JP2008200970A - Led printer and printing control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an LED printer capable of adequately performing correction of jointing by using a divisional type LED head even when a photosensitive drum has eccentricity. <P>SOLUTION: This LED printer comprises the photosensitive drum rotating in a sub-scanning direction around a rotary shaft, the LED head which includes a first divisional LED head and a second divisional LED head and is provided so that the end parts of the first and second divisional LED heads are overlapped in a direction parallel to the main scanning direction and the first and second divisional LED heads are arranged at a prescribed interval, i.e., the LED head interval in the sub-scanning direction, a displacement sensor for detecting an amount of displacement of the LED head in the normal line direction of the rotary shaft along the surface of the photosensitive drum, and a printing control circuit that performs printing by controlling the printing timings of the first and second divisional LED heads according to the LED head interval and the displacement amount detected by the displacement sensor. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a printing control technique for an LED printer, and more particularly to a printing control technique for an LED printer that uses a divided LED head composed of a plurality of LED heads.

  A conventional LED printer will be described with reference to FIG.

  The printing process of the LED printer is such that an LED latent image is formed on the photosensitive drum 2 by flashing (exposing) an LED head provided against the photosensitive drum 2 based on the supplied print data. Then, the developing device 7 develops the toner by supplying toner onto the electrostatic latent image formed on the photosensitive drum 2, and the toner image formed by the development is transferred onto the paper 20 and attached by the transfer device. Is done. The registration roller 5 moves the paper 20 from the right to the left on the paper surface of FIG.

  Thereafter, the toner attached on the paper 20 is fixed to the paper 20 by the fixing device 6 to complete the printing. The LED printer is controlled by the print control circuit 10.

  Hereinafter, the same reference numerals are given to portions corresponding to the respective portions, and description thereof is omitted.

  In such an LED printer, for example, in a large format LED printer, an LED head having a length greater than or equal to the A1 width is required in order to cope with the size of a printing medium such as paper or film that is A1 size. And

  Since an LED head having a length of A1 width or more is expensive, in order to reduce the cost of the LED head, an LED head obtained by dividing the LED head into a plurality of parts (for example, 3 to 5 parts) in the main scanning direction, An LED head in which a plurality of (for example, 3 to 5) LED heads are arranged is used.

  Hereinafter, the LED head in which the LED head is divided in the main scanning direction and the LED head in which a plurality of small LED heads are arranged will be referred to as a divided LED head. An LED head that is not divided into a plurality of divisional LED heads in the main scanning direction will be referred to as a single-type LED head.

  An example of such a divided LED head will be described with reference to FIG. In the following description, it is assumed that the main scanning direction is the Y direction and the sub scanning direction is the X direction.

  The main scanning direction Y is the major axis direction of the split-type LED head 3, and the sub-scanning direction X is perpendicular to the main scanning direction Y and the surface of the photosensitive drum 2 rotates.

  Here, in the divided type LED head 3 (in the case of three divisions), the divided type LED head 3 arranged in the front with respect to the rotation direction of the photosensitive drum 2 is referred to as an LED head A31 and an LED head C33, and rearward. The arranged divided LED head 3 will be referred to as LED head B32.

  The divided LED head 3 in FIG. 7 includes a small LED head A31, an LED head B32, and an LED head C33. The LED head A31, LED head B32, and LED head C33 are arranged in parallel with each other in the main scanning direction Y, and each LED head is arranged with a part of the end overlapping in the sub-scanning direction X. A31 and the LED head C33 are at the same position in the sub-scanning direction X, and the LED head B32 is arranged so as not to overlap with the LED head A31 and the LED head C33 in the sub-scanning direction X.

  Thus, the split-type LED head 3 has a configuration in which small LED heads (LED head A31, LED head B32, and LED head C33) are arranged shifted in the main scanning direction Y and the sub-scanning direction X. . In the small LED head, each LED head is shifted by several mm to several cm in the sub-scanning direction X, and therefore the reference print position in the sub-scanning direction X is different.

  The reference print position is an irradiation position at which each LED head emits LED light for printing by the LED head, and is, for example, a center position in the sub-scanning direction X of the LED head.

  Since the reference print position in the sub-scanning direction X of each LED head is different, if printing is performed in the same manner as when using a single-type LED head, as shown in 81 to 84 in FIG. When a line drawn parallel to the line is printed, the line is shifted in the sub-scanning direction X at the joint between the LED head A31 and the LED head B32 and between the LED head B32 and the LED head C33.

  As described above, since the reference print positions of the LED heads in the sub-scanning direction X are different, by providing a connection correction circuit in the print control circuit 10 of each LED head, even when the split LED head 3 is used, the split type The deviation of the reference print position of each LED head included in the LED head 3 is corrected so that printing equivalent to that when a single LED head is used is obtained.

As such a technique, Patent Literature 1 or Patent Literature 2 is known.
JP 2001-183877 A JP 2001-219594 A

  However, although the split LED head 3 is provided along the surface of the photosensitive drum 2, the photosensitive drum 2 may have a slight eccentricity. By rotating the photosensitive drum 2 having the eccentricity, the position of the split LED head 3 with respect to the center of the photosensitive drum 2 is changed with respect to the rotation axis of the photosensitive drum 2 in accordance with the rotation of the photosensitive drum 2. Displacement in the normal direction.

  When the position of the divided LED head 3 with respect to the center of the photosensitive drum 2 is displaced, the time that the surface of the photosensitive drum 2 crosses the exposure points of the LED heads A31 to A33 that are arranged shifted in the sub-scanning direction X. Changes.

