JP2008260137A - Image recorder, method of detecting conveyance abnormality by this apparatus and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image recorder which can detect a conveyance abnormality by correctly acquiring conveyance information of a recording medium, and to provide a method of detecting the conveyance abnormality by this apparatus, and a program. <P>SOLUTION: The image recorder 1 is equipped with first and second drums 30 and 40 at a plurality of carriers stationed to be able to drive associatively via the recording medium 5 carrying the recording medium 5 at peripheral surfaces, a driving motor 41 which rotates the second drum 40, and first and second encoders 32 and 42 in a position information generating part which generates rotational position information of the first and second drums 30 and 40. A conveyance monitoring part 64 installed in a control part 60 of the image recorder 1 judges the conveyance abnormality of the recording medium 5 by each position signal by the first and second encoders 32 and 42 in the position information generating part, and a drive signal for driving the driving motor 41. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image recording apparatus that has a plurality of recording units and a plurality of carriers and records an image on a recording medium, a recording medium conveyance abnormality detection method using the apparatus, and a program.

  As one of the image recording apparatuses, for example, an ink jet printer performs image recording at high speed and high image quality by ejecting ink droplets from a print head onto a recording medium held and conveyed by a conveying unit. This ink jet printer is widely used as an office application for recording an image on, for example, a cut sheet-like recording medium (paper).

  In recent years, there has also been proposed an ink jet printer in which a line head is configured by arranging and arranging a large number of print heads in a direction substantially perpendicular to the conveyance direction of a recording medium. Thereby, the throughput of the ink jet printer is improved, and the ink jet printer can be widely used as an industrial application for recording a thumbtack on a recording medium (continuous paper) such as roll paper.

  In such an image recording apparatus, friction conveyance by winding continuous paper around a drum as a carrier is known as one of effective means for conveying continuous paper such as roll paper. However, in this frictional conveyance, the continuous paper is not conveyed while being sandwiched by rollers or the like, so that there is a possibility that the continuous paper slides on the drum.

For example, Patent Document 1 discloses a prior-stage roll arranged at the front stage in the sheet material conveyance direction and a rear-stage roll arranged at the rear stage in the sheet material conveyance direction as a conventional technique related to the slip of the sheet material. There is disclosed a technique for comparing the respective rotation speeds and detecting slippage of the sheet material using a signal corresponding to the deviation.
Japanese Patent Laid-Open No. 10-337076

  However, in patent document 1, only the deviation of the rotational speed of a front | former stage roll and a back | latter stage roll is detected. For this reason, Patent Document 1 cannot detect, for example, a change in the conveyance speed of the sheet material, that is, a decrease in speed or an excess of speed relative to the instruction speed.

  On the other hand, in a general image recording apparatus, it is desirable that the conveyance speed of the recording medium is substantially constant. When the conveyance speed of the recording medium changes remarkably or suddenly, the image recording The accuracy of is reduced.

  The present invention has been made to solve such a problem, and provides an image recording apparatus capable of accurately acquiring conveyance information of a recording medium and detecting a conveyance abnormality, a conveyance abnormality detection method using the apparatus, and a program. Objective.

  In order to achieve the above-described object, an image recording apparatus which is one of the aspects of the present invention includes a plurality of carriers that support a recording medium on an outer peripheral surface and are arranged to be interlocked with each other via the recording medium. In an image recording apparatus having a drive motor that drives one of the bodies and a recording unit that is arranged opposite to each of the plurality of carriers and performs recording on a recording medium, the image recording apparatus is provided for each of the plurality of carriers. Abnormal conveyance of the recording medium due to a plurality of position information generation units that generate rotational position information of the plurality of carriers, a plurality of position signals by the plurality of position information generation units, and a drive signal for driving the drive motor A conveyance monitoring unit for determining whether or not.

  In addition, the conveyance abnormality detection method according to another aspect of the present invention includes a plurality of carriers disposed on an outer peripheral surface of a recording medium so as to be interlocked with each other, and a plurality of carriers. A recording medium conveyance abnormality detection method by an image recording apparatus comprising: a drive motor that drives one of the recording medium; and a recording unit that is disposed opposite to each of a plurality of carriers and performs recording on the recording medium. Rotational position information is generated for each carrier, and a plurality of rotational position signals in the generated rotational position information for each of the plurality of carriers are compared with a drive signal for driving the drive motor, and the comparison result is set to a predetermined value. The recording medium conveyance abnormality is detected on the basis of the result of comparison with the threshold value.

