JP2007045001A - Imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging device which can realize the miniaturization of a power source and the saving of a manufacturing cost to a low level. <P>SOLUTION: A detected current value I is acquired from a current detection circuit 113 and a detected temperature T from a temperature detection circuit 112. Further, it is checked whether the detected current value I and the detected temperature T are at least a dangerous current value Id or a dangerous temperature Td level. Then, in case the current value I or the temperature T level is found in the dangerous region (the detected current value I≥Id or the detected temperature T≥Td), a main scan motor 4 and a subscan motor 31 are driven by changing a drive control signal to a motor drive part 104. Thus the printing speed (at least either of the carriage transfer speed or the paper feed rate) is changed in the way that overcurrent from the power source 110 can be inhibited. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that prevents an overcurrent of a power source.

  Various image forming apparatuses such as printers, facsimiles, copiers, plotters, printer / fax / copier multifunction machines, etc., for example, are recorded by a recording head composed of a liquid ejection head that ejects droplets of recording liquid such as ink. Form an image on a medium (hereinafter referred to as “paper”, but the material is not limited to paper, and is also synonymous with a recording medium, recording paper, or transfer material). Printing and printing are also used synonymously.) Inkjet recording type image forming apparatuses and electrophotographic type image forming apparatuses.

For example, in an inkjet recording type image forming apparatus, Patent Document 1 describes changing a driving waveform applied to a recording head according to temperature, changing a carriage moving speed according to a printing mode, and the like. ing.
JP 2003-11351 A

Note that changing the driving waveform for the recording head in accordance with the temperature is also described in Patent Document 2 and the like.
JP 2000-225700 A

  By the way, in the image forming apparatus of the ink jet recording system, since the number of actuator elements of the liquid discharge head constituting the recording head is increasing with high density recording and high speed, a large number of actuator elements are driven simultaneously. Sometimes a lot of inrush current is required. In particular, since the ink viscosity becomes high and a large discharge output is required in a low temperature environment, a larger inrush current is required, and a high output power supply circuit is essential. As a result, the configuration of the power supply circuit is complicated, the cost is high, and it is difficult to secure a space.

  In this case, as described in the above-mentioned patent document, it is necessary to widen the allowable range of the inrush current only by detecting the temperature and controlling the drive waveform for the recording head, thereby reducing the size and cost of the power source. There is a problem that it cannot be achieved.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an image forming apparatus capable of reducing the size and cost of a power supply.

  In order to solve the above problems, the image forming apparatus according to the present invention is configured to include means for changing the printing speed so as to suppress the overcurrent of the power source based on the output side current and the temperature of the power source.

  Here, when one of the output side current and temperature of the power source becomes a current value or temperature at which the predetermined power source becomes overcurrent, the power source at which the output side current and temperature of the power source is overcurrent becomes It is preferable to include means for changing to a print mode in which a drive waveform smaller than the current value or temperature is given to the image forming means. In this case, it is preferable to change the printing mode when either the output side current or the temperature of the power supply reaches a predetermined current value or temperature at which the power supply becomes an overcurrent during printing in the high-speed printing mode.

  Further, when the output-side current and temperature of the power supply become smaller than the current value or temperature at which the predetermined power supply becomes overcurrent, it is preferable to return the print mode after the change to the print mode before the change. In addition, it is preferable that a unit for outputting a message to change the print mode is provided.

  In addition, when either the current on the output side of the power supply or the temperature reaches a current value or temperature at which the predetermined power supply becomes overcurrent, the print mode is changed according to the designated result and printing is continued. It is preferable to execute either the mode or the cancel mode for canceling printing in the print mode. In this case, when either the output side current or the temperature of the power source becomes a current value or temperature at which the predetermined power source becomes an overcurrent, it is possible to designate either the continuation mode or the stop mode. .

