JP2958916B2 - 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, and more particularly, to an image recording apparatus having a standby mode for interrupting / restarting a recording operation.

[Conventional technology]

2. Description of the Related Art Conventionally, a digital recording method is well known as a recording method used for ink jet recording thermal transfer recording and the like.

In particular, the inkjet recording system has advantages such as easy colorization, and has been widely used as a computer graphic output device.

FIG. 5 is a diagram showing a configuration when an ink jet printer is used for outputting computer graphics.

In the figure, 501 is a host computer, 502 and 504 are image signals, 503 is an interface, and 505 is an inkjet printer. Image data accommodated by the host computer 501 is output to the interface 502 as an image signal 502,
It is temporarily stored in a memory (not shown) in the interface 503. The interface 503 rearranges the image data stored in the memory so that the image data can be received by the inkjet printer 505, and sends the image data to the inkjet printer 505 as an image signal 504. The inkjet printer 505 performs printing in accordance with the sent image signal 504, and performs image recording.

FIG. 6 is a schematic sectional view showing a specific configuration of the ink jet printer 505.

In the figure, 602 is a roll paper, 603 and 604 are paper feed rollers, 605 is a cutter, 606 is a carriage, 607 is an inkjet head, 608 is a sub scanning roller, 609 is a platen, and 610 and 611 are paper guides.

Roll paper 602 is fed to platen 609 by two paper feed rollers 603 and 604. In a platen 609 unit, a carriage 606 on which an inkjet head 607 is mounted performs a serial scan, and drives the inkjet head 607 in accordance with an image signal 504 sent from the interface 503 to perform image recording.

The inkjet head 607 is provided with four colors of cyan, magenta, yellow, and black, and is capable of performing full-color printing. When the recording for one line is completed, the roll paper 602 is sub-scanned by the sub-scanning roller 608, and then the recording for one line is repeated. When the portion of the roll paper 602 corresponding to the rear end of the recording paper reaches the position of the cutter 605, the cutter 605 rotates and the roll paper 602 is cut. The recorded image is discharged through paper guides 610 and 611.

The memory capacity of the above-described interface 503 is usually several MB to several tens MB, but the graphic data of the host computer 501 sometimes exceeds this capacity. In such a case, data corresponding to the memory capacity of the interface 503 is transferred and printed, and after the printing is completed, the remaining data is transferred to the interface 503 again and printed. This prints data from the ink jet printer 505 and the interface 503, and then performs sub-feeding of the roll paper 602 and carriage 606.
It is possible to stop sending data and wait until the next data is transferred.

In this way, image recording can be performed regardless of the size of the image data.

[Problems to be solved by the invention]

However, when the above recording method is used, there are the following disadvantages.

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. Also, the image is a total of 14 scans,
It is assumed that the memory capacity on the interface 503 has a capacity of only 5 scans. In such a case, the part A is continuously printed, and then the apparatus enters a standby state until the image data of the part B is transferred. After the image data transfer,
The part B is continuously printed, and then the apparatus enters a standby state again until the image data of the part C is transferred. Then, after the transfer is completed, the portion C is continuously printed, and the image recording ends.

Generally, the temperature of an ink jet recording head increases as printing is continued. When the temperature rises, the viscosity of the ink decreases, and the ink ejection amount increases, so that the recording density increases. However, once the printer enters the standby state, the temperature of the inkjet recording head decreases, and the recording density decreases.
Although this phenomenon applies to any type of ink jet recording head, it is particularly remarkable in a so-called bubble jet head in which a heater is heated to boil the ink and discharge it with the pressure of bubbles.

FIG. 8 is a diagram showing a change in recording density when the image recording shown in FIG. 7 is performed.

When printing is performed continuously, the density increases little by little so that the density change is not conspicuous, but the standby state (D, E
There is a disadvantage that when the point (D) is in between, the density changes rapidly and becomes very noticeable on the image.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the related art, and provides an image recording apparatus capable of obtaining an image having no change in recording density when recording is interrupted and when recording is resumed even if the head temperature is reduced during standby. The purpose is to provide.

[Means for solving the problem]

An image recording apparatus according to an embodiment of the present invention determines whether recording is to be interrupted in an image recording apparatus that interrupts and restarts a recording operation while driving a recording head that performs recording using thermal energy to record an image. Determining means for detecting, a head temperature detecting means for detecting a temperature of the recording head, and a memory for storing a head temperature detected by the head temperature detecting means when the determining means determines interruption of recording. Means for resuming the recording operation, wherein the head temperature detecting means detects the temperature of the recording head at the time of resuming the recording operation, and the head temperature stored in the storage means and the recording head at the time of resuming the recording operation. Control means for correcting an input image signal so as to equalize the recording density at the time of recording interruption and at the time of resuming recording in accordance with the temperature difference.