  According to another aspect of the present invention, a program includes a plurality of carriers arranged on a peripheral surface of a recording medium so as to be interlocked with the recording medium, and one of the plurality of carriers. A processing motor that controls a recording medium conveyance abnormality detection by an image recording apparatus having a drive motor for driving the recording medium and a recording unit that is disposed opposite to each of the plurality of carriers and performs recording on the recording medium. For generating a rotational position information for each of a plurality of carriers, a plurality of rotational position signals in the generated rotational position information for each of the plurality of carriers, and a drive motor. The arithmetic processing unit performs processing for comparing the driving signal for driving and processing for detecting a conveyance abnormality of the recording medium based on a result of comparing the comparison result with the read predetermined threshold value. It is characterized in.

  ADVANTAGE OF THE INVENTION According to this invention, the image recording apparatus which can acquire the conveyance information of a recording medium correctly, and can detect conveyance abnormality, the conveyance abnormality detection method by the apparatus, and a program can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 is a schematic front view showing a conveyance system of a recording medium 5 in the image recording apparatus 1, FIG. 2 is a schematic side view of a printer unit 3, and FIG. 3 is a schematic front view of a first recording unit 50. FIG.

The image recording apparatus 1 includes an unwinder unit 2, a printer unit 3, and a rewinder unit 4. Hereinafter, the configurations of the unwinder unit 2, the printer unit 3, and the rewinder unit 4 will be described.
(Configuration of unwinder section)
The unwinder unit 2 holds the roll paper as the recording medium 5 in a rotatable manner, and serves to unwind the recording medium 5 to the printer unit 3. The unwinder unit 2 includes an unwinder unit stand 6 and a paper tube fixing shaft 7.

  The unwinder unit stand 6 rotatably supports a paper tube fixing shaft 7 that holds the recording medium 5. A driving force of the unwinding drive motor 8 is transmitted to the paper tube fixing shaft 7 via a belt 26. The drive motor 8 is driven in a direction (counterclockwise in FIG. 1) opposite to the direction of the arrow 9 that is the conveyance direction of the recording medium 5 in order to apply tension to the recording medium 5.

Further, a powder clutch 8 a is arranged between the belt 26 and the drive motor 8. The powder clutch 8a functions to give a constant back tension to the recording medium 5 in the direction opposite to the conveying direction (the direction of the arrow 9).
(Configuration of printer unit)
The printer unit 3 introduces the recording medium 5 conveyed from the unwinder unit 2 and winds and holds the recording medium 5 with the first drum 30 in the carrier. Further, the recording medium 5 is conveyed directly below the first recording unit 50. The first recording unit 50 records an image on one surface of the recording medium 5. Next, the recording medium 5 is wound and held by the second drum 40 in the carrier. Further, the recording medium 5 is conveyed directly below the second recording unit 55. Then, image recording is performed on the back side of the other side of the recording medium 5. Thereafter, the recording medium 5 is sent to the rewinder unit 4.

  As shown in FIGS. 1 and 2, the printer unit 3 includes a conveyance unit and a main body of a recording medium 5 having a plurality of rollers (14, 15, 16,...), A first drum 30, and a second drum 40. A frame 25, a first recording unit 50, a second recording unit 55, a first maintenance unit 56, a second maintenance unit 57, and the like are provided.

  Next, the conveyance unit for the recording medium 5 will be described. The recording medium 5 unwound from the unwinder unit 2 is conveyed to the first drum 30 via the free roller 14, the free roller 15, the first dancer roller 16, the free roller 17, and the free roller 18.

  The first dancer roller 16 is rotatably held at the tip of an arm 16b having a rotation center 16a. The rotation center 16 a is supported by the main body frame 25. And the tension | tensile_strength generating means which provides tension | tensile_strength to the recording medium 5 wound around the 1st dancer roller 16 by the dead weight of the 1st dancer roller 16 and the arm 16b is comprised.

  This tension generating means also functions to take up this slack when the recording medium 5 held in the unwinder section 2 is slackened due to fluctuations in back tension due to eccentricity of the paper tube fixing shaft 7 or the like.

  In addition, a potentiometer 16c that detects a rotational position when the first dancer roller 16 moves in the vertical direction is provided at the rotation center 16a of the arm 16b. The potentiometer 16c controls the back tension acting on the recording medium 5 by operating the powder clutch 8a of the unwinder section 2 according to the output signal.

Next, the configuration of the first drum 30 in the printer unit 3 will be described.
The first drum 30 is, for example, a hollow cylinder made of aluminum. The rotating shaft 30 a of the first drum 30 is engaged with one end of a member that supports a first recording unit 50 described later, and is also engaged with one end of a member that supports the first maintenance unit 56. The first drum 30 is supported by the main body frame 25 so that the rotation shaft 30a can rotate.

