JPH02141248A - Ink-jet recording device - Google Patents

Abstract

PURPOSE:To enable optimal wiping corresponding to the quantity of dew condensation actually generated, and to prevent the decrease of printing speed by receiving a printing data, measuring the number of printing dots in the data or the state of the distribution of the printing dots and controlling time intervals executing wiping on the basis of the state of the distribution. CONSTITUTION:When printing operation is started, picture data corresponding to one raster are received, printing dots in the picture data are counted by a counter 13a, and the values are added gradually to the total number Nb of the printing dots. When the picture data are received only by raster sections corresponding to the number of the discharge openings of printing dots, the printing data are transferred to a printing dot 2 while a carriage 3 is moved and the picture data are scanned, and the dot forming element of the recording head 2 is driven and recording pictures are shaped gradually onto a recording medium. When printing corresponding to one line is completed at that time, the carriage 3 is shifted to a home position when the total number Nb of the printing dots reaches a set value Nw requiring wiping. A wiper 10 is moved forward and the recording head 2 is shifted at that time, thus wiping the front of the recording head 2 by a flexible wiper blade.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet recording apparatus, and more particularly to an inkjet recording apparatus equipped with means for wiping the front surface of a recording head in which ejection ports for ejecting ink are formed.

[Conventional technology]

Recording devices such as printers and facsimiles can be classified into thermal types, wire dot types, inkjet types, laser beam types, etc. depending on the recording method.

Also, depending on the scanning method used during recording, there is a serial type in which the recording head is mounted on a carriage and main scans in the direction of the printing digits, a line print type in which one line is recorded at the same time, or a page print type in which one page is recorded all at once. It can be divided into formulas, etc.

The above-mentioned inkjet recording apparatus drives an ink ejection energy generating means provided in a recording head having an ejection port based on print data, thereby ejecting ink droplets from the ejection port onto a recording medium (such as paper). ) is configured to record images.

In this type of inkjet recording device, especially in a bubble jet (BJ) type inkjet recording device, the water vapor generated from the ejected ink droplets condenses on the front surface of the recording head (the surface where the ejection ports are formed), resulting in unstable ejection or non-ejection. To prevent this, it is necessary to periodically wipe the front surface of the recording head.

[Problem that the invention seeks to solve]

The amount of dew condensation on the front surface of the print head depends on the amount of ink ejected from each ejection port.

However, the advantage of conventional inkjet recording devices is that the time interval of the wiping operation is set constant, so wiping is performed based on the amount of dew condensation during solid printing.
If the interval is determined, the wiping operation will unnecessarily reduce the printing speed when recording continuous printing (characters, etc.) with many blank areas (non-printing areas).

An object of the present invention is to solve the above-mentioned problems of the prior art, and to prevent a decrease in printing speed by performing wiping operations at optimal time intervals depending on the amount of dew condensation that actually occurs. The purpose is to provide a recording device.

[Means for solving problems]

The present invention supplies ink to a recording head having an ejection opening and drives an energy generator stage provided in the recording head for ejecting ink from the ejection opening. An inkjet recording apparatus that forms a recorded image on a recording medium by ejecting ink droplets includes a means for receiving print data, a means for measuring the number of print dots or the distribution state of print dots in the received print data, and a recording head. The above object is achieved by a configuration having means for wiping the front surface of the image and means for controlling the time interval at which the wiping is performed based on the number of printed dots or the distribution state of the printed dots.

〔Example〕

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

FIG. 1 is a perspective view of essential parts of an inkjet recording apparatus embodying the present invention.

In Fig. 1, l indicates the chassis (frame body) of the recording device;
2 is a recording head (inkjet head) having an ejection port for discharging ink droplets on the front, 3 is a carriage on which the recording head is mounted, and 4 is a rail for guiding the carriage.
5 is a guide shaft that guides and supports the carriage, 6 is a paper feed roller, 7 is a pinch roller, 8 is a flexible cable that connects the main body board and the circuit on the carriage, 9 is the main body of the device 10 parts for supplying ink from the side ink tank to the recording head.
1 and 2 show wipers that wipe the front surface (discharge port surface) of the recording head 2, respectively.

The recording head 2 is provided with, for example, 128 (lliI) ejection ports arranged vertically, and in the case of a bubble jet type, 128 inkjet nozzles with each ejection port serving as a front end opening are provided.

The carriage 3 is supported by a rail 4 and a guide shaft 5 so as to be able to reciprocate in the printing column direction, and the scanning of the recording head 2 is controlled by the movement of the carriage wheel 3.

