JP2008001482A - Roll sheet conveying device and its roll sheet terminal end detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a constitution capable of immediately and certainly detecting that a roll sheet wound on a winding core is drawn out from the winding core to a terminal end having a simply, inexpensively executable constitution in a roll sheet conveying device. <P>SOLUTION: A motor control circuit 83 drives an LF motor 60 through a motor driver 84 according to instruction from CPU 80. An LF roller is rotated by this and rotatably retained roll paper is drawn out/conveyed from the winding core. A drive current value of the LF motor 60 is detected by a motor current value detection circuit 85 during conveying action, and a detection signal is inputted to the CPU 80. The CPU 80 monitors the drive current value and detects that the roll sheet is drawn out to the terminal end when variation of the drive current value corresponding to specific variation of the drive current value according to variation of drive load of the LF motor 60 when the roll sheet is drawn out from above the winding core to the terminal end is generated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a roll sheet conveying apparatus provided for conveying a roll sheet in a device such as a printer, a facsimile machine, a copying machine or the like using a roll sheet such as roll paper or roll film, and a method for detecting the end of the roll sheet. It is about.

  A conventional general configuration related to roll paper conveyance of a recording apparatus that records an image on a roll paper as a recording medium while conveying the roll paper will be described with reference to FIG.

  Reference numeral 110 denotes a roll paper holder portion that rotatably holds and feeds roll paper (recording paper wound in a cylindrical shape) Pr, and 120 denotes the roll paper Pr that is pulled out of the roll paper holder portion 110 and conveyed. An image forming unit that forms an image. Reference numeral 130 denotes a paper discharge unit for discharging the roll paper Pr on which an image has been formed to the outside of the apparatus.

  In the roll paper holder portion 110, the roll portion (winding portion) of the roll paper Pr is rotatably held by a spool shaft 111 and a pair of spool flanges 112. A torque limiter 113 is provided at one end of the spool shaft 111. As a result, a predetermined load torque Tr is generated with respect to rotation of the roll portion during conveyance of the roll paper Pr (clockwise rotation in FIG. 6). This torque is generally called a roll brake T. As a result, by applying a constant tension force T between the roll paper Pr and the LF roller 121, the skew of the roll paper Pr is corrected, and deviations, slackness, and the like that occur when the user rolls is removed.

  As a configuration for transporting and feeding the roll paper Pr, a pair of transport guides 117 that guide the roll paper Pr to the paper feed roller 115, a plurality of driven rollers 116 that are pressed against the paper feed roller 115 with a predetermined pressure, and the image forming unit 120. , 118 are provided.

  In the image forming unit 120, an LF (line feed) roller 121 for transporting the roll paper Pr by a predetermined amount at the end of one scanning at the time of image formation, and a driven rotation by pressing the roller with a predetermined pressure F A plurality of pinch rollers 122 are provided. Further, a suction platen 123 that sucks the roll paper and holds it in a flat shape, and a paper feed sensor 124 that detects the front end and the rear end (end) of the roll paper are provided. In addition, a carriage 140 that reciprocates in a direction perpendicular to the roll paper conveyance direction is provided to mount the recording head 141 and perform scanning (main scanning).

  Although the configuration in which the end of the roll paper is detected by the paper feed sensor 124 is shown here, a configuration in which detection is performed by other means is also known. For example, there is a configuration in which a mechanical flag type paper feed sensor or a reflection type sensor for detecting the presence or absence of roll paper is provided via a detection lever arranged in the path of the roll paper to be fed to detect the end of the roll paper.

In the configuration described in Patent Document 1, the core around which the roll paper is wound has a darker color than the roll paper, and the optical sensor reduces the roll diameter via a roller (roller) that presses against the roll outer periphery of the roll paper. The distance from the surface to be measured (the outer surface of the roll or core) is kept constant. Then, the end of the roll paper is detected by the change in the intensity of the reflected light detected by the optical sensor (change due to the difference between the reflected light of the roll paper and the core).
JP-A-8-127167

  The configuration of FIG. 6 has the following problems.

  In the transport operation for feeding the roll paper Pr, the paper feed sensor 124 detects the leading edge of the roll paper, and the transport operation by the LF roller 121 is controlled based on the signal. Then, an image is recorded by a predetermined amount and the roll paper is used. When the end of the roll paper is detected by the paper feed sensor 124, the paper feed operation is stopped and the recording operation is interrupted.