  The image forming apparatus according to the present invention includes means for changing the printing speed so as to suppress the overcurrent of the power supply based on the output side current and temperature of the power supply, so that the power supply can be used while being controlled to the limit. Therefore, it is possible to reduce the size and cost.

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory side view for explaining the overall configuration of the image forming apparatus according to the present invention, and FIG.
In this image forming apparatus, a carriage 3 is slidably held in a main scanning direction by a guide rod 1 and a guide rail 2 which are guide members horizontally mounted on left and right side plates (not shown), and a driving pulley 6A is driven by a main scanning motor 4. 2 is moved and scanned in the direction indicated by the arrow (main scanning direction) in FIG. 2 via a timing belt 5 stretched between the roller and the driven pulley 6B.

  The carriage 3 includes, for example, four recording heads 7y, 7c, and 7m including droplet discharge heads that discharge yellow (Y), cyan (C), magenta (M), and black (K) ink droplets, respectively. , 7k (referred to as “recording head 7” when colors are not distinguished) are arranged in a direction crossing the main scanning direction with a plurality of ink ejection openings, and the ink droplet ejection direction is directed downward.

  As a liquid discharge head constituting the recording head 7, a piezoelectric actuator such as a piezoelectric element, a thermal actuator using film boiling of a recording liquid using an electrothermal transducer such as a heating resistor, and a metal phase change due to temperature change are used. A shape memory alloy actuator, an electrostatic actuator using an electrostatic force, or the like provided as energy generating means (pressure generating means) for discharging ink (liquid) can be used. Note that the recording head can also be configured by one or a plurality of liquid droplet ejection heads provided with a plurality of nozzle rows that eject different colors.

  The carriage 3 is equipped with sub-tanks 8 for each color for supplying ink of each color to the recording head 7. Ink is supplied to the sub tank 8 from a main tank (ink cartridge) (not shown) via an ink supply tube 9.

  On the other hand, as a paper feeding unit for feeding paper 12 stacked on a paper stacking unit (pressure plate) 11 such as a paper feeding cassette 10, a half-moon roller (for separating and feeding the paper 12 one by one from the paper stacking unit 11) A separation pad 14 made of a material having a large friction coefficient is provided facing the sheet feeding roller 13 and the sheet feeding roller 13, and the separation pad 14 is urged toward the sheet feeding roller 13 side.

  In order to convey the sheet 12 fed from the sheet feeding unit below the recording head 7, a conveyance belt 21 for electrostatically attracting and conveying the sheet 12 and a guide 15 from the sheet feeding unit. A counter roller 22 for transporting the sheet 12 fed between the conveyor belt 21 and the conveyor belt 21, and for shifting the sheet 12 fed substantially vertically upward by approximately 90 ° to follow the conveyor belt 21. A conveyance guide 23 and a pressing roller 25 urged toward the conveyance belt 21 by a pressing member 24 are provided. In addition, a charging roller 26 as a charging unit for charging the surface of the transport belt 21 is provided.

  Here, the conveyor belt 21 is an endless belt, and is stretched between the conveyor roller 27 and the tension roller 28, and the conveyor roller 27 rotates from the sub-scanning motor 31 via the timing belt 32 and the timing roller 33. By doing so, it is configured to circulate in the belt conveyance direction (sub-scanning direction) of FIG. A guide member 29 is disposed on the back side of the conveying belt 21 corresponding to the image forming area by the recording head 7. The charging roller 26 is disposed so as to come into contact with the surface layer of the transport belt 21 and rotate following the rotation of the transport belt 21.

  Further, as shown in FIG. 2, a slit disk 34 is attached to the shaft of the transport roller 27, and a sensor 35 for detecting the slit of the slit disk 34 is provided. A rotary encoder 36 is configured.

  Further, as a paper discharge unit for discharging the paper 12 recorded by the recording head 7, a separation claw 51 for separating the paper 12 from the transport belt 21, a paper discharge roller 52 and a paper discharge roller 53, and a discharge And a paper discharge tray 54 for stocking the paper 12 to be printed.