  Further, the recording medium 5 is wound around the first drum 30 at a winding angle of approximately 330 degrees. The first drum 30 is set to a circumferential length corresponding to about three A3 size vertical (420 mm) pieces at a winding angle of about 330 degrees.

  The recording medium 5 gives a vertical drag to the outer peripheral surface of the first drum 30 by the back tension at the start of winding of the first drum 30 and the tension at the end of winding. As a result, the recording medium 5 is held on the first drum 30 by the frictional force between the first drum 30 and the recording medium 5. The first drum 30 is a driven drum that is rotated by the second drum 40 (drive drum) via the recording medium 5.

  As shown in FIG. 2, the first encoder 32 in the position information generation unit is connected to the rotation shaft 30 a of the first drum 30 through a coupling 33. The housing of the first encoder 32 is fixed to one end of an encoder fixing member 34 having an L-shaped cross section, and the other end of the encoder fixing member 34 is fixed to the main body frame 25.

  With this configuration, the rotation shaft 32 a of the first encoder 32 rotates with the rotation of the first drum 30. The first encoder 32 outputs a detection pulse corresponding to the rotational position of the first drum 30. This detection pulse is input to the first recording unit 50 via the first conversion unit 68 (see FIG. 4). Further, the print head drives and ejects ink in synchronization with the detection pulse by a head driving unit (not shown) in the first recording unit 50. At the same time, this detection pulse is also input to the comparison / determination unit 67 (see FIG. 4), and is used for detecting a conveyance abnormality of the recording medium 5 described later.

  The first encoder 32 uses, for example, a rotary encoder that outputs 18,000 pulses per revolution. Here, the resolution in the conveyance direction of image recording is set to 300 dpi, and one line is set in the conveyance direction per pulse of the first encoder 32. As a result, the diameter of the first drum 30 is 25.4 inches ÷ 300 dpi × 18,000 pulses ÷ circumference π = 485 mm.

The recording medium 5 is conveyed to the second drum 40 via the free rollers 19, 20, 21 after the end of winding of the first drum 30.
Next, the configuration of the second drum 40 will be described.

  The second drum 40 has the same configuration as the first drum 30 and is, for example, a hollow cylinder made of aluminum. The rotation shaft 40 a of the second drum 40 is rotatably supported by the main body frame 25. In addition, one end of a member that supports a second maintenance unit 57 described later is engaged with the rotation shaft 40a.

  The recording medium 5 can be wound around the second drum 40 at a winding angle of approximately 330 degrees. The recording medium 5 gives a vertical drag to the outer peripheral surface of the second drum 40 by the back tension at the start of winding of the second drum 40 and the tension at the end of winding. As a result, the recording medium 5 is held on the second drum 40 by the frictional force between the second drum 40 and the recording medium 5. The recording medium 5 is conveyed by a driving force of a driving motor 41 as a driving unit via a belt 46 connected to the rotation shaft 40a of the second drum 40. The second drum 40 is a drive drum.

  In addition, the second encoder 42 in the position information generation unit that outputs 18,000 pulses per rotation is connected to the rotation shaft 40a of the second drum 40, similarly to the first drum. The second encoder 42 outputs a detection pulse corresponding to the rotational position of the second drum 40. This detection pulse is input to the second recording unit 55 via the second conversion unit 69 (see FIG. 4). The print head ejects ink in synchronization with the detection pulse. At the same time, this detection pulse is also input to the comparison / determination unit 67 and used to detect a conveyance abnormality of the recording medium 5 described later.

After the end of winding of the second drum 40, the recording medium 5 is sent to the rewinder unit 4 via the free roller 22, the second dancer roller 23, and the free roller 24.
The second dancer roller 23 is rotatably held at the tip of an arm 23b having a rotation center 23a. The rotation center 23 a is supported by the main body frame 25. And the tension | tensile_strength generating means which provides tension | tensile_strength to the recording medium 5 wound around the 2nd dancer roller 23 by the dead weight of the 2nd dancer roller 23 and the arm 23b is comprised.

  This tension generating means also functions to take up the slack when the recording medium 5 held in the unwinder section 2 is slackened due to fluctuations in tension due to eccentricity of the paper tube fixing shaft 7 or the like.

The rotation center 23a is provided with a potentiometer 23c that detects a rotational position when the second dancer roller 23 moves in the vertical direction. The potentiometer 23c controls the tension of the recording medium 5 by operating a powder clutch 12a of the rewinder unit 4 which will be described later according to the output signal.
(Rewinder configuration)
The rewinder unit 4 holds the wound recording medium 5 in a rotatable manner, and serves as a winding unit that winds the recording medium 5 from the printer unit 3. The rewinder unit 4 includes a rewinder unit stand 10 and a paper tube fixing shaft 11.

