus having the following means.
[0022]
Printing means for printing characters or figures on paper
Rear edge detection means for detecting that the rear edge of the paper has passed
A front end detection unit that is disposed between the rear end detection unit and the printing unit and detects that the front end of the sheet has passed.
A first sheet feeding means that is disposed between the trailing edge detection means and the leading edge detection means and feeds the sheet from the trailing edge detection means to the leading edge detection means.
Second paper feeding means that is disposed between the front end detection means and the printing means and feeds the paper to the printing means.
A step of the stepping motor, which is a drive source of the first sheet feeding means, from the time when the front edge detecting means detects the passage of the front edge of the paper to the time when the rear edge detecting means detects the passage of the rear edge of the paper. Counting by number, and when the counted value is smaller than the first predetermined value, the paper length determining means determines that the length of the paper in the paper feeding direction is shorter than the predetermined length
Paper discharge means for discharging the paper when the length of the paper is determined to be shorter than the predetermined length by the paper length determination means
[0023]
In the first invention,
The printing means prints characters or figures on paper,
The trailing edge detection means detects that the trailing edge of the paper has passed,
The front edge detection means detects that the front edge of the paper has passed,
The first paper feeding means is disposed between the trailing edge detection means and the leading edge detection means, and feeds the paper from the trailing edge detection means to the leading edge detection means.
The second paper feeding means is disposed between the front edge detection means and the printing means, and feeds the paper to the printing means.
The paper length determination means is configured to determine a feed amount by the first paper feed means from when the front edge detection means detects passage of the front edge of the paper until the rear edge detection means detects passage of the rear edge of the paper. When the count value is smaller than the first predetermined value, it is determined that the length of the paper in the paper feeding direction is shorter than the predetermined length.
The paper discharge means discharges the paper when it is determined that the length of the paper in the paper feed direction detected by the paper length determination means is shorter than a predetermined length.
[0024]
According to the first aspect of the present invention, there is provided a printing apparatus that feeds a sheet with a plurality of rollers, and when a sheet having a shorter depth than a path between the rollers is inserted into the printing apparatus, To provide a printing apparatus that accurately determines whether a paper length is appropriate using the number of steps necessary for controlling a motor, and discharges the paper to prevent paper jam. Can do.
[0025]
According to a second invention, in the first invention,
The counting is performed by the number of steps of the stepping motor as a unit.
[0026]
According to the second invention, in addition to the first invention, a sheet feeding amount along the sheet feeding path is acquired by the number of steps of the stepping motor itself, and a printing apparatus with a high processing speed with less calculation burden is provided. be able to.
[0027]
According to a third invention, in the first invention,
The predetermined length is determined by adding a gripping distance between the first paper feeding means and the second paper feeding means to a path of a paper feeding path between the first paper feeding means and the second paper feeding means. Device.
[0028]
According to the third invention, an example of a preferred embodiment of the present invention can be provided.
[0029]
According to a fourth invention, in the first invention,
One or both of the trailing edge detection means and the leading edge detection means have a transmissive optical sensor, and the transmissive optical sensor detects the passage of the trailing edge or the leading edge of the paper. Device.
[0030]
According to the fourth aspect of the invention, in addition to the first aspect, it is possible to provide a printing apparatus that can accurately detect the rear end and front end of the paper and can accurately determine the length of the paper.
[0031]
According to a fifth invention, in the first invention,
One or both of the trailing edge detection means and the leading edge detection means have a reflection type optical sensor, and the reflection type optical sensor detects the passage of the trailing edge or the leading edge of the paper. Device.
[0032]
According to the fifth invention, in addition to the first invention, it is possible to further reduce the size of the rear end detection means and the front end detection means, and to provide a printing apparatus capable of increasing the degree of freedom of the arrangement. Can do.
[0033]
According to a sixth invention, in the first invention,
The trailing edge detecting unit, the first sheet feeding unit, the leading end detecting unit, the second sheet feeding unit, and the printing unit are arranged along a curved sheet feeding path.
[0034]
According to the sixth invention, in addition to the first invention, it is possible to provide a printing apparatus having a small installation area of a so-called curl bed type.
