JP2828502B2 - Image recording device - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a recording head for recording an image, and a temperature control means for detecting a temperature of the recording head and controlling the temperature to a predetermined range. And an image recording apparatus comprising the same.

[Prior Art] Digital recording type image recording apparatuses such as ink jet recording and thermal transfer recording are well known.

In particular, ink jet recording has advantages such as easy colorization, and has been widely used as a copier, a facsimile, a computer, a word processor, or a composite device thereof.

When the image recording apparatus is used for outputting computer graphics, generally, image data from a host computer is temporarily stored in a memory in an interface,
The interface arranges the print head in a form acceptable to the print head and sends the print head to the print head, and the print head performs printing in accordance with the image data.

The memory of the interface is usually several MB ~
Although it is several tens MB, 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 data from the interface, the printer can stop recording and wait until the next data is transferred.
In this way, even large image data can be recorded.

However, when recording is interrupted in this way, the following may occur.

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 direction of arrow X. Further, although the image is a total of 14 scans, the memory capacity on the interface is assumed to be only 5 scans.

In such a case, the portion A is printed continuously, and then the recording is interrupted until the image data of the portion B is transferred, and a standby state is entered. 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. Then, after the transfer is completed, 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 the recording is interrupted and enters a standby state, the temperature drops and the recording density decreases. This phenomenon applies to any type of recording head, but is particularly remarkable in a so-called bubble jet head in which a heater is heated to boil ink and eject the ink at the pressure of bubbles.

FIG. 8 shows a change in the recording density when the image recording shown in FIG. 7 is performed. During continuous printing, 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 is abrupt and becomes very conspicuous on the image.

Therefore, in order to reduce the above-described density change by keeping the temperature of the recording head within a certain range, the recording head is provided with a head temperature detecting means such as a thermistor and a heater. It is well known that the temperature of the recording head is detected by a means, and if the temperature is lower than the set temperature, the heater is driven, and if the temperature is higher than the set temperature, the fan is driven to control the temperature of the recording head.

[Problems to be Solved by the Invention] However, in the above-described conventional image recording apparatus, if continuous printing is performed by the recording head, the temperature often rises above a set temperature even when the fan is driven. If the recording is interrupted in this state and the apparatus enters a standby state, the temperature of the recording head continues to decrease until the temperature reaches the set temperature, so that the above-described density change still occurs.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an image recording apparatus capable of obtaining an image having a small change in image density due to interruption of recording.

[Means for Solving the Problems] An image recording apparatus according to the present invention includes a recording head for recording an image using thermal energy, and a temperature for detecting the temperature of the recording head and controlling the temperature to a predetermined range. An image recording apparatus comprising: a control unit; a storage unit configured to store a temperature of the recording head when recording is interrupted; and a storage unit configured to store the temperature of the recording head when recording is resumed after the recording is interrupted. And a resuming means for controlling the temperature control means so that the temperature becomes substantially equal to the temperature of the recording head when the recording is interrupted.

The recording head covers the entire width of the recording area of the recording medium.
A full line type recording head having a plurality of ejection ports can be provided.

The recording head performs image recording using thermal energy, and may include an electrothermal converter as a means for generating thermal energy.

[Operation] When the recording is interrupted, the temperature of the recording head usually changes. Therefore, the temperature of the recording head when the recording was interrupted is stored in the storage means, and when the recording is resumed by the resuming means, the recording of the temperature of the recording head was interrupted when the recording was resumed. The temperature control means is controlled so as to be substantially equal to the temperature at the time of printing, thereby compensating for a change in the temperature of the print head due to the interruption of printing, and a change in the density of the image.

Example An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view showing a first embodiment of the image recording apparatus of the present invention, wherein 1 is an ink jet printer which is a main body of the present embodiment, 2 is a roll paper as a recording medium, and 3 and 4 are paper feeders. Roller, 5 is a cutter, 6 is a carriage, 7 is an inkjet head which is a bubble jet type recording head proposed by Canon Inc., 8 is a sub-scanning roller, 9 is a platen, and 10 and 11 are paper guides. .

Roll paper 2 in the inkjet printer 1
Is fed to the platen peripheral portion around the platen 9 by the paper feed rollers 3 and 4. In the peripheral portion of the platen, the carriage 6 on which the inkjet head 7 is mounted performs a serial scan, and drives the inkjet head 7 in accordance with an image signal 104 from an interface 103 to be described later to record an image (see FIG. 3).

The inkjet head 7 is provided with four colors of cyan, magenta, yellow, and black, and performs full-color recording. When recording for one line is completed, the roll paper 2 is sub-scanned by the sub-scanning roller 8, and then recording for one line is repeated.

When the trailing edge of the copy reaches the position of the cutter 5, the cutter 5 is rotated to cut the roll paper 2. The cut roll paper 2 is used as a recording image as paper guides 10 and 11.
The paper is discharged through.

Here, the head element 20 constituting the ink jet head 7 will be described with reference to FIG.