  Here, a deviation in the sub-scanning direction X between the LED head A31, the LED head B32, and the LED head C33 is defined as an LED head interval. The above meaning is that the time that the surface of the photosensitive drum 2 crosses the LED head interval varies.

  Thus, although the rotational speed of the photosensitive drum 2 is constant, when the position of the split LED head 3 is away from the central axis of the photosensitive drum 2 due to eccentricity, the photosensitive body immediately below the split LED head 3 is located. The peripheral speed of the drum 2 increases, and when it is close to the central axis, the peripheral speed of the photosensitive drum 2 immediately below the split LED head 3 decreases.

  Here, in the splicing correction circuit according to Patent Document 1 or Patent Document 2, splicing correction is performed assuming that the time that the surface of the photosensitive drum 2 crosses the LED head interval is constant.

  For this reason, the photosensitive drum 2 has an eccentricity. When the photosensitive drum 2 having the eccentricity rotates, the time for the surface of the photosensitive drum 2 to cross the LED head interval changes again. 8 has a problem that a shift as indicated by 81 to 84 occurs, and the normal connection correction cannot be performed.

  This phenomenon does not occur in the split type LED head 3 having a single structure.

  However, in the split type LED head 3, each of the split type LED heads 3 is arranged so as to be shifted in the sub-scanning direction X, that is, because there is an LED head interval, There has been a problem that the exposure timing is changed, and the shift of the connection due to the eccentric cycle of the photosensitive drum 2 is generated, thereby degrading the print image quality.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an LED printer that can perform normal connection correction using a split LED head even when there is an eccentricity of the photosensitive drum. It is to provide.

  The present invention has been made to solve the above-described problems. The invention according to claim 1 is a photosensitive drum that rotates in the sub-scanning direction about a rotation axis, a first partial LED head, and a second one. The first partial LED head and the second partial LED head overlap each other in parallel with the main scanning direction at predetermined intervals in the sub-scanning direction. A split-type LED head arranged at a certain LED head interval; a displacement sensor for detecting a displacement amount of the split-type LED head displaced in the normal direction of the rotation axis along the surface of the photosensitive drum; Printing that prints by adjusting the printing timing of printing by the first partial LED head and the second partial LED head according to the LED head interval and the displacement detected by the displacement sensor. And control circuit, an LED printer characterized by having a.

  According to a second aspect of the present invention, the print control circuit is configured such that the other partial LED head of the first partial LED head and the second partial LED head is used as a reference on the other side. 2. The LED printer according to claim 1, further comprising: a print timing calculation unit configured to calculate the print timing of the partial LED head as a delay time corresponding to the amount of displacement and adjust the print timing.

  According to a third aspect of the present invention, the print timing calculation unit includes a displacement amount print timing storage unit in which the delay time is stored in association with the displacement amount, and the displacement amount detected by the displacement sensor. The LED printer according to claim 2, wherein the delay time is calculated by reading out the corresponding delay time from the displacement amount print timing storage unit.

  According to a fourth aspect of the present invention, the LED printer includes a rotation position detection unit that detects a rotation position of the photosensitive drum, and a rotation position displacement amount storage unit that stores the rotation position and the displacement amount in association with each other. The print timing calculation unit includes a displacement amount print timing storage unit that stores the delay time in association with the displacement amount, and corresponds to the rotational position detected by the rotational position detection unit. 3. The delay time is calculated by reading a displacement amount from the rotational position displacement amount storage unit and reading a delay time corresponding to the read displacement amount from the displacement amount print timing storage unit. It is an LED printer of description.

  According to a fifth aspect of the invention, the print control circuit detects the amount of displacement of the photosensitive drum by the displacement sensor while detecting the rotational position of the photosensitive drum by the rotational position detector. The LED printer according to claim 4, further comprising a rotational position displacement amount setting unit that associates the rotational position and the displacement amount with each other and stores the rotational position and displacement amount in the rotational position displacement amount storage unit.

  According to a sixth aspect of the present invention, the displacement sensor detects a first displacement amount of the first partial LED head, and a second displacement amount of the second partial LED head. A second displacement sensor for detecting the first displacement of the first partial LED head according to the first displacement amount detected by the first displacement sensor. The LED according to any one of claims 1 to 5, wherein a printing timing of the second partial LED head is calculated according to the second displacement amount detected by the second displacement sensor. It is a printer.

  According to a seventh aspect of the invention, the displacement sensor detects the amount of displacement of the split LED head that is displaced in the normal direction of the rotation axis along the surface of the photosensitive drum. The LED printer according to any one of claims 1 to 6, wherein a displacement of a surface position of the rotating photosensitive drum at a position facing the split LED head is detected as the displacement amount.

  According to an eighth aspect of the present invention, the displacement sensor is disposed at one end in the rotation axis direction of the photosensitive drum, and detects the displacement of the surface position of the rotating photosensitive drum as the displacement amount. A second displacement sensor that is disposed at the other end of the photosensitive drum in the rotation axis direction and detects a displacement of a surface position of the rotating photosensitive drum as the displacement amount, and the printing control. The circuit calculates the print timing of the first partial LED head according to the first displacement amount detected by the first displacement sensor, and sets the second displacement amount detected by the second displacement sensor. 8. The LED printer according to claim 7, wherein the printing timing of the second partial LED head is calculated accordingly.

  According to a ninth aspect of the present invention, the LED printer delays one of print data simultaneously printed by the first partial LED head and the second partial LED head according to the LED head interval. The LED printer according to any one of claims 1 to 8, further comprising a print data delay unit that stores the print data.

