JP6349988B2 - Image forming apparatus, heater control method, and heater control program - Google Patents

Description

  The present invention relates to an image forming apparatus, a heater control method, and a heater control program.

  In a liquid discharge type image forming apparatus such as an ink jet printing apparatus, ink containing a color material is generally formed into droplets and discharged onto a print object such as a web, thereby forming an image on the print object. . Note that image formation on a print object means not only printing an image having a meaning such as a character or a graphic on the print object but also printing an image having no meaning such as a pattern on the print object. To do. The web is a long band-like print object to which a liquid such as paper or a resin film can be attached.

  In such liquid ejection type image formation, dots formed on a print object by ink droplets are feathered, and a plurality of ink droplets of different colors are adjacent to each other to be printed. When the ink is hit, a color bleed or the like in which the colors of the plurality of ink droplets are mixed with each other and the color boundary becomes unclear may occur. Furthermore, there is a problem that it takes time for the droplets (ink) discharged to the printing object to dry.

  In order to solve these problems, conventionally, a treatment liquid that reacts with ink and promotes prevention of ink bleeding is applied to an object to be printed before ink droplets are ejected. For example, the treatment liquid is applied to a web that is sequentially conveyed by a predetermined treatment liquid application device using an application roller or the like, or is discharged in a mist form from a liquid discharge head and applied to the web. Thereafter, the processing liquid on the web surface needs to be dried before the web is conveyed from the processing liquid coating apparatus into the printer. This is because when the web in which the processing liquid is not dried is transported into the printer, problems such as unintentional adhesion of the processing liquid on the web surface to the transport roller in the printer occur. is there. In order to solve this problem, the treatment liquid coating apparatus is usually provided with a drying mechanism for drying the treatment liquid on the web surface.

  The drying mechanism of the processing liquid coating apparatus generally includes a heater for heating and drying the processing liquid. The heater of the drying mechanism is connected to a commercial AC power supply via a switching control element such as a triac and receives power from the commercial AC power supply. In addition, a drying mechanism using such a heater as a heat source is provided with a temperature detection element such as a thermistor. The temperature of the drying mechanism (specifically, the temperature of the heater portion) is detected by a temperature detection element.

  On the other hand, the engine controller of the image forming apparatus controls the switching control element to be switched between an on state and an off state based on the temperature information of the drying mechanism detected by the temperature detection element (hereinafter referred to as on / off control). Is performed by wave number control or phase control. The engine controller performs power supply to the heater of the drying mechanism or shuts off the power supply through the on / off control of the switching control element, thereby driving the heater so that the temperature of the drying mechanism is maintained at a constant target temperature. Control (temperature control). The wave number control is an electric power control method in which the switching control element is turned on / off, that is, the heater is turned on / off in units of half a wave of the commercial AC power supply. Phase control is a power control in which the switching control element is controlled to be in an ON state at the timing of an arbitrary phase angle within one half wave of a commercial AC power supply, that is, the heater is turned on, thereby supplying power to the heater. It is a method.

  In order to control the power supply from the commercial AC power source to the heater of the drying mechanism, a zero cross circuit is necessary. The zero-cross detection circuit is a circuit that generates a zero-cross signal indicating a zero-cross point in an AC voltage of a commercial AC power supply (hereinafter, abbreviated as a power supply voltage as appropriate). Specifically, the zero-crossing detection circuit monitors the power supply voltage value of the commercial AC power supply, and the power supply voltage value passes 0 [V] when the monitored power supply voltage value falls below a predetermined threshold. Is detected as a zero cross point. The zero-cross detection circuit changes the signal level at the detected timing of the zero-cross point to generate a zero-cross signal.

  The engine controller detects the effective current supplied to the heater based on the zero-cross signal generated and output by the above-described zero-cross detection circuit. Further, the engine controller performs on / off control of the switching control element, that is, on / off control of power supply to the heater based on such a zero cross signal.

  As a conventional technique related to the power supply control to the heater described above, for example, a non-masking section of a predetermined time is provided before and after the waveform center of the power supply current detection signal output when the current value of the commercial AC power supply is equal to or less than a threshold value. The zero cross signal in the section other than the non-masking section (masking section) is invalidated, and the edge of the zero cross signal output from the zero cross detection circuit in the non-masking section is set as the zero cross point, and the heater at the timing of this zero cross point There is one that performs power supply control (see Patent Document 1).

  By the way, in power supply control from the commercial AC power supply to the heater, for example, in the case of phase control, the phase angle within one half wave of the commercial AC power supply is controlled to control the heater switching timing to the zero cross point. Done. In such power supply control to the heater, it is necessary to accurately detect the zero cross point of the power supply voltage.

  However, the waveform of the power supply voltage of the commercial AC power supply (hereinafter abbreviated as a voltage waveform as appropriate) is not necessarily an ideal sine waveform, and varies depending on the area and facility used, the conditions used, etc. Change. For example, if a device that consumes a large amount of power is connected to the same commercial AC power supply or image forming device as a factor that causes distortion in the voltage waveform of the commercial AC power supply, a high level of noise during startup or shutdown When a device that generates light is connected, when a surge such as lightning is mixed, or when an instantaneous interruption occurs in a commercial AC power supply or an image forming apparatus, there are various examples.

  When the image forming apparatus is connected to a commercial AC power supply including such voltage waveform distortion or power supply noise, the zero cross detection circuit in the image forming apparatus accurately detects the zero cross point of the power supply voltage of the commercial AC power supply. This makes it difficult to generate and output a zero cross signal at a timing other than the zero cross point. As a result, waveform disturbance occurs in the zero-cross signal, and as a result, the engine controller of the image forming apparatus correctly performs power supply control (switching control of power supply on / off state) to the heater of the drying mechanism described above. I can't do that. Eventually, a situation occurs in which the power supplied to the heater falls into an uncontrollable state.

  As a countermeasure against the waveform disturbance of the zero-cross signal that causes the above-described problems, conventionally, a period excluding the zero-cross point in a period in which the power supply voltage is applied from the commercial AC power source to the image forming apparatus, that is, no zero-cross signal is generated. A method is employed in which the period is fixed to a predetermined period and the zero cross signal is invalidated during the determined fixed period. However, the disturbance of the waveform of the zero cross signal is likely to occur in the vicinity of the rising or falling edge of the zero cross signal, and the rising and falling timings of the zero cross signal are the peak values of the power supply voltage of the commercial AC power supply (hereinafter referred to as the power supply). (Referred to as voltage peak value). For this reason, it is difficult to avoid disturbance of the waveform of the zero cross signal with the conventional method in which the period during which the zero cross signal is invalidated is fixed as described above.

  The present invention has been made in view of the above, and provides an image forming apparatus, a heater control method, and a heater control program capable of detecting a zero-cross signal more correctly while avoiding waveform disturbance of the zero-cross signal. With the goal.

In order to solve the above-described problems and achieve the object, the present invention provides a power supply voltage peak detection means for detecting a peak value of a power supply voltage of an AC power supply that supplies power to a heater, and detects a zero cross point of the power supply voltage. A zero-cross signal generating means for generating a zero-cross signal indicating the detected zero-cross point, and a timing according to a change in the peak value of the power supply voltage according to the peak value of the power supply voltage detected by the power supply voltage peak detecting means. An invalid period determining means for determining an invalid period in which the detection of the zero cross signal is invalid in a period including the rising edge of the zero cross signal after the falling timing of the zero cross signal for changing The zero cross signal input by the zero cross signal generating means is invalidated and the null cross signal is invalidated. Zero cross signal determination means for detecting the zero cross signal input by the zero cross signal generation means during a period other than the period as a normal waveform zero cross signal, and feeding of the heater based on the normal waveform zero cross signal Control signal output means for outputting a control signal to control the heater to the drive unit of the heater.

  According to the present invention, it is possible to more correctly detect the zero-cross signal by avoiding the waveform disturbance of the zero-cross signal, and it is possible to correctly control the power supplied to the heater based on the detected zero-cross signal. .

FIG. 1 is a block diagram illustrating a configuration example of an image forming apparatus according to the present embodiment. FIG. 2 is a diagram showing a configuration example of the engine unit in the present embodiment. FIG. 3 is a diagram illustrating a configuration example of the treatment liquid coating apparatus in the present embodiment. FIG. 4 is a diagram showing a configuration example of a treatment liquid drying mechanism in the present embodiment. FIG. 5 is a block diagram illustrating a configuration example of the heater control unit according to the present embodiment. FIG. 6 is a diagram illustrating an example of a data table used for determining an invalid period of zero-cross signal detection in the present embodiment. FIG. 7 is a flowchart illustrating an example of a heater control method for the image forming apparatus according to the present embodiment. FIG. 8 is a timing chart showing an example of processing timing in the heater control of the present embodiment. FIG. 9 is a diagram for explaining a conventional zero-cross signal detection process. FIG. 10 is a diagram for explaining the zero-cross signal detection processing of the present embodiment.