  However, the end of the roll paper Pr is usually fixed by being affixed to a core paper tube around which the roll paper is wound. If the tape gets on the paper feed sensor 124, the end detection is delayed by that amount, and there is a case where an image is recorded when there is no roll paper and ink is adhered to the platen. In this case, not only the ink is transferred to the back surface of the leading end portion of the next roll paper, but also the ink enters the clearance of each portion, particularly the sliding rotation portion of the pinch roller 122 and the sliding bearing portion of the LF roller 121. This leads to device failure such as malfunction.

  Further, as shown in FIG. 6, when the length of the path from the roll of the roll paper Pr to the paper feed sensor 124 is long, the tape at the end of the roll paper is drawn into the pair of conveyance guides 117 and 118, and is guided to the guide. There is a possibility of causing jamming by sticking.

  Further, in a configuration in which a mechanical flag type paper feed sensor or a reflection type sensor that detects the presence or absence of roll paper is provided via a detection lever disposed in the path of the roll paper, the sensor has an allowable detection width. In consideration of the flutter of the roll paper, the sensor arrangement is limited to the vicinity of the nip of the pair of conveyance guides or the pair of paper feed rollers, and cannot be arranged in the vicinity of the roll of the roll paper. Therefore, there is a possibility that the end tape is caught in the nip of the pair of conveyance guides and the paper feed roller.

  In order to avoid such a problem, it is desirable that it is possible to immediately detect that the roll paper wound on the core is drawn from the core to the end. In the configuration described in Patent Document 1, this is possible.

  However, in the configuration of Patent Document 1, there is a case where the roll paper is damaged by a roller (roller) being pressed against the outer periphery of the roll paper. In addition, the types of roll paper and the core of the roll core are limited, and it is impossible to reliably detect the end of various roll papers. Further, as a configuration for detecting the end, an optical sensor, a roller that presses against the outer periphery of the roll of roll paper, a support that supports these, and a spring that pulls the roll toward the roll of roll paper are required. For this reason, the configuration of the apparatus becomes complicated and the cost increases. Moreover, the enlargement of an apparatus will be caused.

  SUMMARY OF THE INVENTION An object of the present invention is to immediately and reliably detect that a roll sheet wound on a winding core is drawn from the winding core to the end with a simple and inexpensive configuration in the roll sheet conveying apparatus. An object of the present invention is to provide a configuration and a roll sheet end detection method.

In order to solve the above problems, in the present invention,
In a roll sheet conveying apparatus that pulls and conveys a roll sheet from the core by rotating and holding a roll sheet wound in a cylindrical shape on the core, and rotating a conveying roller by driving a drive motor.
Drive current value detecting means for detecting the drive current value of the drive motor during the conveyance operation of the roll sheet;
The present invention is characterized in that it has end detection means for detecting that the roll sheet is drawn from the winding core to the end based on the change in the drive current value of the drive motor detected by the drive current value detection means.

  Moreover, in this invention, the structure of the roll sheet termination | terminus detection method of the roll sheet conveying apparatus corresponding to the structure of the roll sheet conveying apparatus which concerns on the said invention was employ | adopted.

  According to the present invention, in the roll sheet conveying apparatus, it is detected that the roll sheet is drawn from the winding core to the end based on the change in the drive current value of the drive motor during the roll sheet conveying operation. Therefore, it is possible to immediately and reliably detect that the roll sheet has been drawn from the winding core to the end with a simple and inexpensive configuration. In addition, the end can be reliably detected regardless of the type of roll sheet. Furthermore, the configuration for detection provides an excellent effect that the apparatus is not enlarged and the roll sheet is not damaged.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Here, an embodiment of a roll paper transporting apparatus that transports roll paper in a recording apparatus that records an image on roll paper as a recording medium by an inkjet method will be described.

  FIG. 1 is a perspective view showing an overall schematic configuration of a recording apparatus provided with a roll paper conveying apparatus according to an embodiment of the present invention, and FIG.

  The recording apparatus 1 shown in both drawings includes a roll paper holder unit 10 that rotatably holds a roll of roll paper Pr, an image forming unit 20 that forms an image on roll paper that is drawn out and fed from the held roll, And a paper discharge unit 30 for discharging the roll paper after image formation to the outside of the apparatus. The roll paper Pr is fixed to the outer peripheral surface of the core paper tube 72 shown in FIG. 5, which will be described later, with a tape 71 (71A, 71B, or 71C) and fixed on the paper tube 72 from the end to the cylindrical shape. It is assumed that something wound is used. This is because the end of the roll paper is detected based on the change in the drive current value of the motor, which is a feature of the present invention. Although it is possible to use a roll paper that is not fixed by sticking the end to the core with a tape or the like, in this case, the end cannot be detected based on a change in the drive current value of the motor.