The rewinder unit stand 10 rotatably supports the paper tube fixing shaft 11, and the wound recording medium 5 is held by the paper tube fixing shaft 11.
A driving force of a winding drive motor 12 is transmitted to the paper tube fixing shaft 11 via a belt 48. By this drive motor 12, the recording medium 5 is wound in the direction of the arrow 13. Further, a powder clutch 12 a is disposed between the belt 48 and the drive motor 12. The powder clutch 12a serves to adjust the tension in the conveyance direction of the recording medium 5.
(Configuration of recording unit)
Next, the first recording unit 50 (and the second recording unit 55) will be described with reference to FIG.

FIG. 3 is a schematic front view of the first recording unit 50 disposed to face the first drum 30.
The first recording unit 50 has an ink ejection function for ejecting ink to the recording medium 5. The first recording unit 50 includes print heads 51a, 51b, 51C, 51d of a total of four colors, cyan (C), black (K), magenta (M), and yellow (Y), and a head driving unit (not shown). is doing. The print heads 51a, 51b, 51C, 51d are arranged and fixed in a staggered manner on the head holding plates 52a, 52b, 52C, 52d, respectively.

  The print heads 51a, 51b, 51C, 51d are provided with nozzle surfaces at their tips. The nozzle surface is disposed opposite to the printing surface of the recording medium 5 held on the outer peripheral surface of the first drum 30. The print heads 5la, 51b, 51C, 51d are positioned relative to the first drum 30 by the head holding plates 52a, 52b, 52C, 52d and the head holding member 53.

The second recording unit 55 has the same configuration as the first recording unit 50, but the description thereof is omitted here.
(Control system configuration)
Next, the control unit 60 of the image recording apparatus 1 will be described with reference to FIG.

  The CPU 61 in the arithmetic processing unit is connected to the host device IF unit 62, the storage unit 63, and the conveyance monitoring unit 64 through a data bus. The storage unit 63 stores an operation program of the image recording apparatus 1 and temporarily stores recording data from the higher-level device 65 connected through the higher-level device IF unit 62. Further, the CPU 61 also stores various adjustment parameters of the image recording apparatus 1.

  The conveyance monitoring unit 64 includes a drive signal generation unit 66, a comparison determination unit 67, a first conversion unit 68, and a second conversion unit 69. The drive signal generation unit 66 is a signal generation unit for driving the drive motor 41 that controls conveyance of the recording medium 5. The drive signal generation unit 66 generates a voltage signal corresponding to the conveyance speed of the recording medium 5 and drives the drive motor 41 via a driver (not shown). The drive signal generation unit 66 also outputs a signal to the comparison determination unit 67 in order to detect a conveyance abnormality of the recording medium 5 described later.

  The first conversion unit 68 and the second conversion unit 69 receive detection pulse signals from the first encoder 32 and the second encoder 42. Then, the detection pulse signal is corrected in accordance with the circumferential diameter difference between the first drum 30 and the second drum 40, and output to the first recording unit 50 and the second recording unit 55. Further, the first conversion unit 68 and the second conversion unit 69 convert the detection pulse signal into a voltage signal and send it to the comparison determination unit 67.

The comparison determination unit 67 receives the voltage signal converted by the first conversion unit 68 and the second conversion unit 69 and the signal from the drive signal generation unit 66, and determines the conveyance abnormality of the recording medium 5 under a predetermined condition. When it is determined that the conveyance is abnormal, the CPU 61 is notified.
(Recording medium transport operation)
Subsequently, the conveyance operation of the recording medium 5 will be described.

In the present embodiment, an operation of applying tension to the recording medium 5 is performed before the conveyance operation of the recording medium 5 is started.
That is, in FIG. 1, the first dancer roller 16 is controlled to be in the neutral position (the arm 16b is in a substantially horizontal state). In this case, the powder clutch 8a connected to the paper tube fixing shaft 7 of the unwinder unit 2 is operated by the output signal of the potentiometer 16c. In this way, the power of the drive motor 8 is transmitted to the paper tube fixing shaft 7 to control the tension of the recording medium 5.

