JP4974787B2 - Recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the misregistration of recording due to the eccentricity of a conveyance roller in recording equipment using belt conveyance and rolled paper conveyance. <P>SOLUTION: In the recording equipment which performs recording by using an encoder means attached to the conveyance roller, recording is controlled by using speed information on a conveyance belt acquired by a sensing means of a laser-Doppler system and speed information on the conveyance roller acquired by the encoder means. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a recording apparatus that performs recording on a recording medium and a control method for the recording apparatus, and relates to control of conveyance of the recording medium and control of recording means.

  In recent years, recording devices have been improved in the quality of recorded images and the speed of image recording. In the conveyance system of the recording apparatus, for example, an optical rotary encoder is provided in the conveyance system, and conveyance control is performed using a signal from the rotary encoder. As conveyance control, control of the conveyance amount by a conveyance roller and control of conveyance speed are performed (patent document 1).

  In order to eliminate the uneven speed of the transfer belt, a scale is provided on the transfer belt, the speed of the transfer belt is measured using an optical sensor that detects the scale, and the speed of the motor that drives the belt is determined by the measured speed. (Patent Document 2).

<Recording device using a rotary encoder>
FIG. 2 shows an example of a conventional recording apparatus. Reference numeral 1 denotes a recording head, which is arranged in the transport direction. Reference numeral 2 denotes a recording medium for recording, and reference numeral 3 denotes a conveyance belt for conveying the recording medium 2. Reference numeral 4 denotes a transport roller for rotating the transport belt 3, and reference numeral 5 denotes two follower rollers that support the transport belt 3. Reference numeral 6 denotes a transport roller shaft integrated with the transport roller 4, and reference numeral 7 denotes a transport motor that drives the transport roller shaft 6. Reference numeral 8 denotes a rotary encoder provided on the transport roller shaft 6.

  Reference numeral 101 denotes a head drive control unit that controls the drive timing of the recording head 1 in accordance with the conveyance timing of the recording medium 2. A motor drive unit 102 controls the rotation of the transport motor 7. Reference numeral 201 denotes a rotation pulse signal output from the rotary encoder. A periodic pulse signal is output from the rotary encoder according to the rotation of the transport roller. Reference numeral 202 denotes a recording timing reference signal. Reference numeral 103 denotes recording timing generation means for generating a recording timing reference signal 202 from the rotation pulse signal 201.

  When recording on the recording medium 2, the conveyance motor 7 is driven so as to circulate the conveyance belt 3 at a constant speed, and then the recording head 1 is driven to perform recording.

  FIG. 3A is a view of the conveyor belt 3 as viewed from above. In order to simplify the description, the case of one recording head 1 will be described. A state where an image A is recorded on the recording medium 2 is shown. The number of dots that can be recorded on the recording medium is 12 dots in the transport direction and 9 dots in the direction perpendicular to the transport direction (hereinafter referred to as the transport width direction). The leftmost vertical dot row in the transport direction is called “1st LINE”, and the second dot row from the left is called “2nd LINE”. The rightmost dot row is called “12th LINE”. Numbers 1 to 9 on the recording head 1 indicate nozzle positions.

  FIG. 3B is a diagram illustrating the recording timing reference signal 202 input to the head driving control unit 101 and the driving timing of the recording head 1. It is a figure explaining the recording timing of "7th LINE" and "8th LINE".

  Control is performed to drive the recording head at the timing when the time Δt corresponding to the movement amount of the recording medium ΔX has elapsed.

For example, when the conveyance speed is 300 mm / s and the recording resolution in the conveyance direction is 2400 dpi,
Δt = 35.28 μs ((25.4 mm ÷ 2400 dpi) ÷ 300 mm / s)
It becomes.

  In the timing chart of FIG. 3B, for example, 2 to 9 are driven for “7th LINE”.

  Actually, a plurality of recording heads are arranged in the transport direction in the recording apparatus, and the drive timing is adjusted according to the distance of the heads.

  This drive timing control configuration will be described with reference to FIG.

  4A is a block diagram of the timing generation means 11, and FIG. 4B is a timing chart. The rotation pulse signal 201 has a carrier resolution of 300 dpi, and the carrier reference signal has a carrier resolution of 1200 dpi.

  In FIG. 4, reference numeral 161 denotes a rise detection unit that detects that the rotation pulse signal 201 has changed from “0 (low level)” to “1 (high level)”. Reference numeral 261 denotes the rising edge detection signal. Reference numeral 162 denotes a counter unit that counts intervals at which the rising detection signal 261 is input. Reference numeral 262 denotes a count value that is a result of counting by the counter unit 162.

  Reference numeral 163 denotes a pulse width value holding unit that holds the count value 262. Reference numeral 164 denotes a carrier reference signal pulse period calculation unit that calculates a value obtained by multiplying the pulse width value 263 by ¼.

  Reference numeral 264 denotes a conveyance reference period value calculated by the conveyance reference signal pulse period calculation unit 164. Reference numeral 165 denotes a conveyance reference signal generation unit that generates a pulse signal according to the conveyance reference period value 264.

