pulse generator

Abstract

To improve the image quality of the image forming apparatus. [Solution] The recording encoder processing unit 31 includes a periodic counter 53 and an output timing pulse generation unit 54. The periodic counter 53 calculates time information indicating a time interval each time an encoder signal is output from the rotary encoder 14. The output timing pulse generation unit 54 determines the output timing for outputting an output timing pulse based on at least two pieces of time information. The time difference between the calculation timings of the first and second pieces of time information is longer than the time required for the motor to rotate by an angle equivalent to the cogging distance. The first piece of time information is calculated based on the earliest output encoder signal among the at least two pieces of time information, and the second piece of time information is calculated based on the latest output encoder signal.

Description

Technical Field

[0001] The present disclosure relates to a pulse generation device that generates timing pulses.

Background Art

[0002] Patent Document 1 describes an image forming apparatus configured to detect the position and moving speed of a carriage using a linear encoder that outputs a pulse signal in accordance with the movement of the carriage that moves on a preset movement path by motor driving, and control the ink ejection timing of a recording head mounted on the carriage.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0004] The linear encoder includes a linear scale in which encoder slits are formed at predetermined intervals along the movement direction of the carriage, and detects the position of the carriage using this linear scale. For this reason, the linear encoder has the advantage that it can directly recognize the position of the carriage, and has high detection accuracy for the position and moving speed of the carriage. However, since the linear encoder is to be installed in the vicinity of the recording head mounted on the carriage, for example, when the linear encoder breaks down and is to be replaced, there is a problem that the replacement work of the linear encoder becomes difficult to perform because the recording head is in the way.

[0005] In contrast, the above problem can be solved by detecting the position and moving speed of the carriage using a rotary encoder attached to the motor shaft of the motor that drives the carriage.

[0006] However, using a rotary encoder can sometimes result in printing inconsistencies and a deterioration in image quality that did not occur when using a linear encoder. This disclosure aims to improve the image quality of an image forming apparatus. [Means for solving the problem]

[0007] One aspect of the present disclosure is a pulse generation device that generates timing pulses based on a detection signal acquired from a detection signal output unit configured to output a detection signal each time a motor rotates by a predetermined amount, the device comprising a time information calculation unit and a timing determination unit.

[0008] The time information calculation unit is configured to calculate time information indicating the time interval between the most recently outputted detection signal and the previously outputted detection signal each time a detection signal is output from the detection signal output unit.

[0009] The timing determination unit is configured to determine the output timing for outputting a timing pulse based on at least two pieces of time information. Furthermore, the time difference between the first calculation timing when the first time information is calculated and the second calculation timing when the second time information is calculated is longer than the time required for the motor to rotate by an angle equivalent to the cogging distance. The first time information is time information calculated based on the first detection signal, which is the earliest output detection signal among at least two time information. The second time information is time information calculated based on the second detection signal, which is the latest output detection signal among at least two time information.

[0010] The cogging distance is the value obtained by dividing the angle required for the motor to complete one rotation (i.e., 360°) by the product of the number of magnets in the motor's stator and the number of divisions in the motor's rotor. The pulse generation apparatus of this disclosure, configured in this manner, can suppress deviations in the ejection timing caused by motor cogging fluctuations when generating timing pulses indicating the ejection timing for an ejector, which is moved by a transport device driven by a motor, to eject ink toward a sheet, thereby suppressing the occurrence of uneven printing and improving the image quality of the image forming apparatus.

[0011] Another aspect of the present disclosure is a pulse generation device that generates timing pulses based on detection signals obtained from a detection signal output unit configured to output a detection signal each time a driven object is driven by a predetermined amount, the device comprising a time information calculation unit and a timing adjustment unit.

[0012] The time information calculation unit is configured to calculate time information indicating the time interval between the most recently outputted detection signal and the previously outputted detection signal each time a detection signal is output from the detection signal output unit.

[0013] The timing adjustment unit calculates an adjustment amount using the most recent time information, which is time information before the generation of the timing pulse, and a preset reference time information that serves as the reference for the time interval for generating the timing pulse. Based on the adjustment amount, it determines the output timing for outputting the timing pulse by delaying or advancing the output timing, which is calculated based on the most recent time information and serves as the reference for the output timing.

[0014] The pulse generation apparatus of this disclosure, configured in this manner, can suppress deviations in the ejection timing caused by motor cogging fluctuations when generating timing pulses indicating the ejection timing for an ejector, which is moved by a transport device driven by a motor, to eject ink toward a sheet, thereby suppressing the occurrence of uneven printing and improving the image quality of the image forming apparatus. [Brief explanation of the drawing]

[0015] [Figure 1]is a block diagram showing the configuration of an image forming apparatus. [Figure 2] is a diagram showing the configuration of a printing mechanism. [Figure 3] is a graph showing temporal changes in carriage speed and motor rotation speed. [Figure 4] is a block diagram showing the configuration of a recording encoder processing unit of the first embodiment. [Figure 5] is a diagram for explaining a pulse generation method of the first embodiment. [Figure 6] is a diagram for explaining ejection timing when the carriage motor rotation speed is higher than a reference rotation speed in the first embodiment. [Figure 7] is a diagram for explaining ejection timing when the carriage motor rotation speed is lower than a reference rotation speed in the first embodiment. [Figure 8] is a block diagram showing the configuration of an ejection timing pulse generation unit of the second embodiment. [Figure 9] is a diagram for explaining ejection timing when the carriage motor rotation speed is higher than a reference rotation speed in the second embodiment. [Figure 10] is a diagram for explaining ejection timing when the carriage motor rotation speed is lower than a reference rotation speed in the second embodiment. [Figure 11] is a block diagram showing the configuration of an ejection timing pulse generation unit of the third embodiment. [Figure 12] is a diagram for explaining ejection timing when the carriage motor rotation speed is higher than a reference rotation speed in the third embodiment. [Figure 13] is a diagram for explaining ejection timing when the carriage motor rotation speed is lower than a reference rotation speed in the third embodiment. [Description of Embodiments]

[0016] [First Embodiment] The first embodiment of the present disclosure will be described below with reference to the drawings. (1) Overall structure The image forming apparatus 1 of this embodiment is an inkjet printer and, as shown in Figure 1, comprises a recording head 11, a carriage 12, a carriage motor 13, and a rotary encoder 14.