As a result, on the downstream side of the conveyance path of the recording medium 5, a tension that is about half of the weight of the first dancer roller 16 and the arm 16 b acts on the recording medium 5.
On the other hand, the second dancer roller 23 is controlled to be in a neutral position (the arm 23b is in a substantially horizontal state). In this case, the powder clutch 12a connected to the paper tube fixing shaft 11 of the rewinder unit 4 is operated by the output signal of the potentiometer 23c. Thus, the power of the drive motor 12 is transmitted to the paper tube fixing shaft 11 to control the tension of the recording medium 5.

Thereby, upstream of the conveyance path of the recording medium 5, a tension of about half of the weight of the second dancer roller 23 and the arm 23 b acts on the recording medium 5.
At this time, the recording medium 5 gives a vertical drag to the outer peripheral surface of the first drum 30 by the back tension at the start of winding of the first drum 30 and the tension at the end of winding. At the same time, the recording medium 5 is held on the first drum 30 by the frictional force between the first drum 30 and the recording medium 5. Similarly, the recording medium 5 gives a vertical drag to the outer peripheral surface of the second drum 40 by the back tension at the start of winding of the second drum 40 and the tension at the end of winding. At the same time, the recording medium 5 is held on the second drum 40 by the frictional force between the second drum 40 and the recording medium 5.

When the conveyance operation of the recording medium 5 is started, the drive motor 41 connected to the second drum 40 is driven to rotate the second drum 40. Thereby, the recording medium 5 is conveyed by the rotation of the first drum 30 to be driven.
(Image recording operation to recording medium)
Next, an image recording operation on the recording medium 5 will be described.

  When the image recording operation is started, the above-described tension generation operation and transport operation of the recording medium 5 are started. As a result, each of the first drum 30 and the second drum 40 from the first encoder 32 connected to the rotary shaft 30a of the first drum 30 and the second encoder 42 connected to the rotary shaft 40a of the second drum 40 is obtained. A detection pulse corresponding to the rotational position is output. This detection pulse is input to the first recording unit 50 and the second recording unit 55 via the first conversion unit 68 and the second conversion unit 69, respectively.

  Next, when the conveyance speed of the recording medium 5 reaches a specified speed, an image is formed on the surface (one side surface) of the recording medium 5 by the first recording unit 50 in accordance with a print start signal sent from the control unit 60. Recording is performed. This image recording is performed in synchronization with the detection pulse described above.

  Next, the second recording unit 55 performs image recording on the surface opposite to the recording surface of the recording medium 5 on which the image has been recorded by the first recording unit 50 (the other side back surface). In this case, registration of the recording surface of the recording medium 5 on which the image is recorded by the first recording unit 50 and the recording surface of the recording medium 5 on which the image is recorded by the second recording unit 55 is performed as follows.

For example, from the printing position of the cyan (C) print head of the first recording unit 50 on the recording medium 5, the printing position of the cyan (C) print head of the second recording unit 55 on the recording medium 5. The transport path length up to is converted into the number of detection pulses of the second encoder 42 in advance. When the number of detected pulses of the second encoder 42 reaches a predetermined number of delay pulses after image recording by the first recording unit 50, image recording by the second recording unit 55 is started.
(Detection of conveyance error of recording medium)
Next, a method for detecting an abnormality in conveyance of the recording medium 5 that is a feature of the present embodiment will be described with reference to FIGS.

  The recording medium 5 is conveyed by driving a drive motor 41 connected to the second drum 40. A voltage signal generated by the drive signal generation unit 66 is used as a command signal for driving the drive motor 41. This voltage signal is the target speed of the drive motor 41. In the present embodiment, for example, the signal realizes rotation of 0 to 10 rps at 0 to 5 V.

  On the other hand, a second encoder 42 and a first encoder 32 are disposed on the second drum 40 that is directly driven by the drive motor 41 and the first drum 30 that is rotated via the recording medium 5, respectively. . As described above, the encoders 32 and 42 output 18,000 pulses (18,000 ppr) when the first drum 30 or the second drum 40 makes one rotation.

FIG. 5 shows a control block diagram of the first converter 68A.
The first conversion unit 68A includes a phase lock loop control unit (PLL unit) 70, a correction count setting unit 71, and an FV conversion unit 72. The PLL unit 70 performs frequency conversion using a coefficient set by the correction count setting unit 71 while stabilizing the pulse signal from the first encoder 32.

  As described above, the diameter of the first drum 30 is about 485 mm as a nominal value, but a slight deviation occurs due to a tolerance during processing. This deviation is corrected. If the drum diameter is increased by 1 mm, the outer periphery of the drum becomes 3.14 mm longer than the nominal value. For this reason, for example, in image recording of a long object, the image lengths of the front and back sides are greatly different. The CPU 61 sets the correction value set in the correction count setting unit 71.

