JP2958917B2 - Image recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus capable of appropriately stopping and restarting recording while driving an image recording head to record an image.

[Conventional technology]

2. Description of the Related Art Conventionally, digital recording systems such as ink jet recording and thermal transfer recording are well known as this type of image recording device.

In particular, ink jet recording has advantages such as easy colorization, and is widely used for computer graphic output.

FIG. 7 is a connection diagram when the ink jet recording apparatus is used for outputting computer graphics. 101 is a host computer, 102 and 104 are image signals, 103 is an interface, and 105 is an ink jet printer. The image data of the host computer 10 is an interface
The data is sent to 103 and is stored in a memory (not shown) in the interface. The interface rearranges the image data in the memory into a form that can be received by the inkjet printer, and then sends the image data to the inkjet printer. The ink jet printer performs printing in accordance with the sent image data and performs image output.

FIG. 8 is a schematic cross-sectional view of an ink jet printer, 1 is a printer, 2 is roll paper, 3 and 4 are paper feed rollers, 5 is a cutter, 6 is a carriage, 7 is an ink jet head, 8 is a sub scanning roller, 9 Is a platen, 10,11
Is a paper guide.

The roll paper 2 is fed to the platen 9 by the feed rollers 3 and 4.
Sent to In the platen section, a carriage 6 on which a head is mounted performs a serial scan, and drives a head 7 according to a signal from an interface to record an image.

The heads are cyan, magenta, yellow, and black.
It is provided for each color and performs full color recording.

When the recording for one line is completed, the paper is sub-scanned by the sub-scanning roller 10, and then the recording for one line is repeated.

When the trailing edge of the copy reaches the position of the cutter 5, the cutter is rotated to cut the roll paper. The recorded image is discharged through paper guides 10 and 11.

The memory of the interface is usually several MB to several tens of MB, but the graphic data of the host computer sometimes exceeds this. In such a case, it is possible to transfer data corresponding to the memory capacity of the interface and print it, and after printing, transfer the remaining data to the interface again and print it. This is because, after printing the data from the interface, the printer can stop the sub-scanning of the roll paper and the scanning of the carriage, and can carry on until the next data is transferred.

In this way, it is possible to record even large image data.

[Problems to be solved by the invention]

The above-described conventional image recording apparatus has the following problems.

Consider the case of recording an image as shown in FIG. The print width of the recording head is d, and image recording is performed by scanning in the x direction. In addition, although the image is for 24 scans in total,
It is assumed that the memory capacity on the interface has a capacity of only 5 scans. In such a case, the portion A is continuously printed, and thereafter, a standby state is entered until the image data of the portion B is transferred. After the transfer is completed, the portion B is continuously printed, and then, the image forming apparatus 1 enters the standby state again until the image data of the portion C is transferred. And after the transfer ends,
The portion C is continuously printed, and the image recording ends.

Generally, the temperature of the recording head increases as printing continues. When the temperature rises, the viscosity of the ink decreases, the ink ejection amount increases, and the recording density increases. However,
Once in the standby state, the temperature drops and the recording density drops. This phenomenon applies to any type of recording head, but particularly to a bubble-shett type head proposed by Canon Inc., which heats a heater to boil ink and discharges it with the pressure of bubbles. Notable.

FIG. 10 shows a change in the recording density when the image recording shown in FIG. 9 is performed. When printing is performed continuously, the density increases little by little, so that the density change is not conspicuous. However, when the standby states D, E are interposed, the density change sharply occurs and becomes very conspicuous on the image.

It is well known that a head is generally provided with a temperature detecting means such as a thermistor and a heater to control the temperature in order to keep the head temperature constant.

However, this type of temperature control has a slow response when the temperature is rapidly changing, and it is difficult to perform precise temperature control when the temperature changes like D and E in FIG. . In particular, when one head is provided with one thermistor and heater, and the temperature of the ink in the nozzles is controlled to the same temperature even when the entire head has reached a certain temperature,
In many cases, the temperature detected by the thermistor does not reach the predetermined temperature, and the density difference often remains after printing.

The present invention has been made in view of the above-described problems of the related art, and can provide an image having no change in recording density between when recording is interrupted and when recording is restarted even if the head temperature decreases during standby. It is intended to provide an image recording device.

[Means for solving the problem]

An image recording apparatus according to the present invention is an image recording apparatus capable of temporarily suspending and resuming a recording operation while driving a recording head that performs recording using thermal energy to record an image. Determining means for determining the temporary interruption that occurs in the recording head; head temperature detecting means for detecting the temperature of the recording head; and determining the head temperature when the determining means determines the temporary interruption that occurs during the recording operation. Storage means for storing a head temperature detected by the detection means; interruption time detection means for detecting a recording interruption time; and a head temperature stored in the storage means and an interruption time detected by the interruption time detection means. And correcting means for correcting an image signal given to the print head at the time of resuming printing so as to make the print density at the time of printing interruption and at the time of restarting printing equal.