[0035]
According to a seventh invention, in the first invention,
Close the paper feed path until the front edge detection means detects the passage of the front edge of the paper,
The printing apparatus according to claim 1, further comprising a stopper unit that opens the sheet feeding path after the front end detecting unit detects the passage of the front end of the sheet and drives the first sheet feeding unit to start the sheet feeding.
[0036]
In the seventh invention, the stopper means closes the paper feed path until the front edge detection means detects the passage of the front edge of the paper, and opens the paper feed path after the front edge detection means detects the passage of the front edge of the paper. The means is driven to start paper feeding.
[0037]
According to the seventh invention, in addition to the first invention, it is possible to provide a printing apparatus that can accurately cue the front end of the paper and can accurately determine the paper length.
[0038]
In an eighth aspect based on the first aspect,
The paper feed inheriting means for starting the paper feed by driving the second paper feed means after the count value exceeds a value larger than the second predetermined value larger than the first predetermined value is described. It is a printing device.
[0039]
In the eighth invention, the paper feeding / passing means drives the second paper feeding means to start the paper feeding after the count value exceeds the second predetermined value larger than the first predetermined value.
[0040]
According to the eighth invention, in addition to the first invention, it is possible to provide a printing apparatus capable of smoothly and smoothly performing the role of paper feeding from the first roller to the second roller.
[0041]
According to a ninth aspect of the invention, there is provided a printing apparatus control method comprising the following steps, wherein the trailing edge detecting unit, the first sheet feeding unit, and the leading edge detecting unit are arranged in this order along the sheet feeding path.
[0042]
Front edge detection step of detecting the front edge of the paper by the front edge detection means
A trailing edge detection step for detecting the trailing edge of the paper by the trailing edge detection means.
The amount of feeding by the first paper feeding means from the detection of the front edge of the paper in the front edge detection step to the detection of the rear edge of the paper in the rear edge detection step is counted by the number of steps of the stepping motor that is the drive source of the means, A paper length determination step for determining that the length of the paper in the paper feed direction is shorter than the predetermined length when the count value is smaller than the first predetermined value.
A step of discharging the paper by the paper discharge means when it is determined in the paper length determination step that the length of the paper in the paper feed direction is shorter than a predetermined length
[0043]
According to the ninth aspect of the present invention, there is provided a printing apparatus that feeds a sheet with a plurality of rollers, and when a sheet having a shorter depth than the path between the rollers is inserted into the printing apparatus, A control method for a printing apparatus that accurately determines whether the length of a sheet is appropriate using the number of steps necessary to control a motor, and discharges the sheet to prevent a paper jam. Can be provided.
[0044]
A tenth invention is the ninth invention,
The counting in the paper length determination step (c) is a printing apparatus control method characterized in that the counting is performed in units of the number of steps of the stepping motor.
[0045]
According to the tenth invention, in addition to the ninth invention, the sheet feed amount along the sheet feed path is acquired by the number of steps of the stepping motor itself, and the control method of the printing apparatus with a high processing speed with less calculation load Can be provided.
[0046]
In an eleventh aspect based on the ninth aspect, the printing apparatus further includes stopper means,
A path closing step for driving the stopper means to close the paper feed path;
A path opening step for driving the stopper means to open the paper feed path and driving the first paper feed means to start paper feeding when the front edge of the paper is detected in the front edge detection step;
The method for controlling a printing apparatus according to claim 1, further comprising:
[0047]
According to the eleventh aspect of the invention, in addition to the ninth aspect, it is possible to provide a control method for a printing apparatus that can accurately cue the front end of the sheet and accurately determine the sheet length.
[0048]
In a twelfth aspect based on the ninth aspect, the printing apparatus further comprises a second paper feeding means,
A second paper feed control step of starting the paper feed by driving the second paper feed means after the count value exceeds a value greater than a second predetermined value greater than the first predetermined value. Is a method for controlling the printing apparatus.
[0049]
According to the twelfth invention, in addition to the ninth invention, it is possible to provide a control method for a printing apparatus capable of smoothly and smoothly performing the role of sheet feeding from the first roller to the second roller.