  Exemplary embodiments of an image forming apparatus, a heater control method, and a heater control program will be described below in detail with reference to the accompanying drawings. Note that the drawings are schematic, and it should be noted that the dimensional relationship of each element, the ratio of each element, and the like may differ from the actual ones. Even between the drawings, there are cases in which portions having different dimensional relationships and ratios are included. In each drawing, the same numerals are given to the same component.

(Configuration of image forming apparatus)
First, the configuration of the image forming apparatus according to the present embodiment will be described. FIG. 1 is a block diagram illustrating a configuration example of an image forming apparatus according to the present embodiment. As shown in FIG. 1, the image forming apparatus 1 according to the present embodiment includes a control unit 10, an interface (I / F) unit 20, an FCU 30, and an engine unit 100. The control unit 10 is connected to the I / F unit 20, the FCU 30, and the engine unit 100 via a PCI (Peripheral Component Interface) bus or the like. The image forming apparatus 1 is connected to an AC power supply 40 via a cable or the like.

  The control unit 10 controls the entire image forming apparatus 1 and controls drawing, communication, and signal input / output. For example, the control unit 10 controls communication between the image forming apparatus 1 and the external device via the I / F unit 20 and controls the operation of the FCU 30. The control unit 10 also has a function as an engine controller that controls the operation of the engine unit 100.

  The I / F unit 20 is a signal input / output interface such as USB (Universal Serial Bus), IEEE 1394 (the Institute of Electrical and Electronics Engineers 1394).

  An FCU (Facsimile Control Unit) 30 is a unit that controls facsimile communication and includes a memory (not shown). This memory is used, for example, to temporarily store facsimile data received when the image forming apparatus 1 is powered off. The AC power source 40 is a commercial AC power source that supplies power to the entire image forming apparatus 1, specifically, the control unit 10 and the engine unit 100.

  The engine unit 100 is a printer engine that can be connected to a PCI bus, and is, for example, a monochrome plotter, a 1-drum color plotter, a 4-drum color plotter, a scanner, or a fax unit. The engine unit 100 includes an image processing unit such as error diffusion and gamma conversion in addition to a so-called engine unit such as a plotter. Further, the engine unit 100 includes a pre-processing portion that performs pre-processing for applying a processing liquid to a print object to prevent problems (feathering, color bleeding, etc.) during ink jet printing.

(Configuration of control unit of image forming apparatus)
Next, the configuration of the control unit 10 of the image forming apparatus 1 will be described. As shown in FIG. 1, the control unit 10 includes a CPU 11, a ROM 13, a RAM 14, a non-volatile memory (NVRAM) 15, an ASIC (Application Specific Integrated Circuit) 16, a hard disk drive (HDD) 17, and an operation panel. 18.

  The CPU 11 performs overall control of the image forming apparatus 1, and is connected to the ROM 13, RAM 14, NVRAM 15, ASIC 16, HDD 17, and operation panel 18 via a PCI bus or the like. The CPU 11 executes a program stored in the ROM 13 to control, for example, signal input / output via the I / F unit 20 and control each operation of the FCU 30 and the engine unit 100.

  Further, the CPU 11 has a heater control unit 12. The heater control unit 12 controls the driving of a heater that heats and drys the processing liquid applied to the print object when the print object is preprocessed in the engine unit 100.

  The ROM 13 is a read-only memory used as a memory for storing programs and data. The ROM 13 stores a program executed by the CPU 11 and other fixed data. The RAM 14 is a writable and readable memory used as a program and data development memory, a printer drawing memory, and the like. The NVRAM 15 holds various stored data such as image data not only when the power is supplied from the AC power supply 40 to the image forming apparatus 1 but also during the period when the power supply to the image forming apparatus 1 is cut off. .

  The ASIC 16 is an image processing application IC having hardware elements for image processing. The ASIC 16 includes, for example, a PCI target and an AGP master, an arbiter (ARB) that forms the core of the ASIC 16, a memory controller that controls a local memory used as a copy image buffer, a code buffer, and the like, and hardware logic or the like. It consists of a plurality of DMACs (Direct Memory Access Controllers) that perform rotation and the like, and a PCI unit that performs data transfer between the engine unit 100 via a PCI bus. The ASIC 16 performs various signal processing for image data, image processing for rearranging images, and other processing of input / output signals for controlling the entire image forming apparatus 1.

  The HDD 17 is a storage for storing image data, programs, font data, forms, and the like. Further, the HDD 17 functions as a storage unit that stores a data table and the like used when the heater control unit 12 performs heater drive control of the engine unit 100. The operation panel 18 is a device that inputs and displays information necessary for the image forming apparatus 1 (for example, operation information of the image forming apparatus 1) according to an operation by a user.

(Engine configuration)
Next, the configuration of engine unit 100 in the present embodiment will be described. FIG. 2 is a diagram showing a configuration example of the engine unit in the present embodiment. In FIG. 2, a broken line arrow indicates the conveyance direction of the print target. For example, as shown in FIG. 2, the engine unit 100 of the image forming apparatus 1 according to the present embodiment includes a supply device 110, a treatment liquid coating device 120, a first inkjet printer 130, a reversing device 140, 2 inkjet printers 150 and a post-processing device 160.

  The supply device 110 is set with a roll body formed by winding a belt-like print medium such as paper or a resin film, and feeds out a web 5 which is an example of a printing object from the roll body. The supply device 110 sequentially supplies the fed web 5 to the treatment liquid coating device 120.

  The treatment liquid coating apparatus 120 functions as a pretreatment apparatus that performs pretreatment for preventing problems during ink jet printing such as feathering and color bleeding on a print target. Specifically, the processing liquid coating apparatus 120 applies a predetermined processing liquid to the printing surface (for example, both front and back surfaces) of the web 5 sent from the supply apparatus 110. The processing liquid coating apparatus 120 includes a drying mechanism 70 including a heater and the like, and the processing liquid applied to the web 5 is dried by the drying mechanism 70. In this way, the treatment liquid coating apparatus 120 achieves a pretreatment for the web 5 (pretreatment before ink jet printing). The treatment liquid coating apparatus 120 sends the pre-processed web 5 toward the first inkjet printer 130.

  The first inkjet printer 130 sequentially feeds the web 5 after the pretreatment from the treatment liquid coating apparatus 120. The first inkjet printer 130 sequentially conveys the received web 5 and ejects ink droplets on one surface (for example, the front surface) of the front and back surfaces of the web 5. Thereby, the first inkjet printer 130 forms a desired image on the printing surface of the web 5. The image formed on the web 5 by the first ink jet printer 130 is an image that is print-controlled by the CPU 11 of the control unit 10 shown in FIG. The first inkjet printer 130 sequentially sends the web 5 after such single-sided printing toward the reversing device 140.

  The reversing device 140 sequentially feeds the web 5 after single-sided printing from the first inkjet printer 130. The reversing device 140 sequentially conveys the received webs 5 and reverses the front and back of the webs 5. The reversing device 140 sequentially sends the web 5 after the reversing process toward the second ink jet printer 150.

  The second inkjet printer 150 sequentially feeds the web 5 after the reversal process from the reversing device 140. The second inkjet printer 150 sequentially transports the received web 5 and ejects ink droplets on the remaining surface (for example, the back surface) of the front and back surfaces of the web 5. Thereby, the second inkjet printer 150 forms a desired image on the printing surface of the web 5. Note that the image formed on the web 5 by the second inkjet printer 150 is an image whose printing is controlled by the CPU 11 as in the case of the first inkjet printer 130. The second inkjet printer 150 sequentially sends the web 5 after such double-sided printing to the post-processing device 160.

  The post-processing device 160 sequentially feeds the web 5 after double-sided printing from the second inkjet printer 150. The post-processing device 160 sequentially conveys the received webs 5 and performs predetermined post-processing on the webs 5. As a result, the post-processing device 160 manufactures a printed material that has been printed on both sides. The post-processing device 160 sequentially carries out the manufactured printed matter.

(Configuration of treatment liquid application equipment)
Next, the configuration of the treatment liquid coating apparatus 120 in the present embodiment will be described. FIG. 3 is a diagram illustrating a configuration example of the treatment liquid coating apparatus in the present embodiment. In FIG. 3, broken line arrows indicate the conveyance direction of the print target.

