OBJECT-TO-BE-PRINTED DETECTOR AND PRINT DETECTING METHOD

Abstract: The present invention relates to an apparatus for detecting an object-to-be-printed and aims at providing an apparatus for detecting an object-to-be-printed which is capable of discriminating whether the object-to-be-printed is plain paper or special paper. The apparatus includes an infrared sensor for detecting infrared rays 4 radiated by heating the object-to-be-printed 1 with heating means 2 and is capable of discriminating whether the object-to-be-printed is plain paper or special paper.

Description: FIELD OF THE INVENTION The present invention relates to a printer, comprising an apparatus for detecting the type of paper loaded in the printer and a method for operating the printer. BACKGROUND OF THE INVENTION In association with the trend in recent years toward use of color printers and higher picture-quality printing, as the objects-to-be-printed, paper of which the surface has been processed with some coating, or special types of paper of which the base material itself is special-purpose high-quality paper, glossy film, photographic-quality glossy film, photographic-quality glossy paper, OHP film, or back-printed film, etc., are being commercialized in addition to plain paper. As these special types of paper are expensive, development of means for discriminating them prior to printing the object-to-be-printed has been sought for in order that an operator of a computer and the like can avoid a situation of printing on a special piece of paper against the operator's will of printing on plain paper. Previously, printing had been done by putting plain paper on one of two or more trays loaded on a printer, for example, on an upper tray, and special paper on a lower tray, and the operator selecting in advance which tray to use prior to printing. During this process, in the event a different type of paper was mixed on a predetermined tray, the operator suffered a problem of printing on wrong paper against the will. The present invention addresses the above described previous problem and aims at providing an apparatus and method for detecting objects-to-be-printed with which the object-to-be-printed can be distinguished as to whether it is plain paper or special paper. Infrared rays are used for different kinds of measurements. DE-3 631 652-A uses the infrared rays of a halogen lamp to the measure the thickness of an object. US 3, 043, 956 describes an apparatus to testing material by subject them to modulated infrared radiation to obtain information on the thickness and other characteristics. US 4, 786, 817 measures parameters, including dry basis weight, moisture content of fibrous sheet material during manufacture. JP 10291690A describes a bill thickness detector by heating the paper sheet. JP 5-16462 A describes a recording apparatus in which infrared radiation is used to judge whether recording medium is either transparent or non-transparent. SUMMARY OF THE INVENTION In order to achieve the above object, the present invention comprises an object-to-be-printed, a heating means for heating the object-to-be-printed, and an infrared sensor for detecting infrared rays radiated by the object-to-be-printed heated by the heating means. The present invention provides an apparatus and method for detecting an object-to-be-printed with which the object-to-be-printed can be distinguished as to whether it is plain paper or special paper. The invention is defined by the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view of an apparatus for detecting objects-to-be-printed in a first exemplary embodiment of the present invention. Fig. 2 is a cross-sectional view of an infrared sensor, being a key part of the apparatus for detecting objects-to-be-printed. Fig. 3 is a graph illustrating spectral characteristic in terms of the relation between wavelength of infrared rays from plain paper heated by a heating means, being a key part of the apparatus for detecting objects-to-be-printed, and the radiation rate. Fig. 4 is a graph illustrating spectral characteristic in terms of the relation between wavelength of the infrared rays from special paper heated by the heating means, being a key part of the apparatus for detecting objects-to-be-printed, and the radiation rate. Fig. 5 is a perspective view of a paper transfer mechanism of a bubble-jet printer to illustrate the embodiment. Fig. 6 is a front view of a printing mechanism of a bubble-jet printer to illustrate the embodiment. Fig. 7 is a cross-sectional view of an apparatus for detecting objects-to-be-printed in a second exemplary embodiment of the present invention. Fig. 8 is a cross-sectional view of an apparatus for detecting objects-to-be-printed in a third exemplary embodiment of the present invention. Fig. 9 is a front view of an apparatus for detecting objects-to-be-printed in a fourth exemplary embodiment of the present invention. Fig. 1 is a cross-sectional view of an apparatus for detecting an object-to-be-printed in the first exemplary embodiment. In the drawing, an object-to-be-printed 1 is plain paper or special paper. A heating means 2, comprising a ceramic heater, halogen lamp, or the like provided either in contact with or at some distance from the bottom surface of the object-to-be-printed 1, is heated to