JP3657443B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus configured to control printing timing when an image is formed on a recording sheet using a detecting unit such as a linear encoder.
[0002]
[Prior art]
As a conventional image forming apparatus, for example, a linear encoder composed of a linear scale and a linear sensor is used as a detection means, and the print timing for instructing the start of printing when an image is formed on recording paper is controlled. Ink jet printers are known.
[0003]
FIG. 1 shows a schematic configuration diagram of a main part of such an ink jet printer. The ink jet printer is a conveyance direction of the recording paper 100 (the longitudinal direction of the recording paper 100, hereinafter referred to as “sub-scanning direction”). ) (In the width direction of the recording paper 100, hereinafter referred to as “main scanning direction”), a guide rail 102 is provided, and the guide rail 102 is supported by a carriage 104. Has been. The carriage 104 is driven by a carriage motor (not shown) and is movable on the guide rail 102 in the main scanning direction.
[0004]
The carriage 104 is provided with a print head 106 for forming an image on the recording paper 100 by an ink jet method so as to face the recording paper 100. Accordingly, when the carriage 104 moves in the main scanning direction, the print head 106 disposed on the carriage 104 is also moved in the main scanning direction together with the carriage 104.
[0005]
Further, the inkjet printer is provided with a linear scale 108 that constitutes a linear encoder in parallel with the guide rail 102, that is, in parallel with the main scanning direction that is the moving direction of the carriage 104.
[0006]
Here, the linear scale 108 is formed with slits 108a having a predetermined width W at predetermined intervals (see FIG. 2A). Such a linear scale 108 can be created by, for example, a technique of printing a slit 108a on a film.
[0007]
The slit 108a is formed in a rectangular shape having two sides extending in a direction orthogonal to the main scanning direction in the ground region 108b of the linear scale 108.
[0008]
Further, the carriage 104 is provided with a linear sensor 110 (see FIG. 2A) including a first sensor 110a and a second sensor 110b constituting a linear encoder. 108 slits 108a are detected.
[0009]
Here, the first sensor 110a and the second sensor 110b are arranged in alignment along the main scanning direction.
[0010]
In this ink jet printer, the recording paper 100 is conveyed in the sub-scanning direction, and the carriage 104 is moved in the main scanning direction. At this time, the linear sensor 110 is connected to the linear scale 108. The slit 108a is detected, and the printing timing indicating the start of printing on the recording paper 100 by the print head 106 is controlled according to the detection of the slit 108a. The print head 106 starts to discharge ink onto the recording paper 100 at the printing timing thus controlled, and an image is formed on the recording paper 100.
[0011]
Such control is performed by a control unit (not shown) configured by a CPU that controls the entire apparatus of the inkjet printer.
[0012]
Next, the operation of the above-described conventional image forming apparatus will be described in detail with reference to FIG. 2 and FIG.
[0013]
Here, FIG. 2A is an explanatory diagram conceptually showing the linear scale 108 in which the slit 108a is formed and the linear sensor 110 including the first sensor 110a and the second sensor 110b, and FIG. 2 is a timing chart of an output signal (hereinafter referred to as “A-phase output”) indicating a detection state of the slit 108a by the first sensor 110a (the timing chart shown in FIG. 2B is a linear chart of FIG. 2A). FIG. 2C is a timing chart of an output signal (hereinafter referred to as “B-phase output”) indicating a detection state of the slit 108a by the second sensor 110b. (The timing chart shown in FIG. 2C is shown with reference to the timing chart shown in FIG. 2B.) FIG. There is a timing chart of timing signals serving a trigger pulse indicating the print timing to start ejecting ink onto the recording sheet 100.
[0014]
FIG. 3 is a flowchart showing a processing routine relating to the ink ejection operation of the print head 106. This processing routine starts when the print head 106 starts moving in the main scanning direction.
[0015]
That is, in this ink jet printer, the slit 108a of the linear scale 108 is detected by the first sensor 110a and the second sensor 110b, and the A phase output (FIG. 2B) and the B phase output (FIG. 2C). )) And are obtained respectively.
[0016]
Specifically, the first sensor 110a and the second sensor 110b have a boundary 108c between the ground region 108b of the linear scale 108 and the slit 108a (note that the boundary 108c is a ground region 108b of the linear scale 108 and the slit 108a. The output signal is turned on (OFF) and off (OFF) each time a boundary in the direction orthogonal to the main scanning direction is detected.
