JP2011046173A - Image forming apparatus - Google Patents

Abstract

An image forming apparatus capable of correcting a variation in ejection timing, controlling an appropriate ejection timing of ink droplets at an arbitrary use temperature, and obtaining a good print image quality with little deviation of landing positions of ink droplets from nozzles. I will provide a.
In an image forming apparatus that scans a carriage mounted with a recording head for ejecting ink droplets to form an image on a recording medium, an encoder signal output in accordance with the movement of the carriage is used to generate an image of the carriage. After detecting the position and speed, controlling the position and speed of the carriage, and determining the correction amount of the ink droplet discharge timing based on the correction chart obtained by outputting at different discharge timings under a certain temperature The image forming apparatus is characterized in that a correction amount of ejection timing at a temperature at the time of printing is determined in accordance with a temperature characteristic of an electronic component involved in the encoder signal transmission circuit.
[Selection] Figure 9

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that forms an image on a recording sheet by an inkjet method.

  2. Description of the Related Art Conventionally, an ink jet printer that is an image forming apparatus that forms characters and images by an ink jet recording method has been proposed. The ink jet recording head constituting the ink jet printer is configured to move in the main scanning direction (direction orthogonal to the recording paper traveling direction) by the carriage mechanism, and a plurality of ink jet recording heads in the sub scanning direction (recording paper traveling direction). Equipped with a nozzle. Each nozzle is adapted to eject ink droplets at a timing corresponding to the dot pattern data obtained by expanding the recording data, ink droplets are made adhere to the printing on the recording medium (paper) from each nozzle .

  In an inkjet printer, if there is a physical error typified by a head assembly error, the nozzle position may deviate from the target position, and the ink droplet landing position may deviate. Even when an electrical transmission delay occurs, the landing position may be shifted because the carriage is printing while scanning. Such a shift in the landing position causes a decrease in image quality, and thus needs to be corrected.

  A technique is known in which a correction chart (adjustment chart) is printed in order to correct deviations in the landing positions of ink droplets, and the obtained results are reflected in ejection timing correction, and appropriate correction is performed for each individual. In addition, a technique for correcting the influence of thermal expansion and contraction of a component member from a temperature detection result is also known (see, for example, Patent Document 1).

  Patent Document 1 discloses a temperature detector for detecting an environmental temperature of a base component, and a base component for the purpose of canceling a relative landing position error due to thermal expansion and contraction of the base component having a plurality of inkjet head units assembled thereto. and a recorded memory timing correction value at each environmental temperature, to variations in the separation distance between the plurality of ink jet head units resulting from the base structure material is stretchable under the influence of ambient temperature, correcting the ejection timing A configuration for maintaining good relative landing position accuracy is disclosed.

  However, in the conventional ejection timing correction method, only variations in mechanical factors represented by head assembly errors and thermal expansion and contraction of components are assumed, and the influence of electrical signal delay is not considered. For this reason, there has been a problem that the influence of fluctuation factors such as temperature characteristics of the capacitor capacitance, which is an electrical factor and temperature dependent, cannot be corrected.

  The encoder signal is subjected to a transmission delay in the process of transmitting the circuit, and it has been found that this transmission delay changes in temperature due to the temperature characteristics of the capacitor. Therefore, it is considered that an appropriate timing correction that cancels the signal delay can be performed by obtaining an electrical signal delay amount at an arbitrary temperature in the determination of the correction amount of the ejection timing correction. For example, by taking in the temperature characteristics of the capacitor capacitance that depends on temperature, it is considered that an appropriate correction amount can be applied under any temperature environment and a good print image quality can be obtained. Not proposed.

  An object of the present invention has been made in view of the above problems in the prior art, and corrects variations in discharge timing due to the influence of electrical factors and temperature-dependent variation factors, so that it is suitable for any use temperature. It is an object of the present invention to provide an image forming apparatus capable of controlling the ejection timing of ink droplets and obtaining a good print image quality with little deviation of the landing positions of ink droplets from nozzles.