Further, the correction means corrects an image signal correction amount at the time of resuming recording according to the recording head drive history after resuming recording, and corrects an image signal with the corrected image signal correction amount.

The image processing apparatus further includes an environmental temperature detecting means for detecting an environmental temperature, wherein the correcting means corrects an image signal correction amount at the time of resuming recording in consideration of the detected environmental temperature.

(Operation)

The temperature detecting means and the interruption time detecting means detect the temperature of the image recording head when the recording is interrupted and the time from the interruption to the resumption, and cancel the change in the recording density at the resumption from the detection results. As described above, the correction means corrects the image signal and gives the image signal to the image recording head.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of the image recording apparatus of the present invention, FIG. 2 is a graph showing a table stored in a look-up table 110 of the embodiment of FIG. 1, and FIG. 2 is a graph showing data stored in a memory 114 of the embodiment of FIG.

101 is a host computer, 103 is an interface,
110 is a look-up table (LUT), 111 is a CPU, 112 is a recording head, 113 is a head temperature detecting means such as a thermistor, 114 is a memory, 102 is an image signal from a computer,
104 is an image signal rearranged by the interface, 120
Is a state instruction signal, 121 is an output image signal of the lookup table 110, 112 is a lookup table selection signal, and 123 is a head temperature signal.

The 8-bit image signal transferred from the host computer 101 is temporarily stored in a memory in the interface 103, and then rearranged to provide a look-up table 11
Enter 0 (hereinafter referred to as LUT110). As shown in FIG. 2, the LUT 110 has a slope of 0.01 from Y = 0.69X to Y = 1.32X.
64 sets of different straight lines are prepared as a table,
The input signal is converted according to the table selected by the selection signal 122. The output signal 121 of the LUT 110 is the recording head 1
Entered in 12. The recording head 112 includes a head driving circuit (not shown), and drives the recording head 112 with a driving pulse corresponding to the input image data to eject ink. The ejection ink amount is configured to be substantially proportional to the magnitude of the drive pulse.

When normal printing is started, the state instruction signal of the interface 103 sends a signal indicating the normal printing state to the CPU 111. At this time, the CPU 111 selects the LUT 110 with a slope of 1.0.

When the image recording for the memory capacity of the interface 103 is completed, the interface 103 sends a signal indicating a standby state to the CPU 111. Upon receiving this signal, the CPU 111 detects the temperature T of the recording head 112 and temporarily stores it in a memory (not shown). Then, the time t until the signal indicating the normal printing state is received next is counted. When the data transport is completed and the next printing state is entered, a table to be selected from the LUT 110 when recording is resumed is determined according to the head temperature T and the interruption time t immediately before the interruption.

FIG. 3 is a graph showing conditions for determining the inclination of the graph based on the LUT 110 table stored in the memory 114 and selected at the time of resuming printing.

When the head temperature immediately before the interruption is 25 ° C. or lower, it is determined that the head is at the same temperature as the room temperature, and that the temperature does not decrease due to the interruption. Therefore, the inclination of the graph based on the table of the LUT 110 remains at 1.0.

However, if the head temperature immediately before the interruption is 25 ° C or higher,
It is determined that the head temperature will drop due to the interruption, and the slope of the graph based on the table of the LUT 110 at the time of resumption is made larger than 1.0 so that the same image density as before the interruption is obtained. The gradient of the graph based on the table of the LUT 110 is increased as the interruption time is longer and as the head temperature immediately before the interruption is higher, thereby compensating for the density change during the interruption. After printing is resumed, the coefficient is gradually restored. For example, when the table corresponding to the graph with a gradient of 1.10 is selected from the LUT 110 at the time of restart, and the capacity of the interface memory is for 10 scans, the gradient is reduced by 0.01 for each scan, and the graph with a gradient of 1.01 is displayed on the 10th scan. Is recorded based on the table of the LUT 110 corresponding to. Then, after the next standby, when recording is restarted, tilt 1.
Correction is performed based on the 0 table.

In this way, even if the head temperature decreases during the holding operation, the image signal is corrected, so that a uniform image having no actual density change can be obtained.

In a color image forming apparatus, the above control may be performed independently for each color recording head.

Further, when the inclination of the graph based on the table after the restart of recording is reduced, not only the number of scans but also the recording time, the number of recording pulses, or the like may be counted, and the coefficient may be returned accordingly.

FIG. 4 is a block diagram showing a second embodiment of the present invention.

In this embodiment, an environmental temperature detecting means 115 is added to the embodiment of FIG. 1, and a table determination condition of the LUT 110 is prepared in the memory 114 for each environmental temperature.

