JPH01226342A - Ink jet recording apparatus - Google Patents

Abstract

PURPOSE:To prevent the generation of shift in a droplet spotting point between the forward and backward routes of reciprocating recording, by delaying the emitting reference pulse, which is generated corresponding to the state of the relative reciprocating movement of a head and a material to be recorded, corresponding to the type of an image to be recorded and driving the head using the delayed emitting pulse. CONSTITUTION:When the head 5 starts main scanning, an emitting reference pulse generator 9 generates an emitting reference pulse 10 on the basis of the output signal of an encoder 8. The first and second delay circuits, 11 12 output the first and second emitting pulses 13, 14 having delay times T1, T2 on the basis of the pulse 10 and one of said pulses 13, 14 is selected by the change-over switch 15 driven by a printing mode judge signal 7 to be outputted to a head driver 4. In the case of the recording of an image, an ink droplet is spotted to the point M on a material P to be recorded when an ink jet recording head 5 arrives a point A. In the same way, the ink droplet is spotted to a point N with respect to a point B. In the backward route of main scanning, the ink droplet is spotted to the point N with respect to a point C and to the point M with respect to the point B.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet recording apparatus that performs reciprocating recording by relatively reciprocating an inkjet recording head and a recording medium in the main scanning direction.

[Conventional technology]

Inkjet recording devices such as printers and facsimiles that use inkjet recording heads (hereinafter referred to as heads) generally move the head and a recording medium such as recording paper or film in the main scanning direction (orthogonal to the conveyance direction of the recording medium). direction)
The ink droplets are ejected from the nozzle portion of the head and are moved toward the recording medium to record characters, images, etc. In general, one-way recording is used, in which recording is performed only during reciprocation in the direction of relative movement and not during backward movement, but there are also reciprocating recording devices that record during backward movement as well as forward movement. be. By performing reciprocating recording, the recording time can be reduced to approximately 1/2, and high-speed printing becomes possible.

When performing reciprocating recording, depending on the speed of relative movement between the head and the recording medium and the ejection speed of the ink droplets, the ink droplets ejected from the head at the same relative position on the surface of the recording medium There is a positional shift in the recording position between the forward and backward passes, which causes recording errors.

The following methods have been proposed to solve this problem.

(a) In the forward and backward paths of relative movement, the droplet landing points of ink droplets ejected from relatively the same position on the recording medium are substantially shifted by one dont bit, and correspondingly, The ejection timing of ink droplets on the return path can be varied.

(b) Detects the output of the linear encoder according to the relative movement between the head and the recording medium, compares the output signals, determines the ejection timing, flies the ink droplets, and sets the set level for comparison in the forward direction. Set the droplet point to match on the return trip and on the return trip.

By optimizing the ejection timing on the forward and return passes in this way, the recording positions of the ink droplets on the recording medium match, and no recording errors occur and no deviation occurs in the recorded image. .

In the ink recording apparatus as described above, when gradation is to be represented in an analog manner, this is done by changing the drive voltage applied to the ejection energy generator (that is, changing the dot diameter).

In this case, the range of dot diameters used is different when recording a full-color image and when recording characters. In other words, as shown in Fig. 4, when recording a full-color image, the dots mainly have small to medium diameters, that is, low to medium dot diameters.
A medium voltage value is used as the driving voltage, and when recording characters, a large dot diameter, that is, a high voltage value is used as the driving voltage. Further, as shown in FIG. 5, the ink droplet ejecting speed is faster than the driving voltage.

[Problem to be solved by the invention]

However, with such conventional inkjet recording devices, when recording full-color images, setting the ejection timing to obtain the optimal droplet point makes it difficult to record characters with large dot diameters. Misalignment of the drop point occurs,
Decrease the quality of characters. On the other hand, when recording characters,
If the ejection timing is set according to this, the droplet landing point will be shifted when recording a full color image with a small to medium dot diameter, and the quality of the image will also be degraded. We have developed an inkjet recording device that can solve the problems of the conventional technology and can perform good image recording without causing any deviation in the droplet point during the forward and return passes of reciprocating recording, regardless of the type of recorded content such as images and characters. It is about providing.