[0017]
In the example shown in FIG. 2B and FIG. 2C, when the first sensor 110a and the second sensor 110b move from the slit 108a to the ground area 108b beyond the boundary 108c, the output signal is turned off. On the contrary, the output signal is switched from on to off when moving from the ground region 108b to the slit 108a beyond the boundary 108c.
[0018]
In this ink jet printer, the output signal is switched from ON to OFF (waveform falling) and the output signal is switched from OFF to ON (waveform rising) in the A phase output and the B phase output. An encoder pulse is generated at the timing, and this encoder pulse is used as a trigger pulse (see FIG. 2D).
[0019]
The ink discharge operation in the print head 106 is started at the print timing which is the trigger pulse timing in FIG. 2D, and is completed over a predetermined time required for the ink discharge operation.
[0020]
The above operation will be described with reference to the flowchart of the processing routine relating to the ink ejection operation in the print head 106 shown in FIG. 3. This processing routine starts with the start of movement of the print head 106 in the main scanning direction. The unit determines whether or not a trigger pulse has come (step S302), and repeats this operation until it is determined that a trigger pulse has come.
[0021]
If it is determined in step S302 that the trigger pulse has arrived, the print head 106 is caused to start the ink discharge operation and perform the ink discharge operation (step S304). As described above, it takes a predetermined time to complete the ink ejection operation.
[0022]
Next, when the ink ejection operation is completed, it is determined whether or not the movement of the print head 106 in the main scanning direction is completed (step S306).
[0023]
If it is determined in step S306 that the movement of the print head 106 in the main scanning direction has not been completed, the process returns to step S302 and the process is repeated.
[0024]
On the other hand, if it is determined in step S306 that the movement of the print head 106 in the main scanning direction has ended, the processing routine relating to the ink ejection operation of the print head 106 is ended.
[0025]
Then, as described above, using the A-phase output and the B-phase output to generate an encoder pulse indicating the rising and falling of each waveform is referred to as multiplication by four.
[0026]
That is, in such a conventional ink jet printer, using the A-phase output and the B-phase output based on the position detection of the linear encoder, the position detection signal is obtained by the rising and falling of each waveform corresponding to the position detection of the linear encoder. Since the encoder pulse is generated and the encoder pulse thus generated is used as a trigger pulse for starting the ink ejection operation by the print head, the position detection generated in response to the position detection by the linear encoder as the position detection means There is a problem that printing can be performed only at the timing of the encoder pulse as a signal.
[0027]
That is, in the conventional ink jet printer, the position between the first position continuously detected by the linear encoder as the movement information indicating the movement state of the print head and the second position adjacent to the first position. However, there is a problem that printing cannot be performed.
[0028]
[Problems to be solved by the invention]
The present invention has been made in view of the problems of the prior art as described above, and an object of the present invention is to provide a position between two consecutive positions indicated by movement information indicating a print head movement state. An object of the present invention is to provide an image forming apparatus that can perform printing at an arbitrary position.
[0029]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 of the present invention is a print head that is movable in a main scanning direction orthogonal to a sub-scanning direction that is a conveyance direction of recording paper, and movement information of the print head. A reference pulse signal generating means for generating a reference pulse signal corresponding to the movement of the print head by a predetermined distance, a clock pulse signal generating means for generating a clock pulse signal at a predetermined time interval, and the reference pulse signal generation A count value storage means for storing a count value obtained by counting the clock pulse signals generated by the clock pulse signal generation means between adjacent reference pulse signals generated by the means, and the clock pulse signal generation means for generating a clock pulse signal Every time the multiplication number N is subtracted from the count value stored in the count value storage means, Trigger pulse signal generation means for generating a trigger pulse signal having a shorter time interval than the reference pulse signal obtained by multiplying the reference pulse signal generated by the reference pulse signal generation means by N by the multiplication number N based on the calculation result; And the print timing of the print head is controlled based on the trigger pulse signal generated by the trigger pulse signal generating means.
[0030]
Therefore, according to the first aspect of the present invention, the print timing of the print head can be controlled at an arbitrary time interval shorter than the reference pulse signal by setting the multiplication number N to an arbitrary value. A trigger pulse signal for performing can be generated.
[0031]
According to a second aspect of the present invention, in the first aspect of the present invention, the trigger pulse signal generating means triggers when the subtraction result becomes smaller than “0”. A pulse signal is generated.
[0032]
According to a third aspect of the present invention, in the invention according to the second aspect of the present invention, the trigger pulse signal generating means is configured so that the subtraction result is smaller than “0”. The count value stored in the count value storage means is added to the subtraction result, and the multiplication number N is subtracted using the addition result as the count value.