  When the rotation pulse signal 201 changes from “0” to “1”, a pulse is output to the rising signal 261 from the rising detector 161. In response to this pulse, the count unit 162 resets the count value 262 to 0, and then counts up using a clock signal such as the system clock of this system that is always operating stably. Next, when the rotation pulse signal 201 changes from “0” to “1” and a pulse is generated as the rising signal 261, the count value 262 of the count unit 162 at this time is held in the pulse width value holding unit 163. The As an example of the value held at this time, the number of clocks used in the counter unit is used. The count value 262 of the count unit 162 is held, and at the same time, the count value is returned to 0 and the next pulse is counted. The held value is immediately multiplied by 1/4 by the carrier reference signal pulse period calculation unit 164 with the pulse width value 263, and is output to the carrier reference signal generation unit 165 as the carrier reference period value 264. The transport reference signal generation unit 165 generates the transport reference signal 202 by using the clock signal used in the counting unit 162 and outputting a pulse for each transport reference cycle value 264. By repeating this, a transport reference signal 202 with a transport resolution of 1200 dpi is generated from the rotation pulse signal 201 with a transport resolution of 300 dpi.

  As described above, image formation is performed according to the rotation pulse signal 201 of the rotary encoder 8.

<Recording device using laser Doppler sensor>
FIG. 5 shows an example of another conventional recording apparatus. This is a recording apparatus using a laser Doppler type sensor (laser Doppler type speed sensor) 9. The amount of movement of the conveyor belt is detected using a laser Doppler sensor 9.

  2 is different from FIG. 2 in that a laser Doppler sensor 9 is used instead of the rotary encoder 8. The other configuration is the same as that shown in FIG.

<Description of laser Doppler sensor>
FIG. 6 briefly explains the principle of the laser Doppler sensor.

  Laser light LA is emitted from the laser light source 0301. The emitted laser light LA is divided into two at the beam splitter 0302. One of the bisected laser beams L1 passes through the beam splitter 0302 and is directly irradiated onto the object to be measured 0310. On the other hand, the other divided laser beam L2 is reflected by the beam splitter 0302, and further reflected by the reflecting mirror 0303 and irradiated on the object to be measured 0310. As shown in FIG. 6, the laser beams L <b> 1 and L <b> 2 are incident on the perpendicular of the object to be measured 0310 at an incident angle θ, and irradiate the object to be measured 0310 in a symmetric orbit.

  When the laser beams L1 and L2 are incident on the object to be measured 0310 moving at a certain speed V, the object to be measured 0310 scatters the laser beams L1 and L2 and emits scattered light LB. The scattered light LB passes through the optical system such as the condenser lens 0304 and reaches the light receiving sensor 0305. The light receiving sensor 0305 detects the scattered light LB and performs photoelectric conversion. This converted electric signal is input to the amplifier 0306. The amplifier 0306 amplifies the amplitude of the electric signal and outputs it to the band pass filter 0307. The bandpass filter performs heterodyne detection and outputs a Doppler signal D that is an analog signal to the signal processing circuit 0308.

In the signal processing circuit 0308, Doppler signal D to the above frequency and f _D, also the frequency converted to a pulse signal to f _D, and outputs the pulse signal as a speed signal.

The period T of this pulse signal indicates the time for the device under test 0310 to travel a certain distance L. In this way, the laser Doppler sensor 0300 can output a pulse signal that can detect a precise displacement in real time as a velocity signal without providing a scale on the object to be measured (Patent Document 3).
JP 2002-128313 A JP 2004-287337 A JP 2004-088416 A

  In the control using the rotary encoder as described above, for example, it has been impossible to cope with the speed fluctuation of the transport belt caused by the eccentricity of the transport roller 4. Similarly, when the thickness of the transport belt 3 is uneven, it was not possible to cope with the speed fluctuation of the transport belt.

  FIG. 7 is a cross-sectional view of the roller for explaining the eccentricity of the conveying roller. Reference numeral 400 denotes the center of the rotating shaft, 401 denotes the center of the transport roller 4, r denotes the transport roller radius, and Δr denotes the amount of eccentricity.

  For example, if the conveyance roller 4 having a radius r of 8 mm and an eccentricity amount Δr of 5 μm is rotated at constant speeds so that the apex speed is 100 mm / S, the conveyance roller radius increases or decreases by the amount of the eccentricity Δr. The speed varies as 100 ± 0.0625 mm / s.

  FIG. 8 shows the dot position deviation when an image is formed by the recording apparatus having the configuration shown in FIG. 2 under such conditions. The position deviation in the transport direction when dots are recorded at intervals of 486.8 μm is shown in FIG. The axis represents the position on the recording medium, and the vertical axis represents the amount of positional deviation. As can be seen from FIG. 8, the positional deviation periodically fluctuates at a cycle of about 50.3 mm. This 50.3 mm coincides with the circumferential length L = 2 * π * r = 2 * 8 mm * π = 50.27 mm obtained from the radius r = 8 mm of the conveying roller. As described above, the eccentricity of the conveyance roller greatly affects the image deterioration among the fluctuation factors from the conveyance roller shaft to the recording medium that cannot be controlled by the configuration of FIG.

  As described in the background art section, there is a method in which a scale is provided on the transfer belt and the speed of the transfer belt is measured using an optical sensor that detects the scale. However, when the transport belt is soiled by minute ink droplets or paper dust called mist, the moving speed of the transport belt cannot be read accurately.

  The laser Doppler type speed sensor 9 can directly measure the speed of the conveyor belt, but has the following drawbacks.

  During the operation of the laser Doppler speed sensor 9, there is a period (timing) in which the Doppler signal is weak for some reason, and there is a problem that the speed cannot be measured accurately during that period.

  FIG. 9 shows a pulse waveform output from the laser Doppler type speed sensor 9. In this waveform, 200 μsec to 800 μsec is a period in which the Doppler signal becomes weak, and is called dropout. During the period when the Doppler signal is weak, the moving speed of the conveyor belt cannot be accurately detected.