In order to solve the above problems, an image forming apparatus according to the present invention is as follows.
[1] In an image forming apparatus for forming an image on a recording medium by scanning a carriage mounted with a recording head for discharging ink droplets,
Detecting the position and speed of the carriage from the encoder signal output in accordance with the movement of the carriage, and controlling the position and speed of the carriage;
After determining the correction amount of the ink droplet discharge timing based on the correction chart obtained by outputting at different discharge timings under a certain temperature,
An image forming apparatus characterized in that an ejection timing correction amount at a temperature at the time of printing is determined according to a temperature characteristic of an electronic component involved in the encoder signal transmission circuit.
[2] The image forming apparatus according to [1], wherein the electronic component involved in the encoder signal transmission circuit is a capacitor.
[3] A correction amount table information indicating a correction amount corresponding to the temperature characteristic of the electronic component is provided, and the correction amount determined based on the correction chart is corrected based on the correction amount table at the temperature at the time of printing. The image forming apparatus according to any one of [1] to [2], wherein the correction amount of the ejection timing is determined using the amount.
[4] The correction amount table of the electronic component involved in the encoder signal transmission circuit is created by actually measuring the delay amount of the encoder signal under an arbitrary temperature. An image forming apparatus.

  According to the present invention, it is possible to correct the ejection timing variation due to the influence of electrical factors and temperature-dependent variation factors, and to control the proper ejection timing of ink droplets at an arbitrary use temperature. It is possible to provide an image forming apparatus capable of obtaining a good print image quality with little droplet landing position deviation.

  In other words, the optimal ink droplet ejection timing can be determined by predicting the delay time at any temperature from the capacitor temperature characteristic data against the transmission delay that the encoder signal that changes in temperature according to the capacitor temperature characteristic receives in the process of transmitting the circuit Can be provided.

According to the first aspect of the present invention, in an image forming apparatus that forms an image on a recording medium by scanning a carriage on which a recording head that ejects ink droplets is mounted, an encoder that is output in accordance with the movement of the carriage The position and speed of the carriage is detected from the signal, the position and speed of the carriage are controlled, and the ejection timing of the ink droplet is corrected based on a correction chart obtained by outputting at different ejection timings under a certain temperature. After determining the amount, the image forming apparatus determines the correction amount of the ejection timing at the temperature at the time of printing according to the temperature characteristics of the electronic components involved in the encoder signal transmission circuit. The temperature characteristics of the delay that occurs in the ink can be taken into account, and even if printing at any temperature, the ink droplets landing from the nozzle Less location shift, can form a high quality image.
According to a second aspect of the present invention, in the image forming apparatus of the first aspect, the electronic component involved in the encoder signal transmission circuit is a capacitor, so that correction is made from temperature characteristics that can be easily obtained from a data sheet of the component. The amount can be set in detail, and a high-quality image with little deviation of the landing position of the ink droplet from the nozzle can be formed.
According to a third aspect of the present invention, in the image forming apparatus according to any one of the first to second aspects, the correction chart includes information on a correction amount table indicating a correction amount according to a temperature characteristic of the electronic component, and the correction chart includes Based on the correction amount determined based on the correction amount based on the correction amount table at the temperature at the time of printing, the discharge timing correction amount is determined. An appropriate correction amount can be set based on temperature data at the time of printing, and a high-quality image with little landing position deviation can be provided. According to the invention of claim 4, the invention of claim 3 is provided. In the image forming apparatus, the correction amount table of the electronic component involved in the encoder signal transmission circuit is created by actually measuring the delay amount of the encoder signal under an arbitrary temperature. Therefore, an optimized correction amount can be set even if there are variations in component characteristics, and a high-quality image with less landing position deviation can be provided.