  In order to obtain the correction value, for example, image recording corresponding to 10,000 pulses output from the first encoder 32 is performed, and the difference obtained by comparing the image length with the nominal value of the drum may be stored. Further, the eccentricity of the first drum 30 can be corrected by measuring the speed per rotation of the first drum 30 and the output pulse period of the first encoder 30 in advance. Since these correction methods are already known, a detailed description thereof is omitted here.

The pulse signal subjected to the correction as described above is output to the first recording unit 50, and the print head is driven by a head driving unit (not shown).
On the other hand, the correction pulse signal input to the FV conversion unit 72 via the PLL unit 70 is FV converted here and becomes a voltage signal corresponding to the rotation speed of the drum. This voltage signal is output to the comparison determination unit 67A. The FV conversion rate at this time is, for example, 1 V / 2 rps (= 36,000 pulses / 2 sec = 18 KHz). Since the voltage instruction signal to the drive motor 41 is 5 V / 10 rps, it can be directly compared with the instruction signal to the drive motor 41.

In the present embodiment, the first conversion unit 68A has been described, but the second conversion unit 69A (see FIG. 6) has the same configuration.
When the image recording operation is started, the second drum 40 starts to rotate by the voltage applied to the drive motor 41. As described above, the recording medium 5 is wound around the second drum 40 and conveyed by the action of the first dancer roller 16 and the second dancer roller 23. Along with this, the first drum 30 is driven to start rotating. When the drive motor 41 reaches the specified speed, the instruction voltage to the drive motor 41, the FV conversion output voltage of the first conversion unit 68A, and the FV conversion output voltage of the second conversion unit 69A all show the same voltage when normal. It should be.

FIG. 6 is a control block diagram of the comparison determination unit 67A.
The comparison determination unit 67A includes a first comparator 73A and a second comparator 74A. The first comparator 73A and the second comparator 74A are constituted by a so-called comparator overnight (voltage comparison).

  The first comparator 73A compares and determines the voltages of the first converter 68A and the second converter 69A. In other words, the speed difference between the first drum 30 and the second drum 40 is compared. Here, since the first drum 30 is a driven drum and does not have a drive source, its speed depends on the speed of the second drum 40. For this reason, in the category in which the recording medium 5 is normally conveyed, the speed difference between the two drums does not occur.

  Here, when the recording medium 5 slides on the circumference of the first drum 30, the first drum 30 does not rotate following the conveyance of the recording medium 5. Therefore, the output voltage of the first converter 68A is lower than the output voltage of the second converter 69A that outputs the speed of the second drum 40. This may be due to a decrease in the coefficient of friction due to foreign matter adhering to the first drum 30, or a sliding abnormality of the support shaft portion of the first drum 30.

On the other hand, a case where the recording medium 5 slides on the circumference of the second drum 40 will be considered.
The second drum 40 is a drive drum. Therefore, the speed is governed by the drive motor 41 regardless of the recording medium 5. Therefore, when slippage occurs on the second drum 40, the conveyance speed of the recording medium 5 decreases. As a result, the speed of only the first drum 30 that is the driven drum is reduced. The first comparator 73A determines the aforementioned speed difference using a threshold value set by the CPU 61 in the control unit. If it is determined that there is an abnormality, the CPU 61 is notified of the abnormality.

  That is, when the recording medium 5 slides on the circumference of the first drum 30 or the second drum 40, the speed of the first drum 30 decreases. For this reason, when the degree of the speed reduction of the first drum 30 exceeds a preset value, it is determined as abnormal and the CPU 61 is notified accordingly.

FIG. 7 shows the relationship between the output of each part and the applied voltage to the drive motor 41 when the first comparator 73 </ b> A determines that there is an abnormality.
In the figure, the horizontal axis represents time, and the vertical axis represents the output voltage (conveying speed) of each converter and the motor applied voltage v. The output voltage of the first conversion unit 68A is V1, the output voltage of the second conversion unit 69A is V2, and the difference between the two is Vd. Now, the slip of the recording medium 5 does not occur until time Tl, and Vl and V2 indicate the same voltage. Therefore, the difference Vd is 0 V during this period. Note that the voltage v applied to the drive motor 41 is constant until time T2.

  Next, when the recording medium 5 starts to slide on the second drum 40 from the time Tl, as described above, the speed of the first drum 30, that is, the output of Vl gradually decreases, and the difference Vd between both increases. To do. Then, the first comparator 73A notifies the CPU 61 that the difference Vd has exceeded the slip detection threshold at time T2.