  An object of the present invention is to provide a highly accurate conveyance control method and recording control method that suppresses the influence of eccentricity of the conveyance roller and is not affected by dirt in the apparatus, in order to solve the above problems. It is in.

  In order to achieve the above object, the present invention is characterized by the following.

  According to one aspect of the recording apparatus of the present invention, an ink jet recording head, a conveying means including a roller for conveying the recording medium, and a surface of the recording medium are detected, so that the recording medium is moved according to the moving speed of the recording medium. Generated by a laser Doppler sensor that generates a first signal that is a pulse signal that changes in pulse period, an encoder that generates a second signal that is a pulse signal according to the rotation of the roller, and the laser Doppler sensor A correction means for correcting the first signal when the pulse period of the first signal exceeds a predetermined range; and a component of a pulse period of the first signal that has passed through the correction means, wherein Acquisition means for acquiring periodic fluctuation information with one period of rotation, and control of recording on the recording medium by the second signal generated by the encoder When performing, characterized in that it comprises a control means to be reflected in the control of the recording the variation information so as to suppress the influence of the moving speed fluctuation of the recording medium due to the eccentricity of the roller.

  Another embodiment of the recording apparatus of the present invention includes a plurality of inkjet recording heads arranged from upstream to downstream in the conveyance direction of the roll-shaped recording medium, and an upstream side of the plurality of recording heads. A first roller for transporting the medium in the transport direction and a recording medium that is disposed downstream of the plurality of recording heads and holds the recording medium than the first roller for transporting the recording medium in the transport direction A second roller having a low pressure and a rotation speed larger than that of the first roller; a laser Doppler sensor for generating a first signal corresponding to the movement of the recording medium by detecting the surface of the recording medium; An encoder for generating a second signal corresponding to the rotation of the first roller, and the influence of eccentricity of the first roller is suppressed based on the first signal and the second signal. Characterized in that it comprises a control means for controlling recording on the sea urchin the recording medium.

  According to the present invention, even if the conveyance means such as the conveyance belt becomes dirty, the drive control of the conveyance means can be performed without being affected by the contamination, and image deterioration due to conveyance fluctuation can be suppressed.

  Next, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a configuration diagram of the first embodiment. The recording apparatus has a configuration in which a plurality of recording heads 1 are arranged in the recording medium conveyance direction. A plurality of nozzles are arranged in the recording head 1, and the arrangement direction is a direction that intersects the conveyance direction of the recording medium.

  A control configuration that feeds back conveyance fluctuations to image formation will be described for a recording apparatus that includes four inkjet recording heads 1 that perform recording while conveying a recording medium with a conveyance belt.

  1 are the same as those in FIG. 2 and FIG. In the following description, the rotary encoder 8 is referred to as a rotation detection sensor.

  When the conveyance motor 7 is rotated at a constant speed to record an image and the conveyance belt 3 is rotated (circulated), the rotation pulse signal 201 and the movement pulse signal 203 are input to the timing generation unit 11.

  The rotation pulse signal 201 is a signal output from a rotary encoder (encoder sensor) attached to the conveyance roller shaft 6 in order to detect the rotation of the conveyance roller 4. The movement pulse signal 203 is a signal output from the laser Doppler type speed sensor (movement amount detection sensor) 9.

  Among them, the rotation pulse signal 201 is used as a reference signal when generating a conveyance reference signal 202 that is movement information of the conveyance belt 3. The rotation pulse signal 201 includes speed fluctuations that occur during transmission from the transport motor 7 to the transport roller shaft 6. However, it does not include speed fluctuations such as the conveyance roller eccentricity that occurs during transmission from the conveyance roller shaft 6 to the conveyance belt 3.

  For this reason, if the transport reference signal 202 is generated as it is, transport unevenness due to transport roller eccentricity or the like occurs in the image formed by the head drive control unit 101 in accordance with the transport reference signal 202.

  Therefore, speed fluctuation information due to the conveyance roller eccentricity is extracted from the movement pulse signal 203 which is one piece of information input by the timing generation means, and this speed fluctuation information is corrected when the conveyance reference signal 202 is generated from the rotation pulse signal 201. By this correction, a transport reference signal 202 including speed fluctuations such as transport roller eccentricity can be generated. By performing the image formation timing control by the head drive control unit 101 in accordance with the conveyance reference signal 202, image formation without the influence of the speed fluctuation such as the conveyance roller eccentricity is performed.

<Outline of Processing of Timing Generation Unit 11>
FIG. 10 is a block diagram of the timing generation means 11 shown in FIG. An outline of the processing of the timing generation unit 11 will be described with reference to FIG.

  The signal generation unit 113 receives the information 220 and the information 221 and generates the timing signal 202.

  Information indicating a cycle variation by a first signal correction unit 153 that receives information (pulse signal) 203 and a first signal variation detection unit 154 that receives the output of the first signal correction unit 153 and information (pulse signal) 201. 220 is generated. The second signal period detection unit 112 receives the information 201 and outputs the period information 221.

  The first signal correction unit 153 determines whether the signal 203 is normal. When the state of the information 203 is normal, the information 203 is output to the first signal fluctuation detection unit 154. When the state of the information 203 is not normal, alternative information is output to the first signal fluctuation detection unit 154.

  Thereby, for example, the timing signal 220 obtained by correcting the period of the rotation pulse signal 201 affected by the eccentricity of the roller can be output regardless of the state of the laser Doppler speed sensor. This is because the pulse of the movement pulse signal 203 may be suddenly lost. In this case, the first signal correction unit 153 always checks whether or not the pulse signal 203 from the movement detection sensor 9 is missing, and performs complement processing for the missing portion in the signal.