The paper feed roller 6 and the pinch roller 7 generally feed the recording medium (paper, etc.) in the direction of the throat.

The flexible cable 8 is for transmitting signals for recording and controlling the gutter 2, and the ink supply tube 9 is for supplying ink to the recording head 2.

The wiper IO is provided so as to be movable forward and backward in order to wipe the front surface of the recording head 2. For example,
For recording at the home position, the ink recovery device 10A can be attached to the front surface of the gutter 2 by using the side surface of the ink recovery device 10A, which can be sealed and separated.

In this way, ink is supplied to the recording medium 2 having an ejection opening, and by driving the energy generating means for ejecting ink provided at the throat 2 to the recording based on print data, the ejection opening is Discharge ink droplets to a recording medium (recording medium such as paper or thin plastic plate)
An inkjet recording apparatus is configured to form a recorded image on a surface.

Accordingly, the inkjet printing apparatus according to the present invention includes means for receiving print data transferred from a host computer, etc., means for measuring the number of print dots or the distribution state of print dots in the received print data, and recording. The apparatus is configured to include means for wiping the front surface of the head, and means for controlling the time interval at which the wiping is performed based on the number of printed dots or the distribution state of the printed dots.

The printed dots are not limited to black dots,
It may be a dot of Y (yellow), M (magenta), C (cyan), clear ink, erasing ink, or the like.

Further, the means for controlling the time interval at which the wiping is performed may be one that sets the time interval for wiping based on a predetermined sequence, or may be variable.

FIG. 2 is a block diagram of a control system of an inkjet recording apparatus according to the present invention.

In FIG. 2, the recording device 11 is a host system 12.
An interface circuit 13 is used to receive image (print) data transferred from a serial image interface (video interface).

The interface circuit 13 converts serially transferred print data into parallel data every 8 bits, for example, and converts it into parallel data.
The data is stored in the VRAM 15 through the RAM control circuit 14.

The interface circuit 13 also includes a circuit 13a that counts the number of printed dots in print data.

The VRAM 15 is, for example, a 64K x 8-bit dynamic RAM, and stores approximately 200 rasters of print (image) data.

The VRAM control circuit 14 switches data transfer from the interface circuit 13 to the VRAM 15 and data transfer from the VRAM 15 to the print data transfer circuit 16, and controls the timing of data transfer.

The microprocessor 17 plays a central role in the control of the recording device 11, and the ROM 18 and R
It has built-in AM19, port 20 and timer 21.

The microprocessor 17 includes a portion 19a that uses the RAM 19 to store the total number Nb of printed dots (dots formed by ejecting ink).

The microprocessor 17 controls the interface circuit 13, the print head control circuit 22, and the print data transfer circuit 16 through the HAS signal line, and controls the print mechanism section 23 using the port 20.

The print head control circuit 22 transfers the print data stored in the shift register 24 in the head 2 to the latch 25 according to the latch signal L1, and outputs the drive signal HE O-HE 3.
The head 2 is driven in a time-division manner via a drive C head driver 26.

The print data transfer circuit 16 reads, for example, 128 bits of print data stored in the VRAM 15 in the vertical direction and transfers it to the shift register 24 in the head 2 . The 128 bits of data corresponds to the number 128 of the ink droplet ejecting means, that is, the dot forming elements (printing elements) 27 of the head 2.

The microprocessor 17 via the port 20
Controls the printing mechanism section 23.

The printing mechanism section 23 includes a recording medium feed (conveyance) motor, a carriage motor, a wiper drive source, and the like.

FIG. 3 is a flowchart showing the operation of the ink side recording apparatus according to the present invention, which is equipped with the control system shown in FIG.

3rd I5! When the printing operation is started in J, image data for one raster is received in step LO, and in step 102, the number of printing dots in the image data is counted by the counter 13a, and the value is calculated as the total number of printing dots. It is added to Nb.

Next, in step 103, the image data is converted into 128 rasku (
It is determined whether or not the number of rasters corresponding to the number of ejection ports of the print head has been received.

If it has not been received yet, return to step 101 and repeat the above operation; if one minute of 128 rasters has been received, proceed to step 104, move the carriage 3 and scan, and print the print data in step 105. The image is transferred to the head 2, and in step 106, the dot forming elements of the recording head 2 are driven to form a recorded image on a recording medium such as paper.

In step 107, it is determined whether printing for one line has been completed, and if not, the process returns to step 104 and the above operations are repeated.

