JPH08244246A - Printer - Google Patents

Abstract

PURPOSE: To eliminate the trouble of confirmation by a user, allow full use of ink, minimize poor printing on recording paper and improve economy by detecting an out-of-ink condition automatically and correctly. CONSTITUTION: An image is printed by jetting infrared light absorbing ink on recording paper. After printing action ends, a detection mark is printed in a predetermined detection position on recording paper by infrared light absorbing ink. When infrared light is applied to the detection position on the recording paper from a light-emitting diode 31a, if a detection mark is printed, infrared light is absorbed and the amount of reflected light decreases. On the other hand, if a detection mark is not printed due to the out-of-ink condition, infrared light reflects on the surface of the recording paper. Infrared light reflected from the detection position is received by an optical sensor, and it is decided whether ink is used up or not on the basis of the amount of light received.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet type printer for ejecting ink onto a recording paper to print an image, and more particularly to a printer provided with means for accurately detecting ink shortage of an ink jet head.

[0002]

2. Description of the Related Art In recent years, an ink jet type printing apparatus which has a high image quality and can be manufactured at a low price has been widely used as an output device of a personal computer. This type of printing device prints an image on recording paper by ejecting ink in the form of fine droplets.However, conventional devices equipped with means for automatically detecting ink shortage in the ink cartridge have been used. Therefore, the user replaces the ink cartridge by judging the ink running out from the blur of the image printed on the recording paper or predicting that the ink running out is near from the usage period.

[0003]

As described above, when determining the occurrence of ink shortage due to blurring of the image printed on the recording paper, the user is forced to confirm the printed recording paper, which is complicated. Not only that, but if the confirmation work is neglected, a large amount of recording paper with defective printing is discharged, which may impose an economical burden on the user. Further, even if the ink cartridge is replaced before the ink runs out, which is predicted from the usage period, the remaining ink is discarded, which is a problem in terms of economy.

The present invention has been made in view of the above circumstances, and it is possible to accurately and automatically detect ink shortage, to eliminate the burden of confirmation work by the user, and to use up the ink to the end. The purpose is to minimize printing defects on recording paper and improve economic efficiency.

[0005]

In order to achieve the above object, the present invention is a printing apparatus for printing an image by ejecting ink onto recording paper, and ejecting ink having infrared light absorbing characteristics onto the recording paper. An ink jet head, a means for controlling the ink jet head to print a detection mark at a predetermined position on the recording paper with an ink having an infrared ray absorbing property, and a red mark for the predetermined position on the recording paper where the detection mark should be printed. An infrared light irradiating means for irradiating external light and an ink shortage detecting means for detecting the ink shortage by receiving the infrared light reflected at the predetermined position on the recording paper are provided.

[0006]

When the ink remains, the detection mark is printed at a predetermined position on the recording paper by the ink. When the detection mark is irradiated with infrared light, the ink used has infrared light absorption characteristics, so the infrared light is absorbed by the ink, and the amount of light reflected to the ink shortage detecting means is significantly reduced. On the other hand, when the ink runs out, the detection mark is not printed at a predetermined position on the recording paper, and therefore the infrared light irradiating the position is reflected on the surface of the recording paper and enters the ink shortage detecting means. The ink depletion detection means accurately determines the ink depletion based on such a difference in the amount of received light.

It is also possible to use a printing ink having a characteristic of not absorbing infrared light. In this case, if the infrared light emitted from the infrared light emitting means passes through the ink that constitutes the detection mark and is reflected on the surface of the recording paper and enters the ink shortage detecting means, the And the amount of received light is no longer the same. Therefore, in this case, light other than infrared light, specifically visible light, is emitted and the reflected light is received by the ink shortage detecting means.

However, a light emitting diode which emits visible light, such as a red LED, has a drawback that it is significantly deteriorated and has a short life. In addition, an optical sensor that detects visible light such as red light is generally expensive, and since ambient light having a wavelength similar to visible light (for example, fluorescent light) is also picked up, erroneous detection is likely to occur. There are drawbacks. Therefore, the surroundings of the optical sensor must be structured so as to particularly block external light, and the device becomes bulky.

Therefore, according to the present invention, an ink jet head for printing with an ink having an infrared ray absorbing characteristic is provided, an inexpensive and long-life infrared light emitting diode is used as the infrared ray irradiating means, and the ink shortage detecting means is used. As an optical sensor for detecting infrared light, which is inexpensive and is not easily affected by ambient light (claim 2).