The first signal fluctuation detection unit 154 generates periodic fluctuation information based on the information (signal) 214 output from the first signal correction unit 153 and outputs the periodic fluctuation information to the reference signal generation unit 113.

If the period of the first signal period variation information 220 is f1, the period of the second signal period information 221 is f2, and the period of the timing signal 202 is fout,
It can be obtained by fout = f2 + Σf1 (n = 1 to m).

  Here, m = the number of pulses of the movement pulse signal during the period per rotation of the conveyance roller / the number of pulses of the rotation pulse signal per rotation of the conveyance roller.

  Here, as will be described later, since f1 is a difference value with respect to the reference period, it is a negative value or a positive value.

<Description of Timing Generation Unit 11 (FIG. 10)>
The first signal correction unit 153 in FIG. 10 will be described.

  Reference numeral 101 denotes a first signal period detector that detects pulse period information of the moving pulse signal 203. The first signal cycle detection unit 101 includes a counter that counts cycle information and a latch that holds the value of the counter.

  The latched value is output to the first signal period determination unit 102 and the first signal period correction unit 104 as the first signal period information 210.

  On the other hand, the value counted by the counter of the first signal period detection unit 101 is output to the first signal period determination unit 102 as the first signal period count signal 218.

  Reference numeral 212 denotes first signal cycle determination result information indicating a result determined by the first signal cycle determination unit 102.

  103 is a first signal cycle determination reference storage unit that stores a determination reference value for determination by the first signal cycle determination unit 102, and 211 is first signal cycle determination reference information (reference value) of the determination reference value. .

  Reference numeral 104 denotes a first signal period correction unit that outputs the first signal period information 210 to the first signal fluctuation detection unit 154 if the determination result is determined to be normal, and replaces it with a correction value if the determination result is determined to be abnormal. It outputs to the 1st signal fluctuation | variation detection part 154.

  Reference numeral 214 denotes first signal cycle information output from the first signal cycle correction unit. Reference numeral 105 denotes a first signal cycle correction value storage unit that stores information (correction value) used by the first signal cycle correction unit 104 for correction. Reference numeral 213 denotes first signal cycle correction information that is the correction value.

  Next, the first signal fluctuation detection unit 154 in FIG. 10 will be described. Reference numeral 106 denotes a first signal period average value calculation unit that calculates an average value of the first signal period information 214, and reference numeral 217 denotes a first signal period average value calculation signal as a calculation result. The first signal period average value calculation unit 106 calculates an average value for the period T (for one round of the conveying roller) in the first signal period information 214. This average value is B1 (24.9 μS) in FIG. This average value is stored in the first signal period average value storage unit 110. This average value is stored in the first signal cycle average value storage unit 110 every time the conveying roller makes one round.

  A roller origin generation unit 107 counts the number of rotation pulses from the rotation detection sensor 8 and indicates a reference position for one rotation of the roller. Reference numeral 215 denotes a generated roller origin signal.

  Reference numeral 219 denotes first signal cycle average value information (signal) read from the first signal cycle average value storage unit 110. Reference numeral 111 denotes a first signal period variation detector. In the first signal cycle fluctuation detecting unit 111, the pulse cycle of the transport roller includes a high frequency component as shown in FIG. For this reason, an average value is calculated for each period ΔT. As shown in FIG. 11, C1 and C2 are average values.

  The first signal period variation detector 111 acquires the difference between C2 and B1 for each ΔT. This result (difference value) is the first signal period variation information 220 and is output to the signal generation unit 113.

  For example, C2> B1 indicates that the pulse period is larger than the average and the moving speed is slower than the average speed. Further, C2 <B1 indicates that the pulse period is smaller than the average and the moving speed is faster than the average speed. Information on such period unevenness (speed unevenness) is sent to the signal generation unit 113.

  As described above, it is possible to generate information (variation information) on the periodic unevenness (speed unevenness of the conveying roller) of the rotation pulse signal from the periodic information of the moving pulse signal 203.

  FIG. 14 is an explanatory diagram of the timing at which the first signal cycle average value calculation signal 217 is stored. The first signal cycle average value calculation unit 106 adds the first signal cycle average value calculation signal 217 at the “Nth rotation” of the transport roller. At the start of the next N + 1 rotation, an average value B1 is calculated from the addition result A1, and this value is stored in the first cycle average value storage unit 110. Similarly, the first signal cycle average value calculation signal 217 is added at the “N + 1th rotation” of the transport roller, and the average value B2) is calculated from the addition result A2 at the start of the next N + 2 rotation. Thereafter, the same processing is performed.

  The timing generation unit 11 includes the following blocks in addition to the first signal correction unit 153 and the first signal fluctuation detection unit 154. Reference numeral 112 denotes a second signal period detector that detects the pulse period information (second signal period information signal) 221 of the rotation pulse signal 201. Reference numeral 113 denotes a transport reference signal generator. The carrier reference signal generation unit 221 generates information 202 from the second signal period information 221 using the first signal period variation information 220.

<Pulse signal interpolation processing>
Next, the interpolation processing of the moving pulse signal 203 in the first signal correction unit 153 will be described. The first signal correction unit 153 determines that an abnormality occurs when the period of the moving pulse signal 203 exceeds the range between the upper limit value and the lower limit value, and performs correction when there is an abnormality.

  The missing pulse is detected by the upper limit value, and a short cycle due to a failure or the like is also detected by the lower limit value.

