JPH0229340A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To maintain fixability of an ink onto a sheet even in the case of a high printing density, as in solid printing, without any lowering in effective printing speed by detecting a rise in head temperature and varying a fixing time for which the sheet is maintained on a fixing heater, according to the detected temperature rise. CONSTITUTION:After a power supply is turned ON in a step 100, a reading H1 in an A-D converter 32 before printing is inputted in a step 101, and a one-line amount of data is printed in a step 102. Then, a reading H2 in the converter 32 is inputted in a step 103, and a head temperature rise DELTAH per character is calculated in a step 104. The temperature rise DELTAH is then compared with a set point TEM in a step 105. When DELTAH > TEM, it is judged that the present recording line is a line to be printed in a high density, and a step 106 is carried out in which a sheet is fed at a low velocity to enhance fixability. On the other hand, when DELTAH <= TEM in the step 105, it is judged that the present recording line is not a line to be printed in a high density, and a step 107 is executed in which the sheet is fed at a normal velocity, thereby enhancing effective printing speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet recording apparatus equipped with a fixing heater that promotes fixing of ink attached to a sheet.

[Conventional technology]

Recording methods used in recording devices such as printers and facsimile machines include a thermal type, a wire dot type, and an inkjet type.

Among these, inkjet recording devices supply ink to a head that has an orifice for ink ejection, and eject ink from the orifice by driving the head based on print data transferred from a host computer etc. It is configured to form flying ink droplets and adhere the ink droplets to a sheet (recording medium such as paper) to form a dot pattern.

In addition, in inkjet recording devices, if the sheet is fed before the adhered ink has sufficiently dried, it will come into contact with the guide section and stain the sheet, so in order to increase throughput, it is necessary to fix the adhered ink as soon as possible. This is required.

As a means for promoting the fixing of this ink, a fixing heater is used, which heats the recorded sheet to accelerate drying of the attached ink and shorten the fixing time.

[Problem that the invention seeks to solve]

However, in conventional inkjet recording devices equipped with a fixing heater, the time for heating the sheet on the heater was controlled at a constant rate, regardless of the recording density, so when printing in solid color or during high-density recording, There was a problem that the fixing properties were insufficient.

Furthermore, if the sheet feeding speed is set such that sufficient fixing is achieved even during high-density recording, the effective printing speed decreases, making it difficult to put it to practical use.

The present invention has been made in view of the problems of the prior art, and provides inkjet recording that can maintain the fixation of ink to a sheet even when printing density is high, such as solid printing, without reducing the effective printing speed. The purpose is to provide equipment.

[Means for solving problems]

The present invention provides an inkjet recording apparatus equipped with a fixing heater that promotes fixing of ink attached to a sheet.
The above object is achieved by detecting the temperature rise of the head and changing the fixing time for holding the sheet on the fixing heater according to the detected value.

[Operation] Especially in bubble jet type inkjet recording devices,
By applying electricity to a heater attached to the nozzle wall of the head and heating the ink within the nozzle, bubbles are generated within the nozzle 7' and the ink is ejected.

Therefore, the higher the density (number) of nozzles in the head that are driven in a given period of time, the higher the temperature of the head will be.

Therefore, it detects the temperature rise of the head during recording, and
By changing the fixing time of the sheet on the heater according to the second increase value, necessary and sufficient ink fixing can be achieved.

〔Example〕

The present invention will be specifically described below with reference to the drawings.

FIG. 3 is a perspective view of an inkjet recording apparatus embodying the present invention.

In FIG. 3, a guide shaft 3.4 is installed in front of and parallel to a plate-shaped fixed platen 2 that backs up a sheet 1 as a recording medium such as paper or a thin plastic plate. The carriage 5 is reciprocated left and right along.

A recording head 6 is mounted on this carriage 5.

The carriage 5 is driven by a carriage motor 7 via a transmission system consisting of a pulley 8.9 and a timing belt IO.

The sheet 1 is inserted along the paper pan 11 and is supplied to a recording section between the head 6 and the platen 2 by a sheet feed roller (not shown) driven by a sheet feed motor 12 .