In addition, the control means corrects the image signal correction amount at the time of resumption according to the use condition of the recording head at the time of the recording operation after resumption, and corrects the image signal with the corrected image signal correction amount. Further, the control means corrects the image signal correction amount at the time of resumption according to the current temperature of the recording head at the time of the recording operation after resumption, and corrects the image signal with the corrected image signal correction amount.

(Operation)

When the recording operation is restarted, the image signal is corrected according to the difference between the temperature of the recording head at that time and the temperature of the recording head when the recording operation is interrupted, so that the recording density changes due to the temperature change of the recording head. Can be prevented. Further, when re-correction is performed in accordance with the use condition and temperature of the print head, a change in print density is prevented over the entire printing operation.

〔Example〕

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

FIG. 1A is a block diagram showing the configuration of the first embodiment of the present invention. The specific configuration of the device is the same as that of the conventional device shown in FIG. 6, and a description thereof will be omitted.

In the figure, 101 is an externally provided host computer, 1
03 is interface, 110 is lookup table (LU
T), 111 is a CPU, 112 is an inkjet recording head, 113
Is a head temperature detecting means such as a thermistor, 102 is an image signal from a computer, 104 is an image signal rearranged by the interface 103, 120 is a state instruction signal indicating the current recording operation state of the apparatus, 121 is an output image signal of the LUT 110 , 122
LUT selection signal, 123 is a head temperature signal.
The control means is constituted by T110.

The inkjet recording head 112 includes a plurality of recording heads, and recording liquids of different colors are discharged from each of the recording heads. Also, since each recording head has the same configuration, one of them will be described.

The recording head 112A includes an electrothermal converter 140 that generates thermal energy when an applied voltage is supplied in order to discharge recording liquid from the plurality of discharge ports 130 provided in a row. It is arranged. Then, by applying a drive signal, heat energy is generated in the electrothermal transducer 140 to cause film boiling and form bubbles in the ink liquid path. Then, an ink droplet is ejected from the ejection port 130 by the growth of the bubble [see FIG. 1 (b)].

The 8-bit image signal 102 transferred from the host computer 101 is temporarily stored in a memory in the interface 103, then rearranged and input to the LUT 110.

The LUT 110, as shown in FIG.
Up to 1.32x, a table with a straight line whose inclination differs by 0.01
It accommodates 64 sets and converts the magnitude of the pulse of the input image signal according to the table selected by the LUT selection signal 122. Output image signal 12 output by LUT110
1 is input to the inkjet recording head 112. The inkjet recording head 112 receives the output image signal 1
A head drive circuit (not shown) for driving the head with a drive pulse corresponding to 21 is provided, whereby ink is ejected. The ejection ink amount at this time is configured to be substantially proportional to the magnitude of the drive pulse.

When normal printing starts, the interface 103
Output the status instruction signal 120 indicating the normal printing status. At this time, the CPU 111 outputs to the LUT 110 a LUT selection signal 122 indicating that a table with a slope of 1.0 is to be selected. Subsequently, when the image recording for the memory capacity of the interface 103 is completed, the interface 103 sends a signal to the CPU 111 indicating that it is in a standby state. Upon receiving this signal, the CPU 111 outputs a head temperature signal 123 output by the head temperature detecting means 113.
Accordingly, to detect the temperature T ₁ of the ink jet recording head 12, and temporarily stored in the internal memory (not shown). Subsequently, the process waits until the host computer 101 finishes transferring the next image data to the interface 103. Thereafter, the data transfer is completed, CPU 111 is just before the next printing starts, and detects a temperature T ₂ of the ink jet recording head 112 again (T ₁ -T ₂₎
Is calculated. Subsequently, the CPU 111 selects a table of the LUT 110 at the time of resuming recording according to the value of (T ₁ −T ₂ ).

FIG. 3 shows the relationship between the value of (T ₁ − = T ₂ ) and the inclination of the table of the LUT 110 selected according to this value. As shown, T ₁ is larger than T _2, the table of a large coefficient when the resumption is selected. This is because even if the recording density decreases due to the temperature drop during standby,
This is to compensate for this by increasing the image signal level. The coefficient is gradually restored after printing is resumed. For example, when resuming, a table with a slope of 1.10 is selected, and the memory capacity of the interface 103 becomes 10
In the case of scanning, the tilt is reduced by 0.01 for each scan, and image recording is performed using a table with a tilt of 1.01 at the tenth scan. Then, when recording is resumed after the next standby, similarly, the table of the LUT 110 is selected with reference to the table having the inclination of 1.0, and correction is performed. By doing this,
Even if the head temperature drops during standby, the image signal is corrected in accordance with this temperature drop, and a uniform image with no actual change in density can be obtained.