[Means to solve the problem]

The present invention provides a pulse generating means for generating an ejection reference pulse according to the relative reciprocating situation between a head and a recording object, and a delay means for delaying the ejection reference pulse according to the type of image to be recorded. The head is driven using the ejection pulse generated by the delay means.

[Effect]

With the above configuration, the ejection reference pulse is delayed to an optimal timing depending on the type of image to be recorded, and this becomes the ejection pulse. Since this ejection pulse is selected for each type of image to be recorded and drives the head, it is possible to record high-quality images without shifting the droplet point due to reciprocating recording, regardless of the type of image to be recorded.

〔Example〕

The present invention will be specifically described below with reference to FIGS. 1 to 3.

FIG. 1 is a block diagram showing an inkjet recording apparatus according to the present invention.

In FIG. 1, l is an input terminal to which input data D output from a personal computer or the like is applied. 2 is a memory that temporarily stores the input data D, and 3 is a gradation level that performs correction on the data read from memory 2 in order to reproduce the gradation faithful to the input data D when actually printed by the head. This is a correction circuit. 4 is a head driver that converts the output from the gradation correction circuit 3 into a signal for driving the head; 5 is a head driver that includes an ejection energy generating body (not shown) (piezoelectric vibrator, heating element, etc.) for driving the head driver 4; This is a head that ejects ink droplets accordingly.

6 indicates whether the input data D is image data or a character.
8 is a print mode discriminator that discriminates whether it is a code (that is, a character) and outputs a print mode discrimination signal 7; 8 is a head 5;
This is an encoder that detects relative movement between the recording medium and the recording medium. The encoder 8 includes slits having openings formed at predetermined intervals and a photocoupler that irradiates light toward the slits and receives the transmitted or reflected light to obtain a detection signal. 9 is an ejection reference pulse generator that detects the ejection reference position of an ink droplet from the output of the encoder section 8 and generates an ejection reference pulse signal lO; 11 and 12 have delays of times T1 and T2 with respect to the ejection reference pulse 10; Additionally, there are a first delay circuit and a second delay circuit that output the first ejection pulse 13 and the second ejection pulse. 15 is the first ejection pulse 13
Alternatively, it is a changeover switch that switches and outputs the second ejection pulse 14 according to the print mode discrimination signal 7.

Next, the operation of the inkjet recording apparatus having the configuration shown in FIG. 1 will be explained with reference to FIGS. 2 and 3.

When data D is input to the input terminal 1, the print mode determining section 6 determines whether the recorded data is image data or character data, and outputs a print mode determination signal 7. At the same time, input data D is temporarily stored in memory 2. When the storage of recording data corresponding to one main scanning line in the memory 2 is completed, the head 5 is driven in the main scanning direction, that is, in the directions X1 and X2 in FIG. 3, by a main scanning direction driving means (not shown).
Recording begins. When the head 5 starts main scanning, the encoder 8 generates an input output signal as shown in (a).

Based on this, the ejection reference pulse generator 9 is configured as shown in FIG.
The ejection reference pulse 10 shown in b) is generated.

The ejection reference pulse 10 is input to each of the first delay circuit 11 and the second delay circuit 12, and the first ejection pulse 13 and the second ejection pulse 14 having delay times of times T1 and T2 are input.
((c) and (d) in FIG. 2) are output. One of these ejection pulses 13 and 14 is selected by a changeover switch 15 driven by a print mode discrimination signal 7 output from a print mode discrimination section 6, and is output to the head driver 4.

Here, when the recording data is a full-color image, the changeover switch 15 selects the first ejection pulse 13, and when it is a character, it selects the second ejection pulse 14. therefore,
In the case of image recording, the head driver 4 outputs the first ejection pulse 1
The head 5 is driven at timing 3, and inkjet droplets are ejected from the head 5. If the ejection reference pulse 10 is output when the head 5 arrives at point A, point B, and point 0 in FIG. An ejection pulse lO is output, and an ink droplet is ejected.