[0017] The recording head 11, carriage 12, and carriage motor 13 constitute part of the printing mechanism 15. The printing mechanism 15 is configured to receive power from the carriage motor 13 and move the carriage 12, on which the recording head 11 is mounted, in the main scanning direction. The main scanning direction is perpendicular to the sub-scanning direction in which the paper is transported.

[0018] The recording head 11 is an ejection head configured to eject ink droplets, and is a so-called inkjet head. The recording head 11 performs an ink droplet ejection operation to form an image on the paper as the carriage 12 moves across the paper along the main scanning direction. The carriage motor 13 is a DC motor and functions as a drive source to reciprocate the carriage 12.

[0019] The rotary encoder 14 is an incremental optical rotary encoder used to measure the position and speed of the carriage 12 in the main scanning direction. The image forming apparatus 1 further includes a line feed motor 21 and a rotary encoder 22 to facilitate paper transport. The line feed motor 21 is a DC motor and functions as a drive source for rotating the transport rollers that transport the paper in the sub-scanning direction. The rotary encoder 22 is an incremental optical rotary encoder and is used to measure the amount and speed of rotation of the transport rollers.

[0020] The image forming apparatus 1 further comprises a CPU 2, a ROM 3, a RAM 4, a clock generation unit 5, a user interface 6, a communication interface 7, a bus 8, a recording control unit 16, a carriage motor control unit 17, a line feed motor control unit 23, and an encoder processing unit 30.

[0021] The CPU2, ROM3, RAM4, clock generation unit5, user interface6, communication interface7, recording control unit16, carriage motor control unit17, line feed motor control unit23, and encoder processing unit30 are connected to each other via bus8, enabling data input and output.

[0022] CPU2 is configured to comprehensively control each part of the image forming apparatus 1. ROM3 stores the computer program executed by CPU2. RAM4 is used as a workspace when the CPU2 executes the computer program.

[0023] The clock generation unit 5 generates a clock signal with a period sufficiently shorter than the pulse signals output by the rotary encoders 14 and 22, and supplies it to each part of the image forming apparatus 1. The user interface 6 includes an operating unit that can be operated by the user and a display unit that can display various information to the user.

[0024] Communication interface 7 is an interface for data communication with external devices such as personal computers. The recording control unit 16 is configured to control the ejection of ink droplets by the recording head 11. The carriage motor control unit 17 is configured to control the transport operation of the carriage 12 by the carriage motor 13. The line feed motor control unit 23 is configured to control the transport operation of the paper by the line feed motor 21.

[0025] The encoder processing unit 30 comprises a recording encoder processing unit 31 and a transport encoder processing unit 32. The recording encoder processing unit 31 determines the direction of movement of the carriage 12 based on the encoder signal input from the rotary encoder 14, and also measures the position and speed of movement of the carriage 12.

[0026] The transport encoder processing unit 32 measures the amount of rotation and rotational speed of the transport rollers that transport the paper based on the encoder signal input from the rotary encoder 22. As shown in Figure 2, the printing mechanism 15 includes a guide shaft 41 that extends along the main scanning direction to define the passage for the carriage 12. The carriage 12 is inserted through the guide shaft 41.

[0027] The carriage 12 is further connected to an endless belt 42 provided along the guide shaft 41. The endless belt 42 is wound between a drive pulley 43 installed at one end of the guide shaft 41 and a driven pulley 44 installed at the other end of the guide shaft 41.

[0028] The drive pulley 43 is rotationally driven by the carriage motor 13, which rotates the endless belt 42. The carriage 12 moves along the guide shaft 41 in the main scanning direction by the power of the carriage motor 13 transmitted through the rotation of the endless belt 42.

[0029] The rotary encoder 14 comprises a disc-shaped encoder disk (not shown) and an optical sensor (not shown). The disc-shaped encoder disk is fixed to the carriage motor 13 such that its center is positioned on the rotation axis of the carriage motor 13. The encoder disk has multiple encoder slits formed on it that are arranged at equal intervals on concentric circles of the encoder disk.

[0030] The optical sensor comprises a light-emitting unit that emits light and a light-receiving unit positioned opposite the light-emitting unit across the encoder slit. As a result, the rotary encoder 14 outputs a first pulse signal (hereinafter referred to as the A-phase signal) and a second pulse signal (hereinafter referred to as the B-phase signal) as encoder signals, each time the carriage motor 13 rotates by a predetermined amount in response to the rotation of the carriage motor 13, with a predetermined phase difference (90 degrees in this embodiment).

[0031] (2) Cogging of carriage motor In a DC motor, the torque during one rotation of the motor shaft is not uniform, even if the drive current or drive voltage is constant, due to the structure of the DC motor. This results in a periodic torque fluctuation known as cogging. Consequently, the rotational speed of the DC motor fluctuates periodically.

[0032] Since the carriage motor 13 is a DC motor, its rotational speed fluctuates periodically due to cogging. For example, as shown in graph G1 of Figure 3, the carriage 12 starts accelerating from the acceleration start position at time t1. Then, at time t2, when the carriage 12's moving speed (hereinafter referred to as carriage speed) reaches the reference speed, the carriage 12 moves at a constant speed at the reference speed to the deceleration start position.