  A tenth aspect of the present invention includes a photosensitive drum that rotates in the sub-scanning direction about a rotation axis, a first partial LED head, and a second partial LED head, and the first partial LED head. And the second partial LED head, with the end portions overlapping each other in parallel to the main scanning direction, and the divided LED heads arranged at LED head intervals that are predetermined intervals in the sub-scanning direction; A print control method for an LED printer, comprising: a print control circuit that prints by adjusting a print timing at which the first partial LED head and the second partial LED head print. A split sensor for detecting the amount of displacement of the split LED head along the surface of the body drum in the normal direction of the rotating shaft is provided, and the print control circuit includes the LE A printing control method, wherein printing timing for printing by the first partial LED head and the second partial LED head is adjusted according to a head interval and a displacement amount detected by the displacement sensor. It is.

  According to this invention, the LED printer using the split type LED head has the displacement sensor for detecting the displacement of the split type LED head due to the eccentricity of the photosensitive drum, and the displacement amount detected by the displacement sensor is adjusted. Accordingly, by adjusting the printing timing of the split type LED head, even when the photosensitive drum is decentered, there is an effect that the printing misalignment is eliminated and the deterioration of the printing image quality can be suppressed.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic block diagram showing the configuration of an LED printer according to an embodiment of the present invention.

  In the LED printer of FIG. 1, the print control circuit 10 of FIG. 6 is replaced with the print control circuit 1, and the other configuration is the same as the configuration of the LED printer of FIG. In the following, the configuration of the LED printer of FIG. 1 will be described focusing on differences from the configuration of the LED printer of FIG.

  The LED printer shown in FIG. 1 includes a print control circuit 1, a photosensitive drum 2, a split LED head 3, and a displacement sensor 4.

  The photosensitive drum 2 rotates at a constant rotation speed in the sub-scanning direction X around the rotation axis. In the present invention, the photosensitive drum 2 is not a perfect circle but an ellipse or the like in rotation, and may have an eccentricity.

  For example, the photosensitive drum 2 rotates at a constant rotation speed and is synchronized with LINECLK generated by a LINECLK generation circuit 109 described later.

  The LINECLK number is counted by the LINECLK counter circuit 108. Therefore, the rotation angle of the photosensitive drum 2 can be calculated by multiplying the LINECLK counter circuit 108 by the count value of the number of LINECLKs and a certain rotation angle according to the input of LINECLK.

  The split-type LED head 3 includes a first partial LED head and a second partial LED head, and the first partial LED head and the second partial LED head end to each other in parallel to the main scanning direction Y. The LED heads are arranged at predetermined intervals in the sub-scanning direction X, with the portions overlapping. The LED head interval of the predetermined interval is a predetermined LED head interval.

  In the first partial LED head and the second partial LED head, the first partial LED head in FIG. 7 is the LED head A31 and the LED head C33, and the second partial LED head is the LED head B32.

  Alternatively, the first partial LED head and the second partial LED head are the first partial LED head of FIG. 7 is the LED head B32, and the second partial LED head is the LED head A31 and the LED head C33. It is.

  The split LED head 3 prints print data inputted from the outside by exposing the print data on the surface of the photosensitive drum 2 under the control of the print control circuit 1.

  The displacement sensor 4 detects a displacement amount by which the split LED head 3 is displaced in the normal direction of the rotation axis of the photosensitive drum 2 along the surface of the photosensitive drum 2.

  For example, the displacement sensor 4 outputs a displacement amount of the split LED head 3 from the central axis of the photosensitive drum 2 due to the eccentricity of the photosensitive drum 2 as a displacement amount in a voltage data (voltage value) format. Moreover, the displacement sensor 4 detects and outputs the displacement amount of the split-type LED head 3 at regular time intervals, for example.

  The displacement sensor 4 is installed in the vicinity of the split LED head 3 in order to detect a change in the position of the split LED head 3 from the center of the photosensitive drum 2 caused by the eccentricity of the photosensitive drum 2. The position is fixed in the printer.

  The displacement sensor 4 is a displacement sensor using light such as laser light, for example. The displacement sensor 4 is preferably one that can detect the amount of displacement without disturbing the operation of the split-type LED head 3.

  The print control circuit 1 determines the print timing for printing by the first partial LED head and the second partial LED head in accordance with the LED head interval of the split LED head 3 and the displacement amount detected by the displacement sensor 4. Adjust and print.

  Next, an outline of the operation of the LED printer of FIG. 1 will be described.

  First, the displacement sensor 4 detects a displacement amount by which the split LED head 3 is displaced in the normal direction of the rotation axis along the surface of the photosensitive drum 2, and outputs it to the print control circuit 1.

  Next, the print control circuit 1 adjusts the print timing at which the first partial LED head and the second partial LED head print according to the LED head interval and the displacement amount detected by the displacement sensor 4. Print.

  Next, the configuration of the print control circuit 1 will be described with reference to FIG.

The print control circuit 1 includes a CPU 101, a RAM 102, a ROM 103, a conversion table storage unit 104, an A / D conversion circuit 105, an AC delay register circuit 106, a B delay register circuit 107,
It includes a LINECLK counter circuit 108, a LINECLK generation circuit 109, an AC delay counter circuit 110, a B delay counter circuit 111, an LED head B delay circuit 112, an LED head control circuit 130, and an LED head FIFO circuit 120.

  The LED head B delay circuit 112 (print data delay unit) delays one of the print data simultaneously printed by the first partial LED head and the second partial LED head according to the LED head interval.

  For example, the LED head B delay circuit 112 delays only the print data printed by the LED head B32 by 90 lines in the print data input from the outside.

  The LED head FIFO circuit 120 (print data delay unit) uses the LED head B delay circuit 112 to print one of the print data simultaneously printed by the first partial LED head and the second partial LED head according to the LED head interval. Delay and memorize.