  The moving pulse signal 203 input from the movement detecting sensor 9 is counted by the first signal period detecting unit 101 using a clock signal such as a system clock.

  The first signal period information signal 210 in which the detected pulse period is stored has information on the upper limit value and the lower limit value stored in the first signal period determination reference storage unit 103 by the first signal period determination unit 102. Comparison with the first signal cycle determination reference value signal 211 is performed. That is, the detected pulse period is compared with the upper limit value and lower limit value of the period.

  In this comparison process, if it is within the range between the upper limit value and the lower limit value, it is determined as normal, and if it is out of the range, it is determined as abnormal. Note that the determination reference values (upper limit value and lower limit value) used for the determination are stored in advance in the first signal determination reference storage unit.

  In addition, when the lack of a pulse signal is detected, it is not reflected in the 1st signal period information signal 210 until a pulse is input. For this reason, the first signal cycle count signal 218, which is a counter output counted up by the first signal cycle detection unit 101, is compared with the upper limit value to determine whether the first signal cycle count signal 218 is abnormal. .

  If the result of determination on the first signal cycle count signal 218 is abnormal, the first signal cycle correction unit 104 replaces the correction value stored in the first signal cycle correction storage unit 105. The signal is complemented by this correction value.

  FIG. 12 is a timing chart of the first signal correction unit 153 described above. The rising signal is a signal indicating the rising edge of the moving pulse signal in the first signal period detection unit 101. FIG. 12 shows an example in which the pulse width of only pulse # 3 exceeds the upper limit value among the five pulses from pulse 1 to pulse 5. The internal counter starts counting from 0 from the leading edge of normal pulse # 1. This counter value is a first signal period count signal. The counter value “t1” at the rise of the pulse # 2 is latched and output to the first signal period information signal 210 during the period of the pulse # 2, and at the same time, the counter returns to 0 to count the period of the pulse # 2. start. During the period of the pulse # 2, the first signal cycle information 210 is within the range between the upper limit value and the lower limit value, and the value being counted by the first cycle count signal 218 does not exceed the upper limit value. The period information is determined to be normal, and normality is output to the first period determination result signal 212. In this embodiment, when normal, a “Low” level signal is output.

  The first signal period correction unit 104 that has received the determination result outputs the normal period information “t1” of the first signal period information signal 210 to the corrected first signal period information signal 214 because the determination result is normal. Similarly, since the period “t2” of the latched pulse # 2 is normal at the rising edge of the pulse # 3, “t2” is output to the corrected first signal period information signal 214.

  However, during the period of pulse # 3, it is determined that there is an abnormality when the first signal period count signal, which is the value of the counter that counts the period of pulse # 3, exceeds the upper limit value. It outputs to the period determination result signal 212. In the present embodiment, a “High” level signal is output when there is an abnormality.

  Since the determination result is abnormal in the first signal cycle correction unit 104 that has received this determination result, the first signal cycle correction value signal 213 “tc” stored in the first signal cycle correction value storage unit 105 is corrected. The first signal period information signal 214 is output.

  The period information “t3” of the pulse # 3 latched at the rising edge of the pulse # 4 exceeds the upper limit value of the first signal period information signal 210, so the period of the pulse # 4 is also processed as abnormal. Since the period information “t4” of the pulse # 4 is latched at the rising edge of the pulse # 5, it is normal and the process is performed as normal. In this way, correction processing is performed when the pulse period of the moving pulse signal 203 exceeds the specified range.

<Description of moving pulse signal (FIG. 13)>
FIG. 13 is a diagram for explaining the waveform of the moving pulse signal 203 and the upper limit value and the lower limit value for detecting an abnormality. The waveform of the moving pulse signal 203 is a waveform in which long-period fluctuation and short-period fluctuation are combined. As shown in FIG. 13A, the long cycle fluctuation is the same cycle as one rotation of the transport roller.

  The waveform of the moving pulse signal 203 fluctuates around 24.9 μS, the maximum value is 25.5 μS, and the minimum value is 24.3 μS. Based on such waveform values, an upper limit value and a lower limit value are obtained. An upper limit value is determined based on the maximum value, and is set to 25.9 μS, for example. Similarly, a lower limit value is determined based on the minimum value and set to 24.1 μS. After setting such an upper limit value and lower limit value, the pulse period is determined using the set values.

  As shown in FIG. 13B, the waveform of the moving pulse signal 203 changes with time. For example, during the period from time t1 to time t3, the center value of the waveform of the moving pulse signal 203 was 24.9 μS. However, during the period from time t4 to t6, the center value of the waveform of the moving pulse signal 203 was 25.1 μS.

  For this reason, you may perform control which investigates the waveform of movement pulse signal 203 regularly.

  Note that the preset upper limit value, lower limit value, and correction value may be determined from design values, or may be determined from measured values when operating in advance.

(Second Embodiment)
<Description of First Signal Correction Unit of Timing Generation Unit 11 (FIG. 15)>
FIG. 15 will be described. The first signal correction unit 153 of the timing generation unit 11 of the second embodiment is the same as the first signal correction unit of FIG. The difference is that the first signal period information signal 210 is input to the first signal period determination reference storage unit 103 and the first signal period correction value storage unit 105. Initialization processing (when power is turned on) of the recording apparatus is performed, a predetermined transport operation is performed, and data is stored in the first signal cycle determination reference storage unit 103 and the first signal cycle correction value storage unit 105.