  As shown in FIG. 3, the treatment liquid coating apparatus 120 according to the present embodiment includes a mechanism for securing the conveyance path of the web 5 and smoothly conveying the web 5 along the conveyance path. Specifically, the treatment liquid coating apparatus 120 includes guide rollers 51 a to 51 i, a feed-in roller 52, a feed-in nip roller 53, a pass shaft 54, an edge guide 55, and a tension shaft 56. The treatment liquid coating apparatus 120 includes an infeed roller 57, feed nip rollers 58 and 64, a first dancer unit 59, an outfeed roller 63, and a second dancer unit 65. Furthermore, the processing liquid coating apparatus 120 includes a front side processing liquid coating unit 61 and a back side processing liquid coating unit 62 for coating a predetermined processing liquid 60 on both front and back surfaces of the web 5, and a processing liquid applied to the web 5. And a drying mechanism 70 for drying 60.

  Each of the guide rollers 51a to 51i has a bearing (not shown) at the roller end, and is rotatably supported in the processing liquid coating apparatus 120. As shown in FIG. 3, the guide rollers 51 a to 51 i are installed at a plurality of locations along the conveyance path of the web 5 in the treatment liquid coating apparatus 120. Each of these guide rollers 51a to 51i guides the web 5 from the upstream side to the downstream side of the conveyance path while rotating.

  The feed-in roller 52 is a drive roller that rotates by the action of a drive source (not shown) such as a motor. A feed-in nip roller 53 is pressed against the feed-in roller 52 by a tensile force of a spring (not shown). The feed-in roller 52 sequentially conveys the web 5 from the upstream side to the downstream side of the conveyance path by rotational driving while sandwiching the web 5 in cooperation with the feed-in nip roller 53. As a result, the feed-in roller 52 can draw the web 5 from the supply device 110 shown in FIG.

  The web 5 carried into the processing liquid coating device 120 from the supply device 110 reaches the feed-in roller 52 via the guide roller 51a. Subsequently, the web 5 is sequentially conveyed by the rotational drive of the feed-in roller 52 by the drive source while being sandwiched between the feed-in roller 52 and the feed-in nip roller 53 by the elastic force of the spring. As shown in FIG. 3, the web 5 delivered from the feed-in roller 52 and the feed-in nip roller 53 is conveyed while being slightly loosened, thereby forming an air loop AL. The web 5 having passed through the air loop AL is conveyed so as to pass between the pass shaft 54 and the edge guide 55.

  A plurality of (for example, two) pass shafts 54 are arranged in a direction perpendicular to the conveying direction of the web 5 (this arrangement state is not shown). The plurality of pass shafts 54 feed the web 5 while curving it in an S shape. The pass shaft 54 is provided with a pair of edge guides 55 formed in a plate shape. The distance between the pair of edge guides 55 is set to be the same as the width of the web 5. By the action of the pass shaft 54 and the edge guide 55, the conveyance position in the width direction of the web 5 is regulated, and as a result, the web 5 can be stably traveled (conveyed). The edge guide 55 is fixed to the pass shaft 54 by fixing means such as screws. The position and interval of the edge guide 55 can be adjusted according to the width of the web 5 to be used.

  The tension shaft 56 is fixedly disposed downstream of the path shaft 54 and the edge guide 55 in the conveyance path of the web 5. The tension shaft 56 applies tension to the web 5 while moving the web 5 along the conveyance path. Thereby, the tension shaft 56 contributes to the stable travel (conveyance) of the web 5. The web 5 that has passed through the tension shaft 56 passes between the in-feed roller 57 and the feed nip roller 58.

  The infeed roller 57 is a drive roller that rotates by the action of a drive source (not shown) such as a motor. A plurality of feed nip rollers 58 are arranged along the roll axis direction of the in-feed roller 57 (this arrangement state is not shown). Each of the plurality of feed nip rollers 58 is pressed against the in-feed roller 57 by a tensile force of a spring (not shown). The in-feed roller 57 sequentially conveys the web 5 from the upstream side to the downstream side of the conveyance path by rotational driving while sandwiching the web 5 in cooperation with the feed nip roller 58. The web 5 delivered from the in-feed roller 57 and the feed nip roller 58 is wound around a first dancer unit 59 as shown in FIG.

  The first dancer unit 59 includes a dancer roller 59a and a movable frame 59b. The dancer roller 59a is rotatably attached to the movable frame 59b via a bearing (not shown) provided at the roller end. As shown in FIG. 3, the first dancer unit 59 is in a state where the web 5 is wound around the dancer roller 59 a and is hung by the web 5. The first dancer unit 59 in such a state is movable along the gravity direction A while feeding the web 5 in the conveying direction.

  Although not particularly shown in FIG. 3, position detection means for detecting the position of the first dancer unit 59 is provided in the treatment liquid coating apparatus 120. The position of the first dancer unit 59 is adjusted by the CPU 11 (see FIG. 1) of the control unit 10 drivingly controlling the drive source of the infeed roller 57 in accordance with the output of the position detection means.

  As shown in FIG. 3, the web 5 that has passed through the dancer unit 59 is conveyed into the surface-side treatment liquid application unit 61 via the guide roller 51 b. The front-side treatment liquid application unit 61 applies a predetermined treatment liquid 60 to the surface of both the front and back surfaces that are the printing surface of the web 5. For example, as shown in FIG. 3, the front-side treatment liquid application unit 61 has a treatment liquid 60 that reacts with the ink and promotes prevention of ink bleeding, and an application roller 61 a that applies the treatment liquid 60 to the web 5. And a plurality of rotating rollers. In the front-side treatment liquid application unit 61, the treatment liquid 60 is pumped up by the rotating roller and transferred to the application roller 61a. The surface-side treatment liquid application unit 61 rotates the application roller 61a while bringing the outer peripheral surface of the application roller 61a into contact with the surface of the web 5, whereby the processing liquid is transferred from the outer peripheral surface of the application roller 61a to the surface of the web 5. 60 is transferred and applied.

  As described above, the web 5 coated with the treatment liquid 60 on the surface is fed from the front-side treatment liquid application unit 61 and then conveyed into the back-side treatment liquid application unit 62 via the guide rollers 51c and 51d in sequence. Is done. The back surface side treatment liquid application unit 62 applies the treatment liquid 60 to the back surface of both the front and back surfaces that are the printing surface of the web 5. For example, as shown in FIG. 3, the back-side treatment liquid application unit 62 has a treatment liquid 60 inside, like the front-side treatment liquid application unit 61, and an application roller 62 a that applies the treatment liquid 60 to the web 5. And a plurality of rotating rollers. In the back side treatment liquid application section 62, the treatment liquid 60 is pumped up by the rotating roller and transferred to the application roller 62a. The back side treatment liquid application unit 62 rotates the application roller 62 a while bringing the outer peripheral surface of the application roller 62 a into contact with the back surface of the web 5, whereby the processing liquid is transferred from the outer peripheral surface of the application roller 62 a to the back surface of the web 5. 60 is transferred and applied.

  As described above, the web 5 coated with the treatment liquid 60 on the back surface is fed from the back surface side treatment liquid coating unit 62 and then conveyed into the drying mechanism 70 via the guide rollers 51e and 51f sequentially. The drying mechanism 70 dries the treatment liquid 60 applied to the web 5 and includes a heating and conveying unit 71 and a heater driving unit 75 as shown in FIG. The heating and conveying unit 71 receives the web 5 coated with the treatment liquid 60 and conveys the received web 5 while heating. As a result, the heating and conveying unit 71 dries the treatment liquid 60 on both the front and back surfaces of the web 5 and carries out the web 5 after drying the treatment liquid 60 (hereinafter, abbreviated as the web 5 after drying the treatment liquid as appropriate). . The heater driving unit 75 switches the on / off state of power supply to the heater of the heating / conveying unit 71 based on the control by the heater control unit 12 shown in FIG. Accordingly, the heater driving unit 75 drives the heater of the heating and conveying unit 71 or stops driving the heater of the heating and conveying unit 71. The details of the configuration of the drying mechanism 70 will be described later.

  After the processing liquid is dried by the drying mechanism 70, the web 5 is delivered from the heating and conveying unit 71, and then passes between the outfeed roller 63 and the feed nip roller 64 via the guide roller 51g as shown in FIG. . The outfeed roller 63 is a drive roller that rotates by the action of a drive source (not shown) such as a motor. A plurality of feed nip rollers 64 are arranged along the roll axis direction of the outfeed roller 63 (this arrangement state is not shown). Each of the plurality of feed nip rollers 64 is pressed against the outfeed roller 63 by a tensile force of a spring (not shown). The outfeed roller 63 sequentially conveys the web 5 from the upstream side to the downstream side of the conveyance path by rotational driving while sandwiching the web 5 in cooperation with the feed nip roller 64. The web 5 delivered from the outfeed roller 63 and the feed nip roller 64 is wound around the second dancer unit 65 and the like as shown in FIG.