FIG. 3 is an explanatory diagram illustrating a configuration of main scanning control of a serial type ink jet printer which is an example of an image forming apparatus according to the present invention. It is a figure explaining the output of an encoder sheet and an encoder signal. It is a block diagram explaining scanning control of a carriage. FIG. 6 is a diagram for explaining timing control of carriage scanning and ink ejection. FIG. 5 is a diagram for explaining a flying motion of ink droplets ejected during carriage movement. It is an enlarged view of the carriage part of FIG. It is a figure explaining the gap correction between heads, and an encoder signal. It is explanatory drawing of the transmission circuit of an encoder signal. 3 is a flowchart showing a first embodiment of the image forming apparatus of the present invention. It is a figure explaining the temperature characteristic of a chip ceramic capacitor. 6 is a flowchart illustrating a second embodiment of the image forming apparatus of the present invention. It is an example of a correction amount table. 6 is a flowchart showing a third embodiment of the image forming apparatus of the present invention. It is explanatory drawing of an example of the data measurement for correction amount table preparation. 10 is a flowchart showing a part of a fourth embodiment in the image forming apparatus of the present invention, and (a) is a flowchart for creating a table (b) is a flowchart for printing. 1 is an explanatory diagram illustrating an example of an image forming system in which an image forming apparatus of the present invention is configured with an information processing apparatus. It is a block diagram which shows schematic structure of the information processing apparatus which comprises the image forming system of FIG.

  Hereinafter, an image forming apparatus according to the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments of the examples shown below, other embodiments, add, modify, can be changed within the range that can be and deletion, those skilled in the art will envision, Any aspect is included in the scope of the present invention as long as the operations and effects of the present invention are exhibited.

  An image forming apparatus of the present invention is an image forming apparatus that forms an image on a recording medium by scanning a carriage on which a recording head that ejects ink droplets is mounted, and is output in accordance with the movement of the carriage. The position and speed of the carriage is detected from the encoder signal, the position and speed of the carriage are controlled, and the ink droplet ejection timing is determined based on a correction chart obtained by outputting at different ejection timings under a constant temperature. After determining the correction amount, the discharge timing correction amount at the temperature at the time of printing is determined according to the temperature characteristics of the electronic components involved in the encoder signal transmission circuit.

FIG. 1 is an explanatory diagram showing an example of the configuration of main scanning control of a serial type ink jet printer which is an embodiment of the image forming apparatus of the present invention.
As shown in FIG. 1, the carriage 1 scans in the main scanning direction via a pulley 4 held by a guide lot 2 and passed between the main scanning motor 3. For example, recording heads 9a and 9b that discharge ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K) are mounted on the carriage 1, and are arranged on the recording head. Ink can be ejected from the ejected ink ejection nozzles 10y, 10m, 10c, and 10k. An image is formed on the recording medium by ejecting ink droplets at a necessary position while moving the carriage 1 in the main scanning direction.
By performing the ink ejection operation once while moving the carriage 1 in the main scanning direction, an image can be formed on a band having the same width as the length of the nozzle row. After the image formation for one band is completed, the sub-scanning motor is driven to move the recording medium in the sub-scanning direction, and the operation for forming the image for one band again is repeated, so that the recording medium is placed at an arbitrary place on the recording medium. A desired image can be formed.

  The position information of the carriage 1 is obtained by reading a pattern recorded at equal intervals on the encoder sheet 5 fixed to the casing while moving the encoder sensor 6 fixed to the carriage 1 and adding or subtracting the count. It is done. Encoder sheet and encoder signal output and carriage position detection will be described with reference to FIGS.

FIG. 2 is a diagram for explaining the output of the encoder sheet and the encoder signal.
As shown in FIG. 2, a black-colored light-shielding portion and a transparent transmission portion are arranged at equal intervals on the main scanning encoder sheet. When the encoder sensor moves along this sheet, shielding and transmission of the light beam are switched, and the output signal from the encoder sensor is also switched to Hi-Lo. Here, ENC_A and ENC_B of the encoder signal are connected to the outputs of the light receiving sensors arranged at positions shifted by ½ of the light shielding pitch of the encoder sheet, respectively, so that the relationship is always kept 90 degrees out of phase. It has become. Therefore, the phase relationship between ENC_A and ENC_B differs depending on whether the encoder sensor is moving in the forward direction or the reverse direction. For example, when the state where ENC_B is 90 degrees ahead as shown in FIG. 2 is forward movement, ENC_A is 90 degrees ahead in reverse movement, and direction detection is possible from the phase relationship.