  In response to this notification, the CPU 61 sets the applied voltage v to the drive motor 41 to 0V. Thereby, the drive motor 41 stops according to a certain time constant due to the frictional force and the inertial force. At this time, since the conveyance speed of the recording medium 5 is decreased, the slip is eliminated at time T3, the difference Vd becomes 0 V again, and the conveyance of the recording medium 5 is stopped at time T4.

  Next, in FIG. 6, the second comparator 74A compares the output of the drive signal generator 66 with the output of the second converter 69A. Now, it is assumed that the CPU 61 in the control unit is driving the drive motor 41 at a speed set in the drive signal generation unit 66. However, for example, when the driving force of the driving motor 41 is not normally transmitted to the second drum 40, the output voltage of the second conversion unit 69 </ b> A and the output voltage of the driving signal generation unit 66, which are speed signals of the second drum 40. Differences can occur.

  In this case, the recording medium 5 is not transported at the desired transport speed set by the CPU 61, and the throughput of the recording operation is reduced or the print quality is abnormal. In the second comparator 74A, this speed difference is determined by a threshold value set by the CPU 61 in the control unit, and if it is determined to be abnormal, the CPU 61 is notified of the abnormality.

  That is, even when the recording medium 5 does not slide on the periphery of the drum, the speed signal of the second drum 40 decreases when the driving force of the driving motor 41 is not normally transmitted to the second drum 40. If the difference between the speed signal and the signal from the drive signal generation unit 66 exceeds a preset value, it is determined as abnormal and the CPU 61 is notified of this.

  In response to the abnormality notified from the comparison determination unit 67A, for example, the CPU 61 stops execution of image recording and notifies the higher-level device 65. Alternatively, a known process such as marking that an abnormality has occurred in the recorded image is performed.

According to the present embodiment, the conveyance information of the recording medium 5 can be accurately acquired, and an image recording abnormality can be prevented in advance.
(Modification example of detection of conveyance error of recording medium)
Next, a modification of the present embodiment will be described based on FIGS. FIG. 8 is a diagram illustrating a configuration of the first conversion unit 68B, and FIG. 9 is a diagram illustrating a configuration of the comparison determination unit 67B.

  The first converter 68B of FIG. 8 is different from that of FIG. 5 only in that it does not have the FV converter 72, and the other configurations are the same. For this reason, the pulse signal is output as it is from the first conversion unit 68B to the comparison determination unit 67B. 9 includes a first counter 75, a second counter 76, a first comparator 73B, and a second comparator 74B.

  The first counter 75 and the second counter 76 in FIG. 9 always count the number of pulses input from the first conversion unit 68B and the second conversion unit 69B, respectively. The first comparator 73B acquires the count values of the first counter 75 and the second counter 76, for example, every 4 msec. In this way, the difference between the acquired count values is obtained. If a difference equal to or greater than the threshold value set by the CPU 61 occurs, it is determined that the recording medium 5 has slipped.

  If it is determined that there is an abnormality, the CPU 61 is notified of the abnormality. Since the difference threshold can be set in units of one pulse, more accurate determination is possible, but the configuration of the comparison determination unit 67B is complicated.

  On the other hand, the second comparator 74B calculates the theoretical frequency of the output pulse of the second conversion unit 69B from the voltage signal input from the drive signal generation unit 66, and the theoretical frequency and the pulse input from the second conversion unit 69B. Compare the actual frequency of. The actual frequency is measured by, for example, counting the number of pulses per second. The second comparator 74B determines this speed difference using a threshold value set by the CPU 61 in the control unit. If it is determined that there is an abnormality, the CPU 61 is notified of the abnormality.

  In response to the abnormality notified from the comparison determination unit 67B, for example, the CPU 61 stops execution of image recording and notifies the higher-level device 65. Alternatively, a known process such as marking that an abnormality has occurred in the recorded image is performed.

  As described above, by using this modified example, it is possible to acquire the transport information of the recording medium 5 with higher accuracy while the control configuration is complicated.

