JPS6048367A - Method and apparatus for ink jet recording - Google Patents

Abstract

PURPOSE:To obtain high density sharp recording even to a light pervious recording medium, by changing the amount of ink emitted in order to record one picture element. CONSTITUTION:A film for an overhead projector or recording paper 15 is sent to the direction of a roller 17 along a paper guide 11 and the presence or absence thereof is detected by a microswitch 13 while the kind of a recording medium is discriminated by a transmission type photosensor 14. An ink jet unit 16 is arranged toward a platen 12 and types plural dots more than the number of dots usually formed to one picture element when the sensor 14 detects the film for the overhead projector.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an inkjet recording method and apparatus, and more particularly to an inkjet recording method and apparatus that performs recording by ejecting ink droplets onto a recording medium according to recording information.

[Prior Art] Conventionally, it has been known that the recording quality (print density, dot shape after printing, etc.) of this type of recording apparatus is greatly influenced by the physical properties of the recording medium. Therefore, in any recording device, it is recommended to use paper recommended for inkjet printers, such as a type of special paper, and the current situation is that the desired print quality can be obtained when using this paper.

Recommended paper has finely determined physical properties such as diffusion isotropy, diffusion speed, adsorption speed, and reflection density of the droplets printed on it. When recording by loading film for a projector (hereinafter referred to as OHP), the quality of the print may deteriorate significantly due to differences in the physical properties of the recording medium, or in severe cases, the print may not be fixed. there were. Therefore, attempts have been made to surface-treat OHP films and form a thin film of gelatin or PVA on the surface layer to improve fixing properties.

However, the improved fixing properties have not necessarily improved the characteristics of OHP films in all respects, and OHP films have the major drawback of low printing density due to the basic physical property difference with plain paper as described below. There is.

That is, OHP films, unlike paper, have low diffusivity (that is, dot spread is small), and improved fixing performance also means a decrease in the diffusivity of OHP films. Therefore, when such an OHP film is loaded into a conventional inkjet printer and recorded, the dot of each pixel becomes small, thereby reducing the printing density and resulting in a pale and blurry recording. That is, in the case of an OHP film as shown in FIG. 2, the diameter 3 of the dots ejected into a region 1 of one pixel is smaller than the dot diameter 2 in the case of plain paper shown in FIG.

Furthermore, OHP films transmit light, while conventional recording paper uses the reflected light to express images, so even ink with relatively low ink density is colored throughout (the dots are diffused). (larger and less background)
Even if the reflection density and ink density of an ink are not that low, when viewing an object with wide dot spacing and small dot diameter using transmitted light, the reflection density may seem higher.

There is a method of increasing the dye concentration in order to increase the printing density, but increasing the dye causes problems such as clogging if left for a long time and dye precipitation, so increasing the dye beyond a certain concentration causes problems such as clogging and dye precipitation. The problem is that I can't.

Also, ink is ejected multiple times to form one pixel.
There are ways to improve the recording density on P film, but when recording on plain paper, a large amount of ink is ejected, resulting in problems such as decreased resolution, ink leakage, and wrinkles on the recording paper. Further, since ejection is performed multiple times for one pixel, the recording speed is reduced.

[Objective] Therefore, the present invention eliminates such conventional drawbacks, and provides an inkjet recording method and apparatus that can obtain clear recordings with high density even on light-transmissive recording media such as OHP films. The purpose is to

[Example] Hereinafter, the present invention will be described in detail based on the example shown in the drawings.

In FIG. 3, the reference numeral 11 indicates a paper guide, along which the OHP film or recording paper 15 is sent toward the roller 17. Further, a microswitch 13 is arranged along the paper guide 11', and the presence or absence of a recording medium is detected by this.

Furthermore, a transmission type photosensor 14 is arranged near the roller 17 with a paper guide in between, and when the recording medium is paper, this photosensor 14 is activated, and when the recording medium is
In the case of a light-transmitting film such as a HP film, the type of recording medium is determined by not operating.

Also, the inkjet unit 1 is located opposite the platen 12.
6 are arranged, and ink droplets are ejected according to recording information to record a dot image.

Further, the recording device according to the present invention has Y (yellow), M (-y
It is equipped with an ink nozzle that can eject each color of Y (ink), C (sheer), and 'Black.
, M, C, and Black, one dot is ejected per pixel according to the recording information, and one dot is ejected for each pixel according to the recording information, and subtractive colors such as R (red), G (green), and B (blue) are 1 when developing color by mixing method
Recording is performed by injecting dots of the required color into each pixel one by one to develop the color.

On the other hand, if the photosensor 14 detects an OHP film, the system is changed so that a larger number of dots than are normally formed per pixel are implanted.

For example, dots of the same color are ejected twice to the same pixel of a single color so that they overlap each other, resulting in double striking.This means, for example, that when going backwards, the dots are recorded from the opposite direction so that they overlap with the printed dots that were printed in the forward direction. This is done by advancing the recording paper by one line.