  The LED head FIFO circuit 120 is a circuit that temporarily holds print data. The LED head FIFO circuit 120 is configured as a FIFO (First In, First Out) circuit.

  The LED head FIFO circuit 120 includes an LED head AFIFO circuit 121, an LED head B FIFO circuit 122, and an LED head CFIFO circuit 123.

  The LED head AFIFO circuit 121 is a FIFO circuit that stores the print data of the LED head A31. The LED head B FIFO circuit 122 is a FIFO circuit that stores the print data of the LED head B32. The LED head CFIFO circuit 123 is LED head C33 is a FIFO circuit for storing print data.

  The LED head AFIFO circuit 121, the LED head BFIFO circuit 122, and the LED head CFIFO circuit 123 are circuits having the same configuration.

  As shown in FIG. 1, when there is only the LED head B delay circuit 112 that delays the print data to be printed by the LED head B32, the LED head AFIFO circuit 121 and the LED head CFIFO circuit 123 have print data without delay. The LED head BFIFO circuit 122 stores print data delayed according to the LED head interval.

  For example, when the LED head B delay circuit 112 delays print data input from the outside by 90 lines of only the print data printed by the LED head B32, the LED head AFIFO circuit 121 and the LED head CFIFO circuit 123 Assuming that print data with line number M (where M is a natural number) is stored without delay, the LED head BFIFO circuit 122 stores the line number (M + 90) of the delayed print data. Is stored.

  As described above, the LED head FIFO circuit 120 stores the print data delayed according to the LED head interval for each of the LED head A31, the LED head B32, and the LED head C33, and the stored print data is simultaneously printed. As a result, even when there is an LED head interval, the LED printer can perform connection correction. In the present invention, not only the stored print data is printed at the same time, but also the LED head A31, LED head B32, and LED head C33 according to the displacement amount of the divided LED head 3, as will be described later. By adjusting the printing timing, it is possible to perform printing without any misalignment of printing even when the photosensitive drum is eccentric.

  The A / D conversion circuit 105 converts the displacement amount in the voltage data format from the displacement sensor 4 into a displacement amount in the numerical data format and outputs the displacement amount to the print control circuit 1.

  That is, the A / D conversion circuit 105 converts the displacement amount in the voltage data format output from the displacement sensor 4 according to the rotation of the photosensitive drum 2 into the displacement amount in the numerical data format for processing by the CPU 101.

  The CPU 101 (print timing calculation unit) calculates the print timing at which each of the first partial LED head and the second partial LED head prints according to the amount of displacement.

  As will be described later, the CPU 101 uses the conversion table T1 stored in the conversion table storage unit 104 to print the displacement amount of the divided LED head 3 converted into the numerical data format. Convert to timing.

  For example, the CPU 101 reads the print timing corresponding to the displacement amount from the conversion table T <b> 1 stored in the conversion table storage unit 104.

  The LED head control circuit 130 controls the reading from the LED head FIFO circuit 120 and the exposure timing of the divided LED head 3 according to the eccentricity of the photosensitive drum 2 under the control of the CPU 101.

  Note that the print timing is a timing including a read timing from the LED head FIFO circuit 120 and an exposure timing at which the split LED head 3 is exposed.

The LED head control circuit 130 (print control unit) is configured to print the print data stored in the LED head FIFO circuit 120 (print data delay unit) at each print timing calculated by the CPU 101 (print timing calculation unit). The conversion table storage unit 104 (displacement amount printing timing storage unit) is a circuit that makes the exposure timing variable by printing with the partial LED head and the second partial LED head. And the second partial LED head, the delay time of the printing timing of the other partial LED head is stored as the conversion table T1 in association with the displacement with reference to the printing timing of one of the partial LED heads. .

  As an example, a conversion table T1 stored in the conversion table storage unit 104 will be described with reference to FIG.

  Here, the displacement amount is set to 0 on the basis of the displacement amount when the photosensitive drum 2 is a perfect circle, and the split LED head 3 is located farther from the reference than the rotation axis of the photosensitive drum 2. In the following description, it is assumed that the sign of the displacement amount is positive, and conversely, the sign of the displacement amount when the split LED head 3 is positioned closer to the reference from the rotation axis of the photosensitive drum 2 is negative.

  In the conversion table T1, the displacement amount, the number of delay lines of the LED head A31 and the LED head C33, and the displacement amount and the number of delay lines of the LED head B32 are stored in association with each other. Here, the conversion table T1 is shown as a diagram.

  For example, when the displacement is 0.5 mm, the LED head A31 and the LED head C33 are delayed by one line from the reference, and the LED head B32 is stored in the conversion table T1 as having no delay (0). ing. When the displacement is 1.0 mm, the LED head A31 and the LED head C33 are delayed by 2 lines from the reference, and the LED head B32 is stored in the conversion table T1 as having no delay (0). ing.

  That is, in the conversion table T1, when the displacement amount is positive, the delay time between the LED head A31 and the LED head C33 is stored in association with the displacement amount based on the printing timing of the LED head B32.

  On the contrary, when the displacement amount is −0.5 mm, the LED head A31 and the LED head C33 are set to have no delay (0), and the LED head B32 has a delay of one line delay. It is remembered. When the displacement amount is −1.0 mm, the LED head A31 and the LED head C33 have no delay (0), and the LED head B32 has two delay lines in the conversion table T1. It is remembered.

  That is, in the conversion table T1, when the displacement amount is negative, the delay time of the LED head B32 based on the printing timing of the LED head A31 and the LED head C33 is stored in association with the displacement amount.