approximately 160 to 180 degrees C to heat the object-to-be-printed 1 to approximately 80 degrees C. A lens 3 made of silicon, polyethylene, or the like is provided above the object-to-be-printed 1 for collecting infrared rays 4 radiated by the object-to-be-printed 1 heated by the heating means 2. A filter 5 comprising at least one of filters for selectively passing 9.5 to 10.5 micrometer wavelength band, selectively passing 4.0 to 5.5 micrometer wavelength band, or selectively passing 2.5 to 3.5 micrometer wavelength band is provided above the lens 3. Also, between the filter 5 and the lens 3, an optical chopper 6 made of stainless steel, iron-nickel steel, iron-nickel-cobalt steel, and the like is provided for interrupting or passing the infrared rays 4. An infrared sensor 7 for detecting the infrared rays 4 that have passed the optical chopper 6 is provided above the optical chopper 6. The infrared sensor 7 is configured in the way illustrated in Fig. 2. In Fig. 2, a mount 11 has lead electrodes 12. An infrared ray detecting unit 13 consisting of a thin film or the like made by adding lanthanum to lead titanate, which has a function of absorbing infrared rays, and electrically connected to the lead electrodes 12 is provided on the top surface of the mount 11. A cylindrical sealing member 14 made of iron. Kovar, or the like is provided on the sides of the mount 11 in a manner such that it covers at least the infrared ray detecting unit 13. The pyroelectric infrared sensor 7 is configured in such a way that an infrared ray incident window 15 made of silicon, germanium, or the like is provided to cover an opening of the sealing member 14. Although surface charges always appear in the infrared sensor 7 due to spontaneous polarization, in the steady state in the atmosphere, it remains electrically neutral as the surface charges combine with charges in the atmosphere. When infrared rays 4 enter the infrared sensor 7, the temperature changes, causing a change in the neutral state of the charge conditions. The amount of incident infrared rays is measured by detecting the charges that appear during this change. A description of the method of detection will now be given below on the apparatus for detecting an object-to-be-printed as configured above. To begin with, the object-to-be-printed 1 is laid above the heating means 2, and the object-to-be-printed 1 is heated up to about 80 degrees C by heating the heating means 2 to about 160 degrees C to 180 degrees C. Subsequently, the infrared rays 4 collected by the lens 3 are led to the filter 5 by opening the optical chopper 6. Normally, the optical chopper 6 is closed to the filter 5 and is opened only when to detect the infrared rays 4. Next, the filter 5 allows only those infrared rays 4 to pass that satisfy the conditions of the filter 5 as described below. Finally, the type of the object-to-be-printed 1 is identified by detecting the amount of infrared rays that have passed the filter 5 and arrived at the infrared sensor 7. Referring to drawings and taking plain paper and special paper as examples of the object-to-be-printed, a description will be given in the following on the spectral characteristic based on the relation between the wavelength of the infrared rays radiated by the object-to-be-printed 1 heated by the heating means 2 and the radiation rate. Fig. 3 is a graph illustrating the spectral characteristic of plain paper based on the relation between the wavelength of the infrared rays from the plain paper heated by the heating means, being an essential part of the apparatus for detecting an object-to-be-printed in the first exemplary embodiment of the present invention, and the radiation rate. Fig. 4 is a graph illustrating the spectral characteristic of special paper based on the relation between the wavelength of the infrared rays from the special paper heated by the heating means, being an essential part of the apparatus for detecting an object-to-be-printed, and the radiation rate. While the radiation rate of the plain paper shown in Fig. 3 is from about 60% to 85% in the wavelength passband of 9.5 to 10.5 micrometers, that of the special paper shown in Fig. 4 is from about 15% to 60%. Discrimination as to whether the paper is plain paper or special paper is made based on the difference in the radiation rates of the plain paper and special paper. As has been described above, by using a filter 5 having a wavelength passband of 9.5 to 10.5 micrometers, efficient discrimination between plain paper and special paper is enabled. Also, while the radiation rate of the plain paper shown in Fig. 3 is from about 37% to 43% in the wavelength passband of 4.0 to 5.5 micrometers, that of the special paper shown in Fig. 4 is from about 5% to 10%. In the same manner as above, discrimination as to whether the paper is plain paper or special paper is made based on the difference in the radiation rates of the plain paper and the special paper. As has been described above, by using a filter 5 having a wavelength passband of 4.0 to 5.5 micrometers, efficient discrimination between plain paper and special paper is enabled. Also, while the radiation rate of the plain paper shown in Fig. 3 is from about 15% to 20% in the wavelength passband of 2.5 to 3.5 micrometers, that of the special paper shown in Fig. 