If printing for one line has been completed in step 107, the process proceeds to step 108, where it is determined whether the total number Nb of printed dots has reached the number NW that requires wiping.

If the number of printed dots reaches the set value NW, proceed to step 1.
In step 09, the carriage 3 is moved to the home position, and in step 110, wiping is performed (by advancing the wiper 10 and moving the recording head 2, a flexible wiper blade is used to wipe the front surface of the recording head 2, that is, the surface having the ejection openings). wiping off) and then proceed to the next step 11.
After the counter value (total number) Nb of printed dots is reset to zero in step 1, the recording medium is fed in step 112, and it is determined in step 113 whether printing for one page has been completed.

If the total number of printed dots Nb has not reached the set value Nw in step 108, the recording medium is fed by jumping in step 112, and the process proceeds to step 113.

If printing for one page has been completed in step 113, the printing operation is terminated, and if printing for one page has not yet been completed, the process returns to step 101 and the above steps are repeated again.

FIG. 4 shows the configuration of a print density evaluation circuit built in the interface circuit 13 of the control system in another embodiment of the inkjet recording apparatus according to the present invention.

The print density evaluation circuit shown in FIG. 4 includes an amplifier down counter 31, a comparator 32, a D flip-flop 33, and an output sofa 34.

In FIG. 4, image data from host system 12 (FIG. 2) is sent by an image data signal VDO and a clock signal VDOCK.

In the case of black printing, the up/down counter 31 counts up when the image data is printed, and counts down when it is not printed. Therefore, the black dot is i! ! The count value increases as the time continues.

Comparator 32 compares the output value of counter 31 and the output value of D flip-flop 33. The D flip-flop 33 stores the output value of the counter 31 when the output value of the counter 31 is larger than its own value.

Therefore, the D flip-flop 33 stores the maximum value of the output of the cursor 31 in one raster.

The output value of the D flip-flop 33 is the output value of the output sofa 34.
The data is read out to the microprocessor 17 through the microprocessor 17.

Signal OE is an output control signal for output buffer 34.

An inkjet printer equipped with the print density evaluation circuit shown in FIG.
The number of printed dots is measured in step 1, and wiping is executed when the density of printed dots reaches the set value.
Even with the number of printed dots, when the dots are printed, wiping is performed earlier than when the dots are dispersed.

Therefore, in this embodiment, when the number of printed dots is large and the printed dots are distributed with a concentration higher than a certain level, this is detected and wiping is performed early. Otherwise, the wiping interval is longer. controlled so that

In this way, an inkjet recording apparatus that can prevent a decrease in printing speed by performing the minimum necessary wiping operation is obtained.

Note that wiping methods include a method of wiping the front surface of the recording head 2 with a flexible blade and a method of wiping the front surface of the recording head 2 by pressing a water-absorbing member against the front surface of the recording head 2.

FIG. 5 is a flowchart of a recording operation in which the wiping interval is determined according to the degree of concentration of printed dots using the interface circuit of FIG. 4.

In FIG. 5, when the printing operation is started, step 2
017-1 The image data for one raster is received, and in step 202, the counter 13a counts the number of printed dots in this image data, and the value is calculated as the total number of printed dots Nb.
will be added to.

Next, in step 203, the correction value by the print density evaluation circuit as shown in FIG. 4 is added to the total number Nb,
In step 204, the image data is transferred to a raster number corresponding to the number of dot forming elements (ejection ports) of the head 2 (for example, 128
raster) is received.

If data for the number of rasters has not been received yet, the process returns to step 201 and the above steps are repeated.

If data for the number of rasters has been received, step 2
Proceed to 05 and while moving the carriage 3 and scanning,
In step 206, the print data is transferred to the recording head 2, and in step 207, the energy generating means for ejecting the ink of the recording head 2 is driven to form (record) a recorded image on the recording medium.

In step 208, it is determined whether or not one line of printing has been completed, and if not, the process returns to step 205 and the aforementioned printing operation is repeated, and when one line of printing has been completed, step 209
Then, it is determined whether the total number Nb of printed dots has reached the number Nw that requires wiping.

When the number of printed dots reaches Nw, the carriage 3 is moved to the home position in step 210, and the process proceeds to step 21.
By moving the carriage 3 in step 1, the wiper IO moves forward and wipes the front surface of the recording head 2. In step 212, the number of printed dots (counter value) Nb is reset to O, and then in step 2
At step 13, the recording medium is fed, and at step 214, it is determined whether printing for one page has been completed.