  A double-sided paper feeding unit 55 is detachably mounted on the back. The double-sided paper feeding unit 55 takes in the paper 12 returned by the reverse rotation of the transport belt 21, reverses it, and feeds it again between the counter roller 22 and the transport belt 21.

  Further, as shown in FIG. 2, a maintenance / recovery mechanism 56 for maintaining and recovering the nozzle state of the recording head 7 is disposed in the non-printing area on one side of the carriage 3 in the scanning direction.

  The maintenance / recovery machine 56 is provided with caps 57 for capping each nozzle surface of the recording head 7, a wiper blade 58 as a blade member for wiping the nozzle surface, and for discharging the thickened recording liquid. An empty discharge receiver 59 for receiving droplets when performing an empty discharge for discharging droplets that do not contribute to recording is provided.

  In the image forming apparatus configured as described above, the sheets 12 are separated and fed one by one from the sheet feeding unit, and the sheet 12 fed substantially vertically upward is guided by the guide 15, and includes the transport belt 21 and the counter roller 22. The leading end is guided by the conveying guide 23 and pressed against the conveying belt 21 by the pressing roller 25, and the conveying direction is changed by approximately 90 °.

  At this time, a charging voltage pattern in which a positive output and a negative output are alternately repeated from the AC bias supply unit to the charging roller 26 by a control unit (not shown), that is, an alternating voltage is applied and the conveying belt 21 is alternated. That is, plus and minus are alternately charged in a band shape with a predetermined width in the sub-scanning direction which is the circumferential direction. When the sheet 12 is fed onto the conveyance belt 21 charged alternately with plus and minus, the sheet 12 is attracted to the conveyance belt 21 by electrostatic force, and the sheet 12 is conveyed in the sub-scanning direction by the circular movement of the conveyance belt 21. Is done.

  Therefore, by driving the recording head 7 according to the image signal while moving the carriage 3 in the forward and backward directions, ink droplets are ejected onto the stopped paper 12 to record one line. After transporting a predetermined amount, the next line is recorded. Upon receiving a recording end signal or a signal that the trailing edge of the paper 12 has reached the recording area, the recording operation is finished and the paper 12 is discharged onto the paper discharge tray 54.

  In the case of double-sided printing, when recording on the front surface (surface to be printed first) is completed, the recording paper 12 is fed into the double-sided paper feeding unit 55 by rotating the conveyor belt 21 in reverse. The paper 12 is reversed (with the back surface being the printing surface), fed again between the counter roller 22 and the transport belt 21, controlled in timing, and transported onto the transport bell 21 as described above. After recording on the back side, the sheet is discharged onto the discharge tray 54.

  During printing (recording) standby, the carriage 3 is moved to the maintenance / recovery mechanism 55 side, and the nozzle surface of the recording head 7 is capped by the cap 57, and the nozzles are kept in a wet state. To prevent. In addition, the recording liquid is sucked from the nozzle in a state where the recording head 7 is capped by the cap 57 (referred to as “nozzle suction” or “head suction”), and a recovery operation is performed to discharge the thickened recording liquid or bubbles. Wiping is performed by the wiper blade 58 in order to clean and remove ink adhering to the nozzle surface of the recording head 7 by this recovery operation. In addition, an idle ejection operation for ejecting ink not related to recording is performed before the start of recording or during recording. Thereby, the stable ejection performance of the recording head 7 is maintained.

The power supply and control unit in this image forming apparatus will be described with reference to the block diagram of FIG.
The control unit 100 includes a CPU that controls the entire apparatus, a program that is executed by the CPU, a ROM that stores other fixed data, a RAM that temporarily stores image data, and the like while the apparatus is powered off. Rewritable non-volatile memory for storing image data, various signal processing for image data, image processing such as rearrangement, input / output for controlling other devices including DMA such as transfer of image data to the recording head side The main control unit 101 includes an ASIC for processing signals, data with the host side, an I / F for transmitting and receiving signals, and the like.

