JPH04255354A - Ink jet printer - Google Patents

Abstract

PURPOSE:To prevent the generation of printing shift caused by the rubbing of the ink of printed recording paper with recording paper printed next. CONSTITUTION:The recording paper discharged from a platen 1 is set to a size capable of supporting the whole of the recording paper by a recording paper feed belt 8 and the dot density of printing data printed the last time is operated by a microcomputer. Corresponding to the recording density obtained by operation, the time stopping the feed belt 8 is controlled at the point of time when printing is completed. Since the ink of the recording paper printed the last time is dried during this time, even when the next recording paper is discharged on the printed recording paper, no ink shift is generated.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet printer that makes ink into droplets and flies them onto recording paper.

0002

2. Description of the Related Art Inkjet printers used for producing office documents and the like usually use ink prepared by dissolving pigments in water for reasons such as ease of maintenance and low running costs. When printing data with a relatively low dot density such as text using such water-based ink, the solvent of the ink forming the dots diffuses into the blank area and evaporates from a wide area per dot. The ink dries quickly, and when the recording paper is ejected to the paper ejection tray, the ink does not shift even if it is scratched. On the other hand, when printing high-density data such as images or logos over a large area,
Since there is no blank space for the solvent in the ink to diffuse, it takes a long time for the ink to dry.

0003

[Problem to be Solved by the Invention] For this reason, after printing with a high dot density, if the next recording paper is ejected at the normal timing, the record that the ink of the previous printing was ejected before drying will be lost. There is a problem that the ink is rubbed by the paper and causes ink displacement. Of course, in order to solve this problem, it is possible to set the printing speed according to the drying time of the recording paper on which the highest density dots are printed, but Therefore, it is necessary to set an unnecessarily long printing time, resulting in a decrease in printing speed. The present invention was made in view of these problems, and its purpose is to provide a new inkjet printer that can eliminate unnecessary idle time and prevent ink misalignment on printed recording paper. Regarding.

0004

[Means for Solving the Problems] In order to solve such problems, the present invention provides a means for moving the recording paper along a travel path from the recording paper supply port to the paper discharge port, and a means for moving the recording paper along the travel path from the recording paper supply port to the paper discharge port, and an inkjet print head provided, a paper ejection tray provided in contact with the ejection port for accommodating printed recording paper, paper detection means for detecting the recording paper in the paper ejection tray, and a dot density of previous print data. and means for stopping the conveying means for a set time at the end of printing if the dot density exceeds a set value.

[0005]

[Operation] If printing has finished just before and it takes time for the ink on the recording paper stored in the paper output tray to dry, the recording paper that has just finished printing will be transported when it is transferred to the conveyor belt. Stop the belt. When the ink on the recording paper in the paper ejection tray dries, the conveyor belt is operated again to eject the recording paper to the paper ejection tray. This results in
The next recording paper is stacked only after the ink on the previously printed recording paper has completely dried, thereby preventing ink misalignment.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be explained below based on illustrated embodiments. FIG. 1 shows an embodiment of the present invention, in which reference numeral 1 is a platen, a paper guide plate 2 is provided on the upstream side of the printing area, and a paper feed cassette is set by a pull-out roller 3. The recording paper discharged from the recording paper is conveyed to the printing area in cooperation with the paper pressing roller 5. Guide members 6, 6 are provided parallel to the axis of the platen 1, and an inkjet print head 7 that is guided by the guide members 6, 6 and moves in the direction of the platen axis is provided.

On the downstream side of the printing area, a recording paper conveying belt 8 is stretched around a driving roller 9 and a driven roller 10.
It is configured to transport printed recording paper from the discharge end of the platen 1 to a paper discharge tray 12 provided outside the housing 11. The dimensions of the recording paper conveyance belt 8 are selected to be the length from the print head 7 to the paper discharge tray 12. Further, the paper discharge tray 12 is provided with a recording paper detector 13 that detects when the recording paper is carried out from the recording paper transport belt 8 .

A fan 1 is installed in the housing 11 near the discharge end of the recording paper conveyance belt 8 so that the exhaust air almost hits the tray 12.
4, a sensor box 15 for detecting the surrounding environment, and a notification lamp 16 are also provided. In the figure, reference numeral 17 indicates a circuit board, and 18 indicates a platen roller.