  In the roll paper holder unit 10, the roll paper Pr is mounted by inserting and inserting a core paper tube into the rotatable spool shaft 11, and is rotatably held. The roll paper Pr is non-rotatably mounted on the spool shaft 11, but is held rotatably when the spool shaft 11 is rotatably supported. The roll paper is sandwiched between a pair of spool flanges 12L and 12R attached to both ends of the spool shaft 11 so as not to move in the axial direction. Both ends of the spool shaft 11 are rotatably supported by spool bearing portions 13L and 13R. In order to easily replace the roll paper Pr, a slide slope S is formed on the front side of the bearing portions 13L and 13R. The operator removes the spool shaft 11 from the bearing portions 13L and 13R along the slope S and replaces the roll paper Pr. In a state where the spool shaft 11 is set in the bearing portions 13L and 13R, the driving force of the LF motor 60 shown in FIG. 3 described later is applied to the torque limiter 11a provided at the left end portion of the spool shaft 11 via the gear train 14. It is to be transmitted. However, the driving force is transmitted via the gear train 14 only when the roll of the roll paper Pr is reversed and the roll paper is rewound, and is not transmitted during the feeding of the paper feed for normal rotation of the roll. .

  As shown in FIG. 2, the roll paper Pr mounted on the spool shaft 11 is pulled out from the lower side of the roll and fed to the image forming unit 20. When the operator loads the roll paper and first pulls the roll paper from the roll and feeds it to the image forming unit 20, a paper feed lower guide 15 for guiding the roll paper and a paper feed upper guide 16 opposed thereto are provided on the apparatus main body. It is provided at the bottom.

  The image forming unit 20 is configured by an LF roller 21 for conveying a roll paper by a predetermined amount every time scanning is performed at the time of image formation. Reference numeral 22 denotes a plurality of pinch rollers that are driven to rotate against the LF roller 21 with a predetermined pressure. Reference numeral 23 denotes a suction platen that sucks and holds the roll paper in a flat shape. An arrow Y direction on the suction platen 23 in FIG. 1 is a roll paper conveyance direction on the platen 23 by the LF roller 21 and a sub-scanning direction. Reference numeral 40 denotes a carriage which is mounted with a recording head 41 and reciprocates in the direction of the arrow X perpendicular to the direction of the arrow Y, that is, in both directions of the main scanning direction by driving a carriage motor (not shown). .

  Here, the recording head 41 is of an ink jet type, and is driven by a head driving signal corresponding to image data generated in synchronization with the reciprocating movement of the carriage 40 in the main scanning direction. The ink is discharged toward the surface to form an image.

  The carriage 40 is slidable via a bearing 42 and a slide bearing 43 with respect to a main rail 51 and a sub rail 52 mounted in parallel on a main stay 50 arranged over the entire width in the main scanning direction of the apparatus. Is attached. The bearing 42 and the slide bearing 43 are provided at both ends of the carriage 40 in the main scanning direction, respectively. The slide bearing 43 is movable in the Y direction (sub-scanning direction) and in the opposite direction, and is urged by the slide spring 43a toward the sub rail 52 in the reverse direction with a predetermined pressure. With such a configuration, the carriage 40 is always urged to one side of the main rail 51 to prevent vibrations during scanning, a ramp-up in the fitting backlash of the bearing 42, and the like, thereby enabling higher-quality image formation.

  A linear sensor 44 is provided on the slide bearing 43, thereby reading the slits of the optical linear scale 53 arranged on the main stay 50 in the main scanning direction. Based on the signal of the linear sensor 44, drive control of the carriage 40 and image data generation control are performed. The carriage 40 is reciprocated by transmitting a driving force of a carriage motor (not shown) provided near one end of the main stay 50 by a carriage belt 54.

  The paper discharge unit 30 is provided with a paper discharge cover 31 that receives the discharged roll paper Pr and controls the discharge posture, and a top cover 32 that can be opened and closed to cover the upper surface side of the roll paper Pr on the suction platen 23. It has been. With the top cover 32 closed (FIG. 2), a paper discharge port is formed between the lower end of the top cover 32 and the upper end of the paper discharge cover 31.

  Next, FIG. 3 shows a configuration of a roll paper transport mechanism. The configuration of the LF roller 21 and its periphery will be described with reference to FIG.

  The LF roller 21 is rotated by a predetermined amount each time the recording head 41 is scanned, and conveys the roll paper by a predetermined amount. The conveyance accuracy greatly affects the quality of the recorded image. For this reason, the outer diameter, linearity, etc. of the LF roller 21 are finished with high accuracy. Further, the friction coefficient of the roller surface is increased by sand blasting or ceramic powder coating to prevent the roll paper from slipping as much as possible.