In the head element 20, in order to discharge ink from the plurality of discharge ports 30 provided in a row, an electrothermal converter 40 for generating thermal energy to which an applied voltage is supplied is provided for each liquid path. Have been. 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 ports 30 by the growth of the bubbles.

FIG. 3 is a block diagram showing a connection when the embodiment of FIG. 1 is used for outputting computer graphics, wherein 1 is an inkjet printer, 7 is an inkjet head,
101 is a host computer, 102 is an image signal, 103 is an interface, 104 is an image signal, 111 is a CPU (central processing unit), 113 is a head temperature detecting means such as a thermistor, 114 is a fan, 115 is a head heater, and 120 is an interface An instruction signal, 121 is a head temperature signal, 122 is a fan drive signal, 123 is a head heater drive signal, and 124 is a prohibition signal.

The CPU 111, the head temperature detection means 113, the fan 114, and the head heater 115 constitute a temperature control means. Also,
The CPU 111 also forms a storage unit and a restart unit.

Next, the control of the first embodiment shown in FIGS. 1 and 3 will be described with reference to FIG.

First, it is checked whether or not normal printing is being performed (step S
1). During normal printing, an image signal 102 as image data from the host computer 111 is transmitted to the interface 1
It is temporarily stored in a memory (not shown) in 03. The interface 103 arranges the stored image data in a form acceptable to the inkjet head 7 and sends the image data to the inkjet head 7 as an image signal 104. The ink jet head 7 performs printing in accordance with the image signal 104.

During this time, the interface 103 sends an interface instruction signal 120 indicating the normal printing state to the CPU 111. While this interface instruction signal 120 is being sent, the CPU 111
Sets the set temperature of the temperature control to a normal value, for example, 35 ° C. The CPU 111 receives the head temperature signal 121 from the head temperature detecting means 113, outputs a fan drive signal 122 if the temperature is higher than 35 ° C. to drive the fan 114, and outputs a head heater drive signal 123 if the temperature is lower than 35 ° C. Head heater 1
15 to drive the temperature of the inkjet head 7 (hereinafter, referred to as
It is called "head temperature". ) In a certain range (for example,
(° C) (steps S2, S3, S4).

When the image recording for the memory capacity of the interface 103 is completed, the interface 103 sends the CPU 111 an interface instruction signal 120 indicating a standby state in which the recording is interrupted. When the CPU 111 receives the interface instruction signal 120, the head temperature (T
° C) is temporarily stored, and this is set as the set temperature for temperature control (step S5).

After that, the CPU 111 inputs the head temperature signal 121 from the head temperature detecting means 113 again and checks the head temperature (step S6). When the head temperature is equal to the set temperature (T ° C.) stored in the CPU 111, printing is possible immediately after the standby state ends (step S11). However, the head temperature is not equal to the set temperature (T
(° C.), the CPU 111 sends a prohibition signal 124 to the interface 103, and prohibits sending the image signal 104 to the inkjet head 7 even when the data transfer from the host computer 101 to the interface 103 is completed ( Step S7). When the head temperature is lower than the set temperature (T ° C.), the head heater 115 is driven. When the head temperature is higher than the set temperature (T ° C.), the fan 114 is driven to drive the head temperature. T.degree. C.) (steps S8, S9, S10). When the head temperature becomes equal to the set temperature (T ° C.), the head is returned to a printable state, and image recording is restarted (step S1).
1).

In this manner, even if the recording is interrupted and the head temperature changes after entering the standby state, the recording head is returned to the head temperature immediately before the interruption of the recording, and the recording is restarted, so that a uniform image with no image density change can be obtained. it can.

 Next, a second embodiment will be described.

FIG. 5 shows the control of the second embodiment. The difference from the first embodiment is that when the recording is resumed from the standby state, even if the head temperature reaches the established temperature (T ° C.), Is to enable printing after waiting 5 seconds without making printing possible.

 This is for the following reason.

A thermistor as a head temperature detecting means for detecting a head temperature is generally attached to a substrate of a recording head, but even if the temperature detected by the thermistor has reached a predetermined temperature, for example, in the case of an ink jet head, the inside of a nozzle When the temperature of the ink has not reached that temperature and printing is performed, the density difference still remains.

For this reason, in the second embodiment, by waiting for 5 seconds after the detected temperature of the thermistor reaches the set temperature (T ° C.) (Step S12), the temperature of the ink in the nozzles of the inkjet head is reduced to the set temperature (T12). T.degree. C.). As a result, it can be surely suppressed by a change in density. Step 3 except for step 12
The description is omitted because it is the same as the figure.

In the above-described first and second embodiments, when the ejection is performed by the bubble jet head constituted by the head element as shown in FIG. 2, the temperature of the ink in the nozzle rapidly rises. Can return the ink in the nozzles to the temperature immediately before the interruption of recording.

 Next, a third embodiment will be described.

FIG. 6 is a perspective view of a platen of an ink jet printer according to the third embodiment and a peripheral portion thereof, 132 is a roll paper as a recording medium, 134 is a paper feed roller, 136 is a recording image, and 137 is a bubble as a recording head. Jet head, 1
38 is a sub-scanning roller, 139 is a platen, and 139A is an idle discharge position formed on the platen 139.