[0036]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of an image forming apparatus according to the present invention will be described in detail with reference to the accompanying drawings.
[0037]
FIG. 4 is a perspective view of an ink jet printer as an example of an embodiment of an image forming apparatus according to the present invention.
[0038]
For the sake of easy understanding, the same reference numerals as those used in FIGS. 1 and 2 are used to denote the same or corresponding components as those in the conventional technique shown in FIGS. .
[0039]
The inkjet printer 10 performs printing based on image data input from an external personal computer, and displays an operation element and an operation state for controlling the entire operation and setting a multiplication value N described later. An operation panel 12 including a display, a print head 106 serving as an output unit provided in the carriage 104, and a grid for feeding a recording sheet 100 such as a single sheet or a long wound sheet in the sub-scanning direction (X direction). The roller 17 and a paper feed motor (not shown) that rotates the grid roller 17 are configured.
[0040]
The carriage 104 is supported by both side frames 18 and 18 which are fixing system members of the ink jet printer 10, and extends in the main scanning direction (Y direction) along the guide rail 102 disposed at right angles to the traveling direction of the recording paper 100. It is mounted so that it can reciprocate.
[0041]
In addition, the recording paper 100 is pressed by a pinch roller 24 installed on the upper surface of the base 22 and is sandwiched between the pinch roller 24 and the grid roller 17 and rotated in the sub-scanning direction (X direction) by the rotation of the paper feed motor. ).
[0042]
Further, the inkjet printer 10 is provided with a linear scale 108 that constitutes a linear encoder as detection means in parallel with the guide rail 102, that is, in parallel with the main scanning direction as the movement direction of the carriage 104.
[0043]
Here, in the linear scale 108, slits 108a having a predetermined width W are formed at predetermined intervals (see FIG. 2A). Such a linear scale 108 can be created by, for example, a technique of printing a slit 108a on a film.
[0044]
The slit 108a is formed in a rectangular shape having two sides extending in a direction orthogonal to the main scanning direction in the ground region 108b of the linear scale 108.
[0045]
In addition, the carriage 104 is provided with a linear sensor 110 (see FIG. 2A) including a first sensor 110a and a second sensor 110b that constitute a linear encoder as a detecting means. The slit 108a of the linear scale 108 is detected.
[0046]
Here, the first sensor 110a and the second sensor 110b are arranged in alignment along the main scanning direction.
[0047]
In this ink jet printer, the recording paper 100 is conveyed in the sub-scanning direction, and the carriage 104 is moved in the main scanning direction. At this time, the linear sensor 110 is connected to the linear scale 108. The slit 108a is detected, and the printing timing on the recording paper 100 by the print head 106 is controlled according to the detection of the slit 108a. The print head 106 discharges ink onto the recording paper 100 at the printing timing controlled in this way, whereby an image is formed on the recording paper 100.
[0048]
That is, the inkjet printer 10 repeats the operation of moving the print head 106 together with the carriage 104 in the main scanning direction (Y direction) and printing one line to feed the sheet 106 by a predetermined width in the sub scanning direction (X direction). As a result, the image is printed on the recording paper 100.
[0049]
FIG. 5 shows a block diagram of the above-described ink jet printer 10. The ink jet printer 10 is configured to control the overall operation by a central processing unit (CPU) 200 as a control unit. The CPU 200 is connected to an input / output device (I) from a read-only memory (ROM) 204 storing a program executed by the CPU 200 for controlling the overall operation, an external personal computer 300, and the like. / O) a random access memory (RAM) 206 as a working area in which buffer memory for temporarily storing image data input via 208, various registers necessary for executing a program by the CPU 200, and the like, and an external personal computer Data exchange with computer 300 etc. The above-described input / output device (I / O) 208 that performs output, the head data creation unit 210 that creates and outputs head data indicating the print contents of the print head 106 by converting image data, and output in A-phase output An encoder pulse generator 211 that generates an encoder pulse φE as a reference pulse signal as an encoder pulse at the timing of signal switching from on to off (waveform rise) (the encoder pulse generator 211 includes a linear sensor 110). A clock pulse generator 112 that generates a clock φ0 as a clock pulse (clock signal), an encoder pulse φE, a clock φ0, and a multiplication value N (“N”) supplied from the RAM 206 by the CPU 200 is Arbitrary positive integer, multiplication value N is the operation panel 1 The multiplication value N set in the operation element of the operation panel 12 is stored in the RAM 206 under the control of the CPU 200.) The print head 106 is instructed to start printing. A trigger pulse generator 114 that generates a trigger pulse (trigger pulse signal), a print head 106 that starts an ink ejection operation for printing an image indicated by head data in accordance with the timing of the trigger pulse, and a carriage 104. A carriage motor 214 that moves in the main scanning direction and a paper feed motor 120 that rotates the grid roller 17 to feed the sheet 16 in the sub-scanning direction are connected.