  The LF roller 21 is rotationally driven by a driving force transmitted from an LF motor 60 as a DC motor through a motor pulley 60 a, an LF belt 61, and an LF pulley 62 coaxial with the LF roller 21. The rotation control is performed by detecting the amount of rotation with an LF code wheel 63 provided coaxially with the LF roller 21 and an LF linear sensor 64 that detects the slit. A so-called linear encoder is used to detect the rotation amount. In order to realize high-accuracy conveyance, the resolution of the LF code wheel 63 is set to high resolution so that one slit is several μm as the conveyance amount. A plurality of LF bearings 24 that rotatably support the LF roller 21 are arranged on a lower stay 25 having a hermetic cavity structure.

  A paper feed sensor 26 (see FIG. 2) is provided in the vicinity of the upstream side of the LF roller 21 in the roll paper conveyance direction, and detects the leading edge or trailing edge (termination) of the roll paper. The paper feed sensor 26 detects the end of the roll paper when a roll paper that is not fixed to the winding core with a tape or the like is used.

  A suction platen 23 having a plurality of platen holes 23 a is also sealed and fixed on the lower stay 25. The suction fan 70 connected to one end of the lower stay 25 sucks air from the platen hole 23 a using the lower stay 25 as a duct, and sucks the roll paper Pr onto the suction platen 23. This prevents paper floating during recording, undulation (cockling) after recording, and the like.

  Next, the configuration and operation related to the driving force transmission of the spool shaft 11 via the torque limiter 11a will be described.

  In FIG. 3, a torque limiter 11 a that rotates together with the spool shaft 11 is provided on the left end side of the spool shaft 11. The torque limiter 11a is a type that generates a predetermined load torque Tr with a structure in which the inner peripheral portion rotates by applying a torque of a predetermined value or more to the inner peripheral portion with the outer peripheral portion fixed. In this embodiment, the value of the load torque Tr is set to 1.0 to 1.5 kgf.cm as an example. This torque value Tr is generally called a roll brake T. Accordingly, by applying a constant tension force T between the roll paper Pr and the LF roller 21, skew correction of the roll paper Pr can be performed. Then, the deviation, slack, etc. that occur when the user sets the roll paper can be removed, and a constant load can be applied to the rotation of the roll of the roll paper Pr, so that stable and highly accurate conveyance can be performed.

  The value of the roll brake T is calculated by the following equation (1).

Roll brake T = Tr / (Roll diameter φD / 2) Formula (1)
A housing that fits around the outer periphery of the torque limiter 11a is provided, and a gear 11b is provided at the left end thereof. When the spool shaft 11 loaded with the roll paper Pr is set on the spool bearing portions 13L and 13R, the gear 11b is connected to the gear train 14 for roll driving (rewinding) of the roll paper. Among the gears of the gear train 14, the end gear on the roll paper Pr side is a one-way gear 14a. The gear 14a is configured to be fixed in the rotation direction in which the roll of the roll paper Pr is normally rotated and to be free in the rotation direction in which the roll is rotated reversely.

  The driving force of the LF motor 60 is transmitted to the gear train 14 through a motor pulley 60a, a belt 61, a pulley 62, a gear (not shown), a gear 66, a pulley 67, a belt 68, a pulley 69, and an electromagnetic clutch 65. The electromagnetic clutch 65 is turned on when the roll paper is rewound by reversing the roll of the roll paper Pr. By this turning on, the driving force from the LF motor 60 is transmitted to the spool shaft 11 through the electromagnetic clutch 65, the one-way gear 14a, and the torque limiter 11a, and the spool shaft 11 rotates (reverses) in synchronization with the LF roller 21. Here, regarding the rewinding of the roll paper Pr, the speed is reduced so that the speed V ′ is about 30% faster than the rewind speed V of the LF roller 21 even if the roll paper Pr has the minimum diameter (core diameter). The ratio is set.

  Further, when the roll paper is fed and conveyed, the electromagnetic clutch 65 is turned off, and the transmission of the driving force via the electromagnetic clutch 65 is cut off. Here, the one-way gear 14a is fixed in the rotation direction for rotating the roll of the roll paper Pr and does not rotate, and the gear 11b is engaged with the one-way gear 14a, so that the outer periphery of the torque limiter 11a is also in the normal rotation direction. Fixed without rotating. On the other hand, torque is applied to the inner periphery of the roll, the spool shaft 11 and the torque limiter 11a through the portion of the roll paper drawn from the roll by the rotational driving force of the LF roller 21. When the torque overcomes the load torque Tr of the torque limiter 11a described above, the inner peripheral portion rotates in the normal rotation direction relative to the outer peripheral portion, and the roll paper roll is rotated in the normal rotation direction together with the spool shaft 11. The roll paper can be pulled out from the roll and conveyed. A load as a roll brake T by a load torque Tr acts on the rotation of the spool shaft 11 during the conveyance.