  As shown in FIG. 3, the conversion table T1 is continuously stored between −1.0 mm and 1.0 mm even when the displacement is a value other than 1.0 mm or 1.0 mm. Yes. The range of the amount of displacement is not limited to the above range, but is arbitrary.

  The CPU 101 reads out the printing timing of the first partial LED head or the printing timing of the second partial LED head corresponding to the displacement amount from the conversion table T1, thereby the first partial LED head or the second partial LED. The print timing of the head is calculated.

  That is, the CPU 101 sets the line delay amount (delay time) between the LED head A31 and the LED head C33 based on the LED head B32 according to the displacement amount, or the LED head A31 and the LED head C33 according to the displacement amount. The line delay amount (delay time) of the LED head B32 as a reference is calculated and output.

  Returning to the description of FIG. 2, the AC delay register circuit 106 is a storage unit that stores the line delay amount of the LED head A <b> 31 and the LED head C <b> 33 according to the displacement amount calculated by the CPU 101.

  The B delay register circuit 107 is a storage unit that stores the line delay amount of the LED head B32 calculated by the CPU 101 in accordance with the displacement amount.

  The LINECLK generation circuit 109 generates LINECLK for executing printing as a pulse at regular intervals. This LINECLK is also used as a reference pulse for rotating the photosensitive drum 2.

  For example, the LINECLK generation circuit 109 counts clocks input from the outside, and outputs LINECLK as a pulse when it is detected that the value of the counted number of clocks matches a predetermined value. The LINECLK generating circuit 109 resets the counted number of clocks to 0 after outputting LINECLK as a pulse.

  The LINECLK counter circuit 108 counts the LINECLK pulses generated by the LINECLK generation circuit 109 and stores the counted value.

  The AC delay counter circuit 110 counts clocks input from the outside, and the line delay between the LED head A31 and the LED head C33 according to the counted clock value and the amount of displacement stored in the AC delay register circuit 106. When the values match, the control signal AC is transmitted to the LED head control circuit 130, and the counted clock value is reset to zero.

  The B delay counter circuit 111 counts clocks input from the outside, and compares the counted clock value with the line delay amount of the LED head B32 corresponding to the displacement amount stored in the B delay register circuit 107. If they match, the control signal B is transmitted to the LED head control circuit 130, and the counted clock value is reset to zero.

  When the control signal AC from the AC delay counter circuit 110 or the control signal B from the B delay counter circuit 111 is input, the LED head control circuit 130, in accordance with the input control signal AC or control signal B, After the LED head FIFO circuit 120 outputs an LED head load signal for transmitting print data to the split-type LED head 3 and the transmission of the print data from the LED head FIFO circuit 120 to the split-type LED head 3 is completed, the split is performed. The LED head exposure signal for exposing the type LED head 3 is output to the divided type LED head 3.

  The LED head control circuit 130 includes an LED head A control circuit 131, an LED head B control circuit 132, and an LED head C control circuit 133.

  The LED head A control circuit 131 is a control circuit for controlling the LED head A31, the LED head B control circuit 132 is a control circuit for controlling the LED head B32, and the LED head C control circuit 133 is And a control circuit for controlling the LED head C33.

  The LED head A control circuit 131, the LED head B control circuit 132, and the LED head C control circuit 133 are control circuits having the same configuration.

  However, the control signal AC from the AC delay counter circuit 110 is input to the LED head A control circuit 131 and the LED head C control circuit 133, and the control from the B delay counter circuit 111 is input to the LED head B control circuit 132. The difference is that the signal B is input.

  The RAM 102 is a memory device that provides a volatile memory area that the CPU 101 uses for calculations and the like. The RAM 102 is, for example, a RAM (Random Access Memory).

  The ROM 103 is a memory device that provides a nonvolatile memory area in which a program executed by the CPU 101 or the like is stored. The ROM 103 is, for example, a ROM (Read Only Memory).

  Here, the displacement sensor 4 is described as outputting the detected displacement as voltage data and digitizing the voltage data by the A / D conversion circuit 105. However, the present invention is not limited to this. The displacement sensor 4 and the A / D conversion circuit 105 may be integrally formed, and the displacement sensor 4 may output the detected displacement as numeric data.

  Next, the operation of the LED printer having the print control circuit 1 will be described.

  The photosensitive drum 2 rotates at a predetermined rotational speed around the rotation axis, and the displacement sensor 4 positioned in the vicinity of the divisional LED head 3 provided opposite to the photosensitive drum 2 is accompanied by the rotation and eccentricity of the photosensitive drum 2. The position information of the divided LED head 3 is output as voltage data, and the A / D conversion circuit 105 provided in the print control circuit converts the voltage data of the position information into numerical data and is read by the CPU 101.

  The CPU 101 converts the numerical data indicating the position change into a print timing (delay time) that determines the exposure timing of the split LED head 3 using the conversion table T1 stored in the conversion table storage unit 104.

  Next, based on the converted print timing (delay time), the CPU 101 controls the exposure timing of the LED head FIFO circuit 120 temporarily holding the print data and the divided LED head 3 by the LED head control circuit 130. And control of splice correction in printing of the divided LED head 3 is performed.

  Next, the control operations of the LED head control circuit 130, the LED head FIFO circuit 120, and the distributed division type LED head 3 will be described in detail.

  The LED head control circuit 130, the LED head FIFO circuit 120, and the distributed division type LED head 3 have the same configuration with respect to the LED head A31, the LED head B32, and the LED head C33, respectively.

  Therefore, only the LED head A control circuit 131 of the LED head control circuit 130 and the LED head AFIFO circuit 121 of the LED head FIFO circuit 120 for the LED head A31 will be described here.

