JP4953984B2 - Image forming apparatus, printing method, and printing apparatus - Google Patents

Description

The present invention relates to a printing method, a printing apparatus, and an image forming method that use a high-frequency electromagnetic wave in a millimeter wave to terahertz wave region to monitor a printing state of a medium such as paper and adjust a printing state according to a monitoring result. It relates to devices. In particular, the present invention relates to a technique suitable for a printing method and a printing apparatus that perform printing on paper at high speed.

In recent years, a nondestructive inspection technique using a high-frequency electromagnetic wave (also referred to as a terahertz wave in this specification) having an arbitrary frequency band in a millimeter wave to terahertz wave region (30 GHz to 30 THz) has been developed. It is known that terahertz waves have absorption lines of various substances including biomolecules. As an application field in this frequency domain, there is an imaging technique for performing a safe fluoroscopic inspection instead of X-rays. In addition, there is a spectroscopic technique for examining the binding state of molecules by obtaining an absorption spectrum and a complex dielectric constant inside a substance. In addition, biomolecule analysis technology, technology for evaluating carrier concentration and mobility, and the like are expected.

Incidentally, in an image forming apparatus that forms an image on a paper surface, such as a copier or a printer, it is important to always ensure a uniform printing state. In general, this printing state is susceptible to changes in the printing environment surrounding the inside and outside of the apparatus, such as temperature and humidity. For this reason, in many cases, the printing condition is adjusted / matched with respect to the change in the printing environment by using a detecting unit that detects the change in the printing environment. Then, an image is formed on the paper surface under this printing condition.

As one of such detection means, an apparatus that measures the film thickness and water content of ink using a terahertz wave is disclosed (see Patent Document 1). Here, the change in the transmittance of the terahertz wave is used to constantly monitor the ink film thickness and water content. Then, using this monitoring result, the printing state is controlled, and an attempt is made to realize high quality printed matter.
JP 2002-292832 JP

The above-described printing method sequentially controls the printing state so that the printing result becomes a desired state while monitoring the change in the propagation state of the terahertz wave. Specifically, the film thickness and moisture content of the ink adhering to the drum or paper are measured in the film thickness direction by changing the propagation state of the terahertz wave. However, compared with the wavelength of the terahertz wave used for measurement, the film thickness of the printing region is very thin. Therefore, the region that interacts with the terahertz wave is small, and it is difficult to obtain a sufficient change in the propagation state of the terahertz wave.

In order to sequentially control the printing state, it is basically desirable that the image data on the printed matter is the same. Then, it is necessary to compare the printing states with the image data of the same printed matter. This is because when the printed matter has different image data, the ratio of the print area where the toner or ink is placed is different from the ratio of the non-print area, and the measurement result of the print state is different. That is, since the amount of toner and ink that interact with the terahertz wave differs depending on the ratio of the printing area and the non-printing area, the terahertz wave propagation state may be measured differently even in the same quality printing state. . If the printing state is adjusted / controlled based on such a measurement result, correction is originally made on a desired printing condition. As a result, the quality of the printed matter is deteriorated.

Furthermore, the printing speed of the printing press is about 20 to 30 sheets / minute for home inkjet printers. In a high-speed printing machine for POD (print on demand), it is about 100 to 150 sheets / minute. These printing speeds are improving day by day. Therefore, in such a printing machine, for example, when the printing state for each printed matter is controlled using the terahertz wave, high-speed feedback control is required. However, when feedback control is performed for each medium on such a printing machine, the load on the CPU is large and the efficiency is deteriorated. In particular, in some cases, the speed of this feedback control will limit the printing speed.

In view of the above problems, an image forming apparatus according to a first aspect of the present invention includes a stock unit, an electromagnetic wave generation unit, an electromagnetic wave detection unit, a storage unit, an arithmetic processing unit, and a comparison unit. The stock unit stocks a laminate composed of a plurality of media after image formation. The electromagnetic wave generator generates a terahertz wave that irradiates the laminate. The electromagnetic wave detection unit detects a terahertz wave propagating in the stacking direction of the stacked body. The storage unit stores reference data. The arithmetic processing unit generates data relating to the image forming state from the detection signal from the electromagnetic wave detecting unit, information relating to the number of the media, and information relating to the image formed on the medium. The comparison unit compares the data generated by the arithmetic processing unit with the reference data stored in the storage unit.

In view of the above problems, a printing method according to the second aspect of the present invention for repeatedly printing the same information or unit information on a plurality of media includes a printing process, an irradiation process, a detection process, an arithmetic processing process, and a storage. It has a process, a comparison / judgment process, and a printing control process. In the printing process, the information is printed on the plurality of media. In the irradiation step, the terahertz wave is irradiated so that at least a plurality of sheets are transmitted to the printed medium stack. In the detection step, a terahertz wave propagating in the stacking direction of the stacked body is detected. In the arithmetic processing step, the detection signal obtained in the detection step is converted into data indicating a printing state of the information on the plurality of media. In the storing step, reference data for determining a printing state of the information on the plurality of media is stored. In the comparison / determination step, the data obtained in the arithmetic processing step and the reference data in the storage step are compared, and the printing state of the information on the plurality of media is determined. In the printing control step, the printing conditions in the printing step are adjusted based on the result obtained in the comparison / determination step. Note that this printing control step is a step performed as necessary in the second aspect of the present invention, and can be omitted. For example, the result from the comparison / determination step may be output to the outside, and the operator may control the printing conditions based on the output result.