  With such a configuration, the torque limiter 11a acts as a device that applies the roll brake T when the roll of the roll paper Pr is rotated forward (at the time of paper feed and conveyance). When the roll paper Pr is rotated in the reverse direction (at the time of rewinding), the roll paper Pr functions as a member that generates a torque necessary for rewinding while absorbing the fluctuation of the rewind speed V ′ due to the outer diameter ΦD of the roll paper. .

  Next, the configuration of a control system that controls the driving of the LF motor 60 will be described with reference to FIG. The printing apparatus is also provided with other drive control systems such as a carriage motor drive control system (not shown) and a print head drive control system, which are not related to the features of the present invention. Description is omitted.

  In FIG. 4, the CPU 80 executes a control program stored in the ROM 81 to control the entire recording apparatus. The control includes control of the LF motor 60. The RAM 82 is used for temporarily storing various data used for various processes of the CPU 80.

  The CPU 80 sends, to the motor control circuit 83, a command for starting the LF motor 60 as needed in the recording operation and a command for the rotation direction and rotation amount of the LF motor 60 corresponding to the conveyance direction and conveyance amount of the roll paper. Output. The motor control circuit 83 outputs a control signal for controlling the drive current of the LF motor 60 to the motor driver 84 in order to drive the LF motor 60 in accordance with a command from the CPU 80. The motor driver 84 applies a drive current to the LF motor 60 in accordance with a control signal from the motor control circuit 83 to drive the LF motor 60. The rotation amount of the LF motor 60 is detected by the LF linear sensor 64 and fed back to the motor control circuit 83. The motor control circuit 83 controls the driving of the LF motor 60 based on the feedback. The motor control circuit 83 performs so-called servo control. In addition, a detection signal of the paper feed sensor 26 that detects the leading edge or the trailing edge of the roll paper is input to the CPU 80. In accordance with the detection signal, the CPU 80 outputs a control command corresponding to the front end detection or the end detection to the motor control circuit 83.

  In addition, a motor current value detection circuit 85 is provided in the drive control system of the LF motor 60. This circuit detects the drive current value of the LF motor 60 and outputs a digital signal indicating the drive current value to the CPU 80. The CPU 80 monitors the drive current value of the LF motor 60 by a signal from the motor current value detection circuit 85 during the roll paper transport operation, that is, during driving of the LF motor 60. Then, based on the change in the drive current value according to the change in the drive load of the LF motor 60, it is detected that the roll paper has been drawn from the top of the core of the winding core to the end (hereinafter referred to as roll paper winding). Also called end detection on the core). When the end is detected, the conveyance operation is immediately stopped, the recording operation is interrupted, and the user is warned that the roll paper has run out. The control configuration shown in FIG. 4 is merely an example, and for example, the CPU 80, the motor control circuit 83, and the motor current value detection circuit 85 may be a single integrated circuit (ASIC).

  Next, the details of the end detection method on the roll paper core will be described with reference to FIG. As described above, in this embodiment, as shown in the right side of FIG. 5, the roll paper is fixed by being attached to the outer peripheral surface of the paper core 72 having a winding core with the tape 71 (71 </ b> A, 71 </ b> B or 71 </ b> C). It is assumed that a paper tube 72 wound in a cylindrical shape from the end is used.

  When the roll paper is pulled out from the paper tube 72 to the end during the transport operation of the roll paper Pr, the tape 71 is peeled from the paper tube 72 and the end of the roll paper is peeled off depending on whether the adhesive force of the tape 71 is small or large. Otherwise, the tape 71 does not peel off and the roll paper is prevented from being pulled out at the end. As described above, when the end of the roll paper is to be peeled off from the paper tube 72 together with the tape 71, the driving load of the LF motor 60 fluctuates (increases) due to the shearing force τ acting in the tangential direction of the paper tube 72 by the tape 71. Further, when the tape 71 is peeled off and the roll paper end is peeled off, the load of the roll brake T that has been acting until then does not act, so the driving load of the LF motor 60 fluctuates (reduces). The drive current value of the LF motor 60 changes according to the fluctuation of these drive loads.

  The relationship between this roll brake T, each of the driving loads due to the shearing force τ via the tape 71, and the driving current value will be described below.