  In response to the input of the control signal AC from the AC delay counter circuit 110, the LED head A control circuit 131 outputs an LED head A load signal having a certain time length to the LED head AFIFO circuit 121 and the LED head A31. After the LED head A load signal is output, the LED head A exposure signal is output to the LED head A31.

  The fixed time length of the LED head A load signal output from the LED head A control circuit 131 is a time length determined by the time length for transferring print data from the LED head AFIFO circuit 121 to the LED head A31. .

  The LED head AFIFO circuit 121 transmits the stored print data to the LED head A31 in response to the input of the LED head A load signal from the LED head A control circuit 131. The transmitted print data is deleted from the LED head AFIFO circuit 121.

  On the other hand, in response to the LED head A load signal being input from the LED head A control circuit 131, the LED head A31 sends the print data transmitted from the LED head AFIFO circuit 121 to the storage unit inside the LED head A31. Remember.

  Next, in response to the LED head A exposure signal being input from the LED head A control circuit 131, the LED head A31 exposes the print data stored in the storage unit inside the LED head A31 to the photosensitive drum 2. .

Next, regarding the operation of the print control circuit 1 of the present invention, the displacement amount value detected by the displacement sensor 4 will be described in three cases.
<First case: When the displacement amount is 0>
When the split type LED head 3 is at the reference position of the photosensitive drum 2, that is, when the displacement amount is 0, the peripheral speed of the photosensitive drum 2 is the reference speed, so that the LED head A31 and the LED head The operation of the print correction circuit of C33 and LED head B32 performs the reading of data from the FIFO circuit temporarily holding the print data and the exposure timing of LED head A31, LED head C33, and LED head B32 at the reference timing.

That is, the printing timing of the LED head A31 and the LED head C33 and the printing timing of the LED head B32 coincide.
<Second case: When displacement is positive>
Next, when the split LED head 3 is positioned away from the rotation axis of the photosensitive drum 2, that is, when the displacement amount is positive, the peripheral speed of the photosensitive drum 2 is increased. The time for the surface of the photosensitive drum 2 to cross between the LED head A31 and the LED head C33 to the LED head B32 is shortened.

  In this case, a print correction circuit (LED head A control circuit 131 and LED head C control circuit 133) provided in LED head A31 and LED head C33 is a FIFO circuit (LED head AFIFO circuit) that temporarily holds print data. 121 and the LED head CFIFO circuit 123), the LED head B32 converts the data read timing from the LED head (LED head A31 and LED head C33) and the exposure timing given to the LED head A31 and LED head C33 according to the conversion table T1. Is delayed from the readout timing and the exposure timing.

  As a result, it is possible to perform print correction that brings the exposure timing of the LED head A31 and the LED head C33 closer to the exposure timing of the LED head B32.

  Therefore, even when the divided LED head 3 is positioned away from the rotation axis of the photosensitive drum 2, the printing can be normally connected.

FIG. 4 shows an example of the print control circuit 1 when the split type LED head 3 described above is positioned away from the rotation axis of the photosensitive drum 2.
<Third case: When displacement is negative>
Conversely, when the split LED head 3 is positioned close to the rotation axis of the photosensitive drum 2, that is, when the displacement amount is negative, the peripheral speed of the photosensitive drum 2 is slow. The time that the surface of the photosensitive drum 2 crosses from the LED head A31 and the LED head C33 to the LED head B32 becomes longer.

  In this case, the print correction circuit (LED head B control circuit 132) provided in the LED head B32 reads the data from the FIFO circuit (LED head BFIFO circuit 122) temporarily holding the print data, and the LED head. The exposure timing given to B32 is delayed from the read timing and exposure timing of the LED head A31 and the LED head C33 according to the conversion table T1.

  Accordingly, it is possible to perform print correction that separates the exposure timing of the LED head B32 with reference to the exposure timing of the LED head A31 and the LED head C33.

  Therefore, even when the divided LED head 3 is positioned close to the rotation axis of the photosensitive drum 2, the printing can be normally connected.

  FIG. 5 shows an example of the print control circuit 1 when the split type LED head 3 described above is positioned close to the rotation axis of the photosensitive drum 2.

  As described above, in the present invention, one of the first partial LED head (for example, LED head A31 and LED head C33) and the second partial LED head (for example, LED head B32) is used. Based on the print timing of the partial LED head, the print timing of the other partial LED head is calculated as a delay time according to the displacement, and the print of the other partial LED head is calculated for the print of one partial LED head. Print with a delay of the specified delay time.

  As a result, when printing is performed with an LED printer using a split LED head, even when the photosensitive drum 2 is decentered, there is no printing misalignment, and the print quality can be prevented from deteriorating. .

  Note that the printing timing of one of the partial LED heads (for example, LED head A31 and LED head C33) and the second partial LED head (for example, LED head B32) is used as a reference. The printing timing of the other partial LED head is calculated as a time earlier than the reference according to the displacement, and the printing of the other partial LED head is printed earlier than the printing time of the other partial LED head. May be.

  As a result, when printing is performed with an LED printer using a split LED head, even when the photosensitive drum 2 is decentered, there is no printing misalignment, and the print quality can be prevented from deteriorating. .

  The CPU 101 calculates the printing timing of the first partial LED head or the printing timing of the second partial LED head according to the input displacement amount by a predetermined function according to the input displacement amount. You may make it do.

  Note that this predetermined function is stored in the ROM 103, for example.

  Further, the print control circuit 1 includes a rotational position displacement amount storage unit that stores the rotational position and displacement amount of the photosensitive drum 2 in association with each other, and the CPU 101 uses the rotational position displacement amount storage unit. The print timing may be calculated.