Further, in view of the above problems, the print detection method according to the third aspect of the present invention for determining the printing state in printing in which the same information or unit information is repeatedly printed on a plurality of media includes an irradiation step, a detection step, and an arithmetic processing. It has a process, a memory | storage process, and a comparison and judgment process. In the irradiation step, a terahertz wave is irradiated so that at least a plurality of sheets are transmitted to the printed laminate of the plurality of media obtained by printing the information on the plurality of media. In the detection step, a terahertz wave from the laminate is detected. In the arithmetic processing step, the detection signal obtained in the detection step is converted into data indicating a printing state of the information on the plurality of media. In the storing step, reference data for determining a printing state of the information on the plurality of media is stored. In the comparison / determination step, the data obtained in the arithmetic processing step and the reference data in the storage step are compared, and the printing state of the information on the plurality of media is determined.

In view of the above problems, a printing apparatus according to a fourth aspect of the present invention for repeatedly printing the same information or unit information on a plurality of media includes a printing unit, a stock unit, an electromagnetic wave generation unit, and an electromagnetic wave detection unit. And an arithmetic processing unit, a storage unit, a comparison unit, and a print control unit. The printing unit prints the information on the plurality of media. The stock unit stocks a stack of the plurality of printed media. The electromagnetic wave generation unit irradiates the terahertz wave so as to transmit at least a plurality of sheets to the stacked body of the plurality of printed media in the stock unit. An electromagnetic wave detection part detects the terahertz wave from the said laminated body in the said stock part. The arithmetic processing unit converts the detection signal obtained by the electromagnetic wave detection unit into data indicating a printing state of the information on the plurality of media. The storage unit stores reference data for determining a printing state of the information on the plurality of media. The comparison unit compares the data obtained by the arithmetic processing unit with the reference data in the storage unit, and determines the printing state of the information on the plurality of media. The printing control unit adjusts printing conditions in the printing unit based on the result obtained by the comparison unit.

Further, in view of the above problem, the print detection apparatus according to the fifth aspect of the present invention for determining the printing state in printing in which the same information or unit information is repeatedly printed on a plurality of media includes an electromagnetic wave generation unit, an electromagnetic wave detection unit, It has an arithmetic processing part, a memory | storage part, and a comparison part, It is characterized by the above-mentioned. The electromagnetic wave generator irradiates a terahertz wave so that at least a plurality of sheets are transmitted to the printed laminated body of the plurality of media obtained by printing the information on the plurality of media. The electromagnetic wave detection unit detects a terahertz wave from the laminate. The arithmetic processing unit converts the detection signal obtained by the electromagnetic wave detection unit into data indicating a printing state of the information on the plurality of media. The storage unit stores reference data for determining a printing state of the information on the plurality of media. The comparison unit compares the data obtained by the arithmetic processing unit with the reference data in the storage unit, and determines the printing state of the information on the plurality of media.

According to the present invention, terahertz waves are propagated in the stacking direction to a predetermined number of stacked bodies (printed or stacked media such as paper on which toner or ink is placed). Let The characteristics of the laminated body of the medium are monitored from the change in the propagation state of the terahertz wave. In this way, in the present invention, since the terahertz wave is used as the monitoring means to irradiate the printed or image forming medium formed into a laminated body, the area interacting with the terahertz wave becomes large, and the laminated layer formed of the printing or image forming medium is used. Detection of body characteristics is facilitated.

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

(First embodiment: image forming apparatus)
First, the image forming apparatus according to the present embodiment will be described with reference to FIG. In the drawing, a stock unit 6109 for stocking a laminate 6110 composed of a plurality of media after image formation, and an electromagnetic wave generator 6103 for generating a terahertz wave irradiated on the laminate 6110 are depicted. Yes. Further, an electromagnetic wave detection unit 6104 for detecting a terahertz wave propagating in the stacking direction of the stacked body 6110 and a storage unit 6107 for storing reference data are depicted. Further, an arithmetic processing unit 6105 for generating data relating to an image formation state is drawn from the detection signal from the electromagnetic wave detection unit 6104, information relating to the number of media, and information relating to an image formed on the medium. It is.

The data generated by the arithmetic processing unit 6105 and the reference data stored in the storage unit 6107 are compared by the comparison unit 6106 in FIG. Information on the comparison result in the comparison unit 6106 can be input to a control unit for controlling printing conditions or output to the outside so as to be transmitted to an operator as necessary. Of course, the comparison results in the comparison unit can be stored in sequence. If the comparison results are sequentially stored in this way, it is possible to grasp the processing capability of the image forming apparatus being used (for example, how the image changes according to the number of printed sheets). it can.

In this embodiment, the terahertz wave output from the electromagnetic wave generator 6103 is irradiated in the stacking direction of the stacked body 6110. Therefore, the interaction between the terahertz wave and a substance (a medium such as paper or ink or toner that forms an image) existing in the propagation direction is sufficiently generated.

In the arithmetic processing unit 6105, data relating to the image forming state is generated in consideration of information relating to the number of media constituting the laminate 6110 and information relating to images formed on the media. Here, the information regarding the number of sheets of media is information on the number of all sheets constituting the stack, or information on the number of booklets when the stack is composed of a plurality of booklets. By using the information regarding the number of media, for example, it is possible to grasp in advance whether the signal is a terahertz wave signal transmitted through 10 sheets of paper or a terahertz wave signal transmitted through 500 sheets of paper. Therefore, the accuracy in generating data relating to the image forming state is improved.