[0033] When carriage 12 reaches the deceleration start position at time t3, carriage 12 begins to decelerate. Then, at time t4, the carriage speed becomes 0, and carriage 12 stops at the stopping position.

[0034] Graph G2 in Figure 3 shows the change in rotational speed of the carriage motor 13 (hereinafter referred to as carriage motor rotational speed) over time when the carriage 12 moves as shown in Graph G1.

[0035] As shown in graph G2, the carriage motor 13 starts rotating at time t1. Then, at time t2, when the carriage motor rotation speed reaches the reference rotation speed, the carriage motor control unit 17 controls the carriage motor 13 to rotate at the reference rotation speed. However, due to cogging, the carriage motor rotation speed oscillates around the reference rotation speed with a cogging period.

[0036] At time t3, when carriage 12 reaches the deceleration start position, carriage motor 13 begins to decelerate. Then, at time t4, the carriage motor rotation speed becomes 0, and carriage 12 stops at the stopping position.

[0037] Furthermore, fluctuations in the carriage motor rotational speed due to cogging (hereinafter referred to as cogging fluctuations) are attenuated by the endless belt 42 before being transmitted to the carriage 12 via the endless belt 42. Therefore, the movement speed of the carriage 12 does not oscillate with the cogging period, and the carriage 12 moves at a constant speed at the reference speed.

[0038] (3) Configuration of the recording encoder processing unit As shown in Figure 4, the recording encoder processing unit 31 includes an encoder edge detection unit 51, a position counter 52, a period counter 53, a discharge timing pulse generation unit 54, and a signal processing unit 55.

[0039] The encoder edge detection unit 51 receives pulse signals from each phase of the rotary encoder 14 and detects the rising edge of the A-phase signal and the rotation direction of the carriage motor 13. When the encoder edge detection unit 51 detects the rising edge of the A-phase signal, it outputs an edge detection signal.

[0040] The position counter 52 increments (adds 1) or decrements (subtracts 1) the edge count value each time an edge detection signal is input from the encoder edge detection unit 51, according to the rotation direction of the carriage motor 13 detected by the encoder edge detection unit 51 (i.e., the direction of movement of the carriage 12). The position counter 52 outputs position information indicating the edge count value to the discharge timing pulse generation unit 54 and the signal processing unit 55.

[0041] The periodic counter 53 initializes the edge period count value each time an edge detection signal is input from the encoder edge detection unit 51. The periodic counter 53 also increments the edge period count value each time a clock signal is input from the clock generation unit 5.

[0042] The periodic counter 53 then outputs time information indicating the edge period count value immediately before the edge detection signal was input to the output timing pulse generation unit 54 and the signal processing unit 55 each time an edge detection signal is input from the encoder edge detection unit 51. In other words, each time an edge detection signal is input, the periodic counter 53 measures the time from when the previous edge detection signal was input until when the current edge detection signal is input.

[0043] The discharge timing pulse generation unit 54 comprises a time storage unit 61, an average time calculation unit 62, a discharge time calculation unit 63, and a pulse generation unit 64. The time memory unit 61 stores the time information in chronological order each time it receives time information from the periodic counter 53.

[0044] Each time new time information is stored in the time storage unit 61, the average time calculation unit 62 retrieves a predetermined average number of time pieces of time information from among the multiple time pieces of time information stored in the time storage unit 61, in order from the latest stored timing, and calculates the average of the time indicated by the retrieved average number of time pieces of time information as the predicted period. The average number of retrieved time pieces is an integer of 2 or more. In this embodiment, the average number of retrieved time pieces matches the number of time pieces of time information output by the period counter 53 during one rotation of the carriage motor 13.

[0045] The discharge time calculation unit 63 calculates a division value by dividing the most recently calculated predicted period by the encoder multiplier M each time a new predicted period is calculated by the average time calculation unit 62, and uses this division value as the discharge time. In this embodiment, the encoder multiplier M is 4.

[0046] The pulse generation unit 64 generates and outputs the first discharge timing pulse after a predetermined delay time Td has elapsed since the input of the edge detection signal. Furthermore, the pulse generation unit 64 generates and outputs the second to Mth discharge timing pulses each time the discharge time calculated by the discharge time calculation unit 63 has elapsed.

[0047] The signal processing unit 55 processes various signals such as edge detection signals, edge count values, and edge period count values, and outputs them to the CPU 2 as needed. The signal processing unit 55 also processes various signals input from the CPU 2 and outputs them to the various parts of the recording encoder processing unit 31.

[0048] One example of a signal input from the CPU 2 to the signal processing unit 55 is a signal instructing the ejection timing pulse generation unit 54 whether or not to generate an ejection timing pulse. In the image forming apparatus 1 of this embodiment, it is not always necessary to generate an ejection timing pulse; there are times when an ejection timing pulse is needed (for example, during image formation) and times when it is not needed. Therefore, the CPU 2 instructs the ejection timing pulse generation unit 54 via the signal processing unit 55 whether or not to generate an ejection timing pulse.

[0049] The ejection timing pulse output from the ejection timing pulse generation unit 54 is input to the recording control unit 16. The recording control unit 16 uses the input ejection timing pulse as the operating timing of the recording head 11 (i.e., the ink ejection timing) and controls the operation of the recording head 11.

[0050] Next, we will specifically explain the method for generating discharge timing pulses. As shown in Figure 5, when the rising edge of the A-phase signal is detected at time t11, time t n-1 Time information indicating the period is input from the period counter 53 to the discharge timing pulse generation unit 54. The discharge timing pulse generation unit 54 uses the time information of the average acquired number to predict the period T n-1 Calculate.

[0051] The discharge timing pulse generation unit 54 then generates and outputs the first discharge timing pulse at time t12, which is the time after a predetermined delay time Td has elapsed since the rising edge of the A-phase signal was detected.