  Specifically, an average value of the first signal period information signal 210 is calculated, and a value obtained by adding a certain ratio (for example, 5%) to the average value of the first signal period information signal 210 is an upper limit value for determination ( Threshold). A value obtained by subtracting a certain ratio (for example, 5%) from the average value of the first signal period information signal 210 is defined as a lower limit value (threshold value). Further, the average value of the first signal cycle information signal 210 is stored as a correction value.

  The ratio value is an example, and other values may be used. Moreover, when calculating | requiring an upper limit and a lower limit, you may change a ratio. For example, the upper limit value is obtained by adding 7% to the average value, and the lower limit value is obtained by subtracting 3% from the average value.

  Note that the recording apparatus applied to the second embodiment is the recording apparatus shown in FIG. 1 described in the first embodiment.

(Third embodiment)
<Description of First Signal Correction Unit of Timing Generation Unit 11 (FIG. 16)>
FIG. 16 will be described. The first signal correction unit is the same as the first signal correction unit in FIG. The difference is that the corrected first signal cycle information signal 214 is input to the first signal cycle determination reference storage unit 103 and the first signal cycle correction value storage unit 105. The difference from FIG. 15 is a block diagram when the corrected first signal period information signal 214 is used in place of the first signal period information signal 210 as a signal for storing.

  In the case of FIG. 15, the determination reference value and the correction value are generated from the average value including the information at the time of abnormality, whereas in the block diagram of FIG. 16, the information at the time of abnormality is determined by the already stored determination reference value and correction value. Is corrected, a more accurate determination reference value and correction value can be obtained.

  Note that the recording apparatus applied to the third embodiment is the recording apparatus shown in FIG. 1 described in the first embodiment.

(Fourth embodiment)
<Description of First Signal Correction Unit of Timing Generation Unit 11 (FIG. 17)>
Description of the same parts as those in FIG. 10 is omitted. In FIG. 17, there are two points different from the first embodiment and the second embodiment. One is that the roller origin signal 215 is input to the first signal cycle determination reference storage unit 103 and the first signal cycle correction value storage unit 105. Another difference is that only the first signal period variation information signal 220 is input to the signal generation unit 113. That is, there is no second signal period detector in FIG.

<Description of First Signal Fluctuation Detection Unit (FIG. 17)>
Next, the first signal fluctuation detection unit 154 will be described with reference to FIG.

  In the first signal fluctuation detection unit 154, the determination process and the correction process for determining whether the moving pulse signal 203 is normal are the same as those in the above-described embodiment.

  The difference is that the determination reference value (upper limit value and lower limit value) and correction value used for determination are updated after a certain period of time. For example, the determination reference value (upper limit value and lower limit value) and the correction value are updated every rotation of the transport roller.

  The value used for the update is acquired from the movement pulse signal 203 measured in the period of one rotation of the conveyance roller before the update timing (for example, immediately before). For example, it is obtained from the average value of the pulse period of the moving pulse signal 203.

  This is performed every time the roller origin signal 215 is input as the update timing. FIG. 18 shows the timing. For example, it is updated at timings t1, t9, and t17. At the timing of t9 when the roller origin signal 215 is input, the upper limit value and the lower limit value are obtained using the average value of the first signal period information signal 210 between t1 and t8. Then, the upper limit value, lower limit value, and average value are stored as correction values. Since the calculation of the upper limit value and the lower limit value has already been described, the description thereof will be omitted.

  Note that the recording apparatus applied to the fourth embodiment is the recording apparatus shown in FIG. 1 described in the first embodiment.

(Fifth embodiment)
<Description of First Signal Correction Unit (FIG. 19)>
FIG. 19 will be described. The first signal correction unit in FIG. 19 is the same as the first signal correction unit in FIG. The difference is that the corrected first signal cycle information signal 214 is input to the first signal cycle determination reference storage unit 103 and the first signal cycle correction value storage unit 105.

  In the case of FIG. 17, the determination reference value and the correction value are generated from the average value including the information at the time of abnormality, whereas in the block diagram of FIG. 19, information at the time of abnormality is determined by the already stored determination reference value and correction value. Is corrected, a more accurate determination reference value and correction value can be obtained.

  Note that the recording apparatus applied to the fifth embodiment is the recording apparatus shown in FIG. 1 described in the first embodiment.

(Sixth embodiment)
FIG. 20 is a block diagram of the timing generation means 11 in the case of generating a period for updating from the rotation pulse signal 201. Description of symbols that function in common with FIG. 10 is omitted.

  In FIG. 20, reference numeral 114 denotes a first signal period correction value storage control unit that generates a period for storing the determination reference value and the correction value from the rotation pulse signal 201. Reference numeral 222 denotes a generated first signal storage update signal. A first signal period average value calculation control unit 108 generates a period for updating the average value of the first signal period information for extracting the carrier fluctuation from the rotation pulse signal 201. Reference numeral 216 denotes a generated first signal average value update signal. The first signal period average value calculation unit 106 generates the first signal period average value calculation signal 217 from the value of the corrected first signal period information signal 214 for a plurality of consecutive update periods.

  For example, when the number of pulses of the rotation pulse signal 201 for one rotation of the conveying roller is 600 pulses and updating is performed 30 times during the period, the first signal storage update signal 222 is updated every 20 pulses obtained by dividing 600 pulses by 30 times. Is generated.

  As shown in FIG. 21, the upper limit value and the lower limit value change with time. Thereby, for example, an abnormal value such as time t3 or t4 can be detected.