  For example, the print control circuit 1 includes a rotation position detection unit that detects the rotation position of the photosensitive drum 2 and a rotation position displacement amount storage unit that stores the rotation position and the displacement amount in association with each other. .

  This rotational position detector is, for example, a LINECLK counter circuit.

  Next, the CPU 101 reads out the displacement amount corresponding to the rotational position detected by the rotational position detection unit from the rotational position displacement amount storage unit, and reads out the delay time corresponding to the read displacement amount from the displacement amount print timing storage unit. The delay time may be calculated.

  In addition, the LED printer has a rotational position displacement amount setting unit, and the rotational position displacement amount setting unit responds, for example, at the start of the LED printer, at regular intervals, immediately before starting printing. Alternatively, the displacement position of the photosensitive drum 2 is detected by the displacement sensor 4 while the rotational position of the photosensitive drum 2 is detected by the rotational position detection unit in response to an input of a human operation, and the detected rotational position and displacement are detected. The rotational position displacement amount storage unit may be stored in association with the amount.

  As described above, the CPU 101 calculates the printing timing using the rotational position displacement amount storage unit, and thus there is an effect that it is not necessary to always operate the displacement sensor 4 during printing. Further, for example, the LED printer has the effects of improving power consumption and preventing the displacement sensor 4 from being deteriorated.

  In addition, the displacement sensor 4 is not provided in the center for the split-type LED head 3, but is provided for the LED head A31, the LED head B32, and the LED head C33, so that the position detection accuracy of each LED head can be improved. It is also possible to make detailed corrections.

  For example, the displacement sensor 4 detects the first displacement amount of the first partial LED head, and the second displacement sensor detects the second displacement amount of the second partial LED head. , So that it has.

  Next, the print control circuit 1 calculates the print timing of the first partial LED head according to the first displacement amount detected by the first displacement sensor, and the second displacement detected by the second displacement sensor. The printing timing of the second partial LED head is calculated according to the amount.

  Further, instead of detecting the displacement of the LED head by the displacement sensor 4, the displacement of the surface position of the photosensitive drum 2 may be directly detected by the displacement sensor 4.

  For example, the displacement sensor 4 is positioned to face the divided LED head 3 instead of detecting the displacement amount of the divided LED head 3 that is displaced along the surface of the photosensitive drum 2 in the normal direction of the rotation axis. The displacement of the surface position of the rotating photosensitive drum 2 is detected as a displacement amount.

  As described above, when the displacement sensor 4 detects the displacement of the surface position of the photosensitive drum 2 as a displacement amount, for example, the split LED head 3 is fixed to the LED printer, and the split LED head 3 is Even when the photosensitive drum 2 is not displaced along the surface of the photosensitive drum 2 in the normal direction of the rotation axis of the photosensitive drum 2, the eccentricity of the photosensitive drum 2 is detected, and as described above, the photosensitive drum It is possible to print without being affected by the eccentricity of 2.

  When the displacement sensor 4 detects the displacement of the surface position of the rotating photosensitive drum 2 at the position facing the split LED head 3 as the displacement amount, for example, the displacement sensor 4 is detected by the photosensitive drum 2. And a second displacement sensor disposed at the other end of the photosensitive drum 2 in the rotation axis direction.

  Further, the print control circuit 1 calculates the print timing of the first partial LED head according to the first displacement amount detected by the first displacement sensor, and the second displacement amount detected by the second displacement sensor. The printing timing of the second partial LED head is calculated accordingly.

  By doing so, the displacement sensor 4 detects the displacement of the surface position of the photosensitive drum 2 without the light that detects the displacement output by the displacement sensor 4 affecting the photosensitive drum 2 that performs printing. It can be detected as a displacement amount.

  Moreover, you may detect the displacement of the split-type LED head 3 with an acceleration sensor as the displacement sensor 4. FIG. When an acceleration sensor is used, the acceleration detected by the acceleration sensor is integrated with respect to time to be detected as a displacement.

  As described above, any sensor can be used as the displacement sensor 4 as long as it is a sensor capable of detecting the displacement of the split LED head 3.

  The conversion table storage unit 104 is a non-volatile memory such as a hard disk device, a magneto-optical disk device, or a flash memory, a storage medium such as a CR-ROM that can only be read, and a volatile memory such as a RAM (Random Access Memory) Memory or a combination of these.

  Note that the print control circuit 1 in FIG. 1 may be realized by dedicated hardware, or may be realized by a memory and a microprocessor.

  Also, a program for realizing each function of the print control circuit 1 shown in FIG. 2 is recorded on a computer-readable recording medium, and a program for realizing the function of the processing unit in the print control circuit 1 is stored in the computer. The processing executed by the print control circuit 1 may be performed by recording the program on a readable recording medium, causing the computer system to read and execute the program recorded on the recording medium. Here, the “computer system” may include an OS and hardware such as peripheral devices. Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used. The “computer-readable recording medium” means a flexible disk, a magneto-optical disk, a ROM, a writable nonvolatile memory such as a flash memory, a portable medium such as a CD-ROM, a hard disk built in a computer system, etc. This is a storage device.

  In the present invention, the LED printer has been described. However, the present invention is not limited to this, and the present invention can be applied to a printer using a drum having a plurality of print heads.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design and the like within a scope not departing from the gist of the present invention.

  The present invention is suitable for use in a printer, particularly a printer using a drum having a plurality of print heads.