4 is from about 55% to 70%. In the same manner as above, discrimination as to whether the paper is plain paper or special paper is made based on the difference in the radiation rates of the plain paper and the special paper. As has been described above, by using a filter 5 having a passband of 2.5 to 3.5 micrometers, efficient discrimination between plain paper and special paper is enabled. In this exemplary embodiment, although a description was made based on a pyroelectric infrared sensor, a thermocouple type infrared sensor will also do. A thermocouple type infrared sensor is suitable as it allows high precision measurement even when no chopper is available. A pyroelectric type infrared sensor is suitable as it allows high precision measurement because five to ten times as high S/N ratio as that of the thermocouple type is obtainable. Also, though the configuration in this exemplary embodiment comprised a lens, an optical chopper, and a filter, these may be selectively combined as required. Also, when to use the apparatus for detecting an object-to-be-printed in proximity to the paper transport mechanism inside a bubble-jet printer, the heating means 2 may be disposed, as shown in Pig. 5, close to a paper feed roller 22 which is driven by a motor 21 to be used for feeding paper so that infrared rays 4 from the object-to-be-printed 1 may be collected with the lens 3 as the object-to-be-printed 1 passes above the heating means 2, and detected by the infrared sensor 7 after selectively passing through the filter 5. In this case, the lens 3 and the filter 5 may be used upon selection if need be, and the optical chopper 6 (not shown in the drawing) may be omitted by combining, as the motion of the object-to-be-printed 1 that passes the heating means 2, a forward motion in the direction of transport and a reverse motion in the direction opposite to the direction of transport. Also, when to use the apparatus for detecting an object-to-be-printed in proximity to the printing mechanism inside a bubble- jet printer, the infrared sensor 7 may be integrally provided, as illustrated in Fig. 6, on a printing head (not shown in the drawing) which is moved by a belt 31 when printing and on a printing carriage 32 which supplies ink (not shown in the drawing) to the printing head, and the heating means 2 may be provided underneath the object-to-be-printed 1 so that infrared rays 4 from the object-to-be-printed 1 can be collected by the lens 3 when the object-to-be-printed 1 passes above the heating means 2, selectively passed through the filter 5, and detected by the infrared sensor 7. In this case, the lens 3 and the filter 5 may be used upon selection if need be, and the optical chopper 6 (not shown in the drawing) may be omitted if the apparatus is so designed that infrared rays 4 can be detected when the infrared sensor 7 moves above the heating means 2. Next, referring to a drawing, a description will be given on an apparatus for detecting an object-to-be-printed in the second exemplary embodiment. Fig. 7 is a cross-sectional view of the apparatus for detecting an object-to-be-printed in the second exemplary embodiment. Structural components which are identical as shown in Fig. 1 explained in the first exemplary embodiment are indicated by the same reference numerals and detail description will be omitted. A heating means 2 is provided underneath an object-to-be-printed 1 in contact with or apart from it. A lens 3 is provided above the object-to-be-printed 1 for collecting infrared rays 4 radiated by the object-to-be-printed 1 heated by the heating means 2. An optical chopper 6 for interrupting or passing the infrared rays 4 is provided above the lens 3. A filter window 41 comprising at least one of filter windows for selectively passing a wavelength band of 9.5 to 10.5 micrometer, selectively passing a wavelength band of 4.0 to 5.5 micrometer, or selectively passing a wavelength band of 2.5 to 3.5 micrometer of the infrared rays 4 passed by the optical chopper 6 is provided integrally with the infrared sensor 7 for detecting the infrared rays 4. By configuring the filter window 41 into an integral unit with the infrared sensor 7, a filter and a window can be shared thus presenting an effect of enabling downsizing at a low cost. In this exemplary embodiment, although the apparatus for detecting an object-to-be-printed comprised a lens, an optical chopper and a filter, these may be used in selected combination as required. Now, referring to a drawing, a description will be given on an apparatus for detecting an object-to-be-printed in the third exemplary embodiment. Fig. 8 is a cross-sectional view of the apparatus for detecting an object-to-be-printed in the third exemplary embodiment. Structural components which are identical as in Fig. 1 in the first exemplary embodiment are indicated by the same reference numerals and detail description will be omitted. A heating means 2 is provided underneath an object-to-be-printed 1 in contact with or apart from it. An optical chopper 6 is provided above the object-to-be-printed 1 for interrupting or passing infrared rays 4 radiated by the object-to-be-printed 1 heated by the heating means 2. A filter lens window 51 for collecting the infrared rays 4 passed by the optical chopper 6 and comprising at