  The second dancer unit 65 is configured using dancer rollers 65a and 65b and a movable frame 65c. The two dancer rollers 65a and 65b are rotatably attached to the movable frame 65c via bearings (not shown) provided at the roller ends. In addition, as shown in FIG. 3, a guide roller 51h is rotatably installed on the conveyance path of the web 5 from the upstream dancer roller 65a to the downstream dancer roller 65b in the second dancer unit 65. A guide roller 51i is rotatably installed downstream of the dancer roller 65b in the web 5 conveyance path. As shown in FIG. 3, the second dancer unit 65 wraps the web 5 around the two guide rollers 51 h and 51 i and the two dancer rollers 65 a and 65 b and is suspended by the web 5. It has become. At this time, the web 5 is wound in a W shape over a conveyance path from the dancer roller 65a on the upstream side to the guide roller 51i via the guide roller 51h and the dancer roller 65b on the downstream side. The second dancer unit 65 in such a state is movable along the gravity direction A while feeding the web 5 in the conveying direction.

  Although not particularly shown in FIG. 3, position detection means for detecting the position of the second dancer unit 65 is provided in the treatment liquid coating apparatus 120. The position of the second dancer unit 65 is adjusted by the CPU 11 (see FIG. 1) of the control unit 10 drivingly controlling the drive source of the outfeed roller 63 in accordance with the output of the position detection means.

  The web 5 sent out from the second dancer unit 65 is sequentially conveyed by the action of the rotational drive of the outfeed roller 63 described above, and is carried out of the processing liquid coating apparatus 120 via the guide roller 51i. Thereafter, the web 5 is conveyed into the first inkjet printer 130 shown in FIG.

(Configuration of drying mechanism)
Next, the configuration of the drying mechanism 70 provided in the above-described processing liquid coating apparatus 120 (see FIG. 3) will be described. FIG. 4 is a diagram showing a configuration example of a treatment liquid drying mechanism in the present embodiment. As shown in FIG. 4, the drying mechanism 70 of the treatment liquid coating apparatus 120 in the present embodiment includes a heating and conveying unit 71 and a heater driving unit 75. The heating and conveying unit 71 includes heat rollers 72a to 72j, heaters 73a to 73j, and temperature detecting units 74a to 74j.

  A plurality of (in this embodiment, 10) heat rollers 72a to 72j and heaters 73a to 73j are used to convey the web 5 after the treatment liquid 60 has been applied to both the front and back surfaces along the conveyance path. The processing liquid 60 on both the front and back surfaces of No. 5 is heated and dried.

  Each of the heat rollers 72a to 72j is a cylindrical body that is rotatably supported. These heat rollers 72a to 72j are staggered along the conveyance path of the web 5, for example, as shown in FIG. 4, in order to increase the contact area with the web 5 wound around the outer peripheral surface thereof as much as possible. Placed in. Thereby, the contact angle between each of the heat rollers 72a to 72j and the web 5 is increased to about 100 [°], for example.

  The heaters 73 a to 73 j are heat sources for heating and drying the processing liquid 60 applied to the web 5. As shown in FIG. 4, the heaters 73 a to 73 j are provided on the heat rollers 72 a to 72 j, respectively. The heaters 73a to 73j respectively heat the heat rollers 72a to 72j and raise the temperatures of the heat rollers 72a to 72j to temperatures corresponding to a predetermined target temperature (for example, 100 [° C.]). The heat rollers 72a to 72j heated in this way rotate around the roll axis while contacting the web 5 so as to wrap the web 5 around the outer circumferential surface, and sequentially move the web 5 from the upstream side to the downstream side of the conveyance path. Send it out. The heaters 73a to 73j heat the web 5 through the heated heat rollers 72a to 72j, thereby drying the treatment liquid 60 on both the front and back surfaces of the web 5.

  The temperature detectors 74a to 74j function as heat roller temperature detecting means for detecting each temperature of the heat rollers 72a to 72j. The temperature detectors 74a to 74j are configured using a radiation thermometer or the like, and are arranged in the vicinity of the heat rollers 72a to 72j as shown in FIG. As described above, the temperature detectors 74a to 74j measure and detect each surface temperature of the heat rollers 72a to 72j heated by the heaters 73a to 73j continuously or intermittently in time series. . In each case, the temperature detectors 74a to 74j notify the heater controller 12 (see FIG. 1) of the detected surface temperatures of the heat rollers 72a to 72j by transmitting an electric signal.

  The heater drive unit 75 switches the on / off state of each drive of the heaters 73a to 73j. The heater driving unit 75 is configured using a switching control element or the like, and connects the AC power supply 40 (see FIG. 1) for supplying power to the image forming apparatus 1 and the heaters 73a to 73j so as to be turned on and off. The heater drive unit 75 connects the AC power supply 40 and the heaters 73a to 73j so as to be able to supply power based on the control by the heater control unit 12 of the control unit 10 shown in FIG. 1, or the AC power supply 40 and the heaters 73a to 73a. The connection with 73j is cut off. Thus, the heater driving unit 75 stops driving when the heaters 73a to 73j are driven with the power supplied from the AC power supply 40 (on state) and the power supply from the AC power supply 40 is cut off. Switch to either the off state or the off state.

Further, the drying mechanism 70 has a structure capable of opening and closing the heating conveyance unit 71 as shown in FIG. For example, the drying mechanism 70 separates the heat rollers 72 a to 72 j from the web 5 by opening the heating conveyance unit 71 during a period other than when the processing liquid 60 on the web 5 is dried. Thereby, the drying mechanism 70 can prevent the web 5 from contracting due to overheating.
On the other hand, the drying mechanism 70 closes the heating conveyance unit 71 during the period of drying the processing liquid 60 on the web 5, thereby increasing the contact area between each of the heat rollers 72 a to 72 j and the web 5 as much as possible. To do. Thereby, the drying mechanism 70 can accelerate the drying of the treatment liquid 60 on the web 5.

(Configuration of heater control unit)
Next, the configuration of the heater control unit 12 in the present embodiment will be described. FIG. 5 is a block diagram illustrating a configuration example of the heater control unit according to the present embodiment. The heater control unit 12 functions as a heater control unit in the control unit 10 (see FIG. 1) of the image forming apparatus 1 according to the present embodiment, and is included in the processing liquid coating apparatus 120 shown in FIGS. The heaters 73a to 73j of the drying mechanism 70 are driven and controlled. As shown in FIG. 5, the heater control unit 12 includes a voltage peak detection unit 81, a frequency detection unit 82, a zero cross signal generation circuit 83, an invalid period determination unit 84, a zero cross signal determination unit 85, and a timing counter 86. And a drive signal output unit 87.

  The voltage peak detector 81 functions as a power supply voltage peak detector that detects the power supply voltage peak value of the AC power supply 40 shown in FIG. In the present embodiment, as described above, the AC power supply 40 heats the treatment liquid 60 applied to the web 5 that is an example of the printing object, and heats the heaters 73a to 73j of the drying mechanism 70 (FIG. 3). 4)). The voltage peak detector 81 continuously or intermittently monitors the power supply voltage value of such an AC power supply 40 in time series, and based on each power supply voltage value acquired thereby, the power supply of the AC power supply 40 Detect voltage peak value. Each time, the voltage peak detection unit 81 outputs an electrical signal indicating the detected power supply voltage peak value to the invalid period determination unit 84.

  The frequency detector 82 functions as a frequency detector that detects the frequency of the power supply voltage of the AC power supply 40. Specifically, the frequency detection unit 82 continuously or intermittently monitors the frequency of the power supply voltage of the AC power supply 40 (hereinafter referred to as a power supply frequency) along a time series. Detect power supply frequency. Each time, the frequency detection unit 82 outputs an electrical signal indicating the detected power supply frequency to the invalid period determination unit 84.

  The zero cross signal generation circuit 83 functions as a zero cross signal generation unit that generates a zero cross signal indicating the zero cross point of the power supply voltage of the AC power supply 40. Specifically, the zero cross signal generation circuit 83 continuously or intermittently monitors the power supply voltage value of the AC power supply 40 in time series. The zero-cross signal generation circuit 83 is based on a threshold value set for the power supply voltage value, and for a predetermined period including the timing at which the monitored power supply voltage value passes 0 [V], It is detected as a zero cross point of voltage. Each time, the zero-cross signal generation circuit 83 generates a zero-cross signal indicating the detected zero-cross point, and outputs the generated zero-cross signal to the zero-cross signal determination unit 85.

  The invalid period determination unit 84 functions as a zero cross signal detection invalid period determination unit that determines an invalid period for invalidating the detection of the zero cross signal. The invalid period determination unit 84 determines an invalid period of zero-cross signal detection (hereinafter, abbreviated as invalid period as appropriate) according to the power supply voltage peak value detected by the voltage peak detection unit 81. Here, the timing at which the signal level of the zero-cross signal changes, that is, the timing at which the zero-cross signal falls and rises, changes as the power supply voltage peak value of the AC power supply 40 changes. The invalid period determining unit 84 determines the invalid period in a period including the falling and rising edges of the zero cross signal whose timing is changed in accordance with the change in the power supply voltage peak value.