Of course, the number of media constituting the laminate is determined in advance, and information regarding the number of sheets may not be input to the arithmetic processing unit every time data regarding the image forming state is generated. Also in this case, data relating to the image forming state is generated in consideration of information relating to the number of media constituting the laminate 6110.

The information related to the image formed on the medium includes information that the same image is formed on a plurality of media. Further, information on what kind of image it is (for example, information on where ink or toner exists in the in-plane direction of the medium) may be added. The same image is not necessarily formed on a plurality of media constituting the laminate. For example, if information on what image is formed and where is known, a different image is drawn for each medium. May be. However, from the viewpoint of reducing the number of data, it is preferable to acquire a detection signal by irradiating terahertz waves in a state where the same image is formed on all the media constituting the stacked body. The number of media constituting the laminate can be appropriately set according to the intensity of the terahertz wave to be irradiated, such as 10, 50, 500, and 1000.

Of course, an image to be formed on the medium constituting the laminate is determined in advance, and the image information may not be input to the arithmetic processing unit each time data relating to the image forming state is generated. Also in this case, data relating to the image forming state is generated in consideration of information relating to the image formed on the medium.

The reference data stored in the storage unit and the data generated by the arithmetic processing unit can be obtained as follows, for example. In the case where the same image is formed on all the media, for example, with respect to the reference data, the laminate is composed of media from the first sheet to the 100th sheet from the start of image formation. The laminated body is irradiated with terahertz waves, a terahertz wave signal output through the laminated body is received, and intensity data in a specific wavelength region is used as reference data. For the data generated by the arithmetic processing unit, for example, the laminated body is constituted by media from the 501st sheet to the 600th sheet. The laminated body is irradiated with terahertz waves, a terahertz wave signal output through the laminated body is received, and intensity data in the specific wavelength region is used as generation data. For example, when the reference data and the generated data are compared and change by 10% or more, a process of adjusting the image forming condition can be performed.

The electromagnetic wave generation unit 6103, the stock unit 6109, the electromagnetic wave detection unit 6104, the arithmetic processing unit 6105, the comparison unit 6106, and the storage unit 6107 described above are the second embodiment and examples described later unless there is a technical contradiction. The technical matters described in the above can be applied as they are. In addition, the image forming apparatus described in the present embodiment is appropriately provided with an electrophotographic method (to be described later) or an image forming unit that discharges ink.

(Second embodiment: printing apparatus, printing method)
FIG. 1 is a schematic configuration diagram of a printing apparatus or method according to a second embodiment of the present invention. As shown in FIG. 1, the printing apparatus according to the present embodiment includes a printing unit 101, a printing control unit 102, an electromagnetic wave generation unit 103, an electromagnetic wave detection unit 104, an arithmetic processing unit 105, a comparison unit 106, a storage unit 107, and a paper feeding unit 108. And a paper discharge unit 109. The printing unit 101 is a part that forms an image using ink or toner on a certain printing medium, such as an inkjet method or an electrophotographic method. Here, the same information is repeatedly formed on a plurality of predetermined media. For example, a unit printed product that is a unit printed product by combining a predetermined number of different printed products such as a booklet (information constituting the unit printed product is referred to as unit information) is formed by repeating unit information. Therefore, the printing unit 101 is not limited to the above method as long as the object of forming an image on a certain medium can be achieved.

The print control unit 102 is a part that adjusts and controls image forming conditions in the printing unit 101. For example, in the case of an ink jet method, an ink ejection algorithm, a paper feed speed, and the like are controlled. In the case of an electrophotographic system, toner supply amount control and charge control are performed. The examples given here are merely examples, and the present invention is not limited to these as long as the purpose of adjusting / changing the printing state in the printing unit 101 can be achieved.

The electromagnetic wave generation unit 103 has a function of generating high-frequency electromagnetic waves and irradiating the printed material. In particular, in the present invention, terahertz waves are used as high-frequency electromagnetic waves. Terahertz waves have the characteristics of having both high-frequency electromagnetic wave material permeability and light straightness. Therefore, it has good transmission characteristics for non-conductive materials such as paper. Furthermore, it is known that absorption lines of various substances exist in the electromagnetic wave band of this region, and the detection sensitivity to water is extremely high. By making use of these characteristics, for example, the type of paper can be determined, and the moisture content and resistivity of the paper can be detected by terahertz waves. In addition, regarding chemical materials such as toner and ink, it is possible to detect dryness, component mixing ratio, total amount, film thickness, and the like. Further, by utilizing the characteristics of light, terahertz waves can be freely handled by an optical element such as a lens. Taking advantage of this feature, for example, it is possible to obtain a moisture content dispersion image in paper.

In the present embodiment, as shown in FIG. 1, the electromagnetic wave generation unit 103 is in the vicinity of the paper discharge unit 109. The paper discharge unit 109 corresponds to, for example, a paper discharge tray or a finisher.

In the present specification, the following description will be made using paper as a representative print medium. However, the print medium is not limited to this. For example, any print medium that transmits a terahertz wave, such as a printed material for clothing, may be used. As shown in FIG. 1, in the present embodiment, terahertz waves generated from the electromagnetic wave generation unit 103 are propagated so as to pass through at least a plurality of sheets in the stacking direction of the paper bundle 110 in the paper discharge unit 109.