  In addition, a data memory 102 for storing data and a drive waveform for driving the recording head 7 are generated, and print data for selectively driving the pressure generating means of the recording head 7 and various data associated therewith are generated. A head drive control unit 103 that outputs to the side head driver, a motor drive unit 104 for driving the main scanning motor 4 and the sub-scanning motor 31, an AC bias supply unit 105 for supplying an AC bias to the charging roller 26, and the like. ing.

  Here, the control unit 100 receives print data or the like generated by a host printer driver such as an information processing apparatus such as a personal computer, an image reading apparatus such as an image scanner, or an imaging apparatus such as a digital camera, via a cable or a network. The print data is read and analyzed, and necessary image processing, data rearrangement processing, and the like are performed, transferred to the head drive control unit 103, and print data and drive waveforms are output from the head drive control unit 103 to the head driver. To do.

  The drive waveform generation unit of the head drive control unit 103 includes a D / A converter and an amplifier that perform D / A conversion on drive pulse pattern data stored and read in the ROM, and includes one drive pulse or a plurality of drives. A drive waveform composed of pulses is output to the head driver to drive each pressure generating means of the recording head 107.

  The motor drive unit 104 calculates a control value based on a target value given from the main control unit 101 side and a speed detection value obtained by sampling a detection pulse from a linear encoder (not shown) that detects the movement of the carriage 3. The main scanning motor 4 is driven via an internal motor driver, and the control value is determined based on the target value given from the main control unit 101 side and the speed detection value obtained by sampling the detection pulse from the wheel encoder 36. The sub-scanning motor 31 is driven via the internal motor driver after calculation.

  A power supply (PSU: electrode supply circuit) 110 that supplies a power supply voltage to the control unit 100 and the like includes a temperature detection element 111 that detects the temperature of the power supply 110, and a temperature based on the output of the temperature detection element 111. The power supply temperature is detected by the detection circuit 112, and the detection result is input to the main control unit 101.

  In addition, a current detection circuit 113 that detects a current flowing through the secondary power supply line of the power supply 110 is provided, and the detection result of the current detection circuit 113 is input to the main control unit 101.

  In the data memory 102, data of a predetermined detection temperature value (this is called “dangerous temperature td”) at which the temperature of the power supply 110 may flow overcurrent, and an overcurrent is generated in the secondary power line of the power supply 110. Data of a predetermined detection current value that may flow (this is referred to as “dangerous current value Id”) is stored (can also be stored in the nonvolatile memory of the main control unit 101).

Accordingly, the printing speed change control based on the power supply temperature and current in the control unit will be described with reference to FIGS.
The main control unit 101 acquires the detected current value from the current detection circuit 113 and the detected temperature from the temperature detection circuit 112, and the detected current value I and the detected temperature T are equal to or higher than the dangerous current value Id stored in the data memory 102. Alternatively, it is checked whether or not the temperature is higher than the dangerous temperature Td, and the current value I or the temperature T is in a region where the power source 110 may be overcurrent, that is, a dangerous region (detected current value I ≧ Id or detected temperature T It is determined whether or not ≧ Td).

  For example, as shown in FIG. 5, the current value I when the power source 110 is likely to be overcurrent is defined as a dangerous current value Id, and the temperature T when the power source 110 is likely to be overcurrent is defined as a dangerous temperature Td. It is set in advance and stored in the data memory 102. In this case, the current value and temperature when the power supply 110 becomes overcurrent vary, but here, as a reference for changing the printing speed, the overcurrent can be suppressed (prevented) by changing the printing speed. Current value and temperature.