  Specifically, in the present embodiment, the invalid period determination unit 84 acquires the power supply voltage peak value of the AC power supply 40 from the voltage peak detection unit 81 and the frequency of the power supply voltage of the AC power supply 40 from the frequency detection unit 82 ( Power frequency). Further, the invalid period determining unit 84 reads the data table from the HDD 17 shown in FIG. FIG. 6 is a diagram illustrating an example of a data table used for determining an invalid period of zero-cross signal detection in the present embodiment. As shown in FIG. 6, this data table associates the power supply frequency, the range of the power supply voltage peak value, and the set invalid time indicating the time width of the invalid period.

  The invalid period determination unit 84 extracts a setting invalid time corresponding to the power supply voltage peak value detected by the voltage peak detection unit 81 and the power supply frequency detected by the frequency detection unit 82 from the data table. The setting invalidity time corresponding to the power supply voltage peak value and the power supply frequency is, for example, one of the setting invalidation times t1 to t16 shown in FIG. The invalid period determining unit 84 determines the invalid period having the time width of the set invalid time extracted as described above as a period including the falling and rising edges of the above-described zero cross signal. Each time, the invalid period determination unit 84 transmits an electrical signal indicating the determined invalid period to the zero cross signal determination unit 85.

  The zero-cross signal determination unit 85 functions as a zero-cross signal determination unit that determines and detects a zero-cross signal having a normal waveform from the zero-cross signals generated and output by the zero-cross signal generation circuit 83. Specifically, the zero cross signal determination unit 85 invalidates the zero cross signal input by the zero cross signal generation circuit 83 during the invalid period determined by the invalid period determination unit 84. On the other hand, the zero-cross signal determination unit 85 determines that the zero-cross signal input by the zero-cross signal generation circuit 83 during the period other than the invalid period is a zero-cross signal having a normal waveform to be detected. The zero-cross signal determination unit 85 detects an input signal (zero-cross signal) from the zero-cross signal generation circuit 83 that is determined to be a zero-cross signal having a normal waveform. Each time, the zero cross signal determination unit 85 transmits an electric signal indicating that the zero cross signal has been detected to the timing counter 86.

  The timing counter 86 and the drive signal output unit 87 generate control signals for controlling the power supply of the heaters 73a to 73j of the drying mechanism 70 shown in FIG. 4 based on the normal waveform zero cross signal detected by the zero cross signal determination unit 85. Control signal output means for outputting to the heater driving unit 75 is configured.

  The timing counter 86 functions as a heater drive timing counter that performs a count for determining the timing for driving and controlling the heaters 73a to 73j. Specifically, the timing counter 86 has a preset initial count value (hereinafter referred to as a default value). The timing counter 86 transmits an electric signal indicating the start of counting to the drive signal output unit 87 at the timing when the electric signal indicating the detection of the zero cross signal is received from the zero cross signal determination unit 85, and sets the timing of the heater drive control. Start counting to make a decision. At this time, the timing counter 86 counts down from the default value toward the zero value, for example, by counting the reference clock. The timing counter 86 transmits an electrical signal indicating the completion of counting to the drive signal output unit 87 at the timing when the count value becomes zero as a result of the countdown.

  In addition, the timing counter 86 acquires the surface temperatures of the heat rollers 72a to 72j from the temperature detectors 74a to 74j. The timing counter 86 increases or decreases the count value during counting for each heater in accordance with the deviation between each surface temperature of the obtained heat rollers 72a to 72j and the target temperature. Thereby, the timing counter 86 changes the timing of completion of counting, that is, the timing of turning on the heaters 73a to 73j for each heater so that each surface temperature of the heat rollers 72a to 72j becomes the target temperature.

  The drive signal output unit 87 functions as a heater drive signal output unit that outputs a signal for controlling driving of the heaters 73 a to 73 j to the heater drive unit 75 based on an input signal from the timing counter 86. Specifically, the drive signal output unit 87 outputs a control signal for instructing the heater drive start to the heater drive unit 75 at the timing when the electric signal indicating the completion of the count is received from the timing counter 86. As a result, the drive signal output unit 87 causes the heater drive unit 75 to supply power from the AC power supply 40 to the heaters 73a to 73j, thereby turning on the heaters 73a to 73j. On the other hand, the drive signal output unit 87 outputs a control signal for instructing the heater drive stop to the heater drive unit 75 at the timing when the electric signal indicating the start of counting is received from the timing counter 86. As a result, the drive signal output unit 87 causes the heater drive unit 75 to cut off the power supply from the AC power supply 40 to the heaters 73a to 73j, thereby turning off the drive states of the heaters 73a to 73j.

  Here, the heater control program executed in the image forming apparatus 1 according to the present embodiment is provided by being incorporated in advance in the ROM 13 shown in FIG. The CPU 11 reads out and executes the heater control program from the ROM 13 or the like. Thereby, the CPU 11 includes the voltage peak detection unit 81, the frequency detection unit 82, the zero cross signal generation circuit 83, the invalid period determination unit 84, the zero cross signal determination unit 85, the timing counter 86, and the drive signal output unit 87 shown in FIG. Each function is realized, and each of these functions is executed by the heater control unit 12 (computer). The heater control unit 12 may be realized by a hardware configuration other than the CPU 11.

(Heater control method)
Next, a heater control method of the image forming apparatus 1 according to the present embodiment will be described. FIG. 7 is a flowchart illustrating an example of a heater control method for the image forming apparatus according to the present embodiment. FIG. 8 is a timing chart showing an example of processing timing in the heater control of the present embodiment. In the heater control method of the image forming apparatus 1 according to the present embodiment, the CPU 11 executes the heater control program and causes the heater control unit 12 to appropriately perform the processing steps of steps S101 to S109 shown in FIG. Realized.

  That is, in the heater control method according to the present embodiment, as shown in FIG. 7, the heater control unit 12 heats the heaters 73 a to 73 j (FIGS. 3 and 4) of the drying mechanism 70 that dries the treatment liquid 60 applied to the web 5. The power supply voltage of the AC power supply 40 that supplies power is detected (see step S101). In step S101, the voltage peak detection unit 81 continuously or intermittently monitors the power supply voltage value of the AC power supply 40 along a time series, and based on each power supply voltage value acquired thereby, the AC power supply 40 The power supply voltage peak value is detected. Further, the frequency detector 82 continuously or intermittently monitors the frequency of the power supply voltage of the AC power supply 40 (power supply frequency) along a time series, thereby detecting the power supply frequency of the AC power supply 40.

  Next, the heater control unit 12 generates a zero cross signal of the detected power supply voltage (step S102). In step S102, the zero cross signal generation circuit 83 continuously or intermittently monitors the power supply voltage value of the AC power supply 40 along a time series, and detects the zero cross point of the power supply voltage of the AC power supply 40. Subsequently, the zero cross signal generation circuit 83 generates a zero cross signal indicating the detected zero cross point. At this time, the zero cross signal generation circuit 83 generates a zero cross signal whose signal level changes before and after the power supply voltage passes 0 [V], for example, as shown in FIG.

  Next, the heater control unit 12 determines an invalid period of zero-cross signal detection according to the detection result of the power supply voltage in step S101 (step S103). In step S103, the invalid period determining unit 84 sets the invalid period in which the detection of the zero cross signal is invalid, at least according to the power supply voltage peak value, to the falling edge of the zero cross signal that changes the timing according to the change in the power supply voltage peak value. And a period including the rising edge.

  Specifically, in the present embodiment, invalid period determination unit 84 acquires the power supply voltage peak value detected by voltage peak detection unit 81 and the power supply frequency detected by frequency detection unit 82. Further, the invalid period determining unit 84 reads the data table from the HDD 17. For example, as shown in FIG. 6, this data table shows the correspondence between the power frequency, the range of the power voltage peak value, and the set invalid time. The invalid period determination unit 84 extracts a setting invalid time corresponding to the power supply voltage peak value by the voltage peak detection unit 81 and the power supply frequency by the frequency detection unit 82 from the data table. Next, the invalid period determining unit 84 determines the invalid period having the extracted set invalid time width as shown in FIG. 8, for example, a predetermined time before the next fall from the fall timing of the zero cross signal. Decide on the period until timing. That is, the invalid period in the present embodiment is a period from the falling timing of the zero cross signal to the timing separated by the set invalid time on the next falling side. Further, the period other than the invalid period is an effective period in which the detection of the zero cross signal is valid.