[0052] Furthermore, the discharge timing pulse generation unit 54 predicts the period T after the first discharge timing pulse is output. n-1 At time t13, which is one-quarter of the time elapsed, a second discharge timing pulse is generated and output.

[0053] Furthermore, the discharge timing pulse generation unit 54 predicts the period T after the second discharge timing pulse is output. n-1 At time t14, which is one-quarter of the time elapsed, the third discharge timing pulse is generated and output.

[0054] Furthermore, the discharge timing pulse generation unit 54 predicts the period T after the third discharge timing pulse is output. n-1 At time t15, which is one-quarter of the time elapsed, the fourth discharge timing pulse is generated and output.

[0055] Furthermore, when the rising edge of the A-phase signal is detected at time t16, time t n Time information indicating the period is input from the period counter 53 to the discharge timing pulse generation unit 54. The discharge timing pulse generation unit 54 uses the time information of the average acquired number to predict the period T n Calculate.

[0056] The discharge timing pulse generation unit 54 then generates a predicted period T n At one-quarter time intervals, the 1st, 2nd, 3rd, and 4th discharge timing pulses are generated and output at times t17, t18, t19, and t20, respectively, in the same manner as at times t12 to t15.

[0057] Next, we will explain the discharge timing when the carriage motor rotation speed exceeds the reference rotation speed due to cogging. As shown in Figure 6, when the recording head 11 is moving at a reference speed and the carriage motor rotation speed matches the reference rotation speed, ink is ejected from the recording head 11 at times t30, t31, t32, t33, and t34, as shown in the diagram within frame F1.

[0058] On the other hand, when the recording head 11 is moving at a reference speed and the carriage motor rotation speed is greater than the reference rotation speed, if ejection timing pulses are generated based only on the most recent time information, ink will be ejected from the recording head 11 at times t30, t35, t36, and t37, as shown in the figure within frame F2.

[0059] The time interval between time t30 and time t35 is shorter than the time interval between time t30 and time t31. Note that time t38 corresponds to the discharge timing predicted from the most recently calculated carriage motor rotation speed. Because the carriage motor rotation speed is greater than the reference rotation speed, time t38, which corresponds to the predicted discharge timing, is earlier than time t34 shown in the diagram within frame F1.

[0060] The time t39 shown in the diagram within frame F2 corresponds to the timing when the encoder edge detection unit 51 actually detects an edge. The reason the timing when the encoder edge detection unit 51 actually detects an edge is later than time t38 is because the carriage motor rotation speed slowed down due to cogging.

[0061] Next, when the recording head 11 is moving at a reference speed and the carriage motor rotation speed is greater than the reference rotation speed, if an ejection timing pulse is generated based on the average of the time information of the average number of acquired inks, ink will be ejected from the recording head 11 at times t30, t40, t41, and t42, as shown in the figure in frame F3.

[0062] The time interval between time t30 and time t40 is approximately the same as the time interval between time t30 and time t31. Note that time t43 corresponds to the discharge timing predicted from the average of the carriage motor rotation speeds obtained for the average number of units. Time t43, which corresponds to the predicted discharge timing, is approximately the same as time t34 shown in the figure within frame F1.

[0063] Next, we will explain the discharge timing when the carriage motor rotation speed becomes lower than the reference rotation speed due to cogging. As shown in Figure 7, when the recording head 11 is moving at a reference speed and the carriage motor rotation speed matches the reference rotation speed, ink is ejected from the recording head 11 at times t50, t51, t52, t53, and t54, as shown in the diagram within frame F11.

[0064] Note that time t54 corresponds to the ejection timing predicted from the most recently calculated carriage motor rotation speed. Since the recording head 11 is moving at the reference speed and the carriage motor rotation speed matches the reference speed, ink is ejected at time t54, which matches the predicted ejection timing.

[0065] On the other hand, when the recording head 11 is moving at a reference speed and the carriage motor rotation speed is less than the reference rotation speed, if ejection timing pulses are generated based only on the most recent time information, ink will be ejected from the recording head 11 at times t50, t55, t56, and t57, as shown in the figure within frame F12.

[0066] The time interval between time t50 and time t55 is longer than the time interval between time t50 and time t51. Note that time t58 corresponds to the discharge timing predicted from the most recently calculated carriage motor rotation speed. Because the carriage motor rotation speed is lower than the reference rotation speed, time t58, which corresponds to the predicted discharge timing, is later than time t54 shown in the figure within frame F1.

[0067] The time t59 shown in the diagram within frame F12 corresponds to the timing when the encoder edge detection unit 51 actually detects an edge. The reason the timing when the encoder edge detection unit 51 actually detects an edge is later than time t58 is because the carriage motor rotation speed slowed down due to cogging.

[0068] Next, when the recording head 11 is moving at a reference speed and the carriage motor rotation speed is less than the reference rotation speed, if an ejection timing pulse is generated based on the average of the time information of the average number of acquisitions, ink will be ejected from the recording head 11 at times t50, t60, t61, and t62, as shown in the figure in frame F13.

[0069] The time interval between time t50 and time t60 is approximately the same as the time interval between time t50 and time t51. Note that time t63 corresponds to the discharge timing predicted from the average carriage motor rotation speed of the average number of acquired data points. Time t63, which corresponds to the predicted discharge timing, is approximately the same as time t54 shown in the figure within frame F11.

[0070] (4) Effects The recording encoder processing unit 31 configured in this way generates discharge timing pulses based on the encoder signals obtained from the rotary encoder 14, which is configured to output an encoder signal each time the carriage motor 13 rotates by a predetermined amount.

[0071] The recording encoder processing unit 31 includes a periodic counter 53 and a discharge timing pulse generation unit 54. The periodic counter 53 is configured to calculate time information indicating the time interval between the most recently outputted encoder signal and the previously outputted encoder signal each time an encoder signal is output from the rotary encoder 14.