  Here, when any one of the detected current value I and temperature T is in the dangerous region, the drive control signal for the motor drive unit 104 is changed to reduce the speed of the main scanning motor 4 and the sub-scanning motor 31. By driving in this manner, the printing speed is changed so as to suppress the overcurrent of the power source 110. For example, the main scanning motor 4 is changed so as to decrease the carriage moving speed by decreasing the rotational speed of the main scanning motor 4. Note that the current suppression effect is greater when the carriage movement speed is decreased than when the paper feed speed is decreased.

  Thus, by changing the printing speed so as to suppress the overcurrent of the power supply based on the output side current and temperature of the power supply, it becomes possible to use it while controlling the power supply to the limit, miniaturization, Cost can be reduced.

Next, an example of a print mode change process for changing the print mode based on the output side current and temperature of the power supply will be described with reference to FIG.
Again, the main control unit 101 acquires the detected current value I from the current detection circuit 113 and the detected temperature T from the temperature detection circuit 112, and the detected current value I and the detected temperature T are stored in the data memory 102. It is checked whether or not the dangerous current value Id or higher or the dangerous temperature Td or higher, and it is determined whether or not the current I or temperature T is in the dangerous region (detected current value ≧ Id or detected temperature ≧ Td).

  When either one of the detected current value I and temperature T is in the dangerous region, an automatic control mode including a continuation mode in which the printing speed and the printing mode are automatically changed to continue printing is set. It is determined whether or not.

  Here, when the automatic control mode is set, first, the user is notified that the print mode is to be changed. The output for changing the print mode can be displayed via a printer driver on the host side, or can be displayed using the display unit of the main body of the image forming apparatus.

  Thereafter, the printing speed is changed, and the detected current value I and temperature T are changed so that both the detected current value I and the temperature T become smaller than the dangerous current value Id and the dangerous temperature Td (entering the safe operation region in FIG. 5). Change to the print mode given to 7 and continue printing.

  On the other hand, when the automatic control mode is not set, the user can change the current print mode and continue printing, and the print operation can be stopped (cancelled) and the current value and temperature can be temporarily canceled. When the printer returns to the safe operation area, it is displayed via the printer driver on the host side which of the cancellation modes to perform printing is selected, and the specification result of the mode input corresponding to this is fetched and specified. Whether the result is the continuation mode (printing continuation) or not (discontinuation mode).

  At this time, if the designated result is continuation of printing, the printing speed is changed (slowed) as described above, and a driving waveform in which the current and temperature are lowered (becomes a safe area) is applied to the recording head 7. If the print mode is not to be continued (if cancel), the print cancel process is performed.

  In other words, for example, if it is detected during high-speed printing that the temperature and current are in an overcurrent state, the motor speed is reduced although the high-speed printing is performed, and the printing is continued although the image quality is reduced. In addition, by changing to a print mode in which the drive waveform applied to the recording head is controlled (control so that the flowing current is reduced), printing can be continued without reducing productivity.

  In this case, the user is notified that the print mode has been changed during the process, for example, the image quality has deteriorated by outputting (for example, displaying) that the user has reached the danger area in advance and that the print mode is to be changed. Will be able to know in advance.

  Therefore, by allowing the user to select in advance whether to change the print mode and continue printing or to cancel (cancel) printing in the print mode, the user can continue printing quickly. Alternatively, it is possible to select whether to output a printed matter that is concerned about the image quality and requires high image quality or the like, and the convenience for the user is improved.

  In this case, whether the printing mode is changed and printing is continued or whether printing in the printing mode is to be canceled (cancelled), that is, when the printing mode has to be changed, that is, a stage in which a dangerous area is entered If the user decides that the print mode can be switched automatically, the user can change the print mode and continue printing or cancel printing. You can choose according to the situation.