1 is a schematic front view of an image recording apparatus according to an embodiment. It is a schematic side view of a printer unit. FIG. 3 is a schematic front view of a first recording unit disposed to face a first drum. It is a control block diagram of an image recording apparatus. It is a control block diagram of a 1st conversion part. It is a control block diagram of a comparison judgment part. FIG. 10 is a diagram illustrating output of each unit when a recording medium conveyance abnormality is detected. It is a control block diagram of the 1st conversion part in a modification. It is a control block diagram of the comparison judgment part in a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image recording apparatus 2 Winder part 3 Printer part 4 Rewinder part 5 Recording medium 6 Unwinder part stand 7 Paper tube fixing shaft 8 Unwinding drive motor 9 Arrow 10 which shows conveyance direction Rewinder stand 11 Paper tube fixing shaft 12 For winding Drive motor 13 Arrow 14 indicating transport direction Free roller 15 Free roller 16 First dancer roller 16a Rotation center 16b Arm 16C Potentiometers 17, 18, 19, 20, 21, 22 Free roller 23 Second dancer roller 23a Rotation center 23b Arm 23C Potentiometer 24 Free roller 25 Body frame 30 Carrier (first drum)
30a Rotating shaft 32 Position information generator (first encoder)
33 Coupling 34 Encoder fixing member 40 Carrier (second drum)
40a Rotating shaft 41 Drive motor 42 Position information generator (second encoder)
43 Coupling 44 Encoder fixing member 50 First recording portion 5la, 51b, 51C, 51d Print head 52a, 52b, 52C, 52d Head holding plate 53 Head holding member 55 Second recording portion 56 First maintenance unit 57 Second maintenance Unit 60 control unit 61 arithmetic processing unit (CPU)
62 Host device IF
63 Storage Unit 64 Conveyance Monitoring Unit 65 Host Device 66 Drive Signal Generation Unit 67 Comparison Determination Unit 68 (68A, 68B) First Conversion Unit 69 (69A, 69B) Second Conversion Unit 70 Phase Lock Loop Control Unit (PLL Unit)
71 Correction coefficient setting unit 72 FV conversion unit 73 (73A, 73B) First comparator 74 (74A, 74B) Second comparator 75 First counter 76 Second counter

Claims (9)

A plurality of carriers supported on the outer peripheral surface of the recording medium and arranged to be interlocked via the recording medium, a drive motor for driving one of the plurality of carriers, and the plurality of carriers, respectively In an image recording apparatus having a recording unit arranged to face and record to the recording medium,
A plurality of position information generating units provided for each of the plurality of carriers and generating rotational position information of the plurality of carriers;
An image recording comprising: a conveyance monitoring unit that determines a conveyance abnormality of the recording medium based on a plurality of position signals from the plurality of position information generation units and a drive signal for driving the drive motor. apparatus. A control unit;
The image recording apparatus according to claim 1, wherein the control unit includes the conveyance monitoring unit as a signal processing circuit controlled by an arithmetic processing device of the control unit.   The image recording apparatus according to claim 1, wherein the conveyance monitoring unit includes a conversion unit for converting a position signal generated by the position information generation unit.   The image recording apparatus according to claim 3, wherein the conversion unit includes a correction coefficient setting unit and a phase lock loop control unit.   The conveyance monitoring unit compares the drive signal, a position signal generated by generating the position information of one of the carriers, and a position signal generated by generating the position information of the other carrier. The image recording apparatus according to claim 1, further comprising a comparison / determination unit for determining a result.   The image recording apparatus according to claim 5, wherein the comparison determination unit determines that the conveyance abnormality has occurred when a value obtained as a result of the comparison exceeds a predetermined threshold value set in advance.   The image recording apparatus according to claim 5, wherein the conveyance abnormality determined by the comparison determination unit includes an abnormality in which the recording medium is conveyed while sliding on an outer peripheral surface of the plurality of carriers. . A plurality of carriers supported on the outer peripheral surface of the recording medium and arranged to be interlocked via the recording medium, a drive motor for driving one of the plurality of carriers, and the plurality of carriers, respectively A recording unit that performs recording on the recording medium that is disposed opposite to the recording medium, and a method for detecting an abnormality in conveyance of the recording medium by an image recording apparatus,
Generate rotational position information for each of the plurality of carriers,
Comparing a plurality of rotational position signals in the generated rotational position information for each of the plurality of carriers with a drive signal for driving the drive motor;
A conveyance abnormality detection method, comprising: detecting conveyance abnormality of the recording medium based on a result of comparing the comparison result with a predetermined threshold value. A plurality of carriers supported on the outer peripheral surface of the recording medium and arranged to be interlocked via the recording medium, a drive motor for driving one of the plurality of carriers, and the plurality of carriers, respectively A program for causing an arithmetic processing unit to control conveyance abnormality detection of the recording medium by an image recording apparatus having a recording unit configured to record the recording medium opposed to the recording medium,
A process for causing the position information generator to generate rotational position information for each of the plurality of carriers;
A process of comparing a plurality of rotational position signals in the generated rotational position information for each of the plurality of carriers with a drive signal for driving the drive motor;
A process of detecting a conveyance abnormality of the recording medium based on a result of comparing the comparison result with the read predetermined threshold;
A program for causing the arithmetic processing unit to perform the following.