FIG. 3 is a block diagram illustrating carriage scanning control.
The output encoder signal is input to the encoder analysis unit 25 in the printer control unit and used to acquire carriage position information. For example, from the phase relationship between ENC_A and ENC_B shown in FIG. 2, the moving direction of the encoder sensor, that is, the carriage to which the encoder sensor is attached, is detected, and if the rising edge of ENC_A is detected while moving in the positive direction, the count is incremented. If an edge is detected during movement in the reverse direction, the amount of movement of the carriage can be measured by counting down.
Specifically, when the pitch of the light shielding portions of the encoder sheet is 150 dpi and the count is 600 counts, it can be calculated that the carriage has moved 4 inches (10.16 cm). Further, if the carriage is moved to the limit of the movable range and the portion that contacts the side member is detected as the zero position, the position can be detected by the absolute value by accumulating the count from the zero position.

  On the other hand, the speed of the carriage can also be calculated from the measurement of the pulse period of the encoder signal and the measurement of the number of pulses within a unit time. The acquired position and speed information is fed back to the main scanning motor drive unit and used to place the carriage at a desired position and to control it to a desired moving speed.

  In addition to the encoder sensor, main scanning motor, and sub-scanning motor, the printer is equipped with various sensors and actuators. The printer control unit receives these sensor inputs and performs complex control by cooperatively controlling the actuators. The printing operation is achieved. The thermistor 29 also recognizes the environmental temperature.

Next, carriage scanning and ink ejection timing control will be described with reference to FIG. FIG. 4 is a schematic view of the carriage and the recording paper as viewed from the front of the image forming apparatus. The carriage 1 moves in the forward direction (in the direction of the arrow) from the home position and moves on the recording paper 30. Show.
For example, immediately above when it is desired to land the ink droplets on the coordinates of the print start position X ₀ are kept stationary carriage 1, calculates the position of the carriage by the analysis of the encoder signal, the nozzle to be ejected ink droplets X ₀ It is only necessary to move the carriage so as to come to the position where ink is ejected.

  In FIG. 4, it has been described that ink droplets are ejected while the carriage is stopped. However, in an actual printing operation, ink droplets are ejected while scanning the carriage at high speed. For this reason, as shown in FIG. 5, although the ink droplets are given kinetic energy in the vertical direction by the PZT element, the actual flight movement is a combined movement with the carriage scanning movement.

Therefore, if you want to land ink droplets landing target position X ₀ are not immediately above the X _0, you is necessary to control for droplet ejection in advance the timing when reaching the X _0. Specifically, control is performed so that droplets are ejected by a distance that is obtained by the product of the flight time and the main scanning speed.
For example, when the distance between the recording paper and the nozzle is 1 mm, the main scanning speed is 1,000 mm / s, the PZT discharge speed is 5,000 mm / s, and the encoder resolution is 150 dpi, the discharge timing correction amount is obtained as follows. .
Flight time = 1 (mm) / 5,000 (mm / s) = 200 ns
Flight distance in main scanning direction = 200 (ns) × 1,000 (mm / s) = 200 μm
Therefore, it is necessary to discharge 200 μm before the target position.

The encoder pitch is determined as follows.
150 dpi = 25.4 (mm) / 150 = 169 μm
Therefore, if the ink is ejected after taking into account the delay time (13.8 μs) corresponding to 138 μm from the reference position, the time point when the recording head has reached the position 2 counts before (338 μm before) at the encoder pitch, Since it is 200 μm before the target position X ₀ , ink droplets can be landed on the target position.
That is, by detecting the reference position before the target position with the encoder and setting the delay amount from the reference position, an arbitrary position before the target position can be set as the ejection timing.

The scanning control of the carriage nozzle position will be specifically described with reference to FIG.
FIG. 6 is an enlarged view of the carriage 1 shown in FIG. 1, and shows an encoder sensor 6, recording heads 9a and 9b, and nozzle rows 10k, 10c, 10m, and 10y arranged in the recording head.
As shown in FIG. 6, when in the position where the nozzle 10y for ejecting yellow ink is distanced Xy from the central portion of the encoder sensor 6, to be landed ink droplets to the target position X ₀ of the recording sheet, The carriage 1 may be moved so that the coordinates of the center of the encoder sensor 6 are X ₀ -Xy. The description will be made ignoring the influence of the carriage speed described above.
Here, consider a case where Xy deviates from a design target value due to an assembly error of the recording head.
The amount of deviation is generally an amount determined in the process of assembling (fixing) the recording heads 9a and 9b to the carriage 1, and is an amount that does not change after assembly. Further, since Xy is actually a very small value, in the image design, not the distance from the encoder sensor 6 but the gap between the recording heads 9a and 9b (inter-head gap) becomes a problem. This is because the influence of the ink droplets that should be overlapped at a single point on the recording paper is caused as a problem that can be clearly distinguished visually as a difference in color. On the other hand, it is not a big problem to have a minute right or left image.