As a method for generating the terahertz wave, for example, an antenna structure formed on a semiconductor substrate is used. In the present embodiment, a 100 μm thick GaAs substrate having a 1.5 μm thick LT-GaAs epitaxial growth layer on the surface is used as the semiconductor substrate. In addition, a dipole antenna structure having a gap of 5 μm at the center is used as the antenna structure. The antenna length of this dipole antenna structure is 30 μm, and AuGe / Ni / Au is used as a material, and it is manufactured by a normal vapor deposition process.

As a matter of course, the antenna structure is not limited to this. The size and shape of the antenna change depending on the terahertz wave to be handled. In this embodiment, a bias is applied to the gap of this antenna, the gap is optically gated using a femtosecond laser, and the electromagnetic wave generated at that time is used as a terahertz wave. However, the terahertz wave generation method is not limited to this method. For example, a method using a difference frequency between two types of lasers having different laser wavelengths or a method using a negative resistance element such as a quantum cascade laser. But you can. Further, an oscillator using a nonlinear optical crystal or an oscillator using an electron tube such as a BWO (Backward-Wave-Oscillator) may be used.

The electromagnetic wave detection unit 104 is a part that detects a terahertz wave that has been transmitted through the paper bundle 110 that is a laminate of print media. Similarly to the electromagnetic wave generation unit 103, the electromagnetic wave detection unit 104 is in the vicinity of the paper discharge unit 109. In FIG. 1, the electromagnetic wave detection unit 104 is disposed at a position substantially opposite to the electromagnetic wave generation unit 103 with the paper bundle 110 interposed therebetween. However, the arrangement is not necessarily limited to this. For example, if the optical characteristics of terahertz waves are used, the degree of freedom of arrangement increases depending on the optical system. In some cases, it is not necessary to dispose it near the paper discharge unit 109. These arrangements may be selected in consideration of the signal intensity of the terahertz wave, attenuation due to the measurement environment, and the like.

The terahertz wave detection unit 104 has the same configuration as the electromagnetic wave generation unit 103, for example. Terahertz waves are detected by applying a bias to the antenna gap and optically gating the gap using a femtosecond laser. However, like the electromagnetic wave generation unit 103, the method is not limited to this method. For example, there are a heat detector such as a bolometer and a method using an electro-optic effect. There is also a method using a negative resistance element such as a Schottky diode.

In FIG. 1, the electromagnetic wave generation unit 103 and the electromagnetic wave detection unit 104 are each illustrated as a single unit, but the present invention is not limited thereto, and there may be a plurality. Further, the electromagnetic wave generation unit 103 and the electromagnetic wave detection unit 104 may be separately provided with a mechanism for mechanically scanning the paper bundle 110, or may be provided with a mechanism or means for controlling the directivity of the electromagnetic wave. Good.

The arithmetic processing unit 105 is a part that acquires desired physical property data regarding the paper bundle 110 from the detection signal of the terahertz wave detected by the electromagnetic wave detection unit 104. For example, as shown in FIG. 4, the physical property information is acquired from information such as a change in intensity, phase shift, and waveform change of the detection signal 402 with respect to the reference signal (reference signal 401). The obtained physical property information includes, for example, information on the moisture content of the paper, the resistivity of the paper bundle 110 due to the moisture content, the drying condition of the toner and ink, and the film thickness. Such information can be acquired regarding the propagation direction of the terahertz wave in the paper bundle 110.

In addition, as shown in FIG. 5, the time domain signal is converted into the frequency domain signal, and the physical property information is obtained from the signal change with respect to the reference signal (for example, the difference between the spectrum (1) 501 and the spectrum (2) 502). It can also be acquired. As the physical property information obtained, for example, in addition to the information described above, information on the propagation direction of the terahertz wave in the paper bundle 110 can be acquired regarding information such as the type of paper, the color and total amount of toner and ink, and the like. As an acquisition method, a comparison / determination method in which a mixing ratio of toner and ink is obtained from the obtained spectrum and compared with a color lookup table prepared in advance in the arithmetic processing unit 105 can be considered. As a matter of course, in the present invention, it is only necessary that the parameters relating to the printing state can be detected by the terahertz wave. Therefore, the object of the physical property information is not limited to the above. Moreover, the determination method of color etc. is not restricted to this.

Here, the spectrum information is acquired by converting a terahertz wave pulse signal, but the present invention is not limited to this method. For example, when the wavelength at which the parameter relating to the printing state described above changes characteristically is known, the following method can be used. First, the intensity of each wavelength is monitored using terahertz continuous waves of a plurality of wavelengths corresponding to these wavelengths. And the characteristic change of these parameters can also be estimated from the change of the intensity | strength of each wavelength.

In addition, when the terahertz continuous wave generation source has wavelength variability, a method may be used in which characteristics are acquired by shifting the spectrum in the vicinity of all or part of an arbitrary wavelength in FIG. Further, when such a wavelength-tunable terahertz continuous wave is used, it is not necessary to acquire the characteristic wavelength intensity at a time. For example, a method of detecting a plurality of intensity changes by adjusting the wavelength of the terahertz continuous wave for each characteristic wavelength region and detecting a plurality of times may be used. Further, the number of parameters to be acquired is not limited to one, and there may be a plurality of parameters.