least one of filter lens windows for selectively passing a wavelength band of 9.5 to 10.5 micrometer, selectively passing a wavelength band of 4.0 to 5.5 micrometer, or selectively passing a wavelength band of 2.5 to 3.5 micrometer of the infrared rays 4 passed by the optical chopper 6 is provided above the optical chopper 6 integrally with the infrared sensor 7. By configuring the filter lens window 51 into an integral unit with the infrared sensor 7, a filter, a lens and a window can be shared thus presenting an effect of downsizing at a low cost. In this exemplary embodiment, although the apparatus for detecting an object-to-be-printed comprised a lens, an optical chopper, and a filter, these may be used in selected combination as required. Now, referring to a drawing, a description will be given on an apparatus for detecting an object-to-be-printed in the fourth exemplary embodiment. Fig. 9 is a front view of an apparatus for detecting an object-to-be-printed in the fourth exemplary embodiment of the present invention. Structural components which are identical as in Fig. 1 in the first exemplary embodiment are indicated by the same reference numerals and detail description will be omitted. A trapezoidal optical plate 61 made of silicon, germanium or chalcogenide materials such as zinc sulfur and the like, is provided on the top surface of an object-to-be-printed 1. And the optical plate 61 has, on its upper bottom surface which is in parallel to the object-to-be-printed 1, a reflecting film 62 made of aluminum, gold, copper, or the like. Also, a heating means 2 is provided spaced apart from and perpendicular to one side of the optical plate 61 to supply radiated infrared rays 4 into the optical plate 61. An optical chopper 6 is provided spaced apart from and perpendicular to the other side of the optical plate 61 for interrupting or passing infrared rays 4 radiated by the heating means 2 and reflected sequentially in the order of the object-to-be-printed 1, the reflecting film 62, and the object-to-be-printed 1. A filter 5 comprising at least one of filters for selectiely passing a wavelength band of 9.5 to 10.5 micrometer, selectively passing a wavelength band of 4.0 to 5.5 micrometer, or selectively passing a wavelength band of 2.5 to 3.5 micrometer is provided above the optical chopper 6- An infrared sensor 7 is provided above the filter 5 for detecting infrared rays 4 that have passed the optical chopper 6. In this exemplary embodiment, although reference was made to the use of a pyroelectric infrared sensor, a thermocouple type infrared sensor will also do. A thermocouple type infrared sensor is suitable as it allows high precision measurement even when no chopper is in use. A pyroelectric type infrared sensor is suitable as it allows high precision measurement because of five to ten times as high S/N ratio as that of the thermocouple type. In this exemplary embodiment, although the apparatus for detecting an object-to-be-printed comprised a lens, an optical chopper and a filter, these may be used in selected combination as required. Also, in the above described first to the fourth exemplary embodiments, quality of paper is discriminated by detecting infrared rays radiated by the object-to-be-printed; however, quantity of moisture in the object-to-be-printed such as paper can be measured by using similar apparatus. In this case, the infrared rays radiated by the object-to-be-printed are 2.5 to 3.5 micrometer or 5 to 6.5 micrometer in wavelength, which are radiation bands of water. When compared with a dry object-to-be-printed , a moist object-to-be-printed shows greater amount of radiation in each of the above bands. In other words, radiation corresponding to the quantity of moisture in the object-to-be-printed is made, and, by detecting the amount of radiation, the quantity of moisture of the object-to-be-printed can be measured. A description of an apparatus for detecting an object-to-be-printed in the fifth exemplary embodiment will be given in the following. To begin with, an object-to-be-printed is laid on a heating means, and the heating means is separated from the object-to-be-printed after it has been heated up to about 80 degree C by heating the heating means to about 160 to 180 degree C. Subsequently, infrared rays radiated by the heated object-to-be-printed is collected with a lens if necessary. Next, the infrared rays collected by the lens are transferred to a filter by opening the optical chopper if necessary. Normally, the optical chopper is closed to the filter and is opened only when to detect infrared rays. Finally, the quantity of infrared rays that have passed the filter and arrived at an infrared sensor is detected to measure thickness of the object-to-be-printed. In this case, when the change of sensor output is measured from the moment the heating means is separated, the rate of change is different depending on the thickness of the object-to-be-printed. Namely, as the thickness increases, the rate of change decreases, or the thermal time constant increases. By detecting the difference in the thermal time constants, it is possible to measure the thickness of the object-to-be-printed. Here, change in the output was measured after heating the object-to-be-printed and then separating the heating means; however, it