[0072] The discharge timing pulse generation unit 54 is configured to determine the output timing for outputting a discharge timing pulse based on at least two pieces of time information. Furthermore, the time difference between the first calculation timing when the first time information is calculated and the second calculation timing when the second time information is calculated is longer than the time required for the carriage motor 13 to rotate by an angle equivalent to the cogging distance. The first time information is time information calculated based on the encoder signal that was output earliest among at least two pieces of time information. The second time information is time information calculated based on the encoder signal that was output latest among at least two pieces of time information.

[0073] The cogging distance is the value obtained by dividing the angle required for the carriage motor 13 to complete one rotation (i.e., 360°) by the product of the number of magnets in the stator of the carriage motor 13 and the number of divisions in the rotor of the carriage motor 13.

[0074] For example, suppose the stator of carriage motor 13 has "3" magnets and the rotor of carriage motor 13 has "4" divisions. Note that if the rotor is composed of two north poles and two south poles, the number of divisions of the rotor is "4". In this case, the cogging distance is 360 / (3×4)=30°.

[0075] When such a recording encoder processing unit 31 generates ejection timing pulses that indicate the ejection timing for the recording head 11, which is moved by the carriage 12 driven by the carriage motor 13, to eject ink toward the sheet, it can suppress deviations in ejection timing caused by cogging fluctuations of the carriage motor 13, thereby suppressing the occurrence of uneven printing and improving the image quality of the image forming apparatus 1.

[0076] The recording encoder processing unit 31 determines the output timing based on the average of at least two pieces of time information. Such a recording encoder processing unit 31 can simplify the determination of the output timing and reduce the processing load on the recording encoder processing unit 31.

[0077] The recording encoder processing unit 31 determines the output timing so that it is equally spaced within an average time representing the average of at least two pieces of time information. Such a recording encoder processing unit 31 can simplify the determination of the output timing and reduce the processing load on the recording encoder processing unit 31.

[0078] Furthermore, the time difference between the first calculation timing and the second calculation timing is equal to the time required for the carriage motor 13 to complete one rotation. A recording encoder processing unit 31 like this can reduce the effects of cogging fluctuations more effectively than when the time difference between the first calculation timing and the second calculation timing is shorter than the time required for the carriage motor 13 to complete one rotation.

[0079] In the embodiment described above, the recording encoder processing unit 31 corresponds to a pulse generation device, the carriage motor 13 corresponds to a motor, the encoder signal corresponds to a detection signal, the rotary encoder 14 corresponds to a detection signal output unit, and the discharge timing pulse corresponds to a timing pulse.

[0080] Furthermore, the periodic counter 53 corresponds to the time information calculation unit, the discharge timing pulse generation unit 54 corresponds to the timing determination unit, the earliest output encoder signal corresponds to the first detection signal, and the latest output encoder signal corresponds to the second detection signal.

[0081] [Second Embodiment] A second embodiment of this disclosure is described below with reference to the drawings. Note that the second embodiment will describe parts that differ from the first embodiment. Common components will be denoted by the same reference numerals.

[0082] The image forming apparatus 1 of the second embodiment differs from the first embodiment in that the configuration of the ejection timing pulse generation unit 54 has been changed. As shown in Figure 8, the discharge timing pulse generation unit 54 of the second embodiment includes an adjustment time calculation unit 71, a discharge time calculation unit 72, and a pulse generation unit 73.

[0083] The adjustment time calculation unit 71 calculates the first adjustment time delay1, the second adjustment time delay2, ..., and the Mth adjustment time delayM each time time time information is input from the periodic counter 53.

[0084] The adjustment time calculation unit 71 calculates the Nth adjustment time delayN using equation (1). N is an integer from 1 to M. In equation (1), Ts corresponds to the period during which the A-phase signal is output from the rotary encoder 22 when the carriage motor 13 rotates at the reference rotational speed.

[0085] delayN = (N-1)×(Ts-Te) / M ···(1) Each time time time information is input from the periodic counter 53, the discharge time calculation unit 72 uses the time indicated by the input time information (i.e., the predicted time Te) and the first to M adjustment times delay1 to M input from the adjustment time calculation unit 71 to calculate the Nth discharge time ET_N of the Nth discharge timing pulse using equation (2).

[0086] ET_N = (N-1)×Te / M + delayN ···(2) The pulse generation unit 73 generates and outputs the first discharge timing pulse after a predetermined delay time Td has elapsed since the edge detection signal was input. Furthermore, the pulse generation unit 73 generates and outputs the Nth discharge timing pulse after the Nth discharge time ET_N has elapsed since the output of the first discharge timing pulse. Here, N is an integer from 2 to M.

[0087] Next, we will explain the discharge timing when the carriage motor rotation speed exceeds the reference rotation speed due to cogging. As shown in Figure 9, when the recording head 11 is moving at a reference speed and the carriage motor rotation speed matches the reference rotation speed, ink is ejected from the recording head 11 at times t70, t71, t72, t73, and t74, as shown in the diagram within frame F21.

[0088] On the other hand, when the recording head 11 is moving at a reference speed and the carriage motor rotation speed is greater than the reference rotation speed, if ejection timing pulses are generated based only on the most recent time information, ink will be ejected from the recording head 11 at times t70, t75, t76, and t77, as shown in the figure within frame F22.

[0089] The time interval between time t70 and time t75 is shorter than the time interval between time t70 and time t71. Note that time t78 corresponds to the discharge timing predicted from the most recently calculated carriage motor rotation speed. Because the carriage motor rotation speed is greater than the reference rotation speed, time t78, which corresponds to the predicted discharge timing, is earlier than time t74 shown in the figure within frame F21.