FIG. 2 shows an embodiment of the above-mentioned control device, which is composed of a microcomputer 23 consisting of a CPU 20, a RAM 21, and a ROM 22. Sensor 24, humidity sensor 25, recording paper detector 13
A buffer 27 receives print data from an external device, a character generator 28 converts character codes into bit images, and a print buffer 29 stores bit images. Furthermore, a drive signal is output to a notification lamp 16 that displays the determination result, a fan 14 that generates a drying air flow, and a motor 30 that conveys printing paper and moves the print head. In addition,
Reference numerals 31, 32, and 33 in the figure indicate drivers, respectively.

FIG. 3 shows the microcomputer 23 mentioned above.
This figure schematically shows the functions to be realized by a mechanism control means 40 that controls the driving of the recording paper pull-out roller 3, platen 1, and print head 7 in order to print data input from an external device. , a data processing means 41 that converts data input from an external device into a bit image suitable for printing and outputs it to the print head, and a data processing means 41 that converts data input from an external device into a bit image suitable for printing and outputs it to the print head, and a data processing means 41 that converts the data input from an external device into a bit image suitable for printing and outputs it to the print head. printing duty calculation means 42 for calculating
It is programmed to include a waiting time setting means 43 for setting a drying time based on data from a printing duty calculation means 42.

Next, FIG. 4 shows the operation of the device configured as described above.
This will be explained based on the flowchart shown in .

When print data is input from an external device (step I), this data is stored in the print buffer 27, and if it is a character code signal, it is converted into a bit image by the character generator 28 and output to the print buffer 29. (Stepro). The microcomputer 23 sequentially samples the bit images stored in the print buffer 29 and calculates the print duty (step c).

That is, as shown in FIG. 5, the bit image developed in the print buffer 29 is cut out with a predetermined width W, for example, 32 dots, and this data is further divided into cells S1, S2, S3, and the like with a predetermined length L. Extract as S4... The dot density is calculated for each of these cells S1, S2, S3, S4..., and the number of consecutive cells with a predetermined density, for example, the area occupied by the dots is 70% or more of the cell, is calculated, and this data is calculated. Store it in RAM21.

The microcomputer 23 transfers the bit image developed in the print buffer 29 to the print head 7.
to print the output (step 2). When printing is completed (step E), the microcomputer 23 determines whether a signal is output from the recording paper detector 13 (step F). In this case, since the first sheet is being printed, there is no printed recording paper in the paper ejection tray 12, and therefore no signal is output from the recording paper detector 13, so the paper is ejected from the platen 1. The printed recording paper is placed on the paper output tray 12 by the recording paper conveyance belt 8 with the printing side facing upward (step
nu). This causes the recording paper detector 13 provided on the paper discharge tray 12 to operate and output a signal. If the fan 14 is operated in this state, the airflow will be directed to the paper output tray 12.
The printed recording paper installed in the printer is sprayed to promote the volatilization of ink moisture.

[0015] Subsequently, when the second print data is input (Step 1) and the bit image is developed in the print buffer 29 (Step 2), the data is cut out into cells in the same manner as described above. Calculate dot density (
Step Ha).

Printing is started in this manner (step d), and when printing of the second sheet is completed (step e), the microcomputer 23 detects the recording paper detector 13.
Since the signal from the printer is being input (Step F), the duty of the previous print data is evaluated (Step G), and based on this, the waiting time for the recording paper ejected from platen 1 is set, and 8 (step 1).

That is, when three cells S1, S2, S3, etc. with a predetermined density, for example 70% or more, exist in one band in succession, the predetermined waiting time is, for example, 1 minute. In addition, the waiting time is set so that the longer the number of consecutive cells increases, such as 4 minutes when there are 4 consecutive cells with a predetermined density or higher, and the temperature sensor 24 and humidity sensor are set as necessary. The set waiting time is adjusted according to the drying conditions of the surrounding environment detected based on the data from 25. After printing is performed and the recording paper is ejected from the platen 1 and the entire recording paper is transferred to the conveyor belt 8, the conveyor belt 8 is stopped and the ink on the previously printed recording paper is allowed to dry. .

In this state, the air current generated inside the housing 1 by the fan 14 passes over the surface of the recording paper stopped on the conveyor belt 8, so that the volatilization of the ink solvent is accelerated and the drying of the recording paper is accelerated. Ru. Notice lamp 16 at the same time
By lighting up, the user is informed that the reason why the recording paper is stopped on the conveyor belt 8 is not due to a paper jam but because the ink is waiting for drying.