[0050]
Next, the trigger pulse generator 114, which is a main part of the present invention, will be described in detail with reference to FIGS.
[0051]
The trigger pulse generation unit 114 is composed of two blocks, a period counter block and a pulse generation block.
[0052]
Here, FIG. 6 shows a block diagram of the cycle counter block, FIG. 7 shows a flowchart showing the operation of the cycle counter block, and FIG. 8 shows a block diagram of the pulse generation block. 9 is a flowchart showing the operation of the pulse generation block, FIG. 10 is a waveform timing chart showing an example of operation when “multiplied value N = 3”, and FIG. 11 is an illustration of FIG. An enlarged view of the portion is shown, FIG. 12 shows an enlarged view of the portion B of FIG. 10, and FIG. 13 shows an enlarged view of the portion C of FIG.
[0053]
In this embodiment, setting “multiplied value N = 3” means that three trigger pulses are generated between two consecutive encoder pulses φE.
[0054]
First, the operation of the cycle counter block will be described with reference to FIGS. 6 and 7. In this cycle counter block, the cycle of the encoder pulse φE is counted by the clock φ0 and latched in the flip-flop FF1. .
[0055]
That is, the period of the encoder pulse φE is counted by the clock φ0 using an up counter (UP counter) to obtain the clock count value ECNT, and this clock count value ECNT is latched in the flip-flop FF1 and latched in the flip-flop FF1. Processing for supplying the clock count value ECNT to the pulse generation block as the count value CNT is performed.
[0056]
Specifically, when the clock φ0 arrives, the clock count value ECNT is incremented by “1” (H processing consisting of step S702 and step S704, see FIGS. 10 and 11). When the encoder pulse φE is input, the clock count value ECNT is latched in FF1, supplied to the pulse generation block as the count value CNT, and the clock count value ECNT is cleared to “0” (step S706). This is the process of I consisting of step S708 and step S710 (see FIGS. 10 and 11).
[0057]
Next, the operation of the pulse generation block will be described with reference to FIGS. 8 and 9. In this pulse generation block, the clock φ0, the encoder pulse φE, the count value CNT supplied from the period counter block, and the multiplied value N Based on the above, processing for generating a trigger pulse is performed.
[0058]
In the pulse generation block shown in FIG. 8, the multiplication value N supplied from the RAM 206 by the CPU 200 is latched in the flip-flop FF2, and the counter value CNT and the value obtained by increasing or decreasing the counter value CNT are stored in the flip-flop FF3. And a value obtained by subtracting the multiplied value N is stored in the register NCNT.
[0059]
The processing executed in this pulse generation block will be described with reference to the flowchart of FIG. 9. First, the processing after step S904 is waited until the encoder pulse φE arrives, and the encoder pulse φE arrives. In step S904, the processing after step S904 is executed (the processing of A consisting of step S902).
[0060]
That is, when the encoder pulse φE arrives, the “multiplier value N−1” is stored in the register NCNT, and the count value CNT is latched in the flip-flop FF3 to generate a trigger pulse (steps S904 and S906). And the process of B consisting of step S908 (see FIGS. 10 and 11).
Next, it is determined whether or not the clock φ0 has arrived. When the clock φ0 has arrived, the multiplication value N is subtracted from the value latched in the flip-flop FF3, and the flip-flop FF3 is updated by the subtraction result, The above-described processing is repeated until the updated value of the flip-flop FF3 becomes smaller than “0” (the processing of C including Step S910, Step S912, and Step S914. FIG. 10, FIG. 11, FIG. 12 and FIG. Refer to FIG.
[0061]
When the value of the flip-flop FF3 becomes smaller than “0”, the count value CNT is added to the value of the flip-flop FF3, and the trigger pulse is generated after the flip-flop FF3 is updated with the addition result. Further, the value of the register NCNT is subtracted by “1”, and if the subtraction result is not “0”, the process returns to step S910 to repeat the process, but if the subtraction result becomes “0”, step S902 is performed. The process is repeated after returning to (the process of D comprising step S916, step S918, step S920, and step S922. Refer to FIGS. 10, 12, and 13).
[0062]
As a result, N trigger pulses indicated by a multiplication value N are generated between two consecutive encoder pulses φE (in the example shown in FIGS. 10 to 13, “multiplication value = Since 3 ”is set, three trigger pulses are generated between two consecutive encoder pulses φE.)