  Thereafter, the heater control unit 12 determines whether or not the heater drive timing needs to be changed based on the surface temperatures of the heaters 73a to 73j (step S104). In this step S104, the timing counter 86 acquires the surface temperatures of the heat rollers 72a to 72j fed back from the temperature detectors 74a to 74j. If the deviation between the surface temperature of each of the heat rollers 72a to 72j and the target temperature is equal to or greater than a predetermined value, the timing counter 86 determines that the heater drive timing needs to be changed.

  When the heater drive timing needs to be changed (Yes in step S104), the heater control unit 12 changes the value of the timing counter 86 and appropriately sets the drive timing of the heaters 73a to 73j corresponding to the heat rollers 72a to 72j. Change (step S105). On the other hand, if it is not necessary to change the heater drive timing (No at Step S104), the heater control unit 12 proceeds to Step S106 without performing Step S105.

  Subsequently, the heater control unit 12 determines whether or not a zero cross signal is detected (step S106). In step S <b> 106, the zero-cross signal determination unit 85 receives the zero-cross signal from the zero-cross signal generation circuit 83 and receives the electrical signal indicating the invalid period or the valid period from the invalid period determination unit 84. The zero cross signal determination unit 85 invalidates the zero cross signal input from the zero cross signal generation circuit 83 during the invalid period based on the input signal from the invalid period determination unit 84. In this case, the zero cross signal determination unit 85 has not detected the zero cross signal (No at Step S106), and the heater control unit 12 repeats Step S106.

  On the other hand, in step S <b> 106, the zero cross signal determination unit 85 validates the zero cross signal input from the zero cross signal generation circuit 83 during the valid period based on the input signal from the invalid period determination unit 84. Next, the zero-cross signal determining unit 85 determines that the zero-cross signal in the effective period is a normal waveform zero-cross signal to be detected (step S106, Yes), and timings an electric signal indicating that the zero-cross signal has been detected. Transmit to the counter 86.

  When the zero cross signal is detected in step S106, the heater control unit 12 starts counting for driving the heater of the drying mechanism 70 (step S107).

  In step S <b> 107, the timing counter 86 receives an electrical signal indicating that the zero cross signal is detected from the zero cross signal determination unit 85. As shown in FIG. 8, the timing counter 86 starts counting to determine the heater drive control timing at the timing of receiving this electric signal, that is, the timing of detecting the zero cross signal. At this time, the timing counter 86 counts down from a default value toward a zero value, for example. At the same time, the timing counter 86 transmits an electric signal indicating the start of counting to the drive signal output unit 87.

  If the count is not completed in step S108 (No in step S108), the timing counter 86 continues to count down from, for example, a default value toward a zero value.

  On the other hand, when the counting is completed in step S108 (step S108, Yes), the heater control unit 12 controls the power feeding of the heaters 73a to 73j based on the normal waveform zero-cross signal detected in step S106 described above. Is output to the heater driving unit 75 to start driving the heaters 73a to 73j (step S109). Thereafter, the heater control unit 12 returns to step S104 described above, and repeats the processing steps after step S104 as appropriate.

  In step S109, the timing counter 86 transmits an electric signal indicating the completion of counting to the drive signal output unit 87 at the timing when the count value becomes zero as shown in FIG. The drive signal output unit 87 receives an electrical signal indicating completion of counting from the timing counter 86. As shown in FIG. 8, the drive signal output unit 87 outputs a control signal instructing the heater drive start (ON state) to the heater drive unit 75 at the timing of receiving this electrical signal, that is, at the timing of completion of counting. . The heater driving unit 75 is ON / OFF controlled based on this control signal, and as a result, power is supplied from the AC power supply 40 to the heaters 73a to 73j to turn on the driving states of the heaters 73a to 73j. For example, as shown in FIG. 8, the heaters 73 a to 73 j in the on state correspond to the power supply voltage from the AC power supply 40 during the period from the count completion timing by the timing counter 86 to the zero cross signal detection timing by the zero cross signal determination unit 85. AC current (heater current) is supplied.

  Here, in the detection process of the zero cross signal in the conventional heater control (hereinafter referred to as the conventional zero cross signal detection process), it is difficult to prevent erroneous detection of the zero cross signal. FIG. 9 is a diagram for explaining a conventional zero-cross signal detection process. FIG. 9 shows a power supply voltage having a relatively high power supply voltage peak value Vp1 (hereinafter referred to as a power supply voltage (large)) and a power supply voltage having a relatively low power supply voltage peak value Vp2 that are assumed in the AC power supply 40 described above. Each waveform (hereinafter referred to as power supply voltage (small)) is shown. Further, the waveforms of the zero cross signal of the power supply voltage (large) and the zero cross signal of the power supply voltage (small) are shown. As shown in FIG. 9, the zero cross signal of the power supply voltage (large) falls when the power supply voltage (large) reaches the falling threshold voltage Vthl and rises when the power supply voltage (large) reaches the rising threshold voltage Vthh. . The zero-cross signal width Wb of the power supply voltage (large) is a time width from the falling timing to the rising timing of the zero-cross signal of the power supply voltage (large). On the other hand, the zero cross signal of the power supply voltage (small) falls when the power supply voltage (small) reaches the falling threshold voltage Vthl, and rises when the power supply voltage (small) reaches the rising threshold voltage Vthh. The zero cross signal width Wa of the power supply voltage (small) is a time width from the falling timing to the rising timing of the zero cross signal of the power supply voltage (small). Note that the falling threshold voltage Vthl and the rising threshold voltage Vthh are set as threshold values of the power supply voltage value in the zero-cross signal generation circuit 83 shown in FIG.

  In the conventional zero-cross signal detection process, as shown in FIG. 9, the invalid period M1 is determined so as to invalidate the zero-cross signal other than a fixed time before and after the point where the power supply voltage becomes 0 [V]. The At this time, since the change of the power supply voltage peak value is not taken into consideration, the zero cross signal width Wa corresponding to the power supply voltage (small) of the relatively low power supply voltage peak value Vp2 is set as a fixed period, and the time width T1 excluding this fixed period This period must be fixed to the invalid period M1. Note that the zero cross signal width Wa becomes longer as the power supply voltage peak value of the AC power supply 40 decreases, and the power supply voltage peak value Vp2 is the lowest value assumed for the AC power supply 40 (for example, 255 [V]). The longest time width (for example, 2.7 [milliseconds]) is obtained.

  As shown in FIG. 9, the fixed invalid period M1 includes a period from the rising edge vicinity region 90 of the zero-cross signal of the power supply voltage (small) to the next falling edge vicinity region 90. The edge vicinity region 90 is a region near the rising or falling edge of the zero cross signal. In general, the waveform disturbance of the zero cross signal is likely to occur in the edge vicinity region 90 of the zero cross signal.

  However, when the above-described power supply voltage peak value Vp2 changes to a relatively high power supply voltage peak value Vp1 shown in FIG. 9, the falling and rising timings of the zero cross signal change accordingly. That is, as shown in FIG. 9, the falling timing of the zero cross signal of the power supply voltage (large) having the power supply voltage peak value Vp1 is later than the falling timing of the zero cross signal of the power supply voltage (small). The rise timing of the zero cross signal of the power supply voltage (large) is earlier than the rise timing of the zero cross signal of the power supply voltage (small). As a result, the zero cross signal width Wb of the power supply voltage (large) becomes shorter than the zero cross signal width Wa of the power supply voltage (small), as shown in FIG. For example, when the power supply voltage peak value Vp1 is the highest value (eg, 373 [V]) assumed in the AC power supply 40, the zero cross signal width Wb is the shortest time width (eg, 1.4 [milliseconds]). Become. As described above, as a result of changes in the falling and rising timings of the zero-cross signal, the time width T1 of the invalid period M1 is completely equal to the edge vicinity region 90 of the zero-cross signal of the power supply voltage (large) as shown in FIG. The edge vicinity region 90 that is not covered and is likely to cause the waveform disturbance of the zero-cross signal exists in a period other than the invalid period M1, that is, the valid period R1 of the zero-cross signal detection. For this reason, the detection of the zero cross signal in the edge vicinity region 90 cannot be invalidated at all, and as a result, the zero cross signal is erroneously detected due to the waveform disturbance of the zero cross signal. The erroneous detection of the zero cross signal impairs the accuracy of the heater drive control performed by the heater control unit 12 based on the detection of the zero cross signal as described above.