[0050]
A thirteenth invention is an information recording medium in which a program for causing a computer to execute each step of the control methods of the ninth to twelfth inventions is recorded.
[0051]
According to the thirteenth aspect, the information recording medium on which the program is recorded can be easily distributed or sold as a software product independently of the printing apparatus. Further, if the program recorded on the information recording medium of the present invention is executed by the printing apparatus, the printing apparatus and the control method thereof according to the first to twelfth inventions can be realized.
[0052]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below. In addition, embodiment described below is for description and does not limit the scope of the present invention. Accordingly, those skilled in the art can employ embodiments in which each of these elements or all of the elements are replaced with equivalent ones, and these embodiments are also included in the scope of the present invention.
[0053]
First, the configuration of a printing apparatus according to the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a block diagram showing an example of an embodiment of a printing apparatus according to the present invention. FIG. 2 is an explanatory diagram showing the arrangement of each component of the printing apparatus according to the present invention.
[0054]
The printing apparatus 101 includes a TOF sensor 102 and a BOF sensor 103 that detect the passage of the front end and the rear end of a sheet, respectively. An optical sensor can be used as these sensors.
[0055]
When inserting a sheet into the printing apparatus, the sheet is often inserted so that one of the left end or the right end of the sheet is in contact with a sheet guide parallel to the sheet feeding direction. In this case, if a transmissive optical sensor is used as the BOF sensor 103 and disposed on the paper guide, the passage of the rear end of the paper can be accurately detected.
[0056]
On the other hand, there are various types of printing paper, such as a rounded paper corner, and the corners are often bent. Further, the shape and arrangement of the TOF sensor 102 may be limited due to the arrangement of the power source of the stopper 104 described later. Therefore, the TOF sensor 102 is disposed not at a location where the paper end on the side in contact with the paper guide passes but at a location where the center of the front end of the paper passes. When the reflective optical sensor is used as the TOF sensor 102, Can be accurately detected.
[0057]
The types of these sensors can be arbitrarily changed, and changed embodiments are also included in the scope of the present invention.
[0058]
The stopper 104 and the first roller 105 of the printing apparatus 101 cooperate with the TOF sensor 102 to cue the paper as in the conventional printing apparatus.
[0059]
The first roller 105 and the second roller 106 of the printing apparatus 101 feed the paper. The first roller 105 and the second roller 106 are sandwiched by closing the sheet inserted when opened, and feed the sheet by rotating the roller. A stepping motor can be used as a drive source for the first roller 105 and the second roller 106.
[0060]
When a stepping motor is used, the paper feed amount can be accurately obtained from the rotation amount (number of steps) of the motor. In other words, all the lengths related to the paper feed path, such as the amount of paper feed, can be measured and processed in units of the number of steps of the stepping motor.
[0061]
For example, the printing unit 107 of the printing apparatus 101 prints characters and figures on the paper by driving the print head onto the paper fixed by the platen and hitting the ink ribbon.
[0062]
In addition to such a dot impact printing unit, a printing unit such as an ink jet method, a laser method, or a thermal transfer method can also be adopted, and these embodiments are also included in the scope of the present invention.
[0063]
A CPU (Central Processing Unit) 108 of the printing apparatus 101 acquires detection results of the TOF sensor 102 and the BOF sensor 103, a stopper 104, a first roller 105, a second roller 106, and a printing unit 107. These are driven as necessary.
[0064]
The program for performing this control is read out from a ROM (Read Only Memory) 109 and executed by the CPU 108 when the printing apparatus 101 is powered on.
[0065]
The interface 110 of the printing apparatus 101 receives a print command transmitted from the host computer 120. A print command received by the interface 110 is buffered by a RAM (Random Access Memory) 111. The RAM 111 also serves as a temporary storage area.
[0066]
The CPU 108 interprets the print command received by the interface 110 and buffered in the RAM 111, and if it is a command to print characters, takes out the font definition from the ROM 109 and develops the print image in the RAM 111.
[0067]
When the paper reaches the printing unit 107, the CPU 108 drives the printing unit 107 based on the developed print image, and when the printing for one line is finished, drives the second roller 106 to feed the paper. .