The sheet 1 sent to the recording section is pressed against the sheet pressing plate 13
is in close contact with the platen 2.

The sheet 1 that has passed through the recording section is discharged by a paper discharge roller 14 and a peel wheel 15 that rotate in synchronization with a sheet feed roller (not shown).

An ink recovery device 16 consisting of a cap and an ink suction mechanism that is in close contact with and separated from the orifice surface of the head 6 is disposed at a home position selected outside the length range of the platen 2, that is, a position outside the recordable range. There is.

During recording, the ink droplet ejecting means of the head 6 is driven based on print data in synchronization with the scanning movement of the carriage 5, and ink droplets ejected from the orifice are attached to the sheet l to form a dot pattern. .

After recording is completed, the head 6 is stopped at the home position, and the orifice surface is sealed with the cap of the ink recovery device 16.

A fixing heater 18 consisting of a heating element is provided inside the platen 2. This fixing heater 18 is
The arrangement is such that by heating the sheet 1 from the surface, it dries out the marks that have adhered to the sheet 1 due to recording, thereby shortening the fixing time.

FIG. 4 is a block diagram of a control system of the recording apparatus shown in FIG. 3.

In FIG. 4, a CPU (Central Processing Unit) 21 of the recording apparatus is connected to a computer host 20 via a data receiving section 22, and receives command data and print data.

This CPU 21 includes a timer 25 that regulates the timing of processing operations, and a CG-25 that specifies the printing format (font).
A ROM 26, a ROM 27 storing programs, and a RAM 28 including a receiving buffer and the like are provided.

Therefore, the CPU 21 receives the command data and print data transferred from the host 20 as well as the input port 29.
Based on signals from various sensors and the operation panel that are input via the output port 1-30, the drive of the carriage motor 7, sheet feed motor 12, etc. is controlled, and the drive of the head (inkjet head) 6 is controlled. Controls the ink ejection means.

The head 6 is provided with temperature detection means 3 consisting of a thermistor or the like.
1 is attached to the head 6 to detect the temperature of the head 6 during recording operation and input the detection signal to the AD converter 32.

By reading the data input to the A-D converter 32, the CPU 21 can detect the temperature of the head 6 with a resolution determined by the number of bits of the A-D converter.

The CPU 21 is configured to control the speed of the sheet feeding motor 12 via the output boat 30 in accordance with the temperature rise degree of the head 6 during recording.

In other words, when the density (number) of orifices (or nozzles) driven in the head 6 during a certain period of time is high (many), such as in solid printing or high-density printing, and the amount of ink adhering to the sheet 1 is large, If the orifice driving density is below a certain level, the fixing time for holding the sheet 1 above the fixing heater is controlled to be longer by reducing the feeding speed or stopping the sheet feeding for a predetermined period of time. The sheet is fed at a normal speed and the ink is fixed for a normal fixing time.

FIG. 5 shows a time chart when the sheet feed motor 12, which is composed of a four-phase step motor, is driven by a two-phase excitation method.

In FIG. 5, A phase forming four excitation phases;
The B phase and the π phase are switched and controlled by the two-phase excitation method as shown at the timings indicated by the downward arrows.

In such a sheet feeding motor 12, the sheet feeding speed can be controlled by changing the interval between the downward arrows, that is, the period T of phase switching.

The phase switching period T is determined using a timer.

Therefore, by changing the phase switching period T of the sheet feed motor 12 based on the detection signal from the head temperature detection means 31, the inkjet recording apparatus according to the present invention, that is, fixing of the ink attached to the sheet 1 can be performed. In an inkjet recording apparatus equipped with a fixing heater 18 that accelerates printing, it is possible to detect the degree of temperature rise of the head 6 and change the fixing time for holding the sheet 1 on the fixing heater 18 based on the detected value, thereby improving solid printing. When printing density is high such as
An inkjet recording device was obtained that can automatically increase the fixing time on the heater 18 and improve the fixing properties of the ink to the sheet 1.

Moreover, since the heat of the heater 18 is not particularly required when the printing density is normal (character printing, etc.), the sheet can be fed at high speed, and the effective printing speed can be improved.