goes without saying that similar effect can be obtained by measuring the change of output from the moment the object-to-be-printed is brought into intimate contact with or chose to the heating means. The apparatus for detecting an object-to-be-printed and the method for detecting an object-to-be-printed in the first to the fifth exemplary embodiments can be used in printers. It goes without saying that the printers include ink-jet printers, laser printers, and copying machines. As has been described above, the present invention has an effect of providing an apparatus for detecting an object-to-be-printed which is capable of discriminating whether the object-to-be-printed is plain paper or special paper. LIST OF REFERENCE NUMERALS 1. Object-to-be-printed 2. Heating means 3. Lens 4. Infrared rays 5. Filter 6. Optical chopper 7. Inrared sensor 11. Mount 12. Lead electrodes 13. Infrared ray detecting unit 14. Sealing member 15. Infrared ray incident window 21. Motor 22. Paper feed roller 31. Belt 32. Printing carriage 41. Filter window 51. Filter lenz window 61. Optical plate 62. Reflecting film

Claims: Printer, comprising an apparatus for detecting the type of paper (1) loaded in the printer, including, heating means (2) for heating the paper (1), and an infrared sensor (7, 13) for detecting infrared rays radiated from the paper (1) in response to the heat supplied by the heating means (2), characterized by including a trapezoidal optical plate (61), the heating means (2) provided on one side of the optical plate, and the infrared sensor (7) provided on the other side of the optical plate. Printer according to claim 1, wherein a filter (5) that selectively passes infrared rays is provided between the paper (1) and the infrared sensor (7). Printer according to claim 1 or claim 2, wherein an optical chopper (6) that interrupts or passes infrared rays from the paper (1) is provided between the paper and the infrared sensor (7). Printer according to any of claims 1 to 3, wherein a lens (3) for collecting infrared rays is provided between the paper (1) and the infrared sensor (7). Printer according to claim 2, wherein the filter (5) comprises at least one of a filter that selectively passes 9.5 to 10.5 micrometer wavelength band, a filter that selectively passes 4.0 to 5.5 micrometer wavelength band, and a filter that selectively passes 2.5 to 3.5 micrometer wavelength band. Printer according to any of claims 2-5, comprising a filter window (41) which is integrated with the infrared sensor (7) and which selectively passes the infrared rays. Printer according to claim 6, wherein an optical chopper (6) for interrupting or passing infrared rays is provided between the heating means (2) and the filter window (41). Printer according to claim 6 or claim 7, wherein a lens (3) for collecting infrared rays radiated by the paper (1) heated by the heating means (2) is provided between the heating means and the filter window (41). Printer according to claim 6, wherein the filter window (41) comprises at least one of a filter window that selectively passes 9.5 to 10.5 micrometer wavelength band, a filter window that selectively passes 4.0 to 5.5 micrometer wavelength band, and a filter window that selectively passes 2.5 to 3.5 micrometer wavelength band. Printer according to claim 1, wherein a filter (5) for selectively passing infrared rays is provided between the side of the optical plate (61) opposite to the heating means (2) and the infrared sensor (7). Printer according to claim 1 or claim 10, wherein a lens (3) for collecting infrared rays is provided between the side of the optical plate (61) opposite to the heating means (2) and the infrared sensor (7). Printer according to any one of claims 1-11, wherein the infrared sensor (7) is of either pyroelectric type or thermocouple type. Method for operating a printer according to any of claims 1-12, by detecting the type of paper (1) loaded in the printer by heating the paper with heating means (2) and detecting infrared rays radiated by the paper with the paper being in contact with the heating means, or after the paper is separated from the heating means, by use of a trapezoidal optical plate (61), heating means (2) provided on one side of the optical plate, and an infrared sensor (7) provided on the other side of the optical plate. Method according to claim 13, wherein paper quality is discriminated by detecting infrared rays having wavelength of any of 9.5 to 10.5 micrometer, 4.0 to 5.5 micrometer, or 2.5 to 3.5 micrometer radiated by the paper (1). Method according to claim 13, wherein the amount of moisture contained in the paper (1) is measured by detecting infrared rays having wavelength of either 2.5 to 3.5 micrometer or 5.5 to 6.5 micrometer radiated by the paper. Method according to any of claims 13-15, wherein the thickness of the paper (1) is measured by detecting the wavelength of infrared rays radiated by the paper.

Inventors: FUJIKAWA KAZUHIKO, KAJIWARA JUNJI, MASUTANI TAKESHI, NOMURA KOJI, YOKOTA YASUHIKO, FUJIKAWA, KAZUHIKO, KAJIWARA, JUNJI, MASUTANI, TAKESHI, NOMURA, KOJI, YOKOTA, YASUHIKO
Applicants: MATSUSHITA ELECTRIC IND CO LTD, MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
Application year: 2000
Main classification: B41J11
IPC codes: G01N21, B65H7, B41J13, B41J11