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. The printing apparatus according to this embodiment is of a type called an inkjet printer, and has a structure for printing an image on a recording paper by ejecting ink in small droplets from an inkjet nozzle. Since the structure for printing such an image is a conventionally known structure, detailed description thereof will be omitted. Hereinafter, the main part of the present invention will be mainly described for a structure for automatically detecting ink shortage. I will explain.

FIG. 1 is a block diagram showing a main part of a printing apparatus according to an embodiment of the present invention. In this printing apparatus, a control unit (CPU) 1 controls a print recording unit 2 to print an image on a recording sheet. That is, the print recording unit 2 is provided with an inkjet head 21, a recording paper motor 22, and a head motor 23. The head motor 23 drives the inkjet head 21 to move in the scanning direction, and the recording paper motor 22 performs recording. The paper is conveyed in the sub-scanning direction. The inkjet head 21 is controlled in synchronism with these operations, and ink is ejected onto recording paper from the inkjet nozzles formed in the head 21 in the form of small droplets to print an image.

In this embodiment, the ink jet head 2
As the ink to be supplied to No. 1, an ink having a characteristic of absorbing infrared light (infrared light absorption characteristic) is used. Generally, a light ray having a wavelength of 670 nm or more is infrared light, and any ink can be used as long as it is an ink having a light absorption property for wavelengths longer than that. In addition, there is no influence even if it has a characteristic of absorbing visible light as well as infrared light.

Examples of inks for ink jet printers having infrared light absorbing properties include metal chelate compounds of acetylacetone, anthraquinone compounds, naphthoquinone compounds, diamine disethylene thiolato nickel derivatives, aromatic diamine metal complexes, and aliphatic diamines. Inks containing infrared absorbing agents such as metal complexes, aromatic dithiol metal complexes, and aliphatic dithiol metal complexes are known.

Further, JP-A-50-95008, JP-A-53-135707 and JP-A-57-1466.
No. 0, JP-A-52-41007, JP-A-5-
No. 140493, JP-A-5-163440,
JP-A-3-227378, JP-A-6-10799
The infrared absorbing ink for inkjet printers disclosed in Japanese Patent No. 2 or the like can also be used in the printing apparatus of this embodiment.

The infrared light irradiation / detection section 3 is provided with a photoelectric sensor 31 which constitutes the infrared light irradiation means and ink shortage detection means of the present invention. The light emitting side (infrared light irradiation means) of the photoelectric sensor 31 emits infrared light.
a, and the light receiving side (ink shortage detection means) is
The optical sensor 31b is composed of a phototransistor that senses infrared light. The photoelectric sensor 31 receives the infrared light emitted from the light emitting diode 31a and reflected on the recording paper by the optical sensor 31b. In the optical sensor 31b, the value of the current that flows according to the amount of received light changes, so this change in current is converted into a change in voltage by the fixed resistor 32, and then digitally converted by the A / D converter 33 to obtain a detection signal. It is designed to be sent to the control unit 1.

The wavelength of infrared light emitted from the light emitting diode 31a and sensed by the optical sensor 31b is appropriately selected according to the wavelength of light (infrared light) absorbed by the ink. The fixed resistor 34 is inserted to adjust the characteristics of the light emitting diode 31a.

Further, the printing apparatus of this embodiment has a memory 4
And a display device 5. The memory 4 stores the detection signal sent from the infrared light irradiation / detection unit 3.
Further, the memory 4 stores a threshold value for the control unit 1 to determine whether or not the ink has run out. Display unit 5
Are provided on the upper operation panel of the printing apparatus. When the control section 1 detects that the ink has run out, it sends a display command signal to the display section 5, and in response to this signal, the display section 5 displays that the ink has run out. Each of the above-mentioned components is the bus 6
Signals are input and output via.

FIG. 2 is a plan view showing an example in which a detection mark is printed at a predetermined position (detection position) on the recording paper. Control unit 1
After printing an image for one page on the recording paper P, the inkjet head 21 is arranged so as to face the detection position, for example, with the lower end corner of the recording paper P as the detection position, and the inkjet Ink is ejected from the head 21 to print the detection mark M.

FIG. 3 is a diagram showing an example of a detection signal output from the infrared light irradiation / detection unit 3 when the photoelectric sensor 31 scans the detection position where the detection mark is printed and its peripheral portion. As shown in FIG. 2, when the photoelectric sensor 31 is scanned in the Y direction from the scanning start position a near the detection position, the infrared light emitted from the light emitting diode 31a is recorded in the portion where the image is not printed. Since the light is reflected on the surface of the paper and enters the optical sensor 31b, the detection signal shows a large output value. However, when the detection position where the detection mark M is printed is being scanned, the infrared light emitted from the light emitting diode 31a is absorbed by the ink forming the detection mark M, so that the red light that enters the optical sensor 31b is incident. The amount of outside light is significantly reduced. Therefore, the detection signal from the infrared light irradiation / detection unit 3 has a small value.