As described above, in the present embodiment, either one or both of the electromagnetic wave generation unit 103 and the electromagnetic wave detection unit 104 may have means for scanning terahertz waves. In this case, the arithmetic processing unit 105 may perform a process of plotting the physical property information of each scanning point to form an image. The image obtained at this time corresponds to two-dimensionalized physical property information in the stacking direction among the physical property information of the paper bundle 110.

In this way, the arithmetic processing unit 105 first acquires a time-series or frequency-domain signal from the signal of the electromagnetic wave detection unit 104. Thereafter, characteristic physical property information regarding the paper bundle 110 is extracted from this signal. In particular, the description has been made so far mainly on pulse signals as terahertz waves, but the present invention is not limited to this. For example, the terahertz wave used may be a continuous wave. There may also be a plurality of continuous waves. When a plurality of terahertz waves are used, for example, a method of monitoring the frequency point at which the physical property information of the paper bundle 110 appears characteristically in the spectrum of FIG. 5 and estimating the printing state of the paper bundle 110 may be used. Moreover, the method of improving a sensitivity by calculating | requiring the difference signal of several physical property information may be sufficient.

The comparison unit 106 compares the physical property information of the paper bundle 110 acquired by the arithmetic processing unit 105 with the reference physical property information, and sends the comparison / determination result to the print control unit 102 as information on the state change of the paper bundle 110. Is. The physical property information serving as the reference is stored as reference data in the storage unit 107. In the present embodiment, information on the printed matter itself and information on the terahertz wave to be used are assumed as the reference data. For example, information on the printed matter itself includes paper type, image data, toner and ink application target values, environment (water content, etc.), and the like. The terahertz wave information includes a change in transmission amount and a phase change with respect to the initial value. In the present embodiment, the toner and ink application target values (how much desired image quality can be obtained) among these control objects will be mainly described as control objects. Then, the print control unit 102 adjusts and controls the printing unit 101 so as to approach the given target value. However, the type of reference data and the control target are not limited to this.

The physical property information serving as the reference can be obtained by the following acquisition method. Predetermined physical property information obtained from a terahertz wave response from a predetermined number of paper bundles 110 existing in the paper discharge unit 109 is regarded as reference information and stored in the storage unit 107. In some cases, the initial print state may be determined by associating the response of the terahertz wave with a database of paper types and print types (characters, photographs, graphics, etc.). In short, any method can be used as long as the initial printing state can be determined from the response of the first terahertz wave. The comparison unit 106 sends difference information with the reference physical property information to the print control unit 102 every predetermined number of sheets (the same information or unit information is printed on the predetermined number of sheets), and this difference is minimized. In this way, the printing state is controlled.

However, the method of acquiring the standard physical property information is not limited to this. For example, in the case of a printing machine having a scanner, reference physical property information related to a predetermined number of paper bundles 110 may be predicted or estimated in advance using electronic information of a printing unit captured by the scanner. In addition, when this electronic information is produced by a personal computer or taken into a portable device such as a digital camera, the electronic information is used to set a standard for a predetermined number of paper bundles 110. Physical property information may be predicted in advance. In some cases, the print state may be determined by associating information predicted in advance with a database of paper types and print types (characters, photographs, graphics, etc.). In short, any method can be used as long as the printing state can be determined from the electronic information of the printed matter. Again, the comparison unit 106 sends difference information with the reference physical property information to the print control unit 102 every predetermined number of sheets, and adjusts / controls the printing state so that this difference is minimized.

In addition, the reference information so far uses fixedly the information set at the initial stage of printing or before printing, but is not limited thereto. For example, an average value of physical property values obtained by a predetermined number of printing operations (in this printing operation, a predetermined number of sheets are printed each time) may be used as the reference information. That is, since the reference information is obtained from a predetermined number of printing states including the most recent printing state obtained by multiple detections, strictly speaking, the reference information is updated sequentially. At this time, the comparison unit 106 and the print control unit 102 control the printing state so that the reference information is stabilized in the long term (for example, the drift component is removed).

The paper supply unit 108 has a function of stocking paper used for printing and sending the paper to the printing unit 101 that actually performs the printing operation. In addition to the printing unit 101 and the paper feeding unit 108, the printing machine includes a print control unit 102 that adjusts and controls the printing operation of the printing unit 101, and a paper discharge unit 109 that stocks printed matter. Meet the requirements. The present embodiment further includes a mechanism for propagating the terahertz wave in the stacking direction of the stack of products (that is, the paper bundle 110) in the output unit 109. Then, from the change in the propagation state of the terahertz wave, the print control unit 102 obtains a change from the reference information of the physical property information of the laminated body so that the change becomes a constant value or falls within a certain region. The printing state is changed.

Next, basic operations related to the printing apparatus according to the present embodiment will be generally described. First, the paper feeding unit 108 feeds paper to a portion to be printed, that is, the printing unit 101, and the printing unit 101 prints a desired print pattern on the paper. That is, the same information or unit information is repeatedly printed on a predetermined number of sheets. At this time, the print control unit 102 controls the printing unit 101 according to preset printing conditions. This setting condition is set and measured manually or automatically in advance according to the image data. In the present embodiment, these printing conditions are set according to the type of paper to be used, the type of ink, and the type of toner. And it correct | amends that the printing state of the obtained printed matter changes in the process of printing.