(Description of processing of first signal fluctuation detection unit in FIG. 20)
FIG. 22 is a timing chart in the case where one rotation of the conveying roller is divided into eight sections and the average value of the past eight sections is updated at the boundary times t1 to t17 of each section. For example, the average value updated at time t12 is the average value of 8 sections from time t4 to t12, and the average value updated at time t13 is the average value of 8 sections from time t5 to t13. The average value used for extraction of the period variation at time ta is the average value of eight sections from time t4 to t12. The average value used for extracting the period fluctuation at time tb is the average value of 8 sections from time t5 to time t13. Thus, by providing the number of periods shorter than the time required for one rotation and increasing the number of times of updating during one rotation of the conveying roller, the latest average value of one rotation of the conveying roller can be used.

  In the present embodiment, an update signal indicating the boundary of each section is generated from the rotation pulse signal 201. The update signal is generated by the first signal period average value calculation control unit 108 in the block diagram of FIG. 20, and the generated update signal is the first signal average value update signal 216. For example, when the rotation pulse signal 201 is 600 pulses by one rotation of the transport roller and the rotation pulse signal 201 is to be updated eight times by one rotation, the first signal average value update signal 216 is output every 75 pulses.

  The period fluctuation of the moving pulse signal 203 is extracted using the average value of the period of the moving pulse signal 203 thus obtained. This process is performed by the first cycle variation detection unit 111, but since it is the same as FIG. 10 of the first embodiment, the description thereof is omitted.

  Note that the recording apparatus applied to the sixth embodiment is the recording apparatus shown in FIG. 1 described in the first embodiment.

  As a modification of FIG. 20, a signal input by the first signal period correction value storage control unit 114 or the first signal period average value calculation control unit 108 is an internally generated clock instead of the rotation pulse signal 201. It does not matter as a signal.

(Seventh embodiment)
The block diagram of FIG. 23 is a block diagram in the case where the corrected first signal period information signal 214 is used instead of the first signal period information signal 210 as a signal for performing storage in comparison with the block diagram of FIG. is there. In the case of FIG. 20, the determination reference value and the correction value are generated from the average value including the information at the time of abnormality, whereas in FIG. 23, the information at the time of abnormality is corrected by the already stored determination reference value and correction value. Therefore, more accurate determination reference values and correction values can be obtained.

  Note that the recording apparatus applied to the seventh embodiment is the recording apparatus shown in FIG. 1 described in the first embodiment.

  As a modification of FIG. 23, a signal input by the first signal cycle correction value storage control unit 114 or the first signal cycle average value calculation control unit 108 is an internally generated clock instead of the rotation pulse signal 201. It does not matter as a signal.

(Common Embodiment for Recording Apparatus)
As described above, the correction control means applied to FIG. 1 has been described from the first embodiment to the seventh embodiment.

  The correction control means outputs a signal to the head drive control unit as shown in FIG. 1, but it may be further output to the motor control unit 102 as shown in FIG.

  That is, based on the signal from the correction control means, the head drive control and the transport means control are performed.

  As another form, a configuration in which only the transport unit is controlled based on a signal from the correction control unit may be used.

  In addition, as an example of the embodiment of the recording apparatus, the recording apparatus that transports the recording medium by the transport belt has been described. However, other forms may be used.

  For example, the present invention may be applied to a recording apparatus that conveys a roll-shaped recording medium as shown in FIG. In FIG. 1, the moving speed of the conveying belt that conveys the recording medium is measured using a laser Doppler speed sensor, but in FIG. 25, the conveying speed of the roll-shaped recording medium is measured.

  In the recording apparatus shown in FIG. 25, 2 is a roll-shaped recording medium, and recording is performed while being pulled out from the roll shape. Reference numeral 4 denotes two transport rollers, and 5 denotes two follower rollers. In this figure, the pressure between the right transport roller 4 and the follower roller 5 is stronger than that on the left side so that the transport can be controlled by the right transport roller 4. The left conveyance roller is controlled to rotate at a slightly higher speed than the right side so that the tension is applied so that the recording medium does not loosen between the two conveyance rollers. The rotation detection sensor 8 is attached to the right conveyance roller shaft 6 which has a great influence on the speed of the recording medium. In the case of being composed of three upper conveying rollers, it is attached to the conveying roller shaft that has the greatest influence on the conveying speed of the recording medium.

  As described above, by correcting the eccentricity of the conveying roller based on the rotation of the conveying roller having the most dominant power for conveying the roll-shaped recording medium, it is possible to form an image without the influence of the eccentricity of the conveying roller.

  Alternatively, the toner image formed on the photosensitive drum as shown in FIG. 26 may be applied to a recording apparatus that records on a recording medium after being transferred to a transfer belt.

  Reference numeral 25 denotes a photosensitive drum as an image carrier. A primary charger 26 applies a uniform charge amount to the surface of the photosensitive drum. An optical system 27 generates a light beam such as a laser beam that is modulated in accordance with a recorded image signal. Reference numeral 28 denotes a folding mirror for irradiating the photosensitive drum with light from the optical system to form an electrostatic latent image on the photosensitive drum. A developing device 29 visualizes the electrostatic latent image with toner, which is a stored developer. A cleaning device 30 cleans the drum surface by scraping off toner remaining on the photosensitive drum without being transferred. Reference numeral 20 denotes an intermediate transfer belt for forming toner images formed on a plurality of photosensitive drums as one image and then transferring the image onto a recording medium. Reference numeral 11 denotes a primary transfer charger for performing primary transfer of a toner image formed on a photosensitive drum to an intermediate transfer belt. Reference numeral 24 denotes a registration roller for supplying a recording medium from recording medium supply means (not shown). A secondary transfer roller 21 presses the intermediate transfer member with an appropriate pressure and transfers the toner image formed on the intermediate transfer belt to a recording medium. Reference numeral 22 denotes a secondary transfer counter roller. Reference numeral 24 denotes a guide for leading to a fixing unit not shown in the figure in order to fix the transferred recording medium. An exposure control unit 106 controls the conveyance reference signal so that an image formed by four optical systems is formed on the intermediate transfer belt. The exposure control unit in this configuration performs timing control for starting scanning of each optical system 27 in accordance with the conveyance reference signal 202.