The environmental temperature detecting means 115 is constituted by a thermistor or the like,
Detects the temperature of the environment where the device is placed and generates an environmental temperature signal 125
To the CPU 111. The CPU 111 selects a condition determination curve (not shown) according to the environmental temperature, and further determines the inclination of the graph based on the table of the LUT 110 according to the head temperature before interruption and the interruption time. The condition determination curve is stored in the ROM as the LUT 110, and outputs a slope as an address of each of the environmental temperature, the head temperature before interruption, and the interruption time. The condition determination curve of the graph selection by the LUT110 is as follows:
Because the head temperature drop during suspension is large, select a graph with a larger slope, and if the environmental temperature is high,
Try to select a graph with a small slope.

This makes it possible to more accurately suppress the change in density.

FIG. 5 is a block diagram showing a third embodiment of the present invention. Those denoted by the same reference numerals as those in FIG. 1 indicate the same components.

In this embodiment, the LUT 110 and the recording head 112 of the embodiment shown in FIG.
And a binarizing circuit 130 is inserted and connected.

Although the embodiment shown in FIG. 1 uses a recording head capable of changing the size of a dot in accordance with the size of an input image signal, the present embodiment is directed to a head in which the size of a dot cannot be changed. Is applied.

The binarization circuit 130 converts a multi-level image signal into a binary signal by a binarization method such as a dither method or an error diffusion method. The recording head prints a head of a fixed size according to the binary signal and records an image. Other functions are the same as those of the embodiment shown in FIG.

With such a configuration, even if the temperature decreases during standby, when recording is resumed, more dots are printed to compensate for the decrease in density, and a uniform image with no actual density change can be obtained. .

In the above embodiments, the serial scan type ink jet apparatus has been described, but a full multi type ink jet apparatus may be used.

In addition, the present invention can be implemented not only in the case of a valve-jet type inking jet but also in the case where the temperature of the head rises during driving, such as thermal transfer.

In addition, the status of the mobile device is not always the time for receiving the transfer data, and the head recovers during printing.
The present invention can be applied to a case where the printer enters a standby state during printing for another purpose.

Further, the present invention brings about an excellent effect particularly in a recording head and a recording apparatus of a valve jet type proposed by Canon Inc. among ink jet recording types.

FIG. 6 is a configuration diagram showing a recording head of a valve jet system.

The recording head 1A has a plurality of ejection ports provided in rows.
In order to discharge the recording liquid from 30, an electrothermal converter 40 that generates thermal energy to which a printing applied voltage is supplied is provided for each liquid path. Then, by applying a drive signal, heat energy is generated in the electrothermal transducer 40, causing film boiling and forming bubbles in the ink liquid path. Then, ink droplets are ejected from the ejection port 30 by the growth of the bubble.

For a typical configuration and principle of a recording apparatus using a valve jet recording head, see, for example, US Pat.
It is preferable to use the basic principle disclosed in US Pat. Nos. 23129 and 4740796. This method can be applied to both the so-called on-demand type and the continuous type. In particular, in the case of the on-demand type, it is arranged corresponding to the sheet or the liquid path holding the liquid (ink). By applying at least one drive signal corresponding to the recording information and giving a rapid temperature rise exceeding nucleate boiling to the electrothermal transducer being made, heat energy is generated in the electrothermal transducer, and the recording head is driven. This is effective because the film can be boiled on the heat-acting surface and air bubbles in the liquid (ink) can be effectively formed one-to-one with this drive signal. A liquid (ink) is discharged through a discharge opening due to the growth and contraction of the bubble to form at least one bubble.
When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that a liquid (ink) discharge port having particularly excellent responsiveness can be achieved, which is more preferable. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,434,262 are suitable. Further, if the conditions described in US Pat. No. 4,313,124 relating to the invention relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

As a configuration of the recording head, in addition to the combination of the discharge port, the liquid path, and the electric heat exchanger (a linear liquid flow path or a right-angled liquid flow path) as disclosed in the above-mentioned respective specifications, a heat acting section The configurations described in U.S. Pat. No. 4,558,333 and U.S. Pat. In addition, JP-A-59 / 123670 discloses a configuration in which a slit common to a plurality of weather heat converters is used as a discharge portion of an electric heat exchanger, and an aperture for absorbing a pressure wave of heat energy. The present invention is also effective as a configuration based on JP-A-59-138461 which discloses a configuration corresponding to a discharge unit.

Further, as a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus, the length can be reduced by a combination of a plurality of recording heads as disclosed in the above specification. The present invention can exhibit the above-mentioned effects more effectively, though it may be either a configuration that satisfies or a configuration as a single recording head that is integrally formed.