  In contrast to the conventional zero-cross signal detection process described above, in the zero-cross signal detection process (hereinafter referred to as the zero-cross signal detection process of the present embodiment) in the heater control of the present embodiment, an error of the zero-cross signal is caused for the following reason. Detection can be prevented with high accuracy. FIG. 10 is a diagram for explaining the zero-cross signal detection processing of the present embodiment. In FIG. 10, similarly to FIG. 9 described above, the waveform of the power supply voltage (large) having the power supply voltage peak value Vp1, the waveform of the power supply voltage (small) having the power supply voltage peak value Vp2, and the power supply voltage (large) are shown. The waveforms of the zero-cross signal and the zero-cross signal of the power supply voltage (small) are shown. Further, the falling threshold voltage Vthl, the rising threshold voltage Vthh, and the zero cross signal widths Wa and Wb shown in FIG. 10 are the same as those shown in FIG.

  In the zero-cross signal detection process of the present embodiment, the power supply voltage peak value and the power supply frequency of the AC power supply 40 that supplies power to the heaters 73a to 73j described above are detected, and according to the detected power supply voltage peak value and the power supply frequency, FIG. As shown in FIG. 10, an invalid period M2 of zero cross signal detection is determined. At this time, the time width T2 of the invalid period M2 is determined to be a set invalid time corresponding to the detection result of the power supply voltage peak value and the power supply frequency among the set invalid times t1 to t16 included in the data table shown in FIG. 6, for example. Is done. Such an ineffective period M2 depends on the detection result of the power supply voltage peak value and the power supply frequency even when the falling and rising timings of the zero cross signal change with the change of the power supply voltage peak value and the power supply frequency. It changes so as to follow each timing of falling and rising of the zero-cross signal after the change.

  For example, as shown in FIG. 10, the invalid period M2 is from the falling timing of the zero-cross signal of the power supply voltage (small) immediately before the next falling timing in accordance with the power supply voltage peak value Vp2 of the power supply voltage (small) and the power supply frequency. Until the time width T2. The invalid period M2 includes a period from the rising edge vicinity region 90 of the zero-cross signal of the power supply voltage (small) through the next rising edge vicinity region 90 to immediately before the next falling. That is, the majority (for example, 75%) of the edge vicinity region 90 where the waveform disturbance of the zero-cross signal is likely to occur can be covered by the period of the invalid period M2. Thereafter, when the power supply voltage peak value Vp2 changes (increases) to the power supply voltage peak value Vp1, as shown in FIG. 10, the falling and rising timings of the zero cross signal change in the same manner as in FIG. To do. As a result, the zero-cross signal width Wb of the power supply voltage (large) becomes shorter than the zero-cross signal width Wa of the power supply voltage (small) as shown in FIG. The invalid period M2 changes following such a change in the zero cross signal. That is, as shown in FIG. 10, the invalid period M2 is the next falling timing from the falling timing of the zero cross signal of the power supply voltage (large) according to the detection result of the power supply voltage peak value Vp1 of the power supply voltage (large). It is determined by changing to the period of the time width T2 until immediately before. By this invalid period M2 after the change, the most part (for example, 75%) of the edge vicinity region 90 that easily causes waveform disturbance can be covered by the period of the invalid period M2.

  As described above, the invalid period M2 of the present embodiment has a zero cross signal corresponding to the high power supply voltage peak value Vp1 even when the zero cross signal width Wa is the longest corresponding to the low power supply voltage peak value Vp2. Even when the width Wb is the shortest, the edge vicinity region 90 of the zero cross signal is always included without omission. By determining such an invalid period M2, the detection accuracy of the zero cross signal in the edge vicinity region 90 can be improved. As a result, the zero-cross signal having a normal waveform can be detected in the valid period R2 other than the invalid period M2, and the waveform disturbance of the zero-cross signal can be avoided. Therefore, erroneous detection of the zero-cross signal can be prevented more accurately than in the past.

  For example, any one of the set invalid times t1 to t16 of the data table shown in FIG. 6 is adopted as the time width T2 of the invalid period M2. As shown in FIG. 6, this data table includes 50 [Hz] and 60 [Hz] as the power supply frequency conditions, and less than 269 [V] and 269 [V] as the power supply voltage peak value conditions. ] To less than 283 [V], 283 [V] to less than 297 [V], 297 [V] to less than 312 [V], 312 [V] to less than 326 [V], 326 [V] or more -Less than 340 [V], 340 [V] or more-Less than 354 [V], 354 [V] or more are included. Also, in this data table, set invalid times t1 to t16 [seconds] are associated with each condition of the power supply frequency and the power supply voltage peak value. In the zero cross signal detection processing of the present embodiment, the setting invalid time corresponding to the power frequency condition that matches the power frequency detection result and the power voltage peak value condition that matches the power voltage peak value detection result in this data table. (Any of t1 to t16) is set as the time width T2 of the invalid period M2. At this time, the time width T2 of the invalid period M2 may take into account the time (for example, 1.3 [milliseconds]) of the variation of the circuit elements. The invalid period determination unit 84 determines such an invalid period M2 of the time width T2 as shown in FIG. 10 and sets the invalid period based on a reference timing such as a falling period of the zero cross signal, for example, a period in which the detection of the zero cross signal is invalidated. An electric signal indicating the invalid period M2 is transmitted to the zero-cross signal determination unit 85 until the time elapses.

  As described above, in the present embodiment, the power supply voltage peak value of the AC power supply that supplies power to the heater that dries the treatment liquid applied to the print object is detected, and the detected power supply voltage peak value is detected. Accordingly, the invalid period during which the detection of the zero cross signal of the power supply voltage is invalid is determined in the period including the falling and rising edges of the zero cross signal whose timing changes with the change of the power supply voltage peak value, and the zero cross within the invalid period is determined. Control that invalidates the signal, detects a zero-cross signal within a period (valid period) other than the invalid period as a normal waveform zero-cross signal, and controls power supply to the heater based on the detected normal waveform zero-cross signal A signal is output to the heater driving unit.

  For this reason, it is possible to determine the invalid period of the zero-cross signal detection in consideration of the power supply voltage peak value that is dominant as a parameter of the variation of the zero-cross signal such as the falling timing and rising timing change of the zero-cross signal. By disabling the zero-cross signal during this invalid period, it is possible to avoid the waveform disturbance of the zero-cross signal that is likely to occur in the vicinity of the edge of the zero-cross signal (falling vicinity region, rising vicinity region). As a result, even if the waveform of the zero cross signal is disturbed near the edge of the zero cross signal, it is possible to prevent erroneous detection of the zero cross signal due to the waveform disturbance of the zero cross signal and to detect the zero cross of the normal waveform to be detected. The signal can be detected more correctly. By controlling the heater driving unit based on the correctly detected zero-cross signal in this way, it is possible to correctly control the electric power supplied to the heater described above without being affected by the waveform disturbance of the zero-cross signal.

  In the present embodiment, a data table in which the range of the power supply voltage peak value is associated with the set invalid time indicating the duration of the invalid period is used, and the detection result of the power supply voltage peak value is selected from the data table. The corresponding setting invalid time is extracted, and the extracted setting invalid time is set as the time width of the invalid period of the zero cross signal detection. For this reason, it is possible to easily set the time width of the invalid period necessary for the falling and rising of the zero-cross signal that changes according to the power supply voltage peak value to exist within the invalid period. As a result, it is possible to flexibly determine the invalid period of the time width including the edge vicinity region where the waveform disturbance of the zero cross signal is likely to occur without omission according to the power supply voltage peak value.

  Further, in the present embodiment, the frequency of the power supply voltage (power supply frequency) of the AC power supply described above is detected, and this data table is used by associating the range of the power supply voltage peak value, the power supply frequency, and the set invalid time. The setting invalid time corresponding to the detection result of the power supply voltage peak value and the detection result of the power supply frequency is extracted from the table, and the extracted setting invalid time is set as the time width of the invalid period of the zero cross signal detection. . For this reason, it is possible to easily set the time width of the invalid period necessary for the falling and rising of the zero-cross signal that changes according to the power supply voltage peak value and the power supply frequency to exist within the invalid period. As a result, it is possible to flexibly determine the invalid period of the time width including the region near the edge where the waveform disturbance of the zero cross signal is likely to occur without omission depending on the power supply voltage peak value and the power supply frequency.

  In the present embodiment, the period from the falling timing of the zero cross signal to the timing a predetermined time before the next falling is determined as the invalid period of the zero cross signal detection. For this reason, it is possible to accurately determine the invalid period including the region near the edge where waveform disturbance of the zero-cross signal is likely to occur without omission, and as a result, erroneous detection of the zero-cross signal due to the waveform disturbance of the zero-cross signal is surely prevented. can do.