In a color image forming apparatus, the above control may be performed independently for each color recording head. When returning the inclination of the table after resuming the recording, not only the number of scans but also the recording time and the number of recording pulses may be counted, and the coefficient may be returned accordingly.

 Next, a second embodiment of the present invention will be described.

Although the first embodiment 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 uses a recording head capable of changing the size of a dot according to the present invention. Is applied.

FIG. 4 is a block diagram showing the configuration of this embodiment, and the components denoted by the same reference numerals as those in FIG. 1 indicate the same components.

In the figure, reference numeral 430 denotes a binarizing circuit for converting the output image signal 121 sent from the LUT 110 into a binarized signal by a binarizing method such as a dither method or an error diffusion method. The ink jet recording head 112 outputs a binary signal output from the binarizing circuit 430.
A dot of a certain size is printed according to 431, and an image is recorded. Other operations are the same as those of the first embodiment.

With such a configuration, even if the temperature decreases during standby, printing of more dots at the time of resuming printing compensates for the decrease in density, and a uniform image with no actual density change can be obtained. .

Next, a third embodiment will be described. In each of the above-described embodiments, it has been described that the inclination of the table is returned by a fixed amount every scanning after the printing is restarted. However, in this embodiment, the head temperature is detected, It is the one that returns the inclination.

For example, the temperature difference between before and after the standby is ΔT = (T ₁ −T ₂ ), a table with a slope K is selected corresponding to the temperature difference ΔT, and the head temperature at the start of the n-th printing after restarting printing. Is t. In this case, the inclination as a table in this scan is Choose one.

For example, when △ T = 10 ° K = 1.2 in the table is selected, considerably recovered temperature at the first line, at the beginning the second line, the difference between T ₁ is was gone only 4 ° C..
In this case, the slope of the second row is Becomes

By doing so, the inclination of the table used in a manner more suitable for the actual temperature of the ink jet recording head can be made closer to the original value.

In the present embodiment, the inclination immediately before the next interruption may not return to 1.0. In this case, assuming that the inclination immediately before the next interruption is K ', a table having an inclination obtained by multiplying the inclination obtained from FIG. 3 by K' may be set as the table for the next restart.

In each of the embodiments described above, 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 similarly implemented as long as the temperature of the head rises during driving, such as thermal transfer, as well as the bubble jet type ink jet. Further, the standby state is not necessarily the time for receiving the transfer data, and the present invention can be applied to a case where the standby state is entered during printing for another purpose, such as performing a head recovery operation during printing. Is obvious.

The present invention particularly provides an excellent effect in a bubble jet type recording head and recording apparatus proposed by Canon Inc. among ink jet recording methods.

Regarding the representative configuration and principle, it is preferable to use the basic principle started in, for example, US Pat. Nos. 4,723,129 and 4,740,796. 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). And applying at least one drive signal corresponding to the recording information to the electrothermal transducer to give a rapid temperature rise exceeding each boiling point, thereby generating heat energy in the electrothermal transducer and causing a thermal effect of the recording head. This is effective because the film is boiled on the surface, and as a result, bubbles in the liquid (ink) can be formed in one-to-one correspondence with the drive signal.
By discharging the liquid (ink) through the discharge opening by the growth and contraction of the bubble, at least one droplet is formed. It is more preferable that the driving signal be in a pulse shape, since the growth and shrinkage of the bubble are performed immediately and appropriately. 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 collected, more excellent recording can be performed.

As the configuration of the recording head, in addition to the combination of the ejection port, the liquid path, and the electrothermal converter (a linear liquid flow path or a right-angled liquid flow path) as described in each of the above-mentioned specifications, a heat acting section The arrangements described in U.S. Pat. No. 4,558,333, U.S. Pat. In addition, for a plurality of electrothermal transducers, JP-A-59-123670 discloses a configuration in which a common slit is used as a discharge section of the electrothermal transducer, and an opening for absorbing pressure waves of thermal energy is provided. The present invention is also effective as a configuration based on Japanese Patent Application Laid-Open No. 138461/1984 that starts the configuration corresponding to the 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. Either a configuration that satisfies the above or a configuration as a single recording head that is integrally formed may be used, but the present invention can more effectively exert the above-described effects.