In addition, a replaceable chip-type recording head, which is electrically connected to the apparatus main body and can supply ink from the apparatus main body by being mounted on the apparatus main body, or is provided integrally with the recording head itself. The present invention is also effective when a cartridge type recording head is used.

Further, it is preferable to add recovery means, preliminary auxiliary means, and the like for the print head provided as a configuration of the printing apparatus of the present invention since the effects of the present invention can be further defined. If these are specifically mentioned, a cabin means, a cleaning means, a pressure or suction means, an electric heat exchanger or another heating element for the recording head, or a preliminary ejection mode for ejecting them. Is also effective for performing stable recording.

Further, the printing mode of the printing apparatus is not limited to the printing mode of only the mainstream color such as black, and may be a printing head integrally formed or a combination of a plurality of printing heads. The present invention is extremely effective also in an apparatus provided with at least one of the full color according to the above.

In the embodiments of the present invention described above, the ink is described as a liquid. However, an ink that solidifies at room temperature or higher and softens or becomes liquid at room temperature, or is generally used in an ink jet. The material may be softened or liquid in a temperature range of 30 ° C. or more and 70 ° C. or less, which is the temperature range of the temperature adjustment performed. That is, it is sufficient that the ink is in a liquid state when the use recording signal is applied. In addition, positively prevent the temperature rise due to thermal energy by using the energy of the state change of the ink from the solid state to the liquid state, or use ink that solidifies in a standing state to prevent evaporation of the ink. In any case, starting with thermal energy such as one in which the ink is liquefied and ejected as an ink liquid by the application of the thermal energy according to the recording signal or one that already starts to solidify when reaching the recording medium Use of an ink having a liquefying property is also applicable to the present invention. In such a case, as described in JP-A-54-56847 or JP-A-60-71260, the ink is held as a liquid or solid in a porous sheet recess or through hole, It is good also as a form which opposes an electrothermal transducer. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

〔The invention's effect〕

As described above, the present invention corrects the image signal given to the image recording head when resuming recording from the temperature of the image recording head when the recording is interrupted and the time from when the recording is interrupted to when the recording is resumed. This has the effect of compensating for the image density change due to the interruption, and obtaining a uniform image with no change in the recording density between when the recording is interrupted and when the recording is restarted.

Further, according to the present invention, the processing relating to the correction of the image signal is performed during the interruption period of the recording, so that the processing time and the processing load do not increase, and the recording time and the processing apparatus are prevented from increasing. Becomes possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the image recording apparatus of the present invention, FIG. 2 is a graph showing a table stored in a look-up table 110 of the embodiment of FIG.
FIG. 4 is a graph showing data stored in the memory 114 of the embodiment of FIG. 1, and FIGS.
2, a block diagram showing a third embodiment, FIG. 6 is a configuration diagram showing a valve jet type recording head, FIG. 7 is a configuration diagram showing a conventional example, and FIG. 8 is a conventional ink jet printer shown in FIG. FIG. 9 and FIG. 10 are diagrams for explaining the operation of the conventional example. 102: Host computer, 103: Interface, 110: LUT, 111: CPU, 112: Recording head, 113: Head temperature detecting means, 114: Memory, 115: Environmental temperature detecting means, 130: ... Binarization circuit.

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B41J 2/05 B41J 2/36

Claims (5)

(57) [Claims] An image recording apparatus capable of temporarily suspending and resuming a recording operation when an image is recorded by driving a recording head that performs recording using thermal energy. Determining means for determining the temporary interruption, head temperature detecting means for detecting the temperature of the recording head, and when the determining means determines the temporary interruption occurring during the recording operation, the head temperature detecting means Storage means for storing the detected head temperature; interruption time detection means for detecting the recording interruption time; and when recording is interrupted according to the head temperature stored in the storage means and the interruption time detected by the interruption time detection means. And a correcting means for correcting an image signal given to the recording head at the time of resuming recording so as to make the recording density at the time of resuming printing equal. . 2. The apparatus according to claim 1, wherein said correction means corrects an image signal correction amount at the time of resuming recording in accordance with said recording head drive history after resuming recording, and corrects an image signal with the corrected image signal correction amount. The image recording device according to claim 1. 3. An apparatus according to claim 1, further comprising an environmental temperature detecting means for detecting an environmental temperature, wherein said correcting means corrects an image signal correction amount at the time of resuming recording in consideration of the detected environmental temperature. 2. The image recording device according to 1. 4. The recording head according to claim 1, wherein the recording head discharges the ink from the discharge port using thermal energy, and has an electric heat exchanger as a means for generating the energy. Item 2. The image recording device according to item 1. 5. The recording head according to claim 1, wherein said recording head is a full line type recording head having a plurality of recording elements over the entire recording width of a recording material. The image recording apparatus according to claim 1.