  Note that the recording apparatus shown in FIGS. 25 and 26 may also be configured to output the signal generated by the correction control means to the motor drive unit.

1 is a diagram illustrating a configuration of a recording apparatus according to a first embodiment. Configuration diagram of a conventional recording device Explanatory drawing of image formation for a conventional recording apparatus Explanatory drawing of conventional correction control means Configuration diagram of a conventional recording device Configuration diagram of laser Doppler type speed sensor Cross section of transport roller Diagram explaining the misalignment of the dot position of the recorded image The figure explaining the waveform of the laser Doppler type speed sensor The figure explaining the structure of the timing generation means in 1st Embodiment The figure explaining the process of the timing generation means in 1st Embodiment The figure explaining the block diagram of the timing generation means in 1st Embodiment Explanatory drawing of the correction process in 1st Embodiment Explanatory drawing of the process of the correction control means in 1st Embodiment. The figure explaining the structure of the correction control means in 2nd Embodiment. The figure explaining the structure of the correction control means in 3rd Embodiment. The figure explaining the structure of the correction | amendment control means in 4th Embodiment. The figure explaining the timing of the signal processing in 4th Embodiment The figure explaining the structure of the correction control means in 5th Embodiment The figure explaining the structure of the correction | amendment control means in 6th Embodiment. Explanatory drawing of the correction process in 6th Embodiment Explanatory drawing of the correction process in 6th Embodiment The figure explaining the structure of the correction control means in 7th Embodiment The figure which shows the structure of the recording device in other embodiment. The figure which shows the structure of the recording device in other embodiment. The figure which shows the structure of the recording device in other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Head drive control part 102 Motor drive part 201 Rotation pulse signal 202 Conveyance reference signal 103 Conveyance correction control means 151 Image forming means 152 Processing circuit part

Claims (10)

An ink jet recording head;
Conveying means for conveying a recording medium including a roller;
By detecting the surface of the recording medium, a laser Doppler sensor that generates a first signal which is a pulse signal whose pulse cycle varies according to the moving speed of the recording medium,
An encoder that generates a second signal which is a pulse signal in accordance with rotation of the roller,
Correction means for correcting the first signal when the pulse period of the first signal generated by the laser Doppler sensor exceeds a predetermined range;
An acquisition means for acquiring periodic fluctuation information that is a component of a pulse period of the first signal that has passed through the correction means and that makes one rotation of the roller as one period ;
When controlling the recording with respect to the recording medium by the second signal generated by the encoder, the control of the recording is performed on the variation information so as to suppress the influence of the moving speed variation of the recording medium due to the eccentricity of the roller. And a control means for reflecting the recording apparatus. Said control means, said recording head, a recording apparatus according to claim 1 which controls at least one drive of said roller and performs control of the recording.   The recording apparatus according to claim 1, wherein the recording medium is a roll-shaped recording medium, and a plurality of the recording heads are arranged from upstream to downstream in a conveyance direction of the recording medium. The correction means sets an upper limit value and a lower limit value, and when the pulse period of the first signal exceeds a range between the upper limit value and the lower limit value, it is replaced with a correction value stored in advance. Item 4. The recording device according to any one of Items 1 to 3. The acquisition means calculates a first average value obtained by averaging the first signals for one rotation of the roller, and a second average value obtained by averaging the first signals for each predetermined period shorter than the one rotation. The recording apparatus according to claim 1, wherein a difference between the first average value and the second average value is used as the variation information. The laser Doppler sensor apparatus according to any one of claims 1 to 5, characterized in that for detecting the surface of the recording medium in the upstream of the front type recording head. Said conveying means, conveying a recording medium is disposed upstream of the pre-type recording head and the first roller for conveying the transport direction, the recording medium is disposed downstream from said plurality of recording heads in the conveyance direction And a second roller having an influence on the moving speed of the recording medium to be smaller than the first roller,
The encoder generates the second signal corresponding to the rotation of the first roller, according to claim 1 to 6 and the control means performing control so as to suppress the influence of the eccentricity of the first roller A recording apparatus according to any one of the above.   The recording apparatus according to claim 7, wherein the first roller has a higher pressure for holding the recording medium than the second roller, and the second roller has a higher rotation speed than the first roller. . A plurality of inkjet recording heads arranged from upstream to downstream in the conveying direction of the roll-shaped recording medium; and
A first roller disposed upstream of the plurality of recording heads for conveying a recording medium in the conveying direction;
A pressure which holds the recording medium smaller than the first roller and is higher in rotation speed than the first roller, which is arranged downstream of the plurality of recording heads and conveys the recording medium in the conveying direction. Two rollers,
A laser Doppler sensor for generating a first signal corresponding to the movement of the recording medium by detecting the surface of the recording medium;
An encoder for generating a second signal according to the rotation of the first roller;
A recording apparatus comprising: control means for controlling recording on the recording medium so as to suppress the influence of eccentricity of the first roller based on the first signal and the second signal. It said control means recording apparatus according to claim 9, wherein the controlling the recording timing of the recording head.

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