[0090] The time t79 shown in the diagram within frame F22 corresponds to the timing when the encoder edge detection unit 51 actually detects an edge. The reason the timing when the encoder edge detection unit 51 actually detects an edge is later than time t78 is because the carriage motor rotation speed slowed down due to cogging.

[0091] Next, when the recording head 11 is moving at a reference speed and the carriage motor rotation speed is greater than the reference rotation speed, if ejection timing pulses are generated based on the adjustment time, ink will be ejected from the recording head 11 at times t70, t80, t81, and t82, as shown in the figure within frame F23.

[0092] Time t80 corresponds to the second discharge time ET_2. Time t81 corresponds to the third discharge time ET_3. Time t82 corresponds to the fourth discharge time ET_4. Next, we will explain the discharge timing when the carriage motor rotation speed becomes lower than the reference rotation speed due to cogging.

[0093] As shown in Figure 10, when the recording head 11 is moving at a reference speed and the carriage motor rotation speed matches the reference rotation speed, ink is ejected from the recording head 11 at times t90, t91, t92, t93, and t94, as shown in the diagram within frame F31.

[0094] On the other hand, when the recording head 11 is moving at a reference speed and the carriage motor rotation speed is lower than the reference rotation speed, if ejection timing pulses are generated based only on the most recent time information, ink will be ejected from the recording head 11 at times t90, t95, t96, and t97, as shown in the figure within frame F32.

[0095] The time interval between time t90 and time t95 is longer than the time interval between time t90 and time t91. Note that time t98 corresponds to the discharge timing predicted from the most recently calculated carriage motor rotation speed. Because the carriage motor rotation speed is lower than the reference rotation speed, time t98, which corresponds to the predicted discharge timing, is later than time t94 shown in the figure within frame F31.

[0096] The time t99 shown in the diagram within frame F32 corresponds to the timing when the encoder edge detection unit 51 actually detects an edge. The reason the timing when the encoder edge detection unit 51 actually detects an edge is later than time t98 is because the carriage motor rotation speed slowed down due to cogging.

[0097] Next, when the recording head 11 is moving at a reference speed and the carriage motor rotation speed is less than the reference rotation speed, if ejection timing pulses are generated based on the adjustment time, ink will be ejected from the recording head 11 at times t90, t100, t101, and t102, as shown in the figure in frame F33.

[0098] Time t100 corresponds to the second discharge time ET_2. Time t101 corresponds to the third discharge time ET_3. Time t102 corresponds to the fourth discharge time ET_4. The recording encoder processing unit 31 configured in this way includes a periodic counter 53 and a discharge timing pulse generation unit 54.

[0099] The discharge timing pulse generation unit 54 calculates the first to M adjustment time delay1 to M using time information before generating the discharge timing pulse (hereinafter referred to as recent time information) and a preset reference time information that serves as the reference for the time interval for generating the discharge timing pulse (i.e., information indicating time Ts). Based on the first to M adjustment time delay1 to M, the discharge timing pulse generation unit 54 is configured to determine the output timing for outputting the discharge timing pulse by delaying or advancing the output timing, which is calculated based on the recent time information and serves as the reference for the output timing. The recent time information is information indicating the predicted time Te. The reference output timing is the timing specified by (N-1) × Te / M.

[0100] When such a recording encoder processing unit 31 generates ejection timing pulses that indicate the ejection timing for the recording head 11, which is moved by the carriage 12 driven by the carriage motor 13, to eject ink toward the sheet, it can suppress deviations in ejection timing caused by cogging fluctuations of the carriage motor 13, thereby suppressing the occurrence of uneven printing and improving the image quality of the image forming apparatus 1.

[0101] Furthermore, the output timing pulse generation unit 54 is configured to determine multiple output timings between the time the most recent encoder signal is output and the time the next encoder signal is output. The output timing pulse generation unit 54 then determines the multiple output timings based on the first to M adjustment times delay1 to M, which are calculated independently for each of the multiple output timings. Because the recording encoder processing unit 31 calculates the first to M adjustment times delay1 to M for the multiple output timings independently of each other, it is possible to suppress the degradation of image quality.

[0102] In the embodiments described above, the carriage motor 13 corresponds to the drive target, the 1st to M adjustment time delay1 to M corresponds to the adjustment amount, and the reference rotational speed corresponds to the reference speed. [Third Embodiment] A third embodiment of this disclosure is described below with reference to the drawings. Note that the third embodiment will describe parts that differ from the first embodiment. Common components will be denoted by the same reference numerals.

[0103] The image forming apparatus 1 of the third embodiment differs from the first embodiment in that the configuration of the ejection timing pulse generation unit 54 has been changed. As shown in Figure 11, the discharge timing pulse generation unit 54 of the third embodiment includes an adjustment time calculation unit 81, a discharge time calculation unit 82, and a pulse generation unit 83.

[0104] The adjustment time calculation unit 81 calculates the adjustment time delay using equation (3) each time time time information is input from the periodic counter 53. delay = (Ts-Te) / 2 ···(3) Each time time time information is input from the periodic counter 53, the discharge time calculation unit 72 uses the time indicated by the input time information (i.e., the predicted time Te) and the adjustment time delay input from the adjustment time calculation unit 71 to calculate the Nth discharge time ET_N of the Nth discharge timing pulse using equation (4).

[0105] ET_N = Td + (N-1)×Te / M + delay ···(4) The pulse generation unit 83 generates and outputs the Nth discharge timing pulse after the Nth discharge time ET_N has elapsed since the edge detection signal was input.

[0106] Next, we will explain the discharge timing when the carriage motor rotation speed exceeds the reference rotation speed due to cogging. As shown in Figure 12, the diagrams within frames F21 and F22 in Figure 12 are identical to those in Figure 9, so their explanation is omitted.