A configuration for implementing this method is illustrated in FIG. 4, in which an up/down counter 31 is connected to a CPU (central control unit) 30 that controls the recording system, and this counter The data address corresponding to the counted value is sent via the address decoder 32.

Recorded data 35 at that address is read out from a RAM (random access memory) 33 connected to external data 34 in synchronization with the clock. In that case, the ejection position is checked based on the signal from the carriage position detection unit 36, and the driver 37 is driven, and the inkjet unit (IJU)
38, dot recording is performed according to the data 35 described above.

On the other hand, when returning, the counter 31 is used as a down counter, the number of counters 31 is reduced, and the data is taken out in synchronization with the clock, contrary to the past, and printed during the return.As a result, the same one data is printed twice. Can hit hard. The same can be considered when multiple printing is performed. In this case, the data in the RAM 33 continues to be held until reciprocating printing is performed a predetermined number of times, and the paper is not fed by the paper feeding mechanism 41.

When a certain value N (the number of overprints) initially set in the CPU 30 is reached, the RAM 33 is refreshed, new data is taken in, the paper is fed by the paper feed mechanism 41, and the next printing is started.

The operation of the apparatus configured as described above will be explained with reference to the flowchart of FIG.

When normal recording paper is loaded, the recording paper 15 enters along the paper guide 11, activates the micro switch 13, and blocks the optical path of the photosensor 14, allowing the system to operate normally. After that, the inkjet unit 16 discharges one droplet per pixel to perform recording.

On the other hand, when an OHP film is loaded, the output of the photosensor 14 is not affected because the film is transparent, and as described above, ink droplets are ejected multiple times to one pixel to perform recording.

That is, as shown in FIG. 4, in steps S1 and S2, the outputs of the microswitch 13 and the photosensor 14 are used to perform a routine for recording normal recording paper (step S3) or a routine for recording OHP film (step S).
Proceed to 4). Further, if the output of the microswitch cannot be obtained, a warning is issued in step S5.

In this way, for OHP films, the amount of ink ejected and applied to each pixel is increased, and the recording density per pixel is increased. In this case, the dot diameter is also larger than in the case of one dot, approaching that when the recording medium is paper (this indicates that the space between the dots becomes narrower and the background portion decreases).

With such simple operations, a clear image with high recording density can be obtained even on an OHP film, and a sufficiently good image can be obtained even when projected onto a screen using transmitted light.

In the embodiments described above, the photosensor may be of a reflective type, or the positional relationship between the microswitch and the photosensor may be other than the above.

Further, in order to improve the degree of adhesion between the recording medium and the platen, suction may be applied to the recording medium using a negative pressure source. This example is illustrated in FIG. 6, in which the same parts as in FIG. 3 are given the same reference numerals, and their explanation will be omitted.

In the figure, the recording medium 15 is sucked by a negative pressure source 20 and brought into close contact with the platen, thereby further improving the recording quality. Further, the negative pressure can be released by a release valve 18. Furthermore, a pressure sensor 19 is provided in the suction channel, and the negative pressure in the channel is detected by this. By combining the generation of this negative pressure and the output of the photosensor 14, a relationship equivalent to that of the microswitch and photosensor described above can be obtained.

[Effect] As explained above, according to the present invention, by distinguishing between OHP film and other recording media, one pixel can be recorded without adding special equipment when recording on OHP film. On the other hand, by overlapping dots a plurality of times, it is possible to obtain a vivid image with improved recording quality and recording density.

In addition, OHP film detection and recording method switching can be done automatically using a simple combination of sensors, and in this case, both types of recording media have almost the same performance.
Moreover, an excellent effect can be obtained in that there is almost no change in cost.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram for recording on plain paper, Figure 2 is an explanatory diagram for recording on OHP film, Figure 3 is a side view showing the structure of an inkjet recording device, and Figure 4 is a dot. FIG. 5 is a flowchart explaining the operation, and FIG. 6 is a side view showing another embodiment of the inkjet recording apparatus. ■...Pixel area 2.3...Dot diameter 12...Platen 3...Micro switch 14...Photo sensor 15...Recording medium 16...Inkjet unit 19...Pressure sensor 2o... Negative pressure source patent applicant
Canon Co., Ltd.

Claims (1)

[Claims] l) In an inkjet recording method in which recording is performed by ejecting ink droplets onto a recording medium according to recording information, one pixel is An inkjet recording method characterized by changing the amount of ink ejected for recording. 2) The first aspect of the present invention is characterized in that the amount of ink is changed by changing the number of times the ink droplets are ejected.
The inkjet recording method described in section. 3) In an inkjet recording device that performs recording by ejecting ink droplets onto a recording medium according to recording information, a means for distinguishing between a light-transmissive recording medium and other recording media is provided,
An inkjet recording apparatus characterized in that the number of ink droplets forming one pixel is increased when a light-transmissive recording medium is detected.