FIG. 1 is a flow chart of one example of the operation of the inkjet recording apparatus according to the present invention.

In FIG. 1, after turning on the power in step lOO,
In step 101, the reading value H1 of the A-D converter 32 before printing is taken in, and after printing one line in step 102, the reading value H2 of the A-D converter 32 is taken in in step 103.
In step 104, the head temperature increase value ΔH per character is calculated.

Next, in step 105, the temperature rise value ΔH and the set value TE are determined.
Compare with M.

Therefore, if ΔH>TEM, the current recording line is determined to be high-density printing, and the process proceeds to step 106, where the sheet is fed at a low speed to promote fixation.

On the other hand, if ΔH≦TEM in step 105, it is determined that the current recording line is not high-density printing, and the process proceeds to step 107, where the sheet is fed at the normal speed to increase the effective printing speed.

In addition, you can freely change the sheet feeding speed in three or more steps, and you can also change the sheet feeding speed in one step or more without changing the sheet feeding speed.
A similar effect can also be achieved by changing the time until sheet feeding is started after row recording.

FIG. 2 is a flowchart showing another example of the operation of the ink jet recording apparatus according to the present invention.

The control operation shown in FIG. 2 detects the temperature rise of the head 6 at the sampling time set by the timer 25.
In this embodiment, by shortening the sampling time, it is possible to realize control that freely responds to differences in recording density within one row.

In FIG. 2, the power is turned on in step 200, the sheet feed flag is cleared in step 201, and the sheet feeding flag is cleared in step 201.
After taking in the reading value H1 of the A-D converter 32 at step 02, the recording operation is started at step 203, and at the same time, the timer 25 is started at step 204.

Therefore, when it is detected in step 205 that the timer 25 times out, the reading value H2 of the A-D converter 32 is taken in in step 206, and the temperature rise degree ΔH-H2-H1 is calculated in step 207.

Next, in step 208, the temperature rise degree ΔH is set to the set value TE.
Determine whether or not M has been exceeded, and if so, step 2
After proceeding to step 09 and setting the sheet feed flag (setting it to 1), it is determined in step 210 whether or not there is a sheet feed command.

If the temperature rise degree ΔH has not reached the set value TEM in step 20B, the process directly proceeds to step 210 to determine whether there is a sheet feed command or not.

If there is no sheet feed command, the process returns to step 202 and the above operations are repeated.

If the sheet feed command is determined, the process advances to step 211 to determine whether the sheet feed flag is set (1).

If the sheet feed flag is 1, the sheet is fed at a low speed in step 212 to promote ink fixation, and then the process returns to step 201, and the above operations are repeated.

If the sheet feed flag is O, the process advances to step 213 to improve the effective printing speed by feeding the sheet at the normal speed, and then returns to step 201 described above to repeat the above operations.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, in an inkjet recording apparatus equipped with a fixing heater that promotes fixing of ink attached to a sheet, the degree of temperature rise of the head is detected, and based on the detected temperature, the sheet is fixed to the fixing point. Since we have a configuration that changes the fixing time held on the heater,
An inkjet recording device that can automatically increase the fixing time of the sheet on the heater without any external operation when printing density is high, such as solid printing, and improves the fixation of ink to the sheet. can get.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing one example of the operation of the inkjet recording apparatus according to the invention, FIG. 2 is a flowchart showing another example of the operation of the inkjet recording apparatus according to the invention, and FIG. 3 is an inkjet recording according to the invention. FIG. 4 is a block diagram of the control system of the recording apparatus shown in FIG. 3, and FIG. 5 is a time chart of excitation pulses of a sheet feed motor consisting of a four-phase step motor. 1--------- Sheet, 2------1-
Platen, 6--... Head, 12
Sheet feed motor, 18----- Fixed heater, 21 CPU, 31 Head temperature rise detection means (thermistor).

Claims (1)

[Claims] (1) In an inkjet recording device equipped with a fixing heater that promotes fixing of ink attached to a sheet, detecting the degree of temperature rise of the head and changing the fixing time for holding the sheet on the fixing heater based on the detected value. An inkjet recording device featuring: