Image forming apparatus

Abstract

To provide an image forming apparatus that can reduce the likelihood of image defects occurring in the toner image on the overlapping surface of the pressure-processed recording material when forming a toner image on the front or back surface of a pressure-pressed postcard. [Solution] When performing the "Pressurized Postcard Mode" (YES in S2), which forms an image on the front or back of a pressurized postcard, the user is selectively prompted to input the "Type of Folding Process" (S3). The setting of the heating heater's control temperature is changed according to the "Type of Folding Process" selected by the user (S4). At this time, the heating heater's control temperature is lowered compared to when performing the "Normal Print Mode" (S6) on pressurized paper with a basis weight approximately the same as the net basis weight of the pressurized postcard. In this way, the thermal energy applied to the unfixed toner image is reduced, and the toner of the toner image already formed on the overlapping surface is less likely to remelt. Therefore, when the pressurized postcard is opened, the toner does not transfer from one surface to the other, and image defects are less likely to occur in the toner image on the overlapping surface.

Description

[Technical Field]

[0001] This invention relates to an image forming apparatus that utilizes electrophotographic technology, such as a printer, copier, facsimile, or multifunction device. [Background technology]

[0002] Conventionally, image forming apparatuses capable of forming images using toner on pressure-sensitive printed materials that offer excellent information confidentiality have been proposed (Patent Document 1). Examples of pressure-sensitive printed materials include pressure-sensitive postcards, where personal information is formed as an image on two surfaces and then pseudo-adhered together, making it impossible to read the personal information until the pseudo-adhered surfaces are separated. Hereinafter, "pseudo-adhesion" refers to a form of adhesion that is peelable after adhesion but difficult to re-adhere after peeling, and in this specification, "pseudo-adhesion" will be referred to as "pressure bonding".

[0003] Pressure-sealed postcards can display images not only on the front and back surfaces that are exposed when folded and sealed, but also on the inner surface (called the overlapping surface) when sealed, thus allowing for more information to be displayed than on a regular postcard. Since the image formed on the overlapping surface of a pressure-sealed postcard (hereinafter referred to as a "pressure-sealed postcard" to distinguish it from an unsealed postcard) is not visible until it is peeled off, pressure-sealed postcards are widely used as a printing medium for direct mail that allows for the inexpensive delivery of highly confidential information or a large amount of information. When forming images on a pressure-sealed postcard, it is common to form a predetermined image, such as text, on the overlapping surface before sealing, and then, after sealing, to separately form images such as addresses on the front and back surfaces of the sealed postcard. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2014-35454 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, conventionally, when toner images were formed on the front or back surface of a recording material that had been folded and pressed together, there was a risk of image defects occurring in the toner images on the overlapping surface of the recording material or on the front or back surface.

[0006] The present invention has been made in view of the above problems, and aims to provide an image forming apparatus that is less likely to produce image defects in the toner image on the overlapping surface of the recording material or in the toner image on the front or back surface when a toner image is formed on the front or back surface of a recording material that has been folded and pressed together. [Means for solving the problem]

[0007] An image forming apparatus according to one embodiment of the present invention comprises an image forming unit that forms a toner image on a recording material, a fixing unit that fixes the toner image formed on the recording material by the image forming unit to the recording material, an input unit that inputs information about the recording material, and a control unit, wherein when the control unit performs a first mode in which a toner image is formed on a crimped recording material that has been folded and crimped so that one surface of the recording material becomes an opposing inner surface, it controls the fixing unit based on first information regarding the basis weight of the crimped recording material input by the input unit and second information regarding the folded shape of the crimped recording material.

[0008] An image forming apparatus according to one embodiment of the present invention comprises an image forming unit that forms a toner image on a recording material, a fixing unit that fixes the toner image formed on the recording material by the image forming unit to the recording material, an input unit that inputs information about the recording material, and a control unit, and is capable of performing a first mode in which a toner image is formed on a crimped recording material that has been folded and crimped so that one surface of the recording material becomes an opposing inner surface, and a second mode in which a toner image is formed on the uncrimped recording material, wherein the control unit sets the fixing temperature of the fixing unit to a first temperature when forming a toner image on a recording material of a first basis weight in the first mode, and sets the fixing temperature of the fixing unit to a second temperature when forming a toner image on the recording material of the first basis weight in the second mode, and the first temperature is lower than the second temperature.

[0009] An image forming apparatus according to one embodiment of the present invention comprises an image carrier for carrying a toner image, an image forming unit for forming a toner image on the image carrier, a transfer unit for transferring the toner image formed by the image forming unit and carried on the image carrier to a recording material, a power supply for applying a voltage to the transfer unit, an input unit for inputting information about the recording material, and a control unit, wherein when the control unit performs a first mode for forming a toner image on a crimped recording material that has been folded and crimped so that one surface of the recording material becomes an opposing inner surface, it controls the power supply based on first information regarding the basis weight of the crimped recording material input by the input unit and second information regarding the folded shape of the crimped recording material.

[0010] An image forming apparatus according to an embodiment of the present invention includes an image carrier that carries a toner image, an image forming unit that forms a toner image on the image carrier, a transfer unit that transfers the toner image formed by the image forming unit and carried on the image carrier to a recording material, a power source that applies a voltage to the transfer unit, an input unit that inputs information regarding the recording material, and a control unit. The image forming apparatus can execute a first mode of forming a toner image on a pressure-bonded recording material that is bent and pressure-bonded so that one surface of the recording material faces an inner surface, and a second mode of forming a toner image on a recording material that has not been pressure-bonded. The control unit sets the voltage of the transfer unit to a first voltage when forming a toner image on a recording material having a first basis weight in the first mode, and sets the voltage of the transfer unit to a second voltage when forming a toner image on the recording material having the first basis weight in the second mode, and the absolute value of the first voltage is larger than that of the second voltage.

Advantages of the Invention

[0011] According to the present invention, when a toner image is formed on the outer surface of a bent and pressure-bonded pressure-bonded recording material, it is possible to make it difficult for image defects to occur in the toner image on the inner surface or the outer surface of the pressure-bonded recording material where the surfaces are overlapped.

Brief Description of the Drawings

[0012] [Figure 1] (a) A schematic diagram showing the configuration of the image forming apparatus of the present embodiment, (b) A schematic diagram showing the configuration of the secondary transfer unit. [Figure 2] A control block diagram showing the control configuration of the image forming apparatus. [Figure 3] A diagram showing the folding type and the number of base material layers of the pressure-bonded postcard. [Figure 4] (a) A cross-sectional view showing before double-fold processing, (b) A top view showing before double-fold processing, (c) A perspective view showing during double-fold processing, (d) A cross-sectional view showing after double-fold processing. [Figure 5] A flowchart showing the image forming process of the first embodiment. [Figure 6] A diagram showing the "accommodation location selection screen". [Figure 7] A diagram showing the "Recording Material Type Selection Screen". [Figure 8] This diagram shows an example of the "Pre-sealed Postcard Settings Screen," where (a) the "Folding Process Type" is selected and (b) the "Folding Process Type" is selectable. [Figure 9] (a) Cross-sectional view showing the area before the outer tri-fold process, (b) Cross-sectional view showing the area during the outer tri-fold process, (c) Cross-sectional view showing the area after the outer tri-fold process. [Figure 10] This diagram shows another example of the "Pressed Postcard Settings Screen," where (a) the selected state for "Number of layers of recording material due to folding" and (b) the state where "Number of layers of recording material due to folding" is selectable. [Figure 11] A flowchart illustrating secondary transfer voltage control. [Figure 12] A flowchart showing the image formation process of the second embodiment. [Modes for carrying out the invention]

[0013] [First Embodiment] <Image forming apparatus> The following describes this embodiment. First, the configuration of the image forming apparatus 100 in this embodiment will be described using Figures 1(a) and 1(b). As shown in Figure 1(a), the image forming apparatus 100 is an intermediate transfer type full-color printer having image forming stations Pa, Pb, Pc, and Pd (image forming units) that form yellow, magenta, cyan, and black images, respectively. The image forming apparatus 100 forms a toner image on the recording material S based on image data sent from a document reader (not shown) connected to the main body of the apparatus or from an external device 900 such as a personal computer connected to the main body for data input / output. Note that the image forming apparatus 100 may also be a mono-color printer equipped with only one black image forming station Pd.

[0014] Image forming stations Pa, Pb, Pc, and Pd are arranged in a line within the main body of the image forming apparatus along the direction of movement of the intermediate transfer belt 130. The intermediate transfer belt 130 is stretched and rotated by a plurality of rollers (13, 14, 15). The intermediate transfer belt 130, acting as an image carrier, carries the toner image that is transferred in the primary transfer as described later and transports it to the secondary transfer section 200. The secondary transfer section 200 has a secondary transfer inner roller 14 and a secondary transfer outer roller 11. The secondary transfer inner roller 14 that stretches the intermediate transfer belt 130 and the secondary transfer outer roller 11 positioned opposite the intermediate transfer belt 130 form a secondary transfer nip N1 that transfers the toner image on the intermediate transfer belt 130 (on the image carrier) to the recording material S. A fixing device 8 is located downstream of the secondary transfer section 200 in the direction of recording material transport.

[0015] A cassette 10 containing recording material S is located at the bottom of the image forming apparatus 100. The recording material S is supplied from the cassette 10 by a transport roller 16 and transported toward the registration roller 12. Subsequently, the registration roller 12 starts rotating in synchronization with the toner image formed on the intermediate transfer belt 130, and the recording material S is transported to the secondary transfer section 200. Multiple cassettes 10 may be arranged to accommodate recording material S of different sizes and thicknesses, in which case the recording material S selected by the user is supplied from one of the multiple cassettes 10. Note that the recording material S is not limited to that contained in the cassette 10, but may also be supplied from a manual feed tray 160. In addition, as an option, recording material S contained in a paper feed device (not shown) connected as a separate housing from the image forming apparatus 100 may be supplied to the image forming apparatus 100. Note that the recording material S is typically paper, but is not limited to this, and synthetic paper made of resin such as water-resistant paper, plastic sheets such as OHP sheets, cloth, etc. may also be used.

[0016] The four image forming stations Pa, Pb, Pc, and Pd of the image forming apparatus 100 have substantially identical configurations except for the difference in development color. Therefore, here we will describe the yellow image forming station Pa as a representative example, and omit the descriptions of the other image forming stations Pb, Pc, and Pd.

[0017] The image forming station Pa is equipped with a cylindrical photosensitive drum 3a. The photosensitive drum 3a is driven to rotate in a predetermined direction. A charging device 2a, an exposure device La, a developing device 1a, a primary transfer roller 24a, and a drum cleaning device 4a are arranged around the photosensitive drum 3a.

[0018] The process of forming, for example, a full-color image using the image forming apparatus 100 will now be described. First, when the image forming operation is started, the surface of the rotating photosensitive drum 3a is uniformly charged by the charging device 2a. The charging device 2a is, for example, a corona charger that charges the photosensitive drum 3a to a uniform negative polarity dark potential by irradiating it with charged particles associated with corona discharge. Next, the photosensitive drum 3a is scanned and exposed by laser light corresponding to the image signal emitted from the exposure device La. As a result, an electrostatic latent image corresponding to the image signal is formed on the surface of the photosensitive drum 3a. The electrostatic latent image formed on the photosensitive drum 3a is developed into a toner image, which is a visible image, by a developer containing toner and carriers contained in the developing device 1a.

[0019] In this embodiment, the developing apparatus 1a uses a two-component developer containing a non-magnetic toner and a magnetic carrier as the developer. The toner contains a binder resin, a colorant, and a release agent (wax). The binder resin can be any known type. For example, vinyl copolymers such as styrene-(meth)acrylic copolymer, polyester resins, hybrid resins in which vinyl copolymer units and polyester units are chemically bonded, epoxy resins, styrene-butadiene copolymers, and other resins can be used. For the colorants, known types of yellow, magenta, cyan, and black can be used.

[0020] Examples of release agents include aliphatic hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight olefin copolymer wax, microcrystalline wax, Fischer-Tropsch wax, and paraffin wax, as well as oxides of aliphatic hydrocarbon waxes such as oxidized polyethylene wax, or block copolymers thereof; waxes mainly composed of fatty acid esters such as carnauba wax and montanic acid ester wax; ester waxes which are synthetic reaction products of higher fatty acids and higher alcohols such as behenyl behenate and behenyl stearate; and deoxidized fatty acid esters such as deoxidized carnauba wax, which may be partially or completely deoxidized.

[0021] The toner image formed on the photosensitive drum 3a is transferred to the intermediate transfer belt 130 via a primary transfer nip, which is formed between the drum and the primary transfer roller 24a positioned on either side of the intermediate transfer belt 130. At this time, a primary transfer voltage is applied to the primary transfer roller 24a. After the primary transfer, any toner remaining on the surface of the photosensitive drum 3a is removed by the drum cleaning device 4a.

[0022] This process is performed sequentially at the yellow, magenta, cyan, and black image forming stations Pa to Pd, superimposing the four-color toner images on the intermediate transfer belt 130. Then, in accordance with the toner image formation timing, the recording material S contained in the cassette 10 is transported to the secondary transfer unit 200. A secondary transfer voltage is then applied to the secondary transfer outer roller 11, and the full-color toner image formed on the intermediate transfer belt 130 is transferred to the recording material S in one go. Toner remaining on the intermediate transfer belt 130 after secondary transfer is removed by the belt cleaning device 25. In this embodiment, the image forming unit 150, capable of forming a toner image on the recording material S, is composed of the image forming stations Pa to Pd, the intermediate transfer belt 130, rollers (13, 15), and the secondary transfer unit 200.

[0023] The recording material S on which the toner image has been formed is transported to a fixing device 8, which serves as the fixing unit. The fixing device 8 has a fixing roller 81 as a first rotating body and a pressure roller 82 as a second rotating body. The pressure roller 82 contacts the fixing roller 81, gripping and transporting the recording material S while applying heat and pressure to form a fixing nip N2 that fixes the toner image. A heating heater 84 is arranged inside the fixing roller 81 as a heating unit to heat the fixing roller 81, and a thermistor 85 is arranged outside the fixing roller 81 to detect the temperature of the fixing roller 81. In this embodiment, the pressure roller 82 is provided so as to be able to pressurize the fixing roller 81 by a pressure motor 86 (see Figure 2), and rotates at the same speed as the fixing roller 81 as the fixing roller 81 is rotated by a fixing motor 83 (see Figure 2), which serves as the rotational drive unit.

[0024] In the fixing device 8, as the fixing nip N2 formed by the fixing roller 81 being pressed against the pressure roller 82 passes through it, thermal energy is applied to the unfixed toner image on the recording material S, thereby fixing the unfixed toner image to the recording material S. In this embodiment, the thermal energy applied to the unfixed toner image changes according to the fixing conditions (see Tables 1 and 2 described later) set according to the basis weight of the recording material S. The recording material S on which the toner image has been fixed is discharged from the image forming apparatus 100 after single-sided printing or double-sided printing. Here, a fixing device 8 using a fixing roller 81 and a pressure roller 82 is shown as an example, but it is not limited to this, and a fixing device using an endless belt-shaped fixing belt or a pressure belt may also be used.

[0025] <Secondary Transfer Section> As shown in Figure 1(b), a secondary transfer power supply 20 with a variable output voltage is connected to the secondary transfer outer roller 11. The secondary transfer inner roller 14 is electrically grounded (connected to ground). When the recording material S passes through the secondary transfer nip N1, a secondary transfer voltage, which is a DC voltage with the opposite polarity to the normal charge polarity of the toner, is applied to the secondary transfer outer roller 11 by the secondary transfer power supply 20. Consequently, a secondary transfer current flows through the secondary transfer nip N1, and the toner image on the intermediate transfer belt 130 is secondary transferred onto the recording material S. For example, a secondary transfer current of "+20 to +80 μA" flows through the secondary transfer nip N1.

[0026] In this embodiment, the secondary transfer unit 200 is controlled to maintain a constant voltage based on information regarding the electrical resistance (mainly the electrical resistance of the secondary transfer outer roller 11) obtained when there is no recording material S on the secondary transfer nip N1, so that the voltage applied to the secondary transfer outer roller 11 is a predetermined voltage. To achieve this, the secondary transfer power supply 20 is connected to a current detection circuit 21 that detects the secondary transfer current flowing through the secondary transfer nip N1 and a voltage detection circuit 22 that detects the output voltage of the secondary transfer power supply 20. The secondary transfer power supply 20, the current detection circuit 21, and the voltage detection circuit 22 are, for example, provided on the same high-voltage substrate.

[0027] The secondary transfer outer roller 11 is composed of a core metal and an elastic layer formed of ion-conductive foamed rubber (NBR rubber) surrounding the core metal. For example, the outer diameter of the secondary transfer outer roller 11 is "24 mm", and the surface roughness Rz of the secondary transfer outer roller 11 is "6.0 to 12.0 μm". The electrical resistance of the secondary transfer outer roller 11 is "1 × 10⁻¹⁰" when measured by applying a voltage of "2 kV" in an N / N (23°C, 50% RH) environment. 5 ~1 × 10 7The hardness of the elastic layer is approximately 30-40° on the Asker-C hardness scale. The longitudinal width (rotation axis direction) of the secondary transfer outer roller 11 is approximately 310-340 mm, which is larger than the maximum width of the recording material S that the image forming apparatus 100 guarantees to transport. Since the recording material S is transported with the center of the longitudinal direction of the secondary transfer outer roller 11 as the reference point, all of the recording material S that the image forming apparatus 100 guarantees to transport passes within the longitudinal length range of the secondary transfer outer roller 11. This makes it possible to stably transport recording material S of various sizes and to stably transfer toner images onto recording material S of various sizes.

[0028] The intermediate transfer belt 130 is an endless belt having a three-layer structure of a resin layer, an elastic layer, and a surface layer from the inner circumferential surface to the outer circumferential surface. Polyimide, polycarbonate, etc., can be used as the resin material constituting the resin layer. The thickness of the resin layer is preferably, for example, "70 to 100 μm". Urethane rubber, chloroprene rubber, etc., can be used as the elastic material constituting the elastic layer. The thickness of the elastic layer is preferably, for example, "200 to 300 μm". As the surface layer material, it is desirable to use a material that reduces the adhesion of toner to the surface of the intermediate transfer belt 130, making it easier for the toner to be transferred to the recording material S in the secondary transfer section 200. For example, one or more resin materials from among polyurethane, polyester, epoxy resin, etc., can be used. Alternatively, one or more elastic materials from among elastic materials (elastic rubber, elastomer), butyl rubber, etc., can be used. Furthermore, these materials can be used by dispersing one or more types of powders or particles of materials that reduce surface energy and enhance lubricity, such as fluororesin, or by dispersing one or more types of these powders or particles with different particle sizes. The thickness of the surface layer is preferably "5 to 10 μm". The intermediate transfer belt 130 has an electrical resistance adjustment agent such as carbon black added to it, and preferably has a volume resistivity of "1 × 10 9 ~1 × 10 14 It is stated as "Ω·cm".

[0029] <Department Head> The image forming apparatus 100 includes a control unit 101, which controls the image forming apparatus 100 to form a toner image on the recording material S. The control configuration of the image forming apparatus 100 will be explained using Figure 2 with reference to Figure 1. In addition to those shown in Figure 2, various other devices such as sensors and power supplies may be connected to the control unit 101, but their illustration and explanation are omitted here as they are not essential to the invention.

[0030] As shown in Figure 2, the control unit 101 is connected to an external device 900 such as a personal computer (PC) via a communication cable 500, enabling communication of operation commands and various data. The control unit 101 has a CPU 102 (Central Processing Unit), a ROM 103 (Read Only Memory), and a RAM 104 (Random Access Memory). The ROM 103 and RAM 104 store various programs such as "image forming processing" (see Figure 5), which will be described later, as well as various data such as the number of substrate layers (number of recording material layers, see Figure 3) and setting table data (see Tables 1 and 2) that are pre-associated for each "type of folding process". The RAM 104 can also temporarily store the results of calculations performed as a result of executing various programs.

[0031] The image forming apparatus 100 includes, for example, an operation unit 700 having a liquid crystal display unit 710, and the operation unit 700 is connected to the control unit 101. The operation unit 700 can display various programs, various data, or various screens, which will be described later, on the liquid crystal display unit 710. The operation unit 700, as an input unit, may be a user-operable touch panel, for example, and accepts inputs such as the start of various programs such as "image forming jobs" and various information such as information about the recording material S, in response to the user's touch operation. The information about the recording material S includes attributes based on general characteristics such as plain paper, cardboard, thin paper, glossy paper, coated paper, manufacturer, brand, product number, basis weight, thickness, and other arbitrary information that can distinguish the recording material S, as well as, in this embodiment, the basis weight and folding method of the crimped postcard, and the number of base material layers according to the folding method, which will be described later.

[0032] Furthermore, the control unit 101 is connected to a secondary transfer power supply 20, a current detection circuit 21, and a voltage detection circuit 22. As described above, the secondary transfer power supply 20 is controlled to a constant voltage and applies the secondary transfer voltage to the secondary transfer outer roller 11. In addition, a temperature and humidity sensor 32 is connected to the control unit 101. The temperature and humidity sensor 32, acting as a detection unit, is located inside the main body of the image forming apparatus 100 to detect the temperature and humidity inside the apparatus body. The temperature and humidity detected by the temperature and humidity sensor 32 are input to the control unit 101, and the control unit 101 determines the amount of moisture (moisture content, absolute moisture content) inside the main body of the image forming apparatus 100 based on the temperature and humidity detected by the temperature and humidity sensor 32.

[0033] The user can input the start of an "image forming job" from the operation unit 700 and can also set the printer to print a pre-pressed postcard. When an "image forming job" is input, the CPU 102 can execute the "image forming process (program)" stored in the ROM 103. The control unit 101 is connected to the fixing motor 83, heating heater 84, thermistor 85, and pressure motor 86 of the fixing device 8, and can change the control temperature of the heating heater 84, i.e., the fixing temperature, the speed of the fixing motor 83 (the transport speed of the recording material S), and the pressure applied by the pressure motor 86 according to the recording material S being transported. The control temperature of the heating heater 84 is set so that the fixing temperature of the fixing device 8 is the temperature at which optimal fixing performance and image (color, gloss) can be obtained according to the recording material S.

[0034] The image forming apparatus 100 executes a job (print operation), which is a series of operations that form and output an image on one or more recording materials S, initiated by a single start instruction (print instruction). A job generally includes an image forming process, a pre-rotation process, a paper-to-paper process when forming an image on multiple recording materials S, and a post-rotation process. The image forming process is the period during which the electrostatic latent image of the image to be actually formed and output on the recording material S is formed, the toner image is formed, the toner image is transferred, and the toner image is transferred to its primary and secondary forms. The image forming period refers to this period. The pre-rotation process is the period during which preparatory operations are performed before the image forming process, from when the start instruction is input until the image is actually formed. The paper-to-paper process is the period between recording materials S when image forming is performed continuously on multiple recording materials S (continuous image forming). The post-rotation process is the period during which cleanup operations (preparatory operations) are performed after the image forming process. Non-image forming time (non-image forming period) refers to any period other than the image forming time, and includes the pre-rotation process, inter-paper process, post-rotation process, and pre-multi-rotation process, which is a preparatory operation when the image forming apparatus 100 is powered on or when it returns from sleep mode. Sleep mode refers to a state in which power is stopped to elements of the image forming apparatus 100, except for some elements such as some of the control unit 101, when a predetermined time has elapsed since the output of the last image.

[0035] <Pre-sealed postcard> Next, we will describe a pre-pressed postcard as a pre-pressed recording material. In this embodiment, a pre-pressed postcard is used as the recording material S for image formation. However, "pre-pressed postcard" is just one example, and the size of the folded and pressed recording material S is not limited to postcard size.

[0036] A pre-sealed postcard is created using a sealing device (not shown) that folds and seals the recording material S. Examples of sealing methods include the adhesive method, the varnish method, and the film method. The adhesive method involves applying a pressure-sensitive adhesive to the recording material S and then sealing it by applying heat and pressure. The varnish method involves applying an ultraviolet-curable varnish to the recording material S and then sealing it by irradiating it with ultraviolet light and applying heat and pressure. The film method involves inserting a heat-sensitive sealing film between overlapping surfaces and then sealing it by applying heat and pressure to the recording material S.

[0037] Figure 3 shows typical types of folded (folded) pre-sealed postcards. From left to right, Figure 3 shows unfolded and cross-sectional views of pre-sealed postcards folded in half (V-fold), double gatefold, outer tri-fold, and roll tri-fold. Pre-sealed postcards are made of pressure-sealed paper, which has a base material 1 and an adhesive layer 2. Pre-sealed postcards are created when the adhesive layer 2 is valley-folded inward at the folding point of the pressure-sealed paper and then pressure-sealed. The base material 1 of the pressure-sealed paper is not particularly limited as long as it is a material that can form an adhesive layer 2 on at least one side, and examples include high-quality paper, medium-quality paper, coated paper, synthetic paper, and resin media. However, it is desirable that the base material 1 be opaque from the standpoint of confidentiality.

[0038] The varnish-type adhesive layer 2 is applied to the surface of the substrate 1, which has a pre-printed image, using an ultraviolet-curable resin. After curing by irradiation with ultraviolet light, the substrate is folded, and heat and pressure are applied to bond it. However, when applying varnish to, for example, plain paper as the substrate 1, the varnish easily penetrates into the interior of the paper, and the varnish that has penetrated into the interior is not sufficiently irradiated with ultraviolet light. As a result, the curing is insufficient, the adhesion of the varnish is poor, and there is a risk that the varnish will peel off the substrate 1. In addition, the bonded postcard produced may have a reduced quality due to the odor and texture (e.g., stickiness) caused by the varnish. Therefore, it is desirable to select one of the following as the substrate 1: coated paper, resin media, or synthetic paper that can be varnished.

[0039] The film-type adhesive layer 2 is used to bond a pre-printed image onto a substrate 1 by folding it, inserting two layers of adhesive films that are peelable from one another between the folded substrates 1, and then applying heat and pressure to the substrate 1 with the adhesive films inserted.

[0040] The adhesive layer 2 in the pre-adhesive / post-adhesive method is a pressure-sensitive adhesive that adheres under pressure, and comprises an adhesive base material and an adhesion modifier. The adhesive layer 2 is formed on the surface of the base material 1 before or after image formation, and then bent, heat, and pressure are applied to bond it. The adhesive base material is, for example, a composition containing natural rubber latex or its modified form, synthetic rubber latex, synthetic resin, etc., which exhibits pressure-sensitive adhesive strength. The adhesion modifier is a known wax such as paraffin wax, or a particulate filler such as silica, titanium dioxide, or calcium carbonate. In all cases, it has low affinity with the adhesive base material and adjusts the adhesive strength as a pressure-sensitive adhesive.

[0041] Furthermore, considering the advantage that postage and other transportation costs are cheaper for sealed postcards than for envelopes in either method, the basis weight of the recording material S, which combines the base material 1 and the adhesive layer 2, is "64 g / m²". 2 More than 209g / m 2 It is preferable that it be "below"

[0042] Because pressure-sealed postcards are folded and then pressure-sealed, the base material is layered in multiple layers, and the thickness and net basis weight of a pressure-sealed postcard increase by the number of base material layers compared to pressure-sealed paper. As shown in Figure 3, the number of base material layers for a pressure-sealed postcard is predetermined for each type of folding process: bi-fold, double gatefold, outer tri-fold, and roll tri-fold. For bi-fold and double gatefold, the number of base material layers is "2 layers," while for outer tri-fold and roll tri-fold, the number of base material layers is "3 layers." According to this number of base material layers, the thickness and net basis weight of a bi-fold or double gatefold pressure-sealed postcard is twice the thickness and basis weight of the pressure-sealed paper, and the thickness and net basis weight of an outer tri-fold or roll tri-fold pressure-sealed postcard is three times the thickness and basis weight of the pressure-sealed paper. Note that the "type of folding process" is not limited to those shown in Figure 3. Other types include roll quad-fold and outer quad-fold, which have "4 layers" of base material.

[0043] Here, a pressure-sealed postcard can be delivered at a low cost as a second-class mail item (postcard) by satisfying the provisions set forth in Articles 22 and 24 of the Domestic Mail Regulations, which are established by Japan Post Co., Ltd. based on the provisions of Articles 67 and 68 of the Postal Act. As the above regulations state that the weight of the postcard itself is "2g to 6g", the pressure-sealed paper used for the outer tri-fold and roll tri-fold among the various folding methods shown in Figure 3 needs to be lighter (thinner) than the pressure-sealed paper used for the bi-fold, because the base material is made up of three layers.

[0044] To make the explanation of this embodiment easier to understand, we will first explain using a folded, pre-sealed postcard as an example. Figures 4(a) to 4(d) show the procedure for creating a folded, pre-sealed postcard. The adhesive surfaces A and B in Figures 4(a) and 4(b) are surfaces on which toner images of highly confidential information or more information can be formed. As shown in Figures 4(c) and 4(d), the pre-sealed paper on which toner images have been formed on adhesive surfaces A and B is folded in a valley fold at the folding part 3 so that adhesive surfaces A and B are on the inside, and the adhesive surfaces A and B, which become the overlapping surfaces, are pressed together facing each other.

[0045] On the front and back surfaces (C and D in Figure 4(d)) of the laminated postcard thus created, toner images such as addresses are separately formed. Conventionally, when forming toner images on the front and back surfaces of a laminated postcard, fixing conditions (see the setting table data in Table 1 shown below) were set according to the net basis weight after lamination, and the toner image was fixed by the fixing device 8. In the case of a folded laminated postcard, since the laminated paper is laminated in two layers, the net basis weight of the laminated postcard is twice the basis weight of the laminated paper (recording material before lamination), as described above.

[0046] For example, if the pressure-sensitive paper is "thick paper 1 (106~128 g / m²)" 2)」, when forming a toner image on the adhesive surfaces A and B (the overlapping surfaces) of the pressure-sensitive paper, the fixing device 8 operates at "190°C, 200 mm / sec" (see thick paper 1 in Table 1). That is, regarding the assumed basis weight used for the control of the fixing device 8 as "110 g / m 2 」(see FIG. 7 described later), the control temperature of the heating heater 84 is set to "190°C", and the speed of the fixing motor 83 is set to "200 mm / sec".

[0047] Thereafter, by folding and pressing the pressure-sensitive paper, a double-folded pressure-sensitive postcard is created. Conventionally, when forming a toner image on the front or back surface of a double-folded pressure-sensitive postcard, the fixing device 8 was operating at "200°C, 200 mm / sec" (see thick papers 3, 4, and 5 in Table 1). That is, since the net basis weight of the double-folded pressure-sensitive postcard is "220 (110×2) g / m 2 」, which is twice the assumed basis weight of the pressure-sensitive paper, the control temperature of the heating heater 84 is set to "200°C", which is higher than "190°C", and the speed of the fixing motor 83 is set to "200 mm / sec".

[0048]

Table 1

[0049] However, in the conventional case, the toner of the toner image already formed on the overlapping surface is remelted, and there is a risk that the melted toner will transfer from one surface to the other surface when the pressure-sensitive postcard is opened, resulting in image defects. Therefore, when forming a toner image on the front or back surface of a pressure-sensitive postcard on which a toner image has already been formed on the overlapping surface, it is necessary to make it difficult for the toner image to transfer when the pressure-sensitive postcard is opened. Hereinafter, the image forming process of the first embodiment for realizing this will be described.

[0050] <Image Forming Process> The "image forming process" of the first embodiment will be described with reference to Figure 2 and Figures 5 to 8. The "image forming process" of this embodiment is started by the control unit 101 (specifically the CPU 102) when, for example, an image forming job is input from the operation unit 700 or when an image forming job is received from an external device 900.

[0051] As shown in Figure 5, the control unit 101 identifies the recording material S to be image-formed, which has been previously selected by the user and stored in the RAM 104 (S1). The control unit 101 then determines whether the identified recording material S to be image-formed is a "pressed postcard" or not (S2). In the "Storage Location Selection Screen" shown in Figure 6, the user can select from the paper feed settings either "manual feed," "cassette 1," or "cassette 2" as the storage location where the recording material S to be image-formed is stored. The user can select a storage location that contains unpressed recording material S (hereinafter referred to as "normal recording material S") or a pressed postcard with an image already formed on the overlapping surface, using the "Storage Location Selection Screen" displayed on the liquid crystal display unit 710. The user has also previously selected the recording material S to be image-formed from the "Recording Material Type Selection Screen" shown in Figure 7. The "Recording Material Type Selection Screen" shown in Figure 7 is displayed on the liquid crystal display unit 710 when the user operates the "Settings" button on the "Storage Location Selection Screen" shown in Figure 6.

[0052] In the "Recording Material Type Selection Screen" shown in Figure 7, users can select "Recording Material Type" from options such as "Plain Paper 1, 2, 3" and "Thick Paper 1, 2, 3, 4, 5" with different basis weights. When forming an image on the front or back of a laminated postcard, the user selects the recording material S corresponding to the laminated paper used to create the laminated postcard as the "Recording Material Type". For example, if the basis weight of the laminated paper is "95 g / m²" 2 If it is plain paper, the user should select "Plain Paper 3 (91~105g / m²)". 2 Select "91 or more and 105 or less". In this case, the assumed basis weight is "100g / m²" as shown in Figure 7. 2 "

[0053] Then, when the user operates the "ON" button for "Pre-sealed postcard setting," a "pre-sealed postcard" that has been folded and sealed so that one side faces the other is selected as the recording material S for image formation. When a "pre-sealed postcard" is selected, the image forming apparatus 100 is set to "pre-sealed postcard mode" (first mode). If the "OFF" button for "pre-sealed postcard setting" is operated, a normal recording material S (including recording material S that has not been folded and has not undergone sealing) is selected as the recording material S for image formation. When a normal recording material S is selected, the image forming apparatus 100 is set to "normal printing mode" (second mode).

[0054] Returning to Figure 5, if the recording material S to be image-formed is not a "pressed postcard" (NO in S2), the control unit 101 sets the fixing conditions of the fixing device 8 according to the basis weight of the normal recording material S selected by the user on the "recording material type selection screen" shown in Figure 7 (S6). At this time, the control unit 101 sets the fixing conditions for the normal recording material S by referring to the setting table data in Table 1 above. For example, if the recording material S selected on the "recording material type selection screen" is "cardboard 1 (106~128g / m²)", then the control unit 101 sets the fixing conditions of the fixing device 8 according to the basis weight of the normal recording material S selected by the user on the "recording material type selection screen". 2 )" was selected (deemed basis weight 110g / m²) 2 ), and if the "ON" button for "Pre-pressed postcard setting" is not pressed, the control unit 101 refers to the setting table data in Table 1 and sets the control temperature of the heating heater 84 to "190°C" (second temperature) and the speed of the fuser motor 83 to "200 mm / sec". Then, the control unit 101 starts the "normal printing mode" as image formation on the recording material S in accordance with the set fixing conditions (S5). In this embodiment, the "normal printing mode" is started when forming a toner image on the overlapping surface of the recording material S before the pressure pressing process.

[0055] On the other hand, if the recording material S to be image-formed is a "pressure-sealed postcard" (YES in S2), the control unit 101 identifies the type of folding process (S3). The type of folding process is selected in advance by the user from the "pressure-sealed postcard setting screen" shown in Figures 8(a) and 8(b), and stored in the RAM 104. The "pressure-sealed postcard setting screen" shown in Figure 8(a) is displayed on the liquid crystal display unit 710 as a pop-up screen in response to the operation of the "ON" button of the "pressure-sealed postcard setting" shown in Figure 7.

[0056] When the user manipulates the "Processing Details" corresponding to the "Details of the Crimping Process," a pull-down button as shown in Figure 8(b) appears. The pull-down button displays various folding types (secondary information regarding the folded shape of the crimped recording material), such as bi-fold, double gatefold, outer tri-fold, and roll tri-fold, which the user can select. The user can select the folding method for the "crimped postcard" from the options displayed in the pull-down button. Figure 8(a) shows the state where "roll tri-fold" is selected as the folding method for the crimped postcard.

[0057] Returning to Figure 5, the control unit 101 sets the fixing conditions for the fixing device 8 according to the basis weight of the recording material S selected by the user on the "Recording Material Type Selection Screen" shown in Figure 7 and the type of folding process selected on the "Pre-pressed Postcard Setting Screen" shown in Figures 8(a) and 8(b) (S4). At this time, the control unit 101 sets the fixing conditions for the pre-pressed postcard according to the net basis weight of the pre-pressed postcard, referring to the setting table data in Table 2 shown below, which is prepared separately from the setting table data in Table 1 mentioned above. The net basis weight of the pre-pressed postcard (first information regarding the basis weight of the pre-pressed recording material) is determined according to the "Type of Folding Process" selected on the "Pre-pressed Postcard Setting Screen," using the number of base material layers (see Figure 3) which is associated with the "Type of Folding Process" and is stored in the ROM 103 in advance.

[0058] For example, from the "Recording Material Type Selection Screen," select "Cardboard 1 (106~128g / m²)" as the recording material S. 2 )" was selected (deemed basis weight 110g / m²) 2Furthermore, if the type of folding selected on the "Pre-sealed Postcard Settings Screen" is "Bi-fold," then the number of base material layers associated with "Bi-fold" is "2 layers" (see Figure 3), and therefore the net basis weight of a "Bi-fold" pre-sealed postcard is "220 g / m²." 2 The result is (110 × 2). Therefore, the control unit 101 refers to the setting table data in Table 2 (number of substrate layers "2" and basis weight 151 to 220) and sets the control temperature of the heating heater 84 to "170°C" (first temperature) and the speed of the fixing motor 83 to "200 mm / sec". Then, the control unit 101 starts the "pressed postcard mode" for image formation on the pressed postcard according to the set fixing conditions (S5).

[0059] [Table 2]

[0060] The control temperature of the heating heater 84 in the fuser unit 8 is set to a temperature at which the toners of each color are sufficiently mixed and exhibit the desired gloss without the toner peeling off the recording material S. In other words, if the control temperature of the heating heater 84 is lower than the optimal range, the gloss of the toner image will decrease, the toners of each color will not mix, and the desired color will not be produced. Furthermore, since the toner will not melt sufficiently, it will be more likely to peel off the recording material S. Therefore, the control temperature of the heating heater 84 is set to a temperature that is sufficiently higher than the temperature at which the fixation of the toner is ensured.

[0061] For example, a pressure-sensitive adhesive paper for folding in half is "POSTEX Folding Paper" manufactured by Toppan Forms Co., Ltd. (paper thickness approximately 0.12 mm, basis weight approximately 128 g / m²). 2 A toner image (for example, a maximum toner load of 1.2 mg / cm²) is used on the overlapping surface of this pressure-sensitive paper. 2 When forming and fixing the material, as described above, the basis weight is "110g / m²" according to the setting table data in Table 1. 2 The fixing conditions (190°C, 200 mm / sec) are set.

[0062] On the other hand, toner images of the recipient's postal code, address, and name are formed on the front and back of the laminated postcard. The toner images formed on the front and back of the laminated postcard do not require the same gloss or color as the toner images formed on the overlapping surfaces. In other words, the toner images formed on the front and back of the laminated postcard only need to have sufficient fixation to withstand postal delivery. The laminated postcard, which is made by folding and laminating the laminated paper "POSTEX bi-fold" described above, has toner images (for example, with a maximum toner load of 1.2 mg / cm²) on its front and back. 2 When forming and fixing the material, as described above, the basis weight is 220g / m² according to the setting table data in Table 2. 2 The fixing conditions (170°C, 200 mm / sec) are set. This is based on the setting table data in Table 1, for a basis weight of "220 g / m²". 2 The control temperature is lower than that of the "Pre-pressed Postcard Mode" (200°C). In other words, when using the "Pre-pressed Postcard Mode," the control temperature is lowered compared to when using the "Normal Print Mode" on press-pressed paper with a basis weight approximately the same as the net basis weight of the press-pressed postcard, thereby reducing the thermal energy applied to the unfixed toner image.

[0063] Next, we will explain using a tri-fold, pressure-sealed postcard as an example. Figures 9(a) to 9(c) show the procedure for creating a tri-fold, pressure-sealed postcard. Adhesive surfaces A and B and E and F in Figure 4(a) are surfaces on which toner images can be formed, such as highly confidential information or more information. As shown in Figure 9(b), the pressure-sealed paper with toner images formed on adhesive surfaces A and B is folded in a valley fold at the folding section 4 so that adhesive surfaces A and B are on the inside, and the overlapping adhesive surfaces A and B are pressed together facing each other. Similarly, as shown in Figure 9(c), the pressure-sealed paper with toner images formed on adhesive surfaces E and F is folded in a valley fold at the folding section 5 so that adhesive surfaces E and F are on the inside, and the overlapping adhesive surfaces E and F are pressed together facing each other.

[0064] For the laminated postcard thus created, toner images such as addresses are separately formed on its front and back surfaces (C and D in Figure 9(c)). Conventionally, when forming toner images on the front and back surfaces of a laminated postcard, fixing conditions (see the setting table data in Table 1 above) were set according to the net basis weight after lamination, and the toner images were fixed by the fixing device 8. However, in the case of a laminated postcard with an outer tri-fold, since the laminated paper is laminated in a state where it is stacked in three layers, the net basis weight of the laminated postcard is three times the basis weight of the laminated paper, as described above. Conventionally, in the case of an outer tri-fold, as in the case of a bi-fold described above, the toner of the toner image formed on the overlapping surfaces was remelted, and there was a risk that the molten toner would transfer from one surface to the other when the laminated postcard was opened, causing image defects.

[0065] For use as a pressure-sensitive adhesive paper for external tri-folding, for example, there is the "POSTEX Tri-fold" pressure-sensitive adhesive paper manufactured by Toppan Forms Co., Ltd. (paper thickness approximately 0.08 mm, basis weight approximately 80 g / m²). 2 A toner image (for example, a maximum toner load of 1.2 mg / cm²) is used on the overlapping surface of this pressure-sensitive paper. 2 When forming and fixing the recording material S, use "plain paper 2 (76~90g / m²)". 2 )" is selected (deemed basis weight "80g / m²" 2 The fixing conditions (170°C, 200 mm / sec) are set according to the setting table data in Table 1.

[0066] Recording material S is "plain paper 2 (76~90g / m²)". 2 If ")" is selected and the type of folding process selected is "outer tri-fold", then since the number of base material layers for "outer tri-fold" is "3 layers" (see Figure 3), the net basis weight of an "outer tri-fold" pressure-sealed postcard is "240 g / m²". 2 (80×3)" is used. In this embodiment, a toner image (for example, a maximum toner load of 1.2 mg / cm²) is printed on the front and back surfaces of a pressure-sealed postcard made by folding and pressure-sealing the above-mentioned pressure-sealing paper "POSTEX tri-fold". 2 When forming and fixing the material, the basis weight is 240g / m² according to the setting table data in Table 2. 2The fixing conditions (175°C, 200 mm / sec) are set.

[0067] For example, if the net basis weight is "240g / m²" 2 When forming and fixing a toner image on the front or back of a folded, pressure-sealed postcard, the basis weight should be 240 g / m² according to the setting table data in Table 2. 2 The fixing conditions (180°C, 200 mm / sec) are set. That is, for pressed postcards with the same net basis weight, if the selected number of base material layers is the first layer (2 layers), the control temperature of the heating heater 84 is set to "180°C", and if the selected number of base material layers is the second layer (3 layers), which is greater than the first layer, the control temperature of the heating heater 84 is set to "175°C", which is lower than in the case of the first layer (see Table 2).

[0068] As described above, in this embodiment, when performing the "Pressed Postcard Mode" to form a toner image on the front or back surface of a pressed postcard, the operation unit 700 displays the "Pressed Postcard Setting Screen" (see Figure 8(a)) and selectively prompts the user to input the "Type of Folding Process," or in other words, the "Type of Pressed Postcard." Based on the "Net Basis Weight" and "Number of Substrate Layers" of the pressed postcard according to the "Type of Folding Process" selected by the user, the control temperature setting of the heating heater 84 is changed (see Table 2). When performing the "Pressed Postcard Mode," the control temperature of the heating heater 84 is lowered compared to when performing the "Normal Print Mode" on pressed paper with a basis weight approximately the same as the net basis weight of the pressed postcard. In other words, the thermal energy applied to the unfixed toner image is reduced. By reducing the thermal energy in this way, when a toner image is formed on the front or back surface of a pressed postcard, the toner of the toner image already formed on the overlapping surface is less likely to remelt. If this is the case, toner will not transfer from one side to the other when the sealed postcard is opened, making it less likely for image defects to occur in the toner image on the overlapping surfaces of the sealed postcard.

[0069] In the embodiments described above, the net basis weight of the laminated postcard is determined using the number of base material layers associated with the "folding type" selected on the "laminated postcard setting screen" shown in Figures 8(a) and 8(b), but this is not the only method. Users who are unaware of the "folding type" cannot select the "folding type" on the "laminated postcard setting screen" shown in Figures 8(a) and 8(b). For such users, as shown in Figures 10(a) and 10(b), the "number of paper layers due to folding" can be selected from the "laminated postcard setting screen". In this case, when the user operates on the "processing details" corresponding to the "laminated postcard details", a pull-down button as shown in Figure 10(b) will be displayed. The pull-down button displays the number of base material layers, such as 2 layers, 3 layers, and 4 layers, for user selection. The user can select the "number of base material layers" from those displayed on the pull-down button according to the desired laminated postcard for image formation. Figure 10(a) shows a state where "3 layers" is selected as the "number of base material layers" for a pre-sealed postcard. In this case, the pre-sealed postcard to be used for image formation is a pre-sealed postcard that is folded in three on the outside or in three on the inside.

[0070] In the above-described embodiment, the control temperature of the heating heater 84 was lowered to reduce the thermal energy applied to the crimped postcard, but this is not limited to this, as long as it is possible to reduce the thermal energy applied to the crimped postcard. For example, when forming an image on the front or back surface of a crimped postcard, the thermal energy applied to the crimped postcard can be reduced by shortening the heating time of the recording material S in the fixing device 8 compared to when forming an image on the front or back surface of a normal postcard. To shorten the heating time of the recording material S, the length of the fixing nip N2 in the transport direction may be shortened, or the pressure of the fixing nip N2 in the fixing device 8 may be increased. Alternatively, to shorten the heating time of the recording material S, for example, the speed of the fixing motor 83 (transport speed of the recording material S) may be increased. In that case, if the crimped postcards have the same net basis weight (for example, basis weight "301~400g / m²" in Table 2) 2(See reference below), if the selected number of substrate layers is the first number of layers (2 layers), the speed of the fixing motor 83 is set to the first rotational speed (150 mm / sec), and if the selected number of substrate layers is the second number of layers (3 layers), which is greater than the first number of layers, the speed of the fixing motor 83 is set to the second rotational speed (200 mm / sec), which is faster than the first rotational speed.

[0071] Furthermore, in the embodiments described above, the image formed on the overlapping surface and the image formed on the front and back surfaces of the laminated postcard are formed with the same amount of toner, but this is not limited to this. Normally, since a black text image is formed on the front and back surfaces of the laminated postcard, the maximum amount of toner (for example, 0.45 mg / cm³) is applied to the front and back surfaces of the laminated postcard. 2 A monochrome black toner image is formed and fixed. In this case, the thermal energy applied to the pressed postcard can be reduced compared to when a multi-color toner image is formed and fixed.

[0072] [Second Embodiment] Next, a second embodiment will be described. When an image is formed on the front or back surface of a crimped postcard, there was a risk of image defects occurring in the image formed on the front or back surface in the conventional method. This is because, when forming an image on the front or back surface of a crimped postcard, although the electrical resistance of the crimped postcard increases with the number of substrate layers, that is, with the net basis weight, the same secondary transfer voltage as for a normal recording material S is applied, resulting in insufficient secondary transfer current flowing through the secondary transfer nip N1. Due to the low secondary transfer current, it becomes difficult to properly transfer the toner image from the intermediate transfer belt 130 to the crimped postcard, and the desired image density cannot be obtained. Therefore, in this embodiment, when forming an image on the front or back surface of a crimped postcard, a secondary transfer voltage that allows for proper transfer of the toner image from the intermediate transfer belt 130 to the crimped postcard is set. The image formation process of the second embodiment that achieves this will be described below.

[0073] <Regarding secondary transfer voltage control> First, an overview of secondary transfer voltage control will be explained using Figure 11 with reference to Figure 2. Figure 11 is a flowchart of secondary transfer voltage control. In Figure 11, the processing related to secondary transfer voltage control among the controls performed by the control unit 101 when executing an image formation job is shown in a simplified manner, and many other controls when executing an image formation job are not illustrated. Also, Figure 11 shows an example of an image formation job in which an image is formed on a single recording material S.

[0074] As shown in Figure 11, the control unit 101 acquires an image forming job from the operation unit 700 or an external device 900 (S11). At that time, the control unit 101 acquires the image forming job along with image information specified by the user and information about the recording material S on which the image will be formed. The control unit 101 stores the received information about the recording material S in the RAM 104.

[0075] The control unit 101 determines the base voltage Vb that supplies a predetermined target current Itarget to the secondary transfer nip N1 when the recording material S is not being transported, and stores it in the RAM 104 (S12). This base voltage Vb is a voltage that is determined mainly by the electrical resistance of the secondary transfer outer roller 11, which changes with use. Although not shown in the figure, the ROM 103 has pre-stored current table data that defines the correlation between the amount of moisture inside the device body (called the amount of moisture in the atmosphere) based on environmental information (temperature and humidity) and the target current Itarget for transferring the toner image on the intermediate transfer belt 130 onto the recording material S. This current table data was determined in advance by experiment. The control unit 101 determines the amount of moisture in the atmosphere based on the temperature and humidity detected by the temperature and humidity sensor 32, and identifies the target current Itarget corresponding to the amount of moisture in the atmosphere by referring to the current table data (not shown).

[0076] The control unit 101 then determines the base voltage Vb corresponding to the target current Itarget based on the electrical resistance of the secondary transfer outer roller 11 before the toner image on the intermediate transfer belt 130 and the recording material S to which the toner image is transferred reach the secondary transfer nip N1. In this embodiment, the base voltage Vb is determined by ATVC control (Active Transfer Voltage Control). That is, with the secondary transfer outer roller 11 and the intermediate transfer belt 130 in contact, a predetermined voltage (test voltage) or current (test current) is supplied from the secondary transfer power supply 20 to the secondary transfer outer roller 11. Then, the current detection circuit 21 detects the current value flowing through the secondary transfer nip N1 when the predetermined voltage is supplied, or the voltage detection circuit 22 detects the voltage value of the secondary transfer power supply 20 when the predetermined current is supplied. At this time, multiple levels of test voltage or test current are supplied to obtain a voltage-current characteristic, which is the relationship between voltage and current, and the base voltage Vb corresponding to the target current Itarget is determined based on this voltage-current characteristic. Alternatively, a target current Itarget may be supplied as a test current, and the output voltage value of the secondary power supply 20 at that time may be used as the base voltage Vb.

[0077] The control unit 101 determines the recording material voltage Vp corresponding to the electrical resistance of the crimped postcard on which the image is formed and stores it in the RAM 104 (S13). The ROM 103 has the setting table data shown in Table 3 stored in advance. The setting table data in Table 3 shows the recording material voltage Vp corresponding to the moisture content of the atmosphere for each combination of the assumed basis weight of the crimped postcard (more specifically, the crimped paper) and the number of base material layers due to the folding process. This setting table data in Table 3 was determined in advance through experiments.

[0078] [Table 3]

[0079] The control unit 101 determines the recording material voltage Vp by referring to the setting table data in Table 3, based on the assumed basis weight and number of base material layers of the crimped postcard and the moisture content of the atmosphere described above. Note that the recording material voltage Vp (transfer voltage of the electrical resistance of the crimped postcard) may change not only depending on the basis weight of the recording material S but also on the surface properties of the recording material S. Therefore, the setting table data may be set so that the recording material voltage Vp also changes depending on information regarding the surface properties of the recording material S. Note that information regarding the surface properties of the recording material S is included in the information regarding the recording material S obtained in the processing of step S11.

[0080] The control unit 101 determines the initial value of the secondary transfer voltage Vtr applied from the secondary transfer power supply 20 to the secondary transfer outer roller 11 during paper feeding and stores it in the RAM 104 (S14). In other words, the control unit 101 determines the secondary transfer voltage Vtr as the sum of the base voltage Vb and the recording material-borne voltage Vp, "Vb+Vp", by the time the recording material S reaches the secondary transfer section T2, and stores it in the RAM 104. Then, it prepares for the timing when the recording material S reaches the secondary transfer section T2. ​​In this way, in this embodiment, secondary transfer voltage control is performed to set the initial value of the secondary transfer voltage Vtr when not forming an image.

[0081] <Image Formation Processing> Next, the "image forming process" of the second embodiment will be described using Figure 12 with reference to Figures 2, 7, and 8. The "image forming process" of this embodiment is started by the control unit 101 (specifically the CPU 102) when, for example, an image forming job is input from the operation unit 700 or when an image forming job is received from an external device 900. For processes that are the same as those of the "image forming process" of the first embodiment described above (see Figure 5), the same step numbers are used, and the explanation is simplified or omitted.

[0082] As shown in Figure 12, the control unit 101 identifies the recording material S for which image formation is to be performed, which has been previously selected by the user from the "recording material type selection screen" shown in Figure 7 and stored in the RAM 104 (S1). The control unit 101 then determines whether or not the identified recording material S for which image formation is to be performed is a "pressure-sealed postcard" (S2). Whether or not it is a "pressure-sealed postcard" is determined according to whether or not the user has pressed the "ON" button for "pressure-sealed postcard setting" (see Figure 7), as described above.

[0083] If the recording material S to be image-formed is not a "pressed postcard" (NO in S2), the control unit 101 sets the secondary transfer conditions of the secondary transfer unit 200 according to the assumed basis weight of the normal recording material S selected by the user on the "recording material type selection screen" shown in Figure 7 (S23). At this time, the control unit 101 sets the secondary transfer conditions for the normal recording material S by referring to the setting table data in Table 3 above. As an example, let's assume the moisture content of the atmosphere is "8.9 g / kg". For example, from the "recording material type selection screen" in Figure 7, select "Cardboard 1 (106~128 g / m²)". 2 If ")" is selected and the "ON" button for "Pre-sealed postcard setting" is not pressed, the control unit 101 sets the number of substrate layers to "1 layer" and, referring to the setting table data in Table 3, sets the secondary transfer voltage applied to the secondary transfer power supply 20 to "600V" (second voltage). Then, the control unit 101 starts the "normal printing mode" as image formation on the normal recording material S according to the set secondary transfer conditions (S22).

[0084] On the other hand, if the recording material S to be image-formed is a "pressure-sealed postcard" (YES in S2), the control unit 101 identifies the type of folding process (S3). The type of folding process is selected in advance by the user from the "pressure-sealed postcard setting screen" shown in Figures 8(a) and 8(b) and stored in the RAM 104. The control unit 101 sets the secondary transfer conditions of the secondary transfer unit 200 according to the assumed basis weight of the recording material S selected by the user on the "recording material type selection screen" shown in Figure 7 and the type of folding process selected on the "pressure-sealed postcard setting screen" shown in Figures 8(a) and 8(b) (S21). At this time, the control unit 101 sets the secondary transfer conditions for the pressure-sealed postcard by referring to the setting table data in Table 3 above. Then, the control unit 101 starts the "pressure-sealed postcard mode" as image formation on the pressure-sealed postcard according to the set fixing conditions (S22).

[0085] For example, let's assume the ambient moisture content is "8.9 g / kg". For instance, from the "Recording Material Type Selection Screen", select "Cardboard 1 (106~128 g / m²)" as recording material S. 2 If ")" is selected and the type of folding selected on the "Pre-sealed postcard setting screen" is "double fold", then the number of base material layers associated with "double fold" is "2 layers" (see Figure 3). Therefore, the control unit 101 refers to the setting table data in Table 3 above and sets the secondary transfer voltage to be applied to the secondary transfer power supply 20 to "1050V" (first voltage). For example, if "Cardboard 1 (106~128g / m²)" is selected as the recording material S from the "Recording material type selection screen", then 2 If ")" is selected and the type of folding process selected on the "Pre-sealed postcard setting screen" is "roll tri-fold", then the number of base material layers associated with "roll tri-fold" is "3 layers" (see Figure 3). Therefore, the control unit 101 refers to the setting table data in Table 3 above and sets the secondary transfer voltage to be applied to the secondary transfer power supply 20 to "1550V" (first voltage).

[0086] In this embodiment, when performing the "pressed postcard mode," if the basis weight of the recording material S before pressing is approximately the same, the voltage applied to the secondary transfer unit 200 when the number of recording material layers is the first layer is set to a voltage that is in absolute value larger than the voltage applied when the number of recording material layers is the second layer, which is smaller than the first layer (see Table 3). Also, when performing the "pressed postcard mode," if the basis weight of the recording material S before pressing is approximately the same and the number of base material layers of the pressed postcard is the same, the voltage applied to the secondary transfer unit 200 when the moisture content of the atmosphere is the first moisture content is set to a voltage that is in absolute value smaller than the voltage applied to the secondary transfer unit 200 when the moisture content detected by the detection unit is the second moisture content, which is less than the first moisture content (see Table 3).

[0087] As described above, in the second embodiment, as in the first embodiment, when performing the "pressure-sealed postcard mode" to form an image on the front or back surface of the pressure-sealed postcard, the operation unit 700 displays the "pressure-sealed postcard setting screen" (see Figure 8(a)) and selectively prompts the user to input the "type of folding process". Based on the "estimated basis weight" and "number of base material layers" of the pressure-sealed postcard corresponding to the "type of folding process" selected by the user, the control voltage setting of the secondary transfer power supply 20 that applies the secondary transfer voltage to the secondary transfer unit 200 is changed (see Table 3). When performing the "pressure-sealed postcard mode", the control voltage of the secondary transfer power supply 20 is increased in absolute value compared to when performing the "normal printing mode" on recording material S (single-layer recording material S) with approximately the same basis weight before pressure processing. By increasing the absolute value of the voltage applied to the secondary transfer section 200 in this way, sufficient secondary transfer current flows through the secondary transfer nip N1 when forming a toner image on the front and back surfaces of the crimped postcard, so that the toner image is properly transferred from the intermediate transfer belt 130 to the crimped postcard. In other words, image defects are less likely to occur in the toner image on the front and back surfaces of the crimped postcard.

[0088] In the first and second embodiments described above, an intermediate transfer type image forming apparatus 100 was described as an example in which toner images are first transferred from each color's photosensitive drum 3a to 3d to an intermediate transfer belt 130, and then secondarily transferred from the intermediate transfer belt 130 to the recording material S. However, the apparatus is not limited to this. The second embodiments described above are also applicable to a direct transfer type image forming apparatus in which toner images are directly transferred from each color's photosensitive drum 3a to 3d, which carry and rotate the toner images, to the recording material S. [Explanation of symbols]

[0089] 8... Fixing unit (fixing device), 20... Power supply (secondary transfer power supply), 32... Detection unit (temperature and humidity sensor), 81... First rotating body (fixing roller), 82... Second rotating body (pressure roller), 83... Rotation drive unit (fixing motor), 84... Heating unit (heating heater), 100... Image forming apparatus, 101... Control unit, 130... Image carrier (intermediate transfer belt), 150... Image forming unit, 200... Transfer unit (secondary transfer unit), 700... Input unit (operation unit), 710... Display unit (liquid crystal display unit), Pa, Pb, Pc, Pd... Image forming unit (image forming station), S... Recording material

Claims

1. An image forming unit that forms a toner image on the recording material, A fixing unit that fixes the toner image formed on the recording material by the image forming unit onto the recording material, An input unit for inputting information about the recording material, It comprises a control unit and, When the control unit performs a first mode in which a toner image is formed on a crimped recording material that has been folded and crimped so that one side of the recording material becomes an opposing inner surface, it controls the fixing unit based on first information regarding the basis weight of the crimped recording material input by the input unit and second information regarding the folded shape of the crimped recording material. An image forming apparatus characterized by the following features.

2. An image forming unit that forms a toner image on the recording material, A fixing unit that fixes the toner image formed on the recording material by the image forming unit onto the recording material, An input unit for inputting information about the recording material, It comprises a control unit and, An image forming apparatus capable of performing a first mode in which a toner image is formed on a crimped recording material that has been folded and crimped so that one side of the recording material becomes the inner surface of the opposing surface, and a second mode in which a toner image is formed on the uncrimped recording material, The control unit sets the fixing temperature of the fixing unit to a first temperature when forming a toner image on a recording material of a first basis weight in the first mode, and sets the fixing temperature of the fixing unit to a second temperature when forming a toner image on a recording material of a first basis weight in the second mode. The first temperature is lower than the second temperature. An image forming apparatus characterized by the following features.

3. The fixing unit comprises a first rotating body, a second rotating body that contacts the first rotating body to form a fixing nip for gripping and transporting the recording material, and a heating unit for heating the first rotating body. The control unit controls the heating unit to set the fixing temperature of the fixing unit to the first temperature in the first mode and to the second temperature in the second mode. The image forming apparatus according to feature 2.

4. The input unit includes a display unit that can display information and is operable by the user. The control unit, When executing the first mode, a selection screen is displayed on the display unit that allows the user to select the number of overlapping recording material layers in the crimped recording material. When performing the first mode, the temperature of the heating unit is set to a lower temperature than when the selected number of recording material layers is a second number of layers, which is greater than the number of layers. The image forming apparatus according to feature 3.

5. The first rotating body is driven to rotate by a rotational drive unit, The control unit makes the speed of the rotational drive unit faster when performing the first mode than when performing the second mode. The image forming apparatus according to feature 3.

6. The input unit includes a display unit that can display information and is operable by the user. The control unit, When executing the first mode, a selection screen is displayed on the display unit that allows the user to select the number of overlapping recording material layers in the crimped recording material. When performing the first mode described above, if the selected number of recording material layers is the first number of layers, the rotation drive unit is set to the first rotation speed, and if the selected number of recording material layers is the second number of layers, which is greater than the first number of layers, the rotation drive unit is set to the second rotation speed, which is faster than the first rotation speed. The image forming apparatus according to feature 5.

7. An image carrier that holds the toner image, An image forming unit that forms a toner image on the image carrier, A transfer unit that transfers the toner image formed by the image forming unit and supported on the image carrier to a recording material, A power supply for applying voltage to the transfer section, An input unit for inputting information about the recording material, It comprises a control unit and, When the control unit performs a first mode in which a toner image is formed on a crimped recording material that has been folded and crimped so that one side of the recording material becomes an opposing inner surface, it controls the power supply based on first information regarding the basis weight of the crimped recording material input by the input unit and second information regarding the folded shape of the crimped recording material. An image forming apparatus characterized by the following features.

8. An image carrier that holds the toner image, An image forming unit that forms a toner image on the image carrier, A transfer unit that transfers the toner image formed by the image forming unit and supported on the image carrier to a recording material, A power supply for applying voltage to the transfer section, An input unit for inputting information about the recording material, It comprises a control unit and, An image forming apparatus capable of performing a first mode in which a toner image is formed on a crimped recording material that has been folded and crimped so that one side of the recording material becomes the inner surface of the opposing surface, and a second mode in which a toner image is formed on the uncrimped recording material, The control unit sets the voltage of the transfer unit to a first voltage when forming a toner image on a recording material of a first basis weight in the first mode, and sets the voltage of the transfer unit to a second voltage when forming a toner image on a recording material of a first basis weight in the second mode. The first voltage is greater than the second voltage in absolute value. An image forming apparatus characterized by the following features.

9. The input unit includes a display unit that can display information and is operable by the user. The control unit, When executing the first mode, a selection screen is displayed on the display unit that allows the user to select the number of overlapping recording material layers in the crimped recording material. When performing the first mode, the voltage of the transfer unit when the selected number of recording material layers is the first number of layers is set to a voltage that is in absolute value greater than the voltage when the selected number of recording material layers is the second number of layers, which is smaller than the number of layers. The image forming apparatus according to feature 8.

10. The image forming apparatus further includes a detection unit for detecting the amount of moisture inside the main body of the image forming apparatus, When the control unit performs the first mode, it sets the voltage of the transfer unit to be smaller in absolute value than the voltage when the amount of moisture detected by the detection unit is the first moisture amount, compared to the voltage when the amount of moisture detected by the detection unit is the second moisture amount, which is less than the first moisture amount. The image forming apparatus according to feature 9.

11. The detection unit is a temperature and humidity sensor that detects temperature and humidity. The image forming apparatus according to feature 10.

Images