The moving speed of the head 5 at this time, v (m/5ec
) and the ink droplet ejection speed Vl (m/5ec), the ink droplet arrives at point M on the recording medium P.

Similarly, the flow from point B arrives at point N. On the contrary, in the return path (X2 direction) of the main scan, the ejection reference pulse 10 is output when the head 5 reaches the 0 point, the B point, and the A point, and an ink droplet is ejected after T1 time. To this time.

・Due to the relationship between the moving speed of the j-dove 5, -v (m/s e c), and the ink droplet ejection speed Vl (m/5ee), the ink droplet will arrive at the N point for the 0 point, and will reach the B point. , the current arrives at point M. Therefore, the ink droplets can be made to arrive at the M point and the N point on both the outward and return journeys,
Images of good quality can be obtained.

Next, a case where the recorded data is characters will be explained.

The changeover switch 15 selects the second ejection pulse 14 based on the print mode discrimination symbol 7, and the head driver 4 drives the head 5 according to the timing of the second ejection pulse 14 to eject ink droplets.

Assuming that the ejection reference pulse 10 is output when reaching point A, point B, and point 0 in FIG.
1 direction), the head 5 is driven by the second ejection pulse 14 12 hours after the head 5 passes point A, that is, when it is located at point A''.In this case, the ink droplets are According to the relationship between the moving speed V of 5 and the ejection speed of the ink droplet 2 (however, V2>Vl), the ink droplet lands at point M on the recording medium P.Similarly, for point B, the ink droplet lands at point N. On the other hand, on the return path (X2 direction), ink droplets similarly arrive at point N for point 0, and point M for point B. In this way, ink droplets arrive at point M for point B. Characters of good quality can be obtained in both cases.

In the above embodiment, the ejection timing is obtained using a plurality of delay circuits, but a combination of a CPU and a timer circuit or a software timer may also be used.

Further, although the print mode is determined by the input data motor, the print mode may be specified using an externally operated switch and the ejection timing may be changed.

Furthermore, in this embodiment, the types of recorded images are as follows:
Although the target is full-color images and characters, it is of course possible to set multiple modes such as seven-color images such as graphs and black-and-white multi-gradation images.

〔Effect of the invention〕

As is clear from the above, according to the present invention, there is provided a pulse generating means that generates an ejection reference pulse in accordance with the relative reciprocating situation between the head and the recording object, and a Since the head is equipped with a delay means that delays according to the type of image, and the ejection pulses from this delay means are used to drive the head, the forward path,
It becomes possible to obtain a good recorded image with no deviation of recorded dots on both the return journey.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of an inkjet recording apparatus according to the present invention, FIG. 2 is a time chart explaining the operation of the embodiment of FIG. 1, and FIGS. 3 (a) and (b) are according to the present invention. A schematic diagram explaining the flight status of ink droplets in full-color image recording and character recording. Figure 4 is a characteristic diagram showing the relationship between drive voltages depending on the type of image of the inkjet recording head. Figure 5 is a diagram showing the driving of the inkjet recording head. FIG. 3 is a characteristic diagram showing the relationship between voltage and ejection speed. 4---------1 head driver, 5.--.
-...Inkjet recording head, 6...
-Print mode discrimination section, 8---------- Encoder, 9------- Ejection reference pulse generator, 11
・----------1st delay circuit, 12-...-
・−・−1 second delay circuit, 15・−・・−・− changeover switch.

Claims (1)

[Claims] In an inkjet recording apparatus that performs recording by relatively reciprocating an inkjet recording head and a recording material in a main scanning direction, the pulse generating means generates an ejection reference pulse according to the situation of the reciprocating movement, and the ejection reference An inkjet recording apparatus comprising: a delay means for delaying a pulse according to the type of image to be recorded, and the ejection pulse from the delay means is used to drive the inkjet recording head.