Next, another example of the print mode change process will be described with reference to FIGS.
Here, similarly to the above example, when any one of the detected current value and temperature is in the dangerous region, the detected current value and temperature are both driven to be smaller than the dangerous current value Id and the dangerous temperature Td. Although the waveform is automatically changed to the printing mode applied to the recording head 7, when the detected current value and temperature are both smaller than the dangerous current value Id and the dangerous temperature Td, here, as shown in FIG. In addition, when the critical current value Id, the safe current value Ids obtained by giving a predetermined offset to the dangerous temperature Td, or the safe temperature Tds or less, processing for returning the print mode to the print mode before the change is performed.

  For example, as shown by a broken line in FIG. 8, when the current value I and the temperature T rise and the detected current value I becomes the dangerous current value Id, the print mode is changed once and the current value becomes the dangerous current value. The driving is performed so as to be smaller than Id, but when the detected current value I becomes a predetermined safe current value Ids (Ids <Id), the printing mode is returned to the printing mode before the change and printing is continued.

  Thereby, even when printing is continued, it is possible to reduce the portion where the image quality is lowered.

  In the above embodiment, the present invention has been described with reference to an example in which the present invention is applied to an image forming apparatus using a recording head for discharging liquid droplets of recording liquid as an image forming unit. It can also be applied to.

1 is an explanatory side view illustrating an overall configuration of an example of an image forming apparatus according to the present invention. It is a schematic plane explanatory drawing similarly. It is a block explanatory drawing explaining the outline of a power supply and a control part similarly. It is a flowchart which shows an example of the printing speed change process by the control part. It is explanatory drawing with which it uses for description of the danger area | region of an electric current and temperature similarly. FIG. 6 is a flowchart for explaining the print mode changing process. FIG. 10 is a flowchart for explaining another example of the print mode change process. FIG. 10 is an explanatory diagram for explaining another example of the print mode changing process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 ... Carriage 4 ... Main scanning motor 7 ... Recording head 10 ... Paper feed tray 12 ... Recording medium (paper)
DESCRIPTION OF SYMBOLS 21 ... Conveyance belt 101 ... Main control part 102 ... Data memory 103 ... Head drive control part 104 ... Motor drive part 110 ... Power supply 111 ... Temperature detection element 112 ... Temperature detection circuit 113 ... Current detection circuit

Claims (7)

  An image forming apparatus including an image forming unit that forms an image on a recording medium includes a unit that changes a printing speed so as to suppress an overcurrent of the power source based on an output side current of the power source and a temperature of the power source. An image forming apparatus.   2. The image forming apparatus according to claim 1, wherein when one of the output current and temperature of the power supply reaches a predetermined current value or temperature at which the power supply becomes overcurrent, An image forming apparatus comprising: a means for changing to a print mode in which a driving waveform having a temperature lower than the current value or temperature at which the predetermined power source becomes an overcurrent is applied to the image forming means.   3. The image forming apparatus according to claim 2, wherein, when printing is performed in the high-speed printing mode, printing is performed when one of the output-side current and temperature of the power supply reaches a predetermined current value or temperature at which the power supply becomes overcurrent. An image forming apparatus characterized by changing a mode.   4. The image forming apparatus according to claim 2, wherein when the output side current and temperature of the power source become smaller than a current value or temperature at which the predetermined power source becomes overcurrent, the changed printing mode is set. An image forming apparatus that returns to a print mode before change.   5. The image forming apparatus according to claim 2, further comprising means for outputting a message indicating that the print mode is changed.   5. The image forming apparatus according to claim 2, wherein one of the output-side current and temperature of the power supply is designated when a predetermined current value or temperature at which the power supply becomes overcurrent is set. An image forming apparatus that executes either a continuation mode in which a printing mode is changed according to a result of the printing and a continuation mode in which printing is continued or a suspending mode in which printing in the printing mode is stopped. 7. The image forming apparatus according to claim 6, wherein when one of the output-side current and temperature of the power supply reaches a predetermined current value or temperature at which the power supply becomes overcurrent, the continuation mode and the stop mode are set. Any one of the above can be specified.

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