JP2001105605A - Image recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deterioration of image quality. SOLUTION: In an image recording apparatus wherein a resistance part is provided in a printing head part, the trouble part of the printing head part is detected by measuring the resistance value of the resistance part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of image recording, and more particularly to an image recording apparatus having a print head having a resistance component.

[0002]

2. Description of the Related Art Conventionally, there has been proposed an image recording apparatus for expressing a still image by means such as ink ejection. This type of image recording apparatus receives image data from a host PC or the like (not shown), develops the data with a CPU, a storage device, or a logic circuit to generate a constant electric signal, and inputs the electric signal as a switch input. And a mechanism for energizing a resistor having a resistance component of the printing head unit and discharging ink by heat generated by the energization. And
Along with this operation, an image is recorded by scanning a recording medium such as recording paper while discharging ink.

FIG. 4 shows an ink discharge section of a print head section for performing this image recording.

[0004] Ink ejection ports 41 to 4n are provided at regular intervals on the surface of the printing head section 4a. In the printing head section, ejection ports 41 to 4 are provided in accordance with image data.
Ink is ejected from any one of n, and the printing head unit 4a performs printing while moving in the direction of a or b in accordance with the ejection.

FIG. 5 shows the internal mechanism of the printing head. In the figure, reference numerals 311 to 31n denote printing heater resistors, and reference numerals 321 to 32n denote switching transistor portions for controlling energization of the printing heater resistors. The switch transistor portion includes b1 to bn
The electrical signals developed for printing up to this point are input. One end of the printing heater resistor is commonly used for the head voltage V
H, the other end is connected to the switching transistor, and is connected to GND.

The printing heater resistances 311 to 31n in FIG. 5 and the ink discharge ports 41 to 4n in FIG.
It corresponds to one to one.

When the print head unit is at a certain position, for example, when ink is ejected from all ejection ports, the electric signal b1
ハ イ bn are supplied with logic high. As a result, electricity is supplied to all of the printing heater resistances 311 to 31n, thereby receiving heat. The ink is ejected by the heat, and ink is ejected from all ejection ports.

On the other hand, even when the discharge is not performed from all the discharge ports, the electric signals of the switching transistor portions 321 to 32n connected to the printing heater resistors 311 to 31n corresponding to the discharge ports 41 to 4m desired to be discharged. b1-b
By supplying a logic high only to the desired part of n, the discharge can be realized only from the discharge port desired to discharge, and the desired discharge can be performed.

In this way, the ejection and printing head portions a,
By repeating scanning in the direction b, printing on a recording medium (paper) can be realized.

[0010]

However, the above-mentioned conventional image recording apparatus has the following problems.

[0011] The heater in FIG.
Due to overheating or the like, the printing heater resistors 311 to 31n may fail due to disconnection or short circuit. In such a case, a problem of deterioration of print quality occurs.

For example, there is a deterioration in print quality as shown in FIG. In this figure, the paper 5a, which is a recording medium, is ejected from all ink ejection ports and scanned in the horizontal direction. For example, all black should have been printed. FIG. 5 is a diagram illustrating a case in which any one of the ink ejection ports 41 to 4n in FIG. 4 is not ejected.

As shown in FIG. 1, despite the fact that all black was originally to be printed, the image is divided into a black portion 51 and a black portion 52, and a line of white stripes is provided between the black portions 51 and 52. 53 will occur. The white stripes 53 markedly degrade the print quality and cause a failure to provide a high quality image recording apparatus. This problem can also occur in other colors for the same reason.

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and has as its object to provide an image recording apparatus capable of preventing deterioration of image quality.

[0015]

The image recording apparatus provided by the present invention is as described in the following (1) to (3).

(1) An image recording apparatus having a resistance component in a printing head unit, wherein a failure portion of the printing head unit is detected by measuring a resistance value of the resistance component.

(2) In an image recording apparatus having a resistance component in a print head, a defective portion of the print head is detected by measuring the resistance value of the resistance component, and the original print portion of the defective portion is detected. An image recording apparatus for performing printing by another printing head unit.

(3) In an image recording apparatus having a printing head unit having a resistance component, the printing head unit is sequentially energized, and the resistance value of the resistance component is read for each printing head unit to be energized. An image recording apparatus which determines whether or not the print head is normal and, if an abnormal portion exists, prints the original print portion of the abnormal portion by another print head.

[0019]

Embodiments of the present invention will be described below with reference to embodiments.

FIG. 1 is a diagram showing an internal mechanism of a print head unit in the image recording apparatus of the embodiment.

In FIG. 1, reference numerals 111 to 11n denote printing heater resistors, and reference numerals 121 to 12n denote switching transistor portions for controlling the energization of the printing heater resistors. In this switch transistor part,
Electrical signals developed for printing, a1 to an, are input. One end of the printing heater resistor is commonly connected to the head voltage VH, and the other end is connected to the switching transistor, and is connected to GND. FIG.
The printing heater resistances 111 to 11n correspond to the ink ejection ports 41 to 4n in FIG. 4 in a one-to-one correspondence.