For the reasons described above, the deviation from the design value of the head-to-head distance needs to be corrected, and correction is performed by a method of printing a head position correction chart after assembling the apparatus.
In the case of the configuration of FIG. 6, aiming to land the ink droplets ejected from the recording head 9a and the ink droplets ejected from 9b on one point, the correction amount so that the two droplets overlap exactly on one point. Ask for.
For example, when the interval between 10y and 10c is 0.1 mm larger than the target, and the carriage is ejected while scanning in the positive direction at 1,000 mm / s, the correction time for delaying the ejection timing from 10c by 100 μs from the design value is set. By providing, two drops overlap at one point.
In the inter-head gap correction chart, a plurality of check patterns in which the correction time is increased or decreased step by step are arranged, and the pattern with the largest overlap (small deviation) of the two ink droplets is judged by visual inspection or a sensor and selected. To do. The correction time of the selected check pattern is determined as an appropriate correction amount.

As described above, the correction of the gap between the heads has been described by paying attention to the assembly error of the recording head, but it will be described with reference to FIG. 7 that the correction amount is actually corrected together with the influence of the delay of the encoder signal.
When outputting the correction chart, the mechanical assembly error described above is dominant, but the delay of the encoder signal also contributes to the landing position deviation as shown in FIG.
In signal Enc_A, strictly for detects the light shielding portion of the encoder sheet is rise start time T _1. However, what is recognized as a Hi level as an electric signal becomes T ₂ of the time of exceeding the V _IH input device. Time zone between T ₂ and T ₁ is the time that is not detected in the encoder analysis unit, which because they act to retard the ejection timing appears as the deviation of landing position. In other words, it has the same effect as a mechanical assembly error. Therefore, when the head gap correction for correcting the landing position deviation of the ink droplet is performed, the delay of the encoder signal is also corrected.

FIG. 8 is an explanatory diagram of an encoder signal transmission circuit.
2 and 7, the signals of ENC_A and ENC_B have a waveform shape, and are shown as a shape that slowly rises and falls while drawing an arc. This is due to the transmission circuit as shown in FIG. 8. Yes. In other words, this is an influence that an RC filter such as R1 and C1 is configured as a filter for removing noise caused by external radio waves.
For example, when R1 = 1 kΩ and C1 = 1000 pF, the time constant is 1 μsec. Here, the time constant means the time for the voltage after the RC filter to reach 63% of the input voltage, so the delay time until the encoder analysis unit reaches VIH for recognizing ENC_A (ENC_B) = Hi. Pretty close. Therefore, description will be made assuming that (delay time) = (time constant).

  The problem here is that the delay time (time constant) is given by the product of R and C. In consideration of the variation between R and C, if the individual variation is fixed as described above, it has already been corrected by the gap correction between the heads. However, since both R and C have temperature characteristics, correction is performed. In a temperature environment different from the time, the delay time also changes. For this reason, it is required to perform correction based on the temperature at the time of printing execution.

[First embodiment]
As a first embodiment of the correction of the ejection timing of ink droplets in the image forming apparatus of the present invention, first, printing a correction chart with temperature t _0, to determine the amount of correction of the ejection timing at the temperature t _0. This correction amount includes the mechanical recording head assembly error and the influence of the delay of the encoder signal. Next, the print job is received, and the environmental temperature t ₁ at the time before starting printing is observed. At the time of printing, a delay amount suitable for t ₁ is calculated from the temperature characteristics of the components involved in the delay of the encoder signal, and the correction amount is set again to execute printing.