If the number of printed dots Nb has not reached the set value Nw in step 209, the recording medium is fed by jumping in step 213, and the process proceeds to step 214.

If printing for one page is completed in step 214, printing is completed, and if printing is not completed yet, the process returns to step 201 and repeats each step above the freshness level.

FIG. 6 is a block diagram showing yet another configuration example different from that in FIG. 4 of the print density evaluation circuit provided in the interface circuit 13 in FIG. 2.

In FIG. 6, 41 is an addition constant, 42 is a subtraction constant, 43 is a selector, 44 is an adder, and 45 is a subtraction constant.
is a D flip-flop, 46 is a comparator, 47
48 indicates a D flip-flop, and 48 indicates an output sofa.

The selector 43 selects the set value N of the addition constant 41 when the image data is to be printed, and selects the subtraction constant 4 when the image data is not to be printed.
Select the setting value of 2-M.

Therefore, the value of the D flip-flop 45 is
Each dot is counted as 10N, and each non-printed dot is counted as -M. These setting values N and M are, for example, +3 and -2.
etc., but this can be varied using registers, switches, etc.

Therefore, the relationship between the degree of continuity of printed dots and the degree of increase/decrease of the D flip-flop 45 can be freely set.

Comparator 46 and D flip-flop 47 in Figure 6
, output buffer 48, etc., are substantially the same as those of the comparator 32, D flip-flop 33, output buffer 34, etc. in FIG.

In this case, regarding the concentration of printed dots, when printing data is expanded in the underwater direction as a dot image and serially received, if it is a printed dot, set the register to 10N, and if it is a non-printed dot, set -M to the maximum register in the raster. If the value exceeds a certain value, it is determined that the number of printed dots is concentrated.

As explained above, the present invention evaluates the number and concentration of printed dots in print data in a recording device, and determines the interval of the wiping operation for removing dew condensation on the front surface of the recording head 2 based on this evaluation. Therefore, it is possible to control the wiping interval to always optimize it, prevent unnecessary wiping operations, perform wiping only the minimum number of times necessary, and prevent a drop in printing speed. An inkjet recording device was obtained.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, ink is supplied to a recording head having an ejection port, and energy generating means provided in the recording head for ejecting ink is driven based on print data. Accordingly, in an inkjet recording apparatus that forms a recorded image on a recording medium by ejecting ink droplets from the ejection opening, there is provided a means for receiving print data, and a means for receiving print data and determining the number of print dots or the distribution state of print dots in the received print data. a means of measuring;
Since the configuration has a means for wiping the front surface of the recording head and a means for controlling the time interval at which wiping is performed based on the number of printed dots or the distribution streaks of printed dots, wiping can be performed in response to changes in printing conditions. An inkjet recording device is obtained in which the interval can always be maintained optimally and unnecessary wiping operations can be eliminated, thereby preventing a decrease in printing speed.

[Brief explanation of the drawing]

1 is a perspective view of essential parts of an inkjet recording apparatus embodying the present invention, FIG. 2 is a block diagram of the control system of the recording apparatus of FIG. 1, and FIG. 3 is a flowchart of the operation of the control system of FIG. 2. FIG. 4 is a block diagram of a print density evaluation circuit according to another embodiment of the present invention, FIG. 5 is a flowchart of a recording operation of an inkjet recording apparatus using the evaluation circuit of FIG. 4, and FIG. 6 is a block diagram of a print density evaluation circuit according to another embodiment of the present invention. FIG. 7 is a block diagram of a print density evaluation circuit in another embodiment. 2-・-・-- Recording head, 3 ---------
...-Carriage, 9---111 ink supply tube, lO wiper (wiping means), 13--
・Interface circuit, 13a −・・−・−1−−
--Print dot counter, 19a --・・−・−・−
Total number of printed dots (Nb) storage section, 31 -------...
・-up/down counter, 41-・・・・・・・・・
Addition constant (+N), 42−・−・・−・−Subtraction constant (−
M).

Claims (1)

[Claims] (1) Ink droplets are ejected from the ejection ports by supplying ink to a recording head having an ejection port and driving energy generating means for ejecting ink provided in the print head based on print data. In an inkjet recording apparatus that forms a recorded image on a recording medium by using a recording medium, the inkjet recording apparatus includes a means for receiving print data, a means for measuring the number of printed dots or a distribution state of the printed dots in the received print data, and a means for wiping the front surface of the recording head. and the means to
An inkjet recording apparatus comprising: means for controlling a time interval at which wiping is performed based on the number of printed dots or the distribution state of printed dots.