However, even if the printing conditions described above are not conditions suitable for actual printing, it is possible to correct the printing conditions. For example, even if the set paper type is different, it is possible to specify the paper type according to the type and amount of calcium carbonate which is the main component of the paper, and to change the printing state as appropriate. Even if the type of toner or ink is different, it is possible to specify the type from the propagation information of the terahertz wave and appropriately change it to a printing state suitable for it. In such a case, it is desirable to set the reference information again according to the updated printing conditions.

The paper printed by the printing unit 101 is discharged to the paper discharge unit 109. These printing operations are sequentially performed until the number of printed sheets set by the user is reached. At this time, it is preferable that the paper discharge unit 109 has a function of temporarily stocking printed matter like a finisher.

When the user sets the number of prints in advance, the electromagnetic wave generation unit 103 in the vicinity of the paper discharge unit 109 transmits at least a plurality of sheets with respect to the predetermined bundle of print sheets 110 in the paper discharge unit 109. Irradiate terahertz waves as you do. Thereafter, the terahertz wave propagated through the paper bundle 110 is detected by the electromagnetic wave detection unit 104 in the vicinity of the paper discharge unit 109. As described above, the electromagnetic wave generation unit 103 and the electromagnetic wave detection unit 104 are not necessarily in the vicinity of the paper discharge unit 109.

The terahertz wave detected by the electromagnetic wave detection unit 104 is converted into a predetermined signal format by the arithmetic processing unit 105, and a physical property value indicating the printing state of the paper bundle 110 is obtained from this signal. For example, as shown in FIG. 4, it is converted into time-series terahertz wave data, and the physical property value is obtained from the data of intensity change and / or phase change. Alternatively, as shown in FIG. 5, it is converted into frequency spectrum data, and a physical property value is obtained from data of intensity change and / or phase change of each frequency.

When this physical property value is obtained for the first time from a change in the propagation state of the terahertz wave, information on the initial printing state is stored in the storage unit 107 as reference data using this data. Then, the difference between the physical property data obtained thereafter and the reference data is acquired by the comparison unit 106, and the correction information is transmitted to the print control unit 102. That is, here, the inspection information of the first paper bundle 110 by the terahertz wave is not used for the control of the printing unit 101, and the printing unit 101 is used by using the second and subsequent inspection results and the information of the first inspection result. Control the printing status of However, as described above, the method for obtaining the reference data stored in the storage unit 107 is not limited to this. If the reference data is acquired in advance, the printing state can be controlled from the first inspection result. Further, when the reference data is obtained from the predetermined number of inspection results, the printing state of the printing unit 101 is not controlled in the inspection process in the printing process in which printing on a predetermined number of sheets is less than the predetermined number of times.

In the paper discharge unit 109, when the inspection by the terahertz wave is completed, the paper bundle 110 is moved to a desired location, and a predetermined number of printed materials are stocked again. However, in some cases, it is not necessary to move the paper bundle 110 used for the inspection. For example, the unexamined paper bundle 110 may be stacked on the paper bundle 110 used for the inspection. In this case, for example, in the arithmetic processing unit 105 or the comparison unit 106, the physical property information indicating the printing state is corrected according to the number of bundles of the paper bundle 110.

The printing control unit 102 adjusts and controls the printing unit 101 so that the printing state approaches a desired state based on the correction information obtained from the comparison unit 106. At this time, it is not always necessary to change the print state to a desired state by one-time control, and a control method that gradually approaches the desired state by a plurality of times of control may be used.

The printed material used here is not necessarily the same printed material for each sheet. For example, in this embodiment, since the physical property value in the stacking direction of the paper bundle 110 is monitored, it is sufficient that each paper bundle 110 is a printed matter having the same content as a whole, like a booklet.

As described above, in this embodiment, the printing state of the printed paper bundle 110 is monitored using the terahertz wave, and the printing unit 101 is controlled so as to approach the desired printing state. Therefore, unlike the conventional case, it is not necessary to control the printing state for each printing result on one medium, and the speeding up is facilitated. Further, in the present embodiment, the paper bundle 110 is propagated using the transparency of the terahertz wave to the paper. For this reason, the interaction length between the terahertz wave and the paper, and the ink or toner is increased, and the detection sensitivity is improved.

In addition, terahertz waves are strongly absorbed in water, so that the moisture content of paper, toner, ink, etc. can be detected with high sensitivity. For example, the dryness of ink or toner can be determined from the moisture content. The wavelength of the terahertz wave corresponds to the wavelength of molecular vibration or lattice vibration. For example, it is possible to inspect a difference in the structure of toner or ink. Taking advantage of such characteristics, as described above, the total amount of toner and ink in a bundle of printed materials can be determined. It is also possible to determine the color of the printed matter by separating the difference in the structure of the toner and ink used from the absorption spectrum.

When the same operation is performed with light in the vicinity of visible light, a considerable amount of light is required to transmit the bundled printed matter. However, in the present embodiment, terahertz waves that are originally excellent in transmission power are used for the printed matter. Therefore, in this embodiment, power saving of the printing apparatus can be realized.

In particular, in a high-speed printing machine that handles a large amount of printed matter, the operator controls the printing state of the printing machine according to the state of the printed matter and the surrounding environmental conditions. In this way, the present embodiment can automate the work conventionally performed by the operator, and thus has an effect of reducing the load on the operator.

Hereinafter, more specific embodiments will be described with reference to the drawings. In addition, the same code | symbol is used about the same element in a figure.