FIG. 9 is a flowchart of the first embodiment of correction of ink droplet ejection timing in the image forming apparatus of the present invention. Hereinafter, this embodiment will be described with reference to FIG.
The environmental temperature _{t 0} and to store the measurement (S101), the correction amount of the ejection timing at the temperature _{t 0,} is determined by printing a correction chart (S102). Then, receiving the print command (S103), measures the environmental temperature _{t 1} at the time before starting the printing (S104). Based on the correction amount of the ejection timing at t ₀ is the time of printing performed, the delay amount suitable to t ₁ (e.g., by calculating from the temperature characteristics of the components involved in the delay of the encoder signal) is set (S105), Printing is executed (S106).

[Second Embodiment]
An aspect in which the electronic component involved in the encoder signal transmission circuit is a capacitor will be described.
The temperature characteristic of the chip resistance is ± 100 ppm / ° C., which is relatively small, and when the component temperature is 0 ° C. to 50 ° C., the fluctuation range is 0.5%. Since it is difficult to directly observe the component temperature, the substrate temperature or the environmental temperature is acquired and substituted. The substrate temperature can be obtained by mounting a chip thermistor on the PCB, and the ambient temperature can be obtained by a thermistor disposed at any location inside the machine.

FIG. 10 is a temperature characteristic diagram of a certain chip ceramic capacitor.
In the capacitor shown in FIG. 10, the temperature characteristic shows that the temperature characteristic varies by 5% at 0 ° C. to 50 ° C. That is, even if attention is paid only to the temperature characteristic of C, which has a relatively large influence, it means that the delay time (R × C) varies by 5%.
If the delay time is 1 μsec as described above, 5% corresponds to 50 ns. This is the amount that appears as a landing position shift of 50 nm when the main scanning speed is 1,000 mm / s. When the printer outputs with a resolution of 4,800 dpi in the main scanning direction, the landing interval of ink droplets is 5.3 μm, and 50 nm corresponds to a deviation of 9.4%. This is a size that cannot be ignored. If the speed and the resolution of main scanning are further increased, it becomes a problem as a larger ratio. Therefore, a method of correcting the variation amount of the delay time due to the temperature characteristic of the capacitor having a large influence on the ink droplet ejection timing is preferable.

The second embodiment of the ink droplet ejection timing correction in the image forming apparatus of the present invention is the same as the first embodiment described above, with the correction amount at t _{1 based} on the ejection timing correction amount at t _0. In the setting, the correction amount is obtained using the temperature characteristic data of the capacitor having a large influence on the ejection timing of the ink droplets. The correction amount can be easily obtained by using a data sheet available for the capacitor.

FIG. 11 is a flowchart of the second embodiment of correction of ink droplet ejection timing in the image forming apparatus of the present invention. Hereinafter, the second embodiment will be described with reference to FIG.
First, the environmental temperature _{t 0} and to store the measurement (S201), the correction amount of the ejection timing at the temperature _{t 0,} is determined by printing a correction chart (S202). Then, receiving the print command (S203), measures the environmental temperature _{t 1} at the time before starting the printing (S204). Based on the correction amount of the ejection timing at t ₀ is the time of printing performed, the delay amount suitable to t ₁ is set from the temperature characteristics of the capacitor (S205), it executes the printing (S206).

[Third embodiment]
Equipped with correction amount table information indicating the correction amount according to the temperature characteristics of the electronic component, and using the correction amount based on the correction amount table at the temperature at the time of printing for the correction amount determined based on the correction chart, An aspect of determining the timing correction amount will be described.
In setting the correction amount, an appropriate correction amount corresponding to the temperature characteristic of the electronic component is calculated in advance, and for example, a correction amount can be easily obtained by creating a correction amount table or the like. FIG. 12 shows an example of the correction amount table.
Determining a correction amount d ₀ of the ejection timing by printing a correction chart at a certain temperature t _0, the d ₀ includes the correction amount to correct a mechanical assembly error. Then upon receiving a print job, to observe the environmental temperature t ₁ before printing a job request. If t ₀ is 25 ° C. and t ₁ is 15 ° C., 40 ns−24 ns = 16 ns, and therefore an appropriate correction amount in a 15 ° C. environment can be obtained by d ₀ -16 ns.