[0107] When the recording head 11 is moving at a reference speed and the carriage motor rotation speed is greater than the reference rotation speed, if ejection timing pulses are generated based on the adjustment time, ink will be ejected from the recording head 11 at times t111, t112, t113, and t114, as shown in the figure within frame F41.

[0108] Time t111 corresponds to the first discharge time ET_1. Time t112 corresponds to the second discharge time ET_2. Time t113 corresponds to the third discharge time ET_3. Time t114 corresponds to the fourth discharge time ET_4.

[0109] Note that time t115 corresponds to the timing when the next edge detection signal is input. That is, ink is ejected from the recording head 11 every time the newly calculated 1st, 2nd, 3rd, and 4th ejection times ET_1, 2, 3, and 4 have elapsed since time t115.

[0110] Next, we will explain the discharge timing when the carriage motor rotation speed becomes lower than the reference rotation speed due to cogging. As shown in Figure 13, the diagrams within frames F31 and F32 in Figure 13 are identical to those in Figure 10, so their explanation is omitted.

[0111] When the recording head 11 is moving at a reference speed and the carriage motor rotation speed is less than the reference rotation speed, if ejection timing pulses are generated based on the adjustment time, ink will be ejected from the recording head 11 at times t121, t122, t123, and t124, as shown in the figure in frame F42.

[0112] Time t121 corresponds to the first discharge time ET_1. Time t122 ​​corresponds to the second discharge time ET_2. Time t123 corresponds to the third discharge time ET_3. Time t124 corresponds to the fourth discharge time ET_4.

[0113] The recording encoder processing unit 31 configured in this way determines multiple output timings based on the same adjustment time delay for each of the multiple output timings. Such a recording encoder processing unit 31 can simplify the determination of output timings and reduce the processing load on the recording encoder processing unit 31.

[0114] In the embodiments described above, the adjustment time delay corresponds to the amount of adjustment. Although one embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment and can be implemented in various modified forms.

[0115] [Example 1] In the above embodiment, the time information was shown to be the number of clock cycles required for the carriage motor 13 to rotate by a predetermined amount. However, the time information can be any information indicating the time required for the carriage motor 13 to rotate by a predetermined amount.

[0116] [Differentiation 2] In the above embodiment, a discharge timing pulse with an encoder multiplier M is output each time an encoder signal is detected. However, the discharge timing pulse generation unit 54 may continue to set discharge timing pulses at equal intervals until a discharge timing pulse generated based on a newly detected encoder signal is output. Such a recording encoder processing unit 31 can suppress the occurrence of interruptions in the output of discharge timing pulses, thereby suppressing deterioration of image quality.

[0117] [Difference 3] In the above embodiment, the reference time information is shown to be the time or number of clock cycles required for the carriage motor 13 to rotate a predetermined amount when the carriage motor 13 is driven to rotate at a preset reference rotational speed. However, the reference time information may also be the average time or number of clock cycles obtained by averaging at least two pieces of time information calculated before determining the output timing, or it may be the time or number of clock cycles calculated by the least squares method using at least two pieces of time information.

[0118] Multiple functions of one component in the above embodiment may be realized by multiple components, or one function of one component may be realized by multiple components. Furthermore, multiple functions of multiple components may be realized by one component, or one function realized by multiple components may be realized by one component. Also, some parts of the configuration of the above embodiment may be omitted. Furthermore, at least some parts of the configuration of the above embodiment may be added to or replaced with the configuration of other above embodiments.