In addition, a replaceable chip-type recording head that can be electrically connected to the apparatus main body and supplied with ink from the apparatus main body by being attached to the apparatus main body, or 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 for the printhead provided as a configuration of the printing apparatus of the present invention and preliminary auxiliary means since the effects of the present invention can be further stabilized. To be more specific, a capping unit, a cleaning unit, a pressure or suction unit, a preheating unit using an electrothermal converter, another heating element, or a combination thereof, for the recording head. Performing a preliminary ejection mode in which ejection is performed separately from printing is also effective for performing stable printing.

Further, the printing mode of the printing apparatus is not limited to the printing mode of only the mainstream color such as black, but may be a printing head integrally formed or a combination of a plurality of printing heads. The present invention is extremely effective for an apparatus having at least one of the full colors. In the embodiments of the present invention described above, the ink is described as a liquid, but the ink is solidified at room temperature or lower, and is softened or liquid at room temperature, or the ink itself is 30 ° C. or higher in the above-described inkjet. In general, the temperature is adjusted within a range of 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range. Therefore, any liquid may be used as long as the ink is in a liquid state when a 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, heat energy is applied by heat energy, such as one in which ink is liquefied and ejected as an ink liquid by application of heat energy according to a recording signal, or one which already starts to solidify when reaching a recording medium. The use of an ink that liquefies for the first time is also applicable to the present invention. In such a case, the ink is charged in a state of being held as a liquid or solid in a porous sheet recess or through hole as described in JP-A-54-56847 or JP-A-60-71260. It is good also as a form which opposes a heat converter. 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〕

Since the present invention is configured as described above, the following effects can be obtained.

According to the first aspect, at the time of resuming printing, the image signal is corrected according to the difference between the temperature of the printing head at that time and the temperature of the printing head at the time of printing interruption.
It is possible to prevent a change in the recording density at the time of resuming the recording, and it is possible to obtain a uniform image at the time of recording interruption and at the time of resuming the recording.

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.

According to the second or third aspect, the image signal after resuming recording is re-corrected according to the use condition or temperature of the recording head, so that the image after resuming recording can be made uniform. is there.

[Brief description of the drawings]

FIG. 1 (a) is a diagram showing a configuration of a first embodiment of the present invention,
FIG. 1B shows the recording head unit 11 shown in FIG.
2 is a perspective view showing a specific configuration, and FIG. 2 is FIG.
A diagram for explaining each table accommodated in the LUT110,
FIG. 3 is a diagram for explaining conditions for selecting each table accommodated in the LUT 110 in FIG. 1A, FIG. 4 is a diagram showing a configuration of a second embodiment of the present invention, and FIG. FIG. 6 is a diagram showing a configuration of a conventional example, FIG. 6 is a schematic sectional view showing a specific configuration of the conventional example, FIG. 7 is a diagram showing an example of an image in which a recording operation is interrupted and restarted in the conventional example. FIG. 8 is a diagram showing a change in recording density of the image shown in FIG. 101: Host computer, 102, 104: Image signal, 103: Interface, 110: LUT, 111: CPU, 112, 412: Ink jet recording head 113: Head temperature detecting means, 120: Status indication signal, 121: ... output image signal, 122 ... LUT selection signal, 123 ... head temperature signal, 112A ... print head, 130 ... discharge port, 140 ... electrothermal converter, 430 ... binarization circuit, 431 ... Binary signal.

──────────────────────────────────────────────────続 き Continued on the 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. Determination means for determining the temporary interruption; head temperature detection means for detecting the temperature of the recording head; and detecting the head temperature when the determination means determines the temporary interruption that occurs during a printing operation. Storage means for storing the head temperature detected by the means, and when resuming the recording operation, the head temperature detecting means detects the temperature of the recording head at the time of resuming the recording operation,
Control means for correcting an input image signal so as to equalize the recording density at the time of recording interruption and at the time of recording resumption according to the head temperature stored in the storage means and the temperature difference of the recording head at the time of resuming the recording operation. Image recording apparatus characterized by having 2. The image recording apparatus according to claim 1, wherein said control means corrects an image signal correction amount at the time of resumption according to a use state of the recording head during a recording operation after resumption, and corrects the corrected image signal. An image recording device that corrects an image signal by an amount. 3. The image recording apparatus according to claim 1, wherein said control means corrects the amount of correction of the image signal at the time of resumption according to the current temperature of the recording head during a recording operation after resumption, and corrects the corrected image signal. An image recording device that corrects an image signal with a correction amount. 4. The image recording apparatus according to claim 1, wherein the recording head is a full line type in which a plurality of recording elements are provided over the entire width of a recording area. 5. The image recording apparatus according to claim 1, wherein said recording head ejects ink using thermal energy, and performs electrothermal conversion for generating said energy. An image recording device having a body.