The third embodiment of the correction of the ink droplet ejection timing in the image forming apparatus of the present invention is the same as the first embodiment described above, except that the correction amount at t ₁ is set based on the ejection timing correction amount at t _0. For the setting, a correction amount is obtained using a setting amount table as shown in FIG.

FIG. 13 is a flowchart of a third embodiment of correction of ink droplet ejection timing in the image forming apparatus of the present invention. Hereinafter, this embodiment will be described with reference to FIG.
First, the environmental temperature _{t 0} and to store the measurement (S301), the correction amount of the ejection timing at the temperature _{t 0,} is determined by printing a correction chart (S302). Then, receiving the print command (S303), measures the environmental temperature _{t 1} at the time before starting the printing (S304). At the time of printing, using a set amount table as shown in FIG. 12 with reference to the discharge timing correction amount at t ₀ , a delay amount suitable for t ₁ is set (S 305), and printing is executed (S 306).

[Fourth embodiment]
A description will be given of an aspect in which the correction amount table of the electronic component involved in the encoder signal transmission circuit is created by actually measuring the delay amount of the encoder signal under an arbitrary temperature.
In setting the correction amount, the table in FIG. 12 is created by calculating in advance an appropriate correction amount according to the temperature characteristic of the electronic component, but may be created from an actual measurement value.
FIG. 14 shows an example of an explanatory diagram of data measurement for obtaining an actual measurement value. As shown in FIG. 14, a printed circuit board (hereinafter referred to as “PCB”) on which a circuit 40 that is involved in the delay of the encoder signal is mounted is placed in a temperature environment where data is to be acquired, and is connected to an input line from the encoder sensor. The pseudo encoder signal 41 is input. By observing the input signal 42 of the encoder analysis unit at the same time, the delay amount of the encoder signal at the desired environmental temperature of the PCB can be measured. By repeating this measurement at a necessary environmental temperature, a correction amount table that matches the characteristics of the components actually mounted on each PCB can be created. It is preferable to perform the work of working this table in the manufacturing process.

FIG. 15A shows a table creation flow in this embodiment, and FIG. 15B shows a printing flow in this embodiment.
As shown in FIG. 15A, correction amounts at various temperatures tx are measured (S401), stored in a correction amount table (S402), and a correction table is created in advance.
Further, in the printing, as shown in FIG. 15 (b), it receives the print command (S501), measures the environmental temperature _{t 1} at the time before starting the printing (S502). Then from the correction table created in (a), it sets the correction amount at _{t 1} (S503), executes the printing (S504).

  The image forming apparatus of the present invention, at least it has a discharge unit for forming an image by ejecting an ink jet ink droplets as shown in FIG. 1, a block diagram of a feasible FIG ejection timing control of ink droplets described above And a control unit as shown in FIG. 5 and other means as necessary. Note that the ink droplet ejection timing control method in the image forming apparatus of the present invention can also be realized as a program for causing a computer to execute, and can also be realized by causing a computer to read a recording medium on which this program is recorded. Is possible. For example, the configuration of the ejection timing control function may be carried on the host computer side, or a signal may be transferred according to a desired request and executed.

[Configuration of image forming system, image forming program]
It is also preferable to configure the image forming system (printing system) by connecting the image forming apparatus according to the present embodiment to a personal computer as an information processing apparatus as shown in FIG. In this embodiment, the image forming system 300 includes a personal computer 301 as an example of an information processing apparatus (host PC) that is a host apparatus that transmits print data and a print job including a print condition for printing the print data. A printer apparatus 302 as an example of an image forming apparatus that prints print data is connected via a cable 303 as a connection unit.

  The personal computer 301 uses, for example, print data corresponding to the created document and print condition data set for printing the document (paper orientation, duplex, consolidation, bookbinding, staple, punch, enlargement / reduction, etc.) as a print job. The data is sent to the printer device 302.

  On the other hand, the printer device 302 prints print data in accordance with a print job sent from the personal computer 301. Specifically, the printer device 302 prints the print data included in the print job according to the print condition data included in the print job (for example, paper orientation, double-sided, aggregation, bookbinding, staple, punch, enlargement / reduction, etc.). Print on media such as.