1) Drive load and drive current value by the roll brake T The drive load torque Tm that the roll brake T applies to the rotating shaft of the LF motor 60 is Φd as the outer diameter of the LF roller 21 and the reduction ratio between the LF roller 21 and the LF motor 60. If α is
Tm = T × φd / 2 × α (2)
Furthermore, if this is converted into a drive current value ΔA ₂ and the torque constant is k [kgf.cm/A], then ΔA ₂ = Tm / k (3)
This ΔA ₂ is also a change amount of the drive current value according to the change of the drive load due to the presence or absence of the drive load torque Tm.

In this embodiment, for example, the torque value Tr of the torque limiter 11a is 1.0 [kgf.cm], the roll paper diameter is Φ60 [mm], the LF roller diameter is Φ15 [mm], and the reduction ratio α is 1/5. The torque constant is 0.7 [kgf.cm/A]. In this case, the value of the roll brake T, the driving load torque Tm applied to the LF motor 60, and the fluctuation amount ΔA ₂ of the driving current value depending on the presence or absence of the roll brake T are expressed by the following equations (1), (2), (3), respectively. It becomes like this.

T = 1 / (60/2/10) = 0.33kgf
Tm = 0.33 × 15/20 × 1/5 = 0.05 kgf.cm
ΔA ₂ = 0.05 / 0.7 = 0.07A
That is, the fluctuation amount ΔA ₂ of the driving current value corresponding to the fluctuation of the driving load torque Tm due to the application of the roll brake T applied until then becomes 0.07A.

2) Driving load and driving current value due to roll paper end fixing tape When ΔA ₁ is a current value fluctuation due to a driving load fluctuation due to a shearing force τ acting in the tangential direction of the outer circumference of the paper tube 72 by the tape 71 described above, From (1), (2), and (3), the relationship between the shearing force τ and the current value variation ΔA ₁ is expressed by the following equation (4).

τ = ΔA ₁ × k / α / (Φd / 2) (4)
It becomes. That is, the drive current value fluctuates by a current value fluctuation ΔA ₁ proportional to the shear force τ due to the fluctuation of the drive load due to the action of the shear force τ. Here, since the strength of the shearing force τ depends on the strength of the adhesive force of the tape 71, the magnitude of the current value variation ΔA ₁ depends on the strength of the adhesive strength of the tape 71.

As described above, when the roll paper is pulled out from the top of the paper tube 72 to the end during the roll paper transport operation, the driving load of the LF motor 60 varies due to the shearing force τ applied by the tape 71 and the roll brake T. As a result, the drive current value changes. Since the end of the roll paper core is detected based on the change in the drive current value, the drive current value when the roll paper actually used in the recording apparatus is drawn from the paper tube 72 to the end is unique. Changes (changes in fluctuations ΔA ₁ and ΔA ₂ ) are confirmed by experiments. Further, the unique change data of the confirmed drive current value is stored in the ROM 81. The CPU 80 monitors the drive current value of the LF motor 60 by a signal from the motor current value detection circuit 85 during the roll paper transport operation, and changes in the drive current value corresponding to the unique change data of the drive current value. Check if has occurred. When a corresponding change occurs, it is determined that the roll paper has been drawn from the paper tube 72 to the end, and this is detected.

  FIG. 5 shows a case in which each of the (a) to (d) type roll papers whose ends are fixed by tapes 71A to 71C having different adhesive strengths are pulled from the paper tube 72 to the end by the conveying operation in the recording apparatus. The result of having confirmed the peculiar change of the drive current value of this by experiment is shown. The contents of each type are as follows.

(A) Strong adhesion type (1)
In this type, the end of the roll paper Pr is affixed to the paper tube 72 with a double-sided tape 71A having a particularly strong adhesive force, and the glue component of the tape 71A is rolled paper, such as a flameproof cloth or an outdoor cloth. It is a type that penetrates to the Pr fibers and cannot be peeled off.

As shown in the graph, the drive current value of the LF motor 60 is suddenly increased by the shearing force τ (ΔA ₁ : 0.45 A, shearing force τ: 2.1 kgf or more when pulled to the end of the roll paper. (・ From formula (4)) Therefore, data of this change in drive current value (ΔA ₁ : 0.45 A) is stored in the ROM 81, and when a change in drive current value corresponding to the data occurs during roll paper conveyance, the CPU 80 a) It can be detected that the paper has been pulled out to the end with a type of roll paper.

  In the case of this type (a), since the roll paper end cannot be peeled off, the drive current value of the LF motor 60 becomes an allowable upper limit value for control immediately after being pulled out to the end, and cannot be rotated. The current value is constant at the upper limit value. This data may also be stored in the ROM 81 and used for end detection.