[0119] In addition to the recording encoder processing unit 31 described above, this disclosure can also be realized in various forms, such as a system comprising the recording encoder processing unit 31, a program for causing a computer to function as the recording encoder processing unit 31, a non-transitional physical recording medium such as a semiconductor memory on which this program is recorded, and a pulse generation method. [Technical Concept Disclosed in This Specified Specification] [Item 1] A pulse generation device that generates timing pulses based on a detection signal obtained from a detection signal output unit configured to output a detection signal each time the motor rotates by a predetermined amount, Each time the detection signal is output from the detection signal output unit, a time information calculation unit is configured to calculate time information indicating the time interval between the most recently outputted detection signal and the previously outputted detection signal. A timing determination unit configured to determine an output timing for outputting the timing pulse based on at least two of the aforementioned time pieces of information, Equipped with, A pulse generator wherein, of at least two pieces of time information, the time information calculated based on the first detection signal, which is the earliest output detection signal, is designated as the first time information, and the time information calculated based on the second detection signal, which is the latest output detection signal, is designated as the second time information, and the time difference between the first calculation timing when the first time information is calculated and the second calculation timing when the second time information is calculated is longer than the time required for the motor to rotate by an angle equivalent to the cogging distance. [Item 2] A pulse generator as described in item 1, The pulse generator is such that the time information is the time or number of clock cycles required for the motor to rotate by the predetermined amount. [Item 3] A pulse generator as described in item 1 or item 2, The timing determination unit is a pulse generation device that determines the output timing based on the average of at least two pieces of time information. [Item 4] A pulse generator as described in item 3, The timing determination unit is a pulse generation device that determines the output timing so that it is equally spaced within an average time representing the average of at least two pieces of time information. [Item 5] A pulse generator as described in item 4, The timing determination unit is a pulse generation device that continues to set the output timing at equal intervals until the timing pulse generated based on the newly detected detection signal is output. [Item 6] A pulse generating device described in any one of items 1 to 5, A pulse generating device in which the time difference between the first calculation timing and the second calculation timing is equal to the time required for the motor to complete one rotation. [Item 7] A pulse generation device that generates timing pulses based on a detection signal obtained from a detection signal output unit configured to output a detection signal each time the target to be driven is driven by a predetermined amount, Each time the detection signal is output from the detection signal output unit, a time information calculation unit is configured to calculate time information indicating the time interval between the most recently outputted detection signal and the previously outputted detection signal. A timing adjustment unit is configured to calculate an adjustment amount using the most recent time information, which is the time information before the generation of the timing pulse, and a preset reference time information that serves as the reference for the time interval in which the timing pulse is generated, and to determine the output timing for outputting the timing pulse by delaying or advancing the output timing calculated based on the most recent time information and serving as the reference for the output timing, based on the adjustment amount. A pulse generator equipped with the following features. [Item 8] A pulse generator as described in item 7, The aforementioned time information is a pulse generation device in which the time or number of clock cycles required for the driven object to be driven by the predetermined amount. [Item 9] A pulse generator as described in item 7 or item 8, The pulse generator is a pulse generator in which the reference time information is the time or number of clock cycles required for the target to be driven by a predetermined amount when the target is driven at a preset reference speed. [Item 10] A pulse generator as described in item 7 or item 8, The pulse generator wherein the reference time information is the average time or number of clock cycles obtained by averaging at least two pieces of time information calculated before determining the output timing. [Item 11] A pulse generator described in any one of items 7 to 10, The timing adjustment unit is configured to determine multiple output timings between the time the detection signal is output most recently and the time the detection signal is output again. The timing adjustment unit is a pulse generation device that determines a plurality of output timings based on the adjustment amount calculated independently for each of the plurality of output timings. [Item 12] A pulse generator as described in item 11, Let M be the number of timing pulses output between the most recent output of the detection signal and the next output of the detection signal, let Te be the time indicated by the time information, let Ts be the time indicated by the reference time information, and let delayN be the adjustment amount for the Nth output timing. The timing adjustment unit is a pulse generator that calculates the adjustment amount for the Nth output timing using the formula "delayN = (N-1) × (Ts-Te) / M". [Item 13] A pulse generator described in any one of items 7 to 10, The timing adjustment unit is configured to determine multiple output timings between the time the detection signal is output most recently and the time the detection signal is output again. The timing adjustment unit is a pulse generation device that determines a plurality of output timings based on the same adjustment amount for each of the plurality of output timings. [Item 14] A pulse generator as described in item 13, Let Te be the time indicated by the aforementioned time information, Ts be the time indicated by the aforementioned reference time information, and let delay be the adjustment amount. The timing adjustment unit is a pulse generator that calculates the adjustment amount using the formula "delay = (Ts-Te) / 2". [Item 15] A pulse generating device described in any one of items 1 to 6, The motor drives a transport device that moves an ink dispenser toward the sheet. The timing pulse is generated by a pulse generator that indicates the timing at which the ink is ejected by the ejector. [Item 16] A pulse generator described in any one of items 7 to 14, The aforementioned driven object drives a transport device that moves an ink dispenser that ejects ink toward a sheet, The timing pulse is generated by a pulse generator that indicates the timing at which the ink is ejected by the ejector. [Explanation of Symbols]

[0120] 13...Carriage motor, 14...Rotary encoder, 31...Recording encoder processing unit, 53...Periodic counter, 54...Discharge timing pulse generation unit

Claims

1. A pulse generation device that generates timing pulses based on a detection signal obtained from a detection signal output unit configured to output a detection signal each time the target to be driven is driven by a predetermined amount, Each time the detection signal is output from the detection signal output unit, a time information calculation unit is configured to calculate time information indicating the time interval between the most recently outputted detection signal and the previously outputted detection signal. A timing adjustment unit is configured to calculate an adjustment amount using the most recent time information, which is the time information before the generation of the timing pulse, and a preset reference time information that serves as the reference for the time interval in which the timing pulse is generated, and to determine the output timing for outputting the timing pulse by delaying or advancing the output timing calculated based on the most recent time information and serving as the reference for the output timing, based on the adjustment amount. A pulse generator equipped with the following features.

2. A pulse generation device according to claim 1, The aforementioned time information is a pulse generation device in which the time or number of clock cycles required for the driven object to be driven by the predetermined amount.

3. A pulse generation device according to claim 1 or claim 2, The pulse generator is a pulse generator in which the reference time information is the time or number of clock cycles required for the driven object to be driven by a predetermined amount when the driven object is driven at a preset reference speed.

4. A pulse generation device according to claim 1 or claim 2, The pulse generator wherein the reference time information is the average time or number of clock cycles obtained by averaging at least two pieces of time information calculated before determining the output timing.

5. A pulse generation device according to claim 1 or claim 2, The timing adjustment unit is configured to determine a plurality of output timings between the time the detection signal is output most recently and the time the detection signal is output again. The timing adjustment unit is a pulse generation device that determines a plurality of output timings based on the adjustment amount calculated independently for each of the plurality of output timings.

6. A pulse generation device according to claim 5, Let M be the number of timing pulses output between the most recent output of the detection signal and the next output of the detection signal; Te be the time indicated by the time information; Ts be the time indicated by the reference time information; and delayN be the adjustment amount for the Nth output timing. The timing adjustment unit is a pulse generator that calculates the adjustment amount for the Nth output timing using the formula "delayN = (N-1) × (Ts-Te) / M".

7. A pulse generation device according to claim 1 or claim 2, The timing adjustment unit is configured to determine a plurality of output timings between the time the detection signal is output most recently and the time the detection signal is output again. The timing adjustment unit is a pulse generation device that determines a plurality of output timings based on the same adjustment amount for each of the plurality of output timings.

8. A pulse generation device according to claim 7, Let Te be the time indicated by the aforementioned time information, Ts be the time indicated by the aforementioned reference time information, and let delay be the adjustment amount. The timing adjustment unit is a pulse generator that calculates the adjustment amount using the formula "delay = (Ts - Te) / 2".

9. A pulse generation device according to claim 1, The aforementioned driven object drives a transport device that moves an ink dispenser that ejects ink toward a sheet, The timing pulse is generated by a pulse generator that indicates the timing at which the ink is ejected by the ejector.

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