  FIG. 17 is a block diagram illustrating a schematic configuration of a personal computer 301 as an information processing apparatus. The personal computer 301 includes an input unit 310 for inputting data, a display unit 311 such as a display, a communication unit 312 for performing data communication, a CPU 313 as control means for controlling the entire apparatus, A RAM 314 used as a work area, a recording medium drive device 315 that reads / writes data on the recording medium, a recording medium 316 that stores various programs for operating the CPU 313, and an audio output unit that outputs audio 317.

  The input unit 310 includes a keyboard having cursor keys, numeric input keys, various function keys, and the like, a mouse and a slice pad for selecting keys on the display screen of the display unit 311, and the user operates the CPU 313. This is a user interface for giving instructions and inputting data.

  The display unit 311 includes a CRT, an LCD, or the like, and performs display according to display data input from the CPU 313. The communication unit 312 is for data communication with the outside. For example, the communication unit 312 is for data communication with the printer device 302 or the like via the cable 303.

  The CPU 313 is a central control unit that controls the entire apparatus in accordance with a program stored in the recording medium 316. The CPU 313 includes an input unit 310, a display unit 311, a communication unit 312, a RAM 314, a recording medium drive device 315, and the like. Are connected to control data communication, reading of an application program by accessing a memory, reading / writing of various data, data / command input, display, and the like. Moreover, it functions as a prediction means and a speed profile update means described later.

  Further, the CPU 313 sends the print data input from the input unit 310 and the print condition data of the print data to the printer device 302 via the communication unit 312 as a print job.

  The RAM 314 includes a work memory that stores designated programs, input instructions, input data, processing results, and the like, and a display memory that temporarily stores display data to be displayed on the display screen of the display unit 311.

  The recording medium 316 stores various programs and data such as an OS program executable by the CPU 313 (for example, Microsoft operating system Windows (registered trademark) XP), a document creation application program, a printer driver corresponding to the printer device 302, and the like. Store. As the recording medium 316, for example, an optical / magnetic / electric recording medium such as a floppy (registered trademark) disk, a hard disk, a CD-ROM, a DVD-ROM, an MO, or a PC card can be used.

  Various programs are stored in the recording medium 316 in a data format readable by the CPU 313. Various programs may be recorded in advance on the recording medium 316, downloaded via a communication line such as the Internet, and stored in the recording medium 316.

  A program and data for performing image formation while performing ejection timing control according to the image forming apparatus of the present invention are recorded on a recording medium 316, and the steps in the embodiment of the present invention are executed by a computer, and the above-described image forming method is performed. By recording and distributing a program for realizing the function, the function can be easily realized.

DESCRIPTION OF SYMBOLS 1 Carriage 2 Guide rod 3 Main scanning motor 4 Pulley 5 Encoder sheet 6 Encoder sensor 9 Recording head 10 Nozzle

JP 2001-253066 A

Claims (4)

In an image forming apparatus that scans a carriage mounted with a recording head that discharges ink droplets to form an image on a recording medium.
Detecting the position and speed of the carriage from the encoder signal output in accordance with the movement of the carriage, and controlling the position and speed of the carriage;
After determining the correction amount of the ink droplet discharge timing based on the correction chart obtained by outputting at different discharge timings under a certain temperature,
An image forming apparatus, wherein a correction amount of ejection timing at a temperature at the time of printing is determined according to a temperature characteristic of an electronic component involved in the encoder signal transmission circuit.   The image forming apparatus according to claim 1, wherein the electronic component involved in the encoder signal transmission circuit is a capacitor.   Wherein an information of the electronic component correction amount table showing a correction amount corresponding to the temperature characteristics of the relative correction amount determined based on the correction chart, using the correction amount based on the correction amount table in temperature during printing execution The image forming apparatus according to claim 1, wherein a correction amount of the ejection timing is determined. The image forming apparatus according to claim 3, wherein the correction amount table of the electronic component involved in the encoder signal transmission circuit is created by actually measuring the delay amount of the encoder signal under an arbitrary temperature.

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