(B) Strong adhesion type (2)
In this type, the end of the roll paper is fixed by a short double-sided tape 71B that is not as large as the tape 71A of the above type (a) but has a suitable adhesive force, and is a boundary level type that allows the end of the roll paper to be peeled off. .

As shown in the graph, a sudden increase (ΔA ₁ : 0.45 A) of the drive current value due to the shearing force τ is observed when the roll paper is drawn to the end. In addition, a decrease in drive current value (ΔA ₂ : 0.07 A) is observed immediately after the tape 71A is peeled (immediately after the roll paper is peeled off). This is because the roll brake T has stopped working. Accordingly, when the drive current value change (ΔA ₁ only, or ΔA ₁ and ΔA ₂ ) is stored in the ROM 81 and a change in the drive current value corresponding to the data occurs during the roll paper conveyance. , (B) type paper can be detected to be pulled out to the end.

(C) Weak adhesive type (1)
This type is a general roll paper in which the end surface of the roll paper Pr and the paper tube 72 are fixed by taping using four standard level tapes (single-sided tape) 71C as adhesive strength.

As shown in the graph, an increase in driving current value due to the shearing force τ (ΔA ₁ : 0.15 A, shearing force τ: around 0.7 kgf) is observed when the roll paper is drawn to the end. Further, a decrease in drive current value (ΔA ₂ : 0.07 A) due to the fact that the roll brake T does not act immediately after the tape is peeled is observed.

If the drive current value changes (ΔA ₁ and ΔA ₂ ) are stored in the ROM 81, it can be detected that the paper is drawn to the end by the (c) type roll paper.

(D) Weak adhesive type (2)
In this type, the end of the roll paper is fixed using only two tapes 71C having the above-mentioned adhesive strength, and the adhesive strength is weak and easy to peel.

As shown in the graph, a slight increase in drive current value due to the shearing force τ (ΔA ₁ : 0.1 A, shearing force τ: around 0.5 kgf) is observed when the roll paper is drawn to the end. . In addition, a decrease in drive current value (ΔA ₂ : 0.07 A) due to the release of the roll brake T is observed immediately after the tape is peeled off. If the drive current value change (ΔA ₁ and ΔA ₂ ) data is stored in the ROM 81, it can be detected that the drive paper value has been drawn to the end with the (d) type roll paper.

In the case of the type (c), since the change due to the shearing force τ (ΔA ₁ ) is small, it is considered that accurate detection cannot be performed due to current noise, but the drive current value decreases immediately after peeling (ΔA ₂ ). Can also be detected by making a judgment.

  As described above, the peeling force at the end of the roll paper varies depending on the material, length, and number of the tape that fixes the end, and also depends on the width of the tape, the characteristics of the roll paper, and the like. The end detection on the winding core can be reliably performed based on the change in the drive current value. Even when the end of the roll paper is directly attached without using the tape, similarly, the end detection on the winding core can be reliably performed based on the change in the driving current value of the LF motor.

  That is, according to the apparatus of the present embodiment, it is possible to reliably detect the end of various types of roll paper. Also, in this embodiment, when the roll paper is pulled out from the paper core of the core to the end, that is, when the adhesive strength of the end fixing tape is weak, immediately when the tape is peeled off from the paper tube together with the end of the roll paper. Can detect this. Therefore, by immediately stopping the transport operation in response to the detection, the tape is not pulled between the pair of transport guides, and it is possible to prevent the occurrence of problems such as jamming. Further, by immediately stopping the recording operation in response to the end detection, it is possible to prevent the image recording on the platen from occurring.

  Further, unlike in Patent Document 1, there is no case where the roll paper is damaged by a roller pressed against the outer periphery of the roll paper for end detection. Also, the types of roll paper and the core of the roll core are not limited.

  Furthermore, the configuration of this embodiment can be implemented simply and inexpensively, and does not increase the size of the apparatus. That is, the motor current detection circuit 85 is added to the conventional general printer hardware configuration, and the control program for the CPU 80 to detect the end as described above and the data of the change in the drive current value of the LF motor are stored in the ROM 81. Should be stored.

  In the recording apparatus, “end free roll paper” in which the end is not fixed to the core with a tape or the like may be used. In this case, since the shearing force τ is not generated when the terminal is pulled out to the terminal, the terminal cannot be detected based on the change in the driving current value of the LF motor in accordance with the load fluctuation. However, in this case, the paper feed sensor 26 can detect the end (rear end) of the roll paper. In this case, since no tape is attached to the end of the roll paper, problems such as jamming due to drawing of the tape and image recording on the platen do not occur.