It is a block diagram which shows the structure of the LED printer by one Embodiment of this invention. FIG. 2 is a configuration diagram illustrating a configuration of a print control circuit in FIG. 1. It is the graph which illustrated the conversion table as an example. It is a sequence diagram of a print control circuit when the amount of displacement is positive. It is a sequence diagram of a print control circuit when the amount of displacement is negative. It is a block diagram which shows the structure of the conventional LED printer. It is a block diagram which shows the structure of the division | segmentation print head as an example. It is a printing result figure which shows the example of the printing result of the conventional LED printer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 10 Print control circuit 2 Photosensitive drum 3 Split type LED head 4 Displacement sensor 5 Registration roller 6 Fixing device 7 Developing device 20 Paper 31 LED head A
32 LED head B
33 LED head C
101 CPU
102 RAM
103 ROM
104 Conversion Table Storage Unit 105 A / D Conversion Circuit 106 AC Delay Register Circuit 107 B Delay Register Circuit 108 LINECLK Counter Circuit 109 LINECLK Generation Circuit 110 AC Delay Counter Circuit 111 B Delay Counter Circuit 112 LED Head B Delay Circuit 120 LED Head FIFO Circuit 121 LED Head AFIFO Circuit 122 LED Head B FIFO Circuit 123 LED Head CFIFO Circuit 130 LED Head Control Circuit 131 LED Head A Control Circuit 132 LED Head B Control Circuit 133 LED Head C Control Circuit

Claims (10)

A photosensitive drum that rotates in the sub-scanning direction about the rotation axis;
A first partial LED head and a second partial LED head, wherein the first partial LED head and the second partial LED head overlap each other in parallel to the main scanning direction, A split type LED head arranged at an LED head interval which is a predetermined interval in the sub-scanning direction;
A displacement sensor that detects the amount of displacement of the split LED head in the normal direction of the rotation axis along the surface of the photosensitive drum;
A print control circuit that prints by adjusting the print timing of printing by the first partial LED head and the second partial LED head according to the LED head interval and the displacement detected by the displacement sensor; ,
An LED printer comprising: The print control circuit is
Based on the print timing of one of the first partial LED heads and the second partial LED head as a reference, the print timing of the other partial LED head is a delay time corresponding to the amount of displacement. A printing timing calculation unit for adjusting the printing timing,
The LED printer according to claim 1, comprising: The print timing calculation unit
A displacement amount print timing storage unit in which the delay time is stored in association with the displacement amount;
Calculating the delay time by reading out the delay time corresponding to the displacement detected by the displacement sensor from the displacement printing timing storage unit;
The LED printer according to claim 2. The LED printer is
A rotational position detector for detecting a rotational position of the photosensitive drum;
A rotational position displacement amount storage unit in which the rotational position and the displacement amount are stored in association with each other;
Have
The print timing calculation unit
A displacement amount print timing storage unit in which the delay time is stored in association with the displacement amount;
The amount of displacement corresponding to the rotational position detected by the rotational position detection unit is read from the rotational position displacement amount storage unit, and the delay time corresponding to the read amount of displacement is read from the displacement amount print timing storage unit to thereby delay the delay. Calculate the time,
The LED printer according to claim 2. The print control circuit is
While detecting the rotational position of the photosensitive drum with the rotational position detecting unit, the displacement amount of the photosensitive drum is detected with the displacement sensor, and the rotational position displacement amount is associated with the detected rotational position and displacement amount. A rotational position displacement amount setting unit to be stored in the storage unit;
The LED printer according to claim 4. The displacement sensor is
A first displacement sensor for detecting a first displacement amount of the first partial LED head;
A second displacement sensor for detecting a second displacement amount of the second partial LED head;
Have
The print control circuit is
Printing timing of the first partial LED head is calculated according to the first displacement amount detected by the first displacement sensor, and according to the second displacement amount detected by the second displacement sensor. Calculating the printing timing of the second partial LED head;
The LED printer according to any one of claims 1 to 5, wherein The displacement sensor is
Instead of detecting the amount of displacement of the split LED head that is displaced in the normal direction of the rotation axis along the surface of the photosensitive drum, the rotating photosensitive at a position facing the split LED head. Detecting the displacement of the surface position of the body drum as the displacement amount;
The LED printer according to claim 1, wherein: The displacement sensor is
A first displacement sensor disposed at one end of the photosensitive drum in the rotation axis direction and detecting a displacement of a surface position of the rotating photosensitive drum as the displacement amount;
A second displacement sensor disposed at the other end of the photosensitive drum in the rotation axis direction and detecting a displacement of a surface position of the rotating photosensitive drum as the displacement amount;
Have
The print control circuit is
The printing timing of the first partial LED head is calculated according to the first displacement amount detected by the first displacement sensor, and the second displacement sensor detects the second displacement amount. Calculating the printing timing of the second partial LED head;
The LED printer according to claim 7. The LED printer is
A print data delay unit for storing any one of print data simultaneously printed by the first partial LED head and the second partial LED head in accordance with the LED head interval;
The LED printer according to claim 1, further comprising: A photosensitive drum that rotates in the sub-scanning direction about the rotation axis;
A first partial LED head and a second partial LED head, wherein the first partial LED head and the second partial LED head overlap each other in parallel to the main scanning direction, A split type LED head arranged at an LED head interval which is a predetermined interval in the sub-scanning direction;
A print control circuit that prints by adjusting a print timing at which the first partial LED head and the second partial LED head print;
A printing control method for an LED printer having
The LED printer has a displacement sensor that detects a displacement amount along which the split LED head is displaced in the normal direction of the rotation axis along the surface of the photosensitive drum.
The print control circuit is
Adjusting the printing timing at which the first partial LED head and the second partial LED head print according to the LED head interval and the amount of displacement detected by the displacement sensor;
The printing control method characterized by the above-mentioned.

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