[0068]
The reception of these print commands, the development of the print image, and the printing on the paper can use known techniques similar to those of conventional printing apparatuses.
[0069]
The CPU 108 is connected to the TOF sensor 102, the BOF sensor 103, the stopper 104, the first roller 105, the second roller 106, the printing unit 107, the ROM 109, the interface 110, the RAM 111, and the bus. Is done.
[0070]
For this connection method, a known technique similar to that of a conventional printing apparatus can be used.
[0071]
FIG. 2 shows an arrangement of the BOF sensor 103, the first roller 105, the TOF sensor 102, the stopper 104, the second roller 106, and the printing unit 107. In the embodiment shown in FIG. 2, the present invention is applied to a curled bed type printer, and the respective constituent elements are arranged in the above-mentioned order of enumeration. The paper feed path 201 is curved, and the first roller 105 and the second roller 106 are arranged so as to sandwich the curved portion 202.
[0072]
In the above configuration,
The TOF sensor 102 functions as a front end detection unit,
The BOF sensor 103 functions as a rear end detection unit,
The stopper 104 serves as a stopper means,
The first roller 105 functions as a first paper feeding unit,
The second roller 106 functions as a second paper feeding means,
The printing unit 107 functions as a printing unit,
The CPU 108 functions as a paper length determination unit, works together with the first roller 105 as a paper discharge unit, works together with the first roller 105 and the second roller 106 as a paper feeding / passing unit,
The ROM 109 functions as an information recording medium that records a program for controlling the printing apparatus.
[0073]
If the program recorded in the ROM 109 can be updated from the host computer 120, the host computer 120 itself, a hard disk operating in cooperation with the host computer 120, a CD-ROM, a floppy disk, etc. can also be used as a printing device. It functions as an information recording medium that records a program to be controlled.
[0074]
Hereinafter, with reference to FIG. 3, a procedure for discharging a sheet when a sheet with a short depth is inserted into the printing apparatus of the present invention will be described. FIG. 3 is a flowchart showing an outline of processing for discharging the short sheet.
[0075]
First, the CPU 108 cooperates with the TOF sensor 102, the stopper 104, and the first roller 105 to perform cueing of a sheet (step S301). For this processing, the above-described known technique can be used.
[0076]
Next, the CPU 108 starts counting the number of steps of the stepping motor that drives the first roller 105 (step S302). For example, a counter for recording the number of steps is prepared in the RAM 111, and the counter is set to zero.
[0077]
Further, the CPU 108 drives the stepping motor of the first roller 105 for a predetermined number of steps (for example, one step), rotates the first roller 105 in the forward direction, and feeds the paper by a predetermined length (step S302).
[0078]
Next, the CPU 108 increases the value of the counter in the RAM 111 by the predetermined number of steps (for example, 1) (step S303).
[0079]
Further, the CPU 108 acquires the detection result of the BOF sensor 103 and checks whether or not the trailing edge of the sheet has been detected (step S304). If it is detected (step S304: Yes), it is checked whether or not the counter value in the RAM 111 is equal to or greater than a predetermined threshold value x (step S305).
[0080]
When the value of the counter is less than the predetermined threshold x (step S305: No), the length of the sheet is shorter than the path between the first roller 105 and the second roller 106. Therefore, the CPU 108 rotates the first roller 105 in the reverse direction, discharges the paper (step S311), and ends the process.
[0081]
On the other hand, when the value of the counter is equal to or greater than the predetermined threshold value x (step S305: Yes), it can be estimated that the length of the sheet is sufficiently longer than the path between the first roller 105 and the second roller 106. Therefore, the CPU 108 checks whether or not the counter value is greater than or equal to a predetermined threshold value y (step S306).
[0082]
If it is equal to or greater than the predetermined threshold value y (step S306: Yes), it can be estimated that the front edge of the sheet has reached the second roller 106. Therefore, the CPU 108 closes the second roller 106 to take over the role of paper feeding from the first roller 105 (step S307), drives the printing unit 107 to perform printing processing (step S308), and ends the processing.