  In the above description, the embodiment of the roll paper transport apparatus that transports the roll paper as the recording paper in the recording apparatus has been described. However, the present invention is naturally applicable to a roll sheet transport apparatus that transports other roll sheets. . Of course, the arrangement of the roll sheet, the guide member, the sheet feeding roller, the configuration of the transport mechanism, and the like in the roll sheet transport apparatus to which the present invention can be applied are not limited to those in the embodiment.

1 is a perspective view illustrating a schematic configuration of an entire recording apparatus including a roll paper transport device according to an embodiment of the present invention. It is a sectional side view in the center part of the apparatus. It is a perspective view which shows the structure of the roll paper conveyance mechanism of the same apparatus. It is a block diagram which shows the structure of the control system which controls the drive of LF motor of the apparatus. FIG. 6 is a graph showing changes in the drive current value of the LF motor when four types of roll papers whose ends are fixed by tapes having different adhesive forces are pulled out from the paper tube to the end by a conveying operation in the recording apparatus. FIG. 10 is a side sectional view of a central portion showing a configuration related to roll paper conveyance of a conventional recording apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording device 10 Roll paper holder part 11 Spool axis | shaft 11a Torque limiter 14a One-way gear 20 Image formation part 21 LF roller 26 Paper feed sensor 30 Paper discharge part 40 Carriage 41 Recording head 60 LF motor 63 LF code wheel 64 LF linear sensor 65 Electromagnetic Clutch 80 CPU
81 ROM
82 RAM
83 Motor control circuit 84 Motor driver 85 Motor current value detection circuit

Claims (7)

In a roll sheet conveying apparatus that pulls and conveys a roll sheet from the core by rotating and holding a roll sheet wound in a cylindrical shape on the core, and rotating a conveying roller by driving a drive motor.
Drive current value detecting means for detecting the drive current value of the drive motor during the conveyance operation of the roll sheet;
A roll having end detection means for detecting that the roll sheet is drawn from the winding core to the end based on a change in the drive current value of the drive motor detected by the drive current value detection means. Sheet conveying device.   The end detection means drives the roll sheet according to fluctuations in the drive load of the drive motor due to a shearing force acting when the roll sheet is drawn from the end of the core to the end and the end attached to the core is about to peel off. 2. The roll sheet conveying apparatus according to claim 1, wherein it is detected that the roll sheet is drawn from the winding core to the end based on a change in current value. A rotatable spool shaft that holds a roll sheet wound on the core;
Load generating means for generating a load as a brake against rotation of the spool shaft during roll sheet conveyance;
The termination detecting means is configured such that when the roll sheet is pulled out from the winding core to the termination and the termination attached to the winding core is peeled off, the load acting as the brake that has been applied until then stops working. The roll sheet conveyance according to claim 2, wherein it is detected that the roll sheet is drawn from the winding core to the end based on a change in a driving current value according to a change in a driving load of the driving motor. apparatus.   A detecting means for detecting the end of the roll sheet whose end is not fixed to the core at a position in the middle of the path of the roll sheet between the roll sheet held rotatably and the drive roller; The roll sheet conveying apparatus according to claim 1, wherein the apparatus is a roll sheet conveying apparatus. A roll of a roll sheet conveying apparatus that draws and conveys the roll sheet from the core by rotatingly holding the roll sheet wound in a cylindrical shape on the core and rotating the conveying roller by driving a drive motor. A sheet end detection method,
A roll characterized by detecting a drive current value of the drive motor during a roll sheet conveying operation, and detecting that the roll sheet is drawn from the winding core to the end based on a change in the drive current value. Sheet end detection method.   During the transport operation of the roll sheet in the roll sheet transport device, the roll motor is pulled out from the winding core to the end, and the end of the drive motor is applied by the shearing force that acts when the end attached to the winding core is about to peel off. 6. The roll sheet end detection method according to claim 5, wherein it is detected that the roll sheet is drawn from the winding core to the end based on a change in the drive current value according to a change in the drive load. The roll sheet conveying device includes a rotatable spool shaft that holds a roll sheet wound on the winding core, and a load generating unit that generates a load as a brake against rotation of the spool shaft during conveyance of the roll sheet. Have
During the roll sheet conveying operation in the roll sheet conveying device, when the roll sheet is pulled out from the core to the end and the end attached to the core is peeled off, It is detected that the roll sheet is drawn from the winding core to the terminal end based on a change in the driving current value according to a change in the driving load of the driving motor due to the load no longer acting. Item 7. The roll sheet end detection method according to Item 6.

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