Roll paper 132 is fed to platen 139 by paper feed roller 134
Sent to the surrounding area. At the periphery of the platen 139, a carriage (not shown) on which a valve jet head 137 is mounted performs a serial scan in the direction of arrow S, and drives the bubble jet head 137 in accordance with the image signal, thereby recording the image 1
Get 36.

When recording of the recording image 136 for one line is completed, the roll paper 132 is sub-scanned by the sub-scanning roller 138,
Repeat the record for the line.

This third embodiment utilizes the thermal energy of the bubble jet head. When the temperature of the bubble jet head 137 is lower than the set temperature (T ° C.), in addition to driving a head heater (not shown), Platen 139
The ink is ejected at the idle ejection position 139A provided in the non-image area at the left end of the drawing, and the heat generated at that time causes the temperature of the bubble jet head 137 to reach the set temperature (T ° C.) more quickly. It was made.

By doing so, the temperature of the ink in the nozzles of the bubble jet head 137 can be quickly returned to the temperature before the interruption of recording, and time loss can be reduced.

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

Further, the standby state is not necessarily the time for receiving the transfer data, and the present invention is not limited to the case where the standby state is entered during printing for another purpose such as performing a recovery operation of the recording head during printing. Applicable.

Further, the recording head is not limited to the ink jet type, and can be similarly applied to other general recording heads. However, a recording head that performs image recording using thermal energy, such as a bubble jet or thermal transfer, is not applicable. The effects of the invention are remarkable.

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

Regarding the representative configuration and principle, it is preferable to use the basic principle disclosed 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). 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, 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 as a result, bubbles in the liquid (ink) can be formed one-to-one corresponding to this 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. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of liquid (ink) 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 employed, more excellent recording can be performed.

As a configuration of the recording head, in addition to a combination configuration (a linear liquid flow path or a right-angle liquid flow path) of a discharge port, a liquid path, and an electrothermal converter as disclosed in each of the above-mentioned specifications, May be described in U.S. Pat. No. 4,558,333 and U.S. Pat. No. 4,459,600, respectively, which disclose a configuration in which are disposed in a bending region. In addition, JP-A-59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, and an aperture for absorbing pressure waves of thermal 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. 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.

It is preferable to add recovery means for the printhead, preliminary auxiliary means, and the like, which are provided as components of the printing apparatus of the present invention, 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. However, an ink that solidifies at room temperature or lower and softens or becomes liquid at room temperature, or is generally used in ink jet. It 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. 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, 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 disclosed in JP-A-54-56847 or JP-A-60-56847.
As described in -71260, in a state of being held as a liquid or solid in a porous sheet concave portion 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.

[Effects of the Invention] As described above, according to the present invention, when recording is interrupted and then resumed, the temperature of the recording head is controlled to be substantially equal to the temperature at which the recording was interrupted. There is an effect that a change in image density due to interruption of recording is compensated and a uniform image with a small change in density can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a first embodiment of the image recording apparatus of the present invention, FIG. 2 is a perspective view showing a part of a head element cut away, and FIG. 3 is an embodiment of FIG. FIG. 4 is a block diagram showing a connection when used for outputting computer graphics, FIG. 4 is a flowchart showing control of the first embodiment of the present invention, and FIG. 5 is a flowchart showing control of a second embodiment of the present invention. 6, FIG. 6 is an explanatory view showing a platen of an ink jet printer according to a third embodiment of the present invention and its peripheral portion, FIG. 7 is an explanatory view in the case of performing image output by serial scan, and FIG. 7 is a graph of a density change when an image is output. 1 ... inkjet printer, 2 ... roll paper, 3,4 ... paper feed roller, 5 ... cutter, 6 ... carriage, 7 ... inkjet head, 8 ... sub-scanning roller, 9 ... platen, 10 , 11 paper guide, 20 head element, 30 discharge port, 40 electrothermal transducer, 101 host computer, 103 interface, 111 CPU, 113 head temperature detecting means 114 Fan fan 115 Head heater 132 Roll paper 134 Paper feed roller 136 Recorded image 137 Bubble jet head 138 Subscanning roller 139 Platen 139A …… Empty discharge position.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B41J 2/01 B41J 2/36

Claims (3)

(57) [Claims] 1. An image recording apparatus comprising: a recording head that records an image using thermal energy; and a temperature control unit that detects a temperature of the recording head and controls the temperature within a predetermined range. Storage means for storing the temperature of the recording head when the recording was interrupted, and when resuming the recording after interruption, the temperature of the recording head interrupted the recording stored in the storage means. An image recording apparatus comprising: a resuming unit that controls the temperature control unit so that the temperature of the recording head becomes substantially equal to the temperature of the recording head. 2. The image recording apparatus according to claim 1, wherein the recording head is a full line type recording head having a plurality of ejection ports over the entire width of the recording area of the recording medium. 3. The image recording apparatus according to claim 1, wherein the recording head performs image recording using thermal energy, and has an electrothermal converter as a means for generating energy.