[0083]
On the other hand, if it is less than the predetermined threshold value y (step S306: No), it is estimated that the front edge of the paper has not reached the second roller 106, and the CPU 108 drives the first roller 105 a predetermined number of steps to feed the paper ( In step S309), the number of counters is increased by the number of steps (step S310), and the process returns to step S306.
[0084]
here,
・ The distance between the TOF sensor 102 and the first roller 105 is a [step].
The distance between the BOF sensor 103 and the first roller 105 is b [step]
The counter value in the RAM 111 is c [step]
The distance between the first roller 105 and the second roller 106 is m [step]
・ Establish the e-step
Then, the length of the paper can be estimated as a + b + c. On the other hand, the length of the sheet needs to be at least m + e. Therefore, a + b + c ≧ m + e. By arranging this, c ≧ m + e−a−b, that is, the threshold value x can be obtained by x = m + e−a−b.
[0085]
Further, when the front end of the sheet reaches the second roller 106, the following condition is satisfied.
[0086]
a + c ≧ m + e That is, the threshold value y can be obtained by y = m + e−a.
[0087]
On the other hand, when the BOF sensor 103 does not detect the trailing edge of the sheet (step S304: No), it is checked whether or not the counter value in the RAM 111 is equal to or greater than a predetermined threshold value y (step S307). If it is equal to or greater than the predetermined threshold value y (step S307: Yes), the front end of the sheet has reached the second roller 106, and it is estimated that the sheet is sufficiently long, so the process proceeds to step S307.
[0088]
When it is less than the predetermined threshold value y (step S307: No), the process returns to step S302.
[0089]
In the above embodiment, the paper length is estimated in units of the number of steps, but the paper length itself may be handled. This is because the number of steps and the amount of paper feed along the path are in a proportional relationship.
[0090]
【The invention's effect】
As described above, the present invention has the following effects.
[0091]
First, a printing device that feeds paper with a plurality of rollers, and when a paper having a shorter depth than the path between the rollers is inserted into the printing device, a stepping motor as a drive source is set. It is possible to provide a printing apparatus that accurately determines whether or not the length of a sheet is appropriate using the number of steps necessary for control, and discharges the sheet to prevent a paper jam. .
[0092]
Secondly, it is possible to provide a high-speed printing apparatus with a small calculation burden because the sheet feed amount along the sheet feed path is acquired by the number of steps of the stepping motor itself.
[0093]
Thirdly, it is possible to provide a printing apparatus that can accurately detect the trailing edge and the leading edge of a sheet and can accurately determine the length of the sheet.
[0094]
Fourthly, it is possible to provide a printing apparatus capable of reducing the size of the rear end detection means and the front end detection means and increasing the degree of freedom of their arrangement.
[0095]
Fifth, it is possible to provide a printing apparatus with a small installation area of a so-called curl bed type.
[0096]
Sixth, it is also possible to provide a printing apparatus that can accurately cue the front end of the paper and can accurately determine the paper length.
[0097]
Seventh, it is also possible to provide a printing apparatus that can smoothly and smoothly perform the role of paper feeding from the first roller to the second roller.
[0098]
Eighth, it is possible to provide a method for controlling the printing apparatus.
[0099]
Ninth, an information recording medium in which a program for controlling the printing apparatus is recorded can be easily distributed or sold as a software product independently of the printing apparatus. Moreover, if the program recorded on the information recording medium of the present invention is executed by the printing apparatus, the printing apparatus and the control method thereof according to the above-described invention can be realized and the above-described effects can be achieved.
[Brief description of the drawings]
FIG. 1 is a block configuration diagram illustrating an example of an embodiment of a printing apparatus according to the present invention.
FIG. 2 is an explanatory diagram showing an arrangement of each component of the printing apparatus according to the present invention.
FIG. 3 is a flowchart illustrating a procedure for discharging a sheet when a sheet with a short depth is inserted into the printing apparatus of the present invention.
[Explanation of symbols]
101 Printing device
102 TOF sensor
103 BOF sensor
104 stopper
105 1st roller
106 2nd roller
107 Printing section
108 CPU
109 ROM
110 interface
111 RAM
120 Host computer
201 Paper feed path
202 Curved part

Claims (13)

A printing apparatus comprising the following means.