(Example 1)
Embodiment 1 shows an example in which a printing apparatus according to the present invention is applied to a copying apparatus using an electrophotographic system.

FIG. 2 is a schematic configuration diagram of a printing apparatus or method according to the present embodiment. In particular, FIG. 2 shows the printing means 101 in FIG. 1 more specifically, and the other components are basically the same as those in FIG. That is, the printing means 101 in FIG. 1 is configured as shown in FIG. The pattern of the process of detecting the printing state of the paper bundle 110 using the terahertz wave propagating through the paper bundle 110 is the same as that described in the embodiment.

In this embodiment, as shown in FIG. 2, the printing unit 101 includes a drum 201, a charging unit 202, a toner supply unit 203, a fixing unit 204, an image forming unit 205, a transfer unit 206, and a transfer control unit 207. In particular, the operation of the portion that greatly contributes to printing on paper can be adjusted and controlled by the print control unit 102 as shown in FIG.

The drum 201 is a part that attaches toner to a desired pattern and transfers it to paper. The charging unit 202 is a part that charges a desired charge for attaching toner to the drum 201. For example, by controlling the charging unit 202, the amount of toner attached to the drum can be controlled. The toner supply unit 203 is a part that supplies toner to a latent image of charges existing on the drum 201. For example, by controlling the amount of toner supplied to the drum 201, it is possible to control the density and color of printing. In this embodiment, only one drum 201 and one toner supply unit 203 are shown, but the present invention is not limited to this. There may be a plurality of these parts depending on the type of toner used.

The fixing unit 204 is a part that fixes the toner transferred onto the paper by heat. For example, the fixing state can be controlled by adjusting the fixing temperature. The image forming unit 205 is a part that forms a latent image by irradiating a laser beam onto the electric charge charged on the drum 201. For example, the charged state on the drum 201 can be controlled by adjusting the laser intensity. The transfer unit 206 is a part that applies an electric field between the drum 201 and the transfer unit 206 and transfers the toner on the drum 201 to the paper 210. This electric field is applied by the transfer control unit 207. For example, the transfer state can be controlled by adjusting the electric field.

The operation will be described below. Since a method for printing on paper by an electrophotographic method is general and well known, a description thereof is omitted here. Here, a specific part to be controlled will be described using the above-described inspection result of the printed state by the terahertz wave.

Consider a case where the water content of the paper bundle 110 is monitored by terahertz waves. The change in moisture content is closely related to the resistivity of paper. The paper resistivity largely contributes to the toner transfer conditions and fixing conditions to the paper. Therefore, in this example, the printing control unit 102 controls the next part so that the printing state becomes constant regardless of the change in the moisture content of the paper bundle 110. For example, the bias of the voltage applied from the transfer control unit 207 to the transfer unit 206 is controlled. In addition, the charging amount of the charge to the drum 201 may be controlled by the charging unit 202. Further, the fixing temperature of the fixing unit 204 may be controlled.

Consider a case in which the amount of toner and color attached to the paper bundle 110 are monitored by terahertz waves. In this example, the print control unit 102 controls the next part so that the toner amount and color of the paper bundle 110 are constant. For example, the voltage applied by the charging unit 202 and the laser intensity of the image forming unit 205 are controlled to control the charge of the latent image charged on the drum 201. Further, the amount of toner supplied from the toner supply unit 203 may be controlled.

Thus, in this embodiment, the terahertz wave propagating through the paper bundle 110 is used to monitor the printing state from the water content, toner amount, and color of the paper bundle 110 in the electromagnetic wave propagation direction. And each part which contributes to a printing process is controlled so that this printing state may become constant.

Conventionally, in a high-speed printing machine or the like, a dedicated operator is required to perform these series of control operations. In the present embodiment, since these operations are automatically performed, there is an effect that the load on the operator is reduced. Even when the operator performs the adjustment work, the adjustment work cannot be performed throughout. In this embodiment, since these adjustment operations are performed almost continuously, there is an effect that printing defects are reduced and reliability is improved. Further, the above apparatus or method can also be used as a print detection apparatus or method. For example, when it is applied to a bookbinding check, it is possible to detect a product that is out of order or missing, or a printing defect. For example, by providing a separate mechanism for removing such a product by the paper discharge unit 109, the reliability of the product can be improved.

(Example 2)
Embodiment 2 shows an example in which the printing apparatus according to the present invention is applied to a printer apparatus using an ink jet system.

FIG. 3 is a schematic configuration diagram of a printing apparatus or method according to the present embodiment. In particular, also in FIG. 3, the printing means 101 in FIG. 1 is shown more specifically, and other components are omitted. That is, the description of the process of detecting the printing state of the paper bundle 110 using the terahertz wave propagating through the paper bundle 110 is the same as that described in the above embodiment, and is omitted here.

In the present embodiment, as shown in FIG. 3, the printing unit 101 includes a discharge unit 301, a discharge control unit 302, a scanning mechanism unit 303, a paper feed unit 304, and a scanning control unit 305. In particular, the operation of the portion that greatly contributes to printing on the paper 310 can be controlled by the print control unit 102 as shown in FIG.

The ejection unit 301 is an ink jet head part, and is a part that ejects desired ink onto the paper 310. The discharge control unit 302 is a part that controls the discharge algorithm of the discharge unit 301. By controlling the ejection algorithm, the color and the amount of ink printed on the paper 310 are controlled. The scanning mechanism unit 303 is a mechanism that mechanically moves the discharge unit 301 in a direction perpendicular to the paper feeding direction, and the paper feeding unit 304 is a mechanism that mechanically feeds the paper 310. The operations of these mechanisms are controlled by the scanning control unit 305.