[0063]
By using the trigger pulse thus generated, the print head 106 is controlled by the same processing as that of the conventional ink jet printer described above, so that the print head is between two positions where two successive encoder pulses φE are generated. Printing is performed by 106.
[0064]
In the period counter block, in the above-described embodiment, only one period is counted and latched. However, a plurality of periods may be counted and an average value thereof may be used as the count value CNT. By obtaining the count value CNT, the trigger pulse can be generated at a timing that is relatively close to equal.
[0065]
【The invention's effect】
Since the present invention is configured as described above, it is possible to perform printing at an arbitrary position between two consecutive positions indicated by the movement information indicating the print head movement state. Play.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a main part of an ink jet printer as a conventional image forming apparatus.
FIG. 2A is an explanatory diagram conceptually showing a linear scale having a slit and a linear sensor composed of a first sensor and a second sensor, relating to an inkjet printer as a conventional image forming apparatus; (b) is a timing chart of the A phase output showing the detection state of the slit by the first sensor (the timing chart shown in (b) is shown corresponding to the linear scale of (a)), (c). ) Is a B phase output timing chart showing the detection state of the slit by the second sensor (the timing chart shown in (c) is shown corresponding to the linear scale in (a)), (d). FIG. 4 is a timing chart of trigger pulses for instructing the timing at which the print head discharges ink onto the recording paper.
FIG. 3 is a flowchart illustrating a processing routine relating to an ink ejection operation in a print head of an ink jet printer as a conventional image forming apparatus.
FIG. 4 is a perspective view of an ink jet printer as an example of an embodiment of an image forming apparatus according to the present invention.
FIG. 5 is a block diagram of an inkjet printer as an example of an embodiment of an image forming apparatus according to the present invention.
FIG. 6 is a block configuration diagram of a cycle counter block.
FIG. 7 is a flowchart showing the operation of a cycle counter block.
FIG. 8 is a block configuration diagram of a pulse generation block.
FIG. 9 is a flowchart showing the operation of a pulse generation block.
FIG. 10 is a waveform timing chart showing an operation example when “multiplied value N = 3”;
11 is an enlarged view of a portion of FIG.
12 is an enlarged view of a portion B in FIG. 10;
13 is an enlarged view of a portion C in FIG.
[Explanation of symbols]
10 Inkjet printer
12 Operation panel
17 Grid Roller
18 Side frame
22 base
24 Pinch roller
100 recording paper
102 Guide rail
104 Carriage
106 Print head
108 linear scale
108a slit
108b Ground area
108c boundary
110 Linear sensor
110a first sensor
110b Second sensor
112 Clock pulse generator
114 Trigger pulse generator
200 Central processing unit (CPU)
202 Bus
204 Read-only memory (ROM)
206 Random access memory (RAM)
208 Input / output unit (I / O)
210 Head data generator
211 Encoder pulse generator
212 Discharge instruction data creation unit
214 Carriage motor
216 Paper feed motor
300 Personal computer

Claims (3)

A print head movable in a main scanning direction orthogonal to a sub-scanning direction as a recording paper conveyance direction;
A reference pulse signal generating means for generating a reference pulse signal corresponding to the movement of the print head by a predetermined distance based on the movement information of the print head;
Clock pulse signal generating means for generating a clock pulse signal at a predetermined time interval;
A count value storage means for storing a count value obtained by counting the clock pulse signals generated by the clock pulse signal generation means between adjacent reference pulse signals generated by the reference pulse signal generation means;
Every time the clock pulse signal generating means generates a clock pulse signal, the multiplication number N is subtracted from the count value stored in the count value storing means, and the reference pulse signal generating means is generated based on the subtraction result. Trigger pulse signal generating means for generating a trigger pulse signal having a shorter time interval than the reference pulse signal obtained by multiplying the reference pulse signal by N by the multiplication number N;
An image forming apparatus, wherein the print timing of the print head is controlled based on a trigger pulse signal generated by the trigger pulse signal generating means. The image forming apparatus according to claim 1.
The image forming apparatus, wherein the trigger pulse signal generation unit generates a trigger pulse signal when the subtraction result becomes smaller than “0”. The image forming apparatus according to claim 2.
The trigger pulse signal generation means adds the count value stored in the count value storage means to the subtraction result when the subtraction result becomes smaller than “0”, and uses the addition result as the count value as the multiplication number. An image forming apparatus characterized by subtracting N.

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