When the set waiting time has elapsed (Step 1), the ink on the recording paper on the paper ejection tray 12 is substantially dry, so the microcomputer 23 drives the conveyor belt 8 to remove the printed paper. The recording paper is conveyed to the paper ejection tray 12 and ejected onto the previously printed recording paper (Step 1). As a result, even if the next recording paper is placed on top of a recording paper with extremely high dot density, ink shift will not occur on the previously printed recording paper.

On the other hand, if the duty of the data printed immediately before is small, the waiting time will be shortened because the paper will dry during the process of being transported by the transport belt 8 and before the next recording paper is transported to the paper output tray. If the ink is ejected from the platen 8 without setting , the ink will not be misaligned if it is ejected directly to the paper ejection tray 12 by the conveyor belt 8. Therefore, the microcomputer discharges the recording paper onto the paper discharge tray 12 without stopping the conveyor belt 8. Thereafter, such a process is repeated for the number of prints.

In this embodiment, the data printed at the beginning of the recording paper and the data printed at the end are evaluated equally, but a small weight is given to the data printed at the beginning. By attaching and evaluating, it is possible to set a waiting time that is more in line with the ink drying process.

Furthermore, although a drying fan is provided in this embodiment, the exhaust air from the fan is used to cool the circuit boards and mechanisms housed in the casing and hits the top surface of the paper output tray. It is clear that the same effect can be obtained even if the guide is provided with a hood or the like.

Further, in this embodiment, the drying time is adjusted according to the surrounding environment using a temperature sensor and a humidity sensor. It is clear that the same effect can be obtained even if the conveyor belt is stopped for a period of time determined by the print density when the conveyor belt is used in a place where the conveyor belt is stopped.

Furthermore, although this embodiment has been explained using a serial printer as an example, if it is applied to a page printer that starts printing after expanding one page's worth of print data into a buffer, data expansion will be possible. Drying can be carried out using time effectively.

Furthermore, although this embodiment has been explained using an example in which water-based ink is used, it is clear that the same effects can be achieved even when applied to those using oil-based ink.

[0026]

[Effects of the Invention] As explained above, in the present invention,
A means for moving the recording paper along the movement path from the recording paper supply port to the paper ejection port, an inkjet print head provided in the middle of the movement path, and an ejector for accommodating the printed recording paper provided in contact with the ejection port. A paper tray, a paper detection means for detecting the recording paper in the paper output tray, a means for determining the dot density of the previous print data, and a means for determining the dot density of the previous print data, and if the dot density exceeds a set value, the transport means is activated for a set time at the end of printing. Since the device is equipped with a means for stopping the recording paper for a predetermined period of time, only if printing with a high dot density was performed last time, the recording paper that has just been printed is stopped for a predetermined time on the movement path and the recording paper on the paper output tray is removed. It is possible to wait for the paper to dry before it is discharged onto a tray, and it is possible to reliably prevent ink misalignment on recording paper with high print density without causing an unnecessary decrease in printing speed. In addition, in a so-called page printer that develops one page's worth of print data into bitmap data and executes printing, the image is Ink can be reliably dried by effectively utilizing the time required to develop data.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an apparatus showing an embodiment of the present invention.

FIG. 2 is a block diagram showing an embodiment of a control device of the same device.

FIG. 3 is a block diagram showing the functions that a microcomputer should perform.

FIG. 4 is a flowchart showing the operation of the above device.

FIG. 5 is an explanatory diagram showing a printing duty calculation method in the same apparatus as above.

[Explanation of symbols]

1 Platen 2 Paper information board 3 Paper drawer roller 4 Paper cassette 5 Paper press roller 7 Inkjet print head 8 Recording paper conveyance belt 12 Paper output tray 13 Recording paper detector 14 Fan 15 Sensor box

Claims (2)

[Claims] 1. Means for moving recording paper along a movement path from a recording paper supply port to a paper discharge port, an inkjet print head provided in the middle of the movement path, and a print head provided in contact with the paper discharge port. a paper output tray for storing recorded paper, a paper detection means for detecting the recording paper on the paper discharge tray, a means for determining the dot density of the previous print data, and a means for determining the dot density of the previous print data; An inkjet printer comprising means for stopping the conveyance means for a set time at the end of printing. 2. The inkjet printer according to claim 1, further comprising means for changing the stop time depending on temperature or humidity.