The operation will be described below. Since a method for printing on paper by an ink jet method is also common and well known, description thereof is omitted here. Here, a specific part to be controlled will be described using the above-described inspection result of the printed state by the terahertz wave.

In the ink jet system, the amount of ink ejected from the ejection unit 301 is basically determined. Therefore, as a printing state control method, a discharge algorithm (for example, discharge speed, discharge direction, discharge interval, total discharge amount, ratio of each ink) by the discharge control unit 302 and a scanning method by the scan control unit 305 are integrated. Adjust and control. For example, consider a case where the dryness of ink is monitored from the moisture content by terahertz waves. In this case, in order to ensure time for ink to dry, the scanning control unit 305 changes the feeding speed of the paper feeding unit 304. At this time, the discharge controller 302 changes the discharge algorithm in accordance with the feed speed of the paper 310.

Also, consider the case where the total amount and color of ink adhering to the paper bundle 110 are monitored by terahertz waves. In this case, the ejection control unit 302 controls the amount of ink ejected from the ejection unit 301 and the ink ratio so as to approach a desired printing state. At this time, depending on circumstances, the scanning control unit 305 changes the scanning time and pattern of the ejection unit 301.

Thus, in this embodiment, the terahertz wave propagating through the paper bundle 110 is used to monitor the printing state from the water content, ink amount, color, etc. of the paper bundle 110 in the electromagnetic wave propagation direction. And each part which contributes to a printing process is controlled so that this printing state may become constant.

In a conventional ink jet printer, a margin is provided for the printing time for each sheet in order to make the printed matter completely dry. Therefore, there is a limit to the printing speed. In this embodiment, according to the printing state, the dryness of the printed matter is monitored and the printing state is controlled. Therefore, there is an effect that the printing speed can be increased depending on how the printed matter is dried.

FIG. 5 is a schematic diagram for explaining an image forming apparatus, a printing apparatus, and a method thereof according to a second embodiment of the present invention. 1 is a schematic configuration diagram for explaining a printing apparatus or method in Embodiment 1 of the present invention. FIG. FIG. 5 is a schematic configuration diagram for explaining a printing apparatus or method in Embodiment 2 of the present invention. It is an image figure of the terahertz wave of the time domain which changes with printing states. It is an image figure of the terahertz wave of the frequency domain which changes with printing states. 1 is a schematic diagram for explaining an image forming apparatus, a printing apparatus, or a method thereof according to a first embodiment of the present invention.

Explanation of symbols

101 Printing means
102 Print controller
103, 6103 Electromagnetic wave generator
104, 6104 Electromagnetic wave detector
105, 6105 processing unit
106, 6106 comparator
107, 6107 Memory unit
109, 6109 Stock section (paper output section)
110, 6110 Printed media stack (paper bundle)

Claims (6)

A printing method for repeatedly printing the same information or unit information on a plurality of media,
A printing process for printing the information on the plurality of media;
Irradiation step of irradiating terahertz waves so as to transmit at least a plurality of sheets on the printed medium stack;
A detection step of detecting terahertz waves propagating in the stacking direction of the stack;
An arithmetic processing step for converting the detection signal obtained in the detection step into data indicating a printing state of the information on the plurality of media;
A storage step of storing reference data for determining a printing state of the information on the plurality of media;
A comparison / determination step of comparing the data obtained in the arithmetic processing step with the reference data of the storage step and determining the printing state of the information on the plurality of media;
A printing method characterized by comprising: A printing control step for adjusting printing conditions in the printing step based on the result obtained in the comparison / determination step;
2. The printing method according to claim 1 , further comprising: The reference data stored in the storage step is
From the detection signal of the first terahertz wave detected in the detection step, the initial printing state of the information on the plurality of media is obtained and stored as reference data.
3. The printing method according to claim 2 , wherein: The reference data stored in the storage step is
From electronic information relating to the information prepared in advance, a response and a printing state with respect to the terahertz wave of the laminate of the plurality of media are estimated and stored as reference data.
3. The printing method according to claim 2 , wherein: The reference data stored in the storage step is
The print state of the information on the plurality of media is obtained from the terahertz wave detection signals detected a plurality of times, including the most recent terahertz wave detection signal detected in the detection step, and stored as reference data. The
3. The printing method according to claim 2 , wherein: A printing apparatus for repeatedly printing the same information or unit information on a plurality of media,
A printing unit for printing the information on the plurality of media;
A stock section for stocking a stack of the plurality of printed media;
An electromagnetic wave generating unit that irradiates terahertz waves so as to transmit at least a plurality of sheets to the stacked body of the plurality of printed media in the stock unit;
An electromagnetic wave detection unit for detecting a terahertz wave from the laminated body in the stock unit;
An arithmetic processing unit that converts a detection signal obtained by the electromagnetic wave detection unit into data indicating a printing state of the information on the plurality of media;
A storage unit for storing reference data for determining a printing state of the information on the plurality of media;
A comparison unit that compares data obtained by the arithmetic processing unit with reference data in the storage unit and determines a print state of the information on the plurality of media;
Based on the result obtained by the comparison unit, a print control unit that adjusts printing conditions in the printing unit;
A printing apparatus comprising:

Images