The above configuration is the same as that of the conventional image recording apparatus. The image recording apparatus of the embodiment differs from the conventional one in the following points.

That is, in the present embodiment, output signals are respectively taken out from between each printing heater resistance and the VH signal, and are converted into analog / digital converters (AD converters) 131 to 131.
13n, and outputs the output digital signal to the selector 1
40 is input. The selector is controlled by a control signal ax, which operates in conjunction with the ON signals of the electric signals a1 to an and selects the output of the AD converter corresponding to the ON signal among the electric signals a1 to an at all times. It is configured to be. The electric signals a1 to an and the control signal ax are output from a so-called logic circuit (not shown) or C
Input directly from PU. 150 is the selector 14
0 is an output signal, which can be read from an external port of the CPU.

Next, the operation based on the above configuration will be described with reference to FIG. FIG. 2 is a flowchart illustrating a procedure of one printing operation in the embodiment.

Starting from S200, first, in S201, m = 0. Then, in S202, m = 1 is entered. At this time, the signal a1 is turned on in S203, and at the same time, the selector 140 selects the output from the AD converter 131 and outputs the output signal 150.

When the a1 signal is turned on, a current from VH flows to GND via the printing heater resistance and the switching transistor portion. As a result, a voltage substantially proportional to the printing heater resistance is generated at the upper end of the printing heater resistance 111. This value is AD-converted by the AD converter 131, selected by the selector 140, and read as an output signal 150 by the CPU (S204).

The value read in S204 is compared with a standard value that the printing heater resistance can normally take (S20).
5). If the resistance is significantly different from the standard value,
On the other hand, when it is extremely small, it is determined that the printing heater resistance by the a1 switch is abnormal, and the printing heater resistance 111 is stored in a storage device (not shown) as NG. vice versa,
If the printing heater resistance 111 is within a certain range from the standard value, it is determined that there is no abnormality in the printing heater resistance by the a1 switch, and the printing heater resistance 111 is stored in a storage device (not shown) as OK. (S206).

Since the inspection for one heater resistance is completed as described above, the heater resistance is inspected for all the heads thereafter (S207, S202 to S206).

When the inspection of all heater resistances is completed, printing is started.

First, according to a normal printing method, one horizontal scan is performed while repeating ejection (one-pass printing, S208). In the above inspection process, if there is no abnormality in all the heater resistances, the printing apparatus shifts in the vertical direction by all the ink discharge ports, and proceeds to printing from the next horizontal scan.

On the other hand, if there is an abnormal printing heater resistance, a minute vertical shift is performed to make up for this from the other ink discharge ports, thereby discharging from the other discharge ports to complete printing (S209). ). When printing is completed, the image is shifted in the vertical direction to the same position as in the case where there is no abnormal printing heater resistance, and the printing proceeds from the next horizontal scanning (S
210, S211).

As a result, the white stripes shown in FIG. 6 are eliminated, a clear image is obtained as shown in FIG. 3, and printing with stable image quality can be performed.

In order to obtain a stable printing quality, there are various methods for complementing the abnormal printing heater after it has been detected. In this embodiment, however, when the printing head is slightly moved in the vertical direction. Was explained as an example. However, in the present invention, it is sufficient that an abnormal printing heater can be detected, and the present invention is not limited to this embodiment.

[0034]

As described above, according to the present invention,
Since the abnormality of the printing head is detected by a simple electronic circuit, the image quality can be dramatically improved by preventing white stripes or the like.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an internal mechanism of a print head unit in an image recording apparatus according to an embodiment.

FIG. 2 is a flowchart illustrating a printing operation procedure in the image recording apparatus according to the embodiment.

FIG. 3 is a diagram illustrating print quality of the image recording apparatus according to the embodiment.

FIG. 4 is a diagram illustrating an ink ejection unit of a print head unit in a conventional image recording apparatus.

FIG. 5 is a diagram showing an internal mechanism of the printing head unit of FIG. 4;

FIG. 6 is a diagram showing print quality in a conventional image recording apparatus.

[Explanation of symbols]

 4a Print head part 41-4n Ink ejection port 111-11n Print heater resistance 121-12n Switch transistor part 131-13n AD converter 140 Selector

Claims (3)

[Claims] 1. An image recording apparatus having a printing head part having a resistance component, wherein a failure portion of the printing head part is detected by measuring a resistance value of the resistance component. 2. An image recording apparatus having a printing head having a resistance component, wherein a resistance value of the resistance component is measured to detect a failure portion of the printing head portion and to replace the original printing portion of the failure portion with another. An image recording apparatus for performing printing by using a printing head unit. 3. An image recording apparatus having a printing head unit having a resistance component, wherein the printing head unit is sequentially energized, and the resistance value of the resistance component is read for each printing head unit to be energized. An image recording apparatus which determines whether or not a print head is normal and, if an abnormal portion exists, prints an original print portion of the abnormal portion by another print head.