(A) Printing means for printing characters or graphics on paper (b) Rear edge detection means for detecting passage of the rear edge of the paper (c) Arranged between the rear edge detection means and the printing means A front end detecting means for detecting that the front end of the paper has passed (d) disposed between the rear end detecting means and the front end detecting means, and the direction of the paper from the rear end detecting means to the front end detecting means (E) a second paper feeding means that is disposed between the front edge detection means and the printing means and sends the paper to the printing means. (F) the front edge detection means passes through the front edge of the paper. The amount of feeding by the first sheet feeding means until the trailing edge detecting means detects the passage of the trailing edge of the sheet is detected by the number of steps of the stepping motor that is the driving source of the means, Count value is A paper length determining means for determining that the length of the paper in the paper feed direction is shorter than a predetermined length when the paper length is less than a predetermined value; (g) the length of the paper in the paper feed direction is determined by the paper length determination means; Paper discharge means for discharging the paper when it is determined that it is shorter than the predetermined length   The printing apparatus according to claim 1, wherein the counting is performed in units of the number of steps of the stepping motor.   The predetermined length is determined by adding a grip margin between the first paper feeding means and the second paper feeding means to a path of a paper feeding path between the first paper feeding means and the second paper feeding means. The printing apparatus according to claim 1.   2. One or both of the trailing edge detection means and the leading edge detection means have a transmissive optical sensor, and detects the passage of the trailing edge or the leading edge of the paper by the transmissive optical sensor. The printing apparatus as described in.   2. One or both of the trailing edge detection means and the leading edge detection means have a reflection type optical sensor, and the reflection type optical sensor detects passage of the trailing edge or the leading edge of the sheet. The printing apparatus as described in.   2. The rear end detecting unit, the first sheet feeding unit, the front end detecting unit, the second sheet feeding unit, and the printing unit are arranged along a curved sheet feeding path. Printing device. further,
The paper feed path is closed until the front edge detection means detects the passage of the front edge of the paper, the front edge detection means detects the passage of the front edge of the paper and then opens the paper feed path, and the first paper feed means is driven to feed the paper. The printing apparatus according to claim 1, further comprising stopper means for starting. further,
Characterized in that it has a paper feed transfer means for starting the paper feed by driving the second paper feed means after the count value exceeds a value greater than a second predetermined value greater than the first predetermined value. The printing apparatus according to claim 1. A control method for a printing apparatus, comprising the following steps, wherein a trailing edge detection unit, a first sheet feeding unit, and a leading edge detection unit are arranged in this order along a sheet feeding path.
(A) A front end detecting step for detecting the front end of the sheet by the front end detecting means (b) A rear end detecting step for detecting the rear end of the sheet by the rear end detecting means (c) In the front end detecting step (a), The feed amount by the first paper feed means from the detection of the front edge of the paper to the detection of the rear edge of the paper in the rear edge detection step (b) is counted by the number of steps of the stepping motor which is the drive source of the means. When the count value is smaller than the first predetermined value, a paper length determination step for determining that the length of the paper in the paper feed direction is shorter than a predetermined length. (D) The paper length determination step (c) If it is determined that the length of the paper in the paper feeding direction is shorter than a predetermined length in step 1, the paper is ejected by the paper ejecting means.   The method according to claim 9, wherein the counting in the sheet length determination step (c) is performed in units of the number of steps of the stepping motor. Further, the printing apparatus has stopper means, and
(E) a path closing step of driving the stopper means to close the paper feed path;
(F) a path opening step in which when the front end of the sheet is detected in the front end detecting step (a), the stopper unit is driven to open the sheet feeding path, and the first sheet feeding unit is driven to start sheet feeding; ,
The method of controlling a printing apparatus according to claim 10, comprising: Further, the printing apparatus has a second paper feeding means, and
(G) a second paper feed control step of starting the paper feed by driving the second paper feed means after the count value exceeds a value greater than a second predetermined value greater than the first predetermined value. The method of controlling a printing apparatus according to claim 10.   An information recording medium on which a program for causing a computer to execute each step of the control method for a printing apparatus according to claim 9 is recorded.

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