Next, the operation of detecting ink shortage under the control of the controller 1 will be described with reference to the flow chart shown in FIG. After printing an image for one page on the recording paper P and further printing the detection mark M at the detection position, the photoelectric sensor 31 is arranged so as to face the scanning start position a in the vicinity of the detection position, and the ink runs out. The detection operation of (S
1). First, the light emitting diode 31a is turned on, the detection signal output from the infrared light irradiation / detection unit 3 is sampled, and the detection signal is used as the ground color part detection data (white data) and the print part detection data ( It is temporarily stored in the memory 4 as black data).

Then, while scanning the photoelectric sensor 31,
The detection signal output from the infrared light irradiation / detection unit 3 is sampled a second time (S2), and the sampled data is compared with the previously stored white data (S).
3). If the current sampling data has a larger value, it is rewritten with the previously stored white data to store the current sampling data as white data (S
5).

On the other hand, if the current sampling data has a smaller value than the white data stored previously, it is compared with the black data stored further (S4). If the current sampling data has a smaller value, the previously stored black data is rewritten and the current sampling data is stored as black data (S5). In this way, the sampling of the detection signal is repeated, the stored white data and black data are rewritten, and the sampling operation is executed a prescribed number of times (S6). If the sampling data has a smaller value than the previously stored white data but has a larger value than the previously stored black data, the sampling data is not stored and the next sampling operation starts.

By the above detection operation, the maximum value of the detection signal is stored in the memory 4 as white data, while the minimum value of the detection signal is stored as black data. Therefore, the difference between the white data and the black data is obtained, and the value is compared with the threshold value stored in the memory 4 in advance (S
7).

Here, the white data indicates a value when the amount of infrared light reflected on the surface of the recording paper P and incident on the optical sensor 31b is large, and the black data indicates ink for forming the detection mark M. The values are shown when infrared light is absorbed and the amount of infrared light incident on the optical sensor 31b is significantly reduced. However, when the detection mark M is not printed at the detection position due to ink shortage or the print density is low, the amount of infrared light absorbed by the ink is reduced, and the amount of light incident on the optical sensor 31b is reduced. Since it increases, the difference between the white data and the black data becomes smaller.

The threshold value indicates the limit value of the difference between the white data and the black data which can be regarded as ink shortage. Therefore, the control unit 1 determines that the ink has run out when the difference between the white data and the black data stored by the detection operation is smaller than the threshold value, outputs a display command signal to the display unit 5, and indicates that the ink runs out. It is displayed (S8). On the other hand, when the difference between the white data and the black data is equal to or more than the threshold value, the detection operation is ended without outputting the display command signal.

[0026]

As described above, according to the present invention,
Accurate and automatic detection of ink depletion in the printing device eliminates the burden of confirmation work by the user, the ink can be used up to the end, and printing defects on the recording paper are minimized, which is economical. improves.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main part of a printing apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view showing an example in which a detection mark is printed on recording paper.

FIG. 3 is a diagram showing an example of a detection signal output from an infrared light irradiation / detection unit during an ink out detection operation.

FIG. 4 is a flowchart showing an operation of detecting ink shortage under the control of the control unit.

[Explanation of symbols]

 1: Control unit 2: Print recording unit 3: Infrared light irradiation / detection unit 4: Memory 5: Display unit 21: Inkjet head 22: Recording paper motor 23: Head motor 31: Photoelectric sensor 31a: Light emitting diode 31b: Optical sensor 32, 34: Fixed resistor 33: A / D converter

Claims (2)

[Claims] 1. A printing apparatus for printing an image by ejecting ink onto a recording paper, the inkjet head ejecting ink having an infrared light absorbing property onto the recording paper, and the infrared light by controlling the inkjet head. A means for printing a detection mark at a predetermined position on the recording paper with ink having an absorption characteristic; an infrared light irradiating means for irradiating a predetermined position on the recording paper where the detection mark should be printed with infrared light; A printing apparatus, comprising: an ink shortage detection unit that receives the infrared light reflected at the predetermined position on the paper to detect the ink shortage. 2. The printer according to claim 1, wherein a light emitting diode that emits infrared light is used as the infrared light irradiating means, and an optical sensor that detects infrared light is used as the ink shortage detecting means. A printing device characterized by the above.