  On the other hand, in the present embodiment, as described above, the zero cross signal detection invalid period is determined using the data table (see FIG. 6) in which the power supply voltage peak value and the like are associated with the set invalid time. Instead of using this data table, the invalid period can be calculated based on a predetermined calculation formula. That is, in the present embodiment, the invalid period determination unit 84 illustrated in FIG. 5 calculates the time width of the invalid period of the zero cross signal detection based on the power supply voltage peak value detected by the voltage peak detection unit 81. The invalid period of the zero cross signal detection having the calculated time width can be determined. As a result, the invalid period determining unit 84 can determine an invalid period having a time width that includes a region near the edge where the waveform disturbance of the zero-cross signal is likely to occur, according to the power supply voltage peak value. As a result, it is possible to achieve the same effect as when the zero cross signal detection invalid period is determined using the data table described above.

  Further, in the embodiment in which the invalid period is determined by calculation processing, the above-described frequency detection means for detecting the frequency of the power supply voltage (power supply frequency) of the AC power supply is provided, and each detection result of the power supply voltage peak value and the power supply frequency is provided. The invalid period can be calculated according to the above. In other words, in the present embodiment, the invalid period determining unit 84 sets the invalid period time based on the power supply voltage peak value detected by the voltage peak detecting unit 81 and the power supply frequency detected by the frequency detecting unit 82. By calculating the width, it is possible to determine the invalid period of the zero cross signal detection having the calculated time width. As a result, the invalid period determining unit 84 can determine an invalid period having a time width that includes a region near the edge where waveform disturbance of the zero-cross signal is likely to occur according to the power supply voltage peak value and the power supply frequency. As a result, it is possible to achieve the same effect as when the zero cross signal detection invalid period is determined using the data table described above.

  In the above-described embodiment, the power supply voltage peak value and the power supply frequency of the AC power supply 40 are detected, and the zero-cross signal detection invalid period is determined according to the detected power supply voltage peak value and the power supply frequency. However, the present invention is not limited to this, and the zero-cross signal detection invalid period may be determined according to the detection result of the power supply voltage peak value without using the power supply frequency. Specifically, if the power supply frequency is constant (for example, 50 [Hz] or 60 [Hz]), the invalid period determination unit 84 determines the power supply voltage peak value detected by the voltage peak detection unit 81 as described above. The invalid period of the zero-cross signal invalidity may be determined by using a data table or performing arithmetic processing based on the detected power supply voltage peak value. In this case, the heater control unit 12 may not include the frequency detection unit 82 that detects the power supply frequency. Further, the data table described above may be a table in which the range of the power supply voltage peak value is associated with the setting invalid time.

  In the above-described embodiment, the surface temperatures of the heater rollers 72a to 72j are individually monitored, and the driving state of the heaters 73a to 73j is determined based on the deviation between the detection result of each surface temperature and the target temperature. Although individually controlled, the heater control unit 12 is not limited to this, and the heater control unit 12 controls the heaters 73a to 73j based on the deviations between the surface temperatures of the heater rollers 72a to 72j and the target temperatures through the control of the heater driving unit. You may control a drive state collectively.

  Furthermore, in the above-described embodiment, the drying mechanism 70 that dries the treatment liquid 60 applied to the web 5 includes the ten heat rollers 72a to 72j. However, the number of heat rollers included in the drying mechanism 70 is as follows. The number is not limited to ten. The drying mechanism 70 may include one or more (preferably plural) heat rollers. Further, the number of heaters and temperature detection units provided in the drying mechanism 70 is not limited to the above-described ten, and may be the same as the number of heat rollers. That is, in the present embodiment, the numbers of the heat roller, the heater, and the temperature detection unit of the drying mechanism 70 are not particularly limited.

  In the above-described embodiment, the program executed by the CPU 11 is stored in advance in the ROM 13 or the like. However, the present invention is not limited to this, and the program executed in the image forming apparatus 1 according to this embodiment can be installed. It may be configured to be recorded on a computer-readable recording medium such as a CD-ROM, a flexible disk (FD), a CD-R, a DVD (Digital Versatile Disk) or the like in a format or executable file. Good.

  Furthermore, the program executed by the image forming apparatus 1 according to the present embodiment may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Furthermore, the program executed by the image forming apparatus 1 according to the present embodiment may be provided or distributed via a network such as the Internet.

  In the above-described embodiment, the image forming apparatus according to the present invention is described as an example in which the image forming apparatus is applied to a multifunction machine having at least two functions among a copy function, a printer function, a scanner function, and a facsimile function. The present invention can be applied to any image forming apparatus such as a printer, a printer, a scanner apparatus, and a facsimile apparatus.

  Further, the present invention is not limited by the above-described embodiment, and the present invention includes a configuration in which the above-described constituent elements are appropriately combined. In addition, all other embodiments, examples, operation techniques, and the like made by those skilled in the art based on the above-described embodiments are included in the present invention.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 5 Web 10 Control part 11 CPU
12 Heater control unit 13 ROM
14 RAM
15 NVRAM
16 ASIC
17 HDD
18 Operation panel 20 I / F section 30 FCU
40 AC power supply 51a to 51i Guide roller 52 Feed-in roller 53 Feed-in nip roller 54 Pass shaft 55 Edge guide 56 Tension shaft 57 In-feed roller 58, 64 Feed nip roller 59 First dancer unit 59a, 65a, 65b Dancer roller 59b, 65c Movable frame 60 treatment liquid 61 front side treatment liquid application part 61a, 62a application roller 62 back side treatment liquid application part 63 outfeed roller 65 second dancer unit 70 drying mechanism 71 heating conveyance part 72a-72j heat roller 73a-73j heater 74a to 74j Temperature detection unit 75 Heater drive unit 81 Voltage peak detection unit 82 Frequency detection unit 83 Zero cross signal generation circuit 84 Invalid period determination unit 85 Zero cross signal determination unit 8 6 Timing counter 87 Drive signal output unit 90 Edge vicinity region M1, M2 Invalid period R1, R2 Valid period

JP 2013-68803 A

Claims (8)

Power supply voltage peak detection means for detecting the peak value of the power supply voltage of the AC power supply that feeds the heater;
Zero-cross signal generating means for detecting a zero-cross point of the power supply voltage and generating a zero-cross signal indicating the detected zero-cross point;
According to the peak value of the power supply voltage detected by the power supply voltage peak detection means, after the falling timing of the zero cross signal that changes the timing in accordance with the change of the peak value of the power supply voltage , the zero cross An invalid period determining means for determining an invalid period for invalidating the detection of the zero-cross signal in a period including a rising edge of the signal;
The zero-cross signal input by the zero-cross signal generation unit during the invalid period is invalidated, and the zero-cross signal input by the zero-cross signal generation unit during a period other than the invalid period is determined as a zero-cross signal having a normal waveform. Zero-cross signal determining means to detect;
Based on the zero-cross signal of the normal waveform, control signal output means for outputting a control signal for controlling the power supply of the heater to the heater drive unit;
An image forming apparatus comprising: Storage means for storing a data table in which a range of the peak value of the power supply voltage is associated with a set invalid time indicating a time width of the invalid period;
The invalid period determining means extracts the setting invalid time corresponding to the peak value of the power supply voltage detected by the power supply voltage peak detecting means from the data table, and has the extracted setting invalid time. The image forming apparatus according to claim 1, wherein an invalid period is determined. Comprising a frequency detection means for detecting the frequency of the power supply voltage;
The data table is a data table in which the range of the peak value of the power supply voltage, the setting invalid time, and the frequency of the power supply voltage are associated with each other.
The invalid period determination means corresponds to the peak value of the power supply voltage detected by the power supply voltage peak detection means and the frequency of the power supply voltage detected by the frequency detection means from the data table. The image forming apparatus according to claim 2, wherein a setting invalid time is extracted and the invalid period having the extracted setting invalid time is determined.   The invalid period determining means calculates a time width of the invalid period based on a peak value of the power supply voltage detected by the power supply voltage peak detecting means, and determines the invalid period having the calculated time width. The image forming apparatus according to claim 1. Comprising a frequency detection means for detecting the frequency of the power supply voltage;
The invalid period determining unit is configured to determine a time width of the invalid period based on a peak value of the power supply voltage detected by the power supply voltage peak detecting unit and a frequency of the power supply voltage detected by the frequency detecting unit. The image forming apparatus according to claim 4, wherein the invalid period having the calculated time width is determined.   6. The invalid period determining means determines the invalid period in a period from a falling timing of the zero-cross signal to a timing a predetermined time before the next falling. The image forming apparatus according to one. A power supply voltage peak detection step for detecting the peak value of the power supply voltage of the AC power supply that feeds the heater;
A zero cross signal generating step of detecting a zero cross point of the power supply voltage and generating a zero cross signal indicating the detected zero cross point;
According to the peak value of the power supply voltage detected by the power supply voltage peak detection step, after the falling timing of the zero cross signal that changes the timing in accordance with the change of the peak value of the power supply voltage , the zero cross An invalid period determining step for determining an invalid period for invalidating detection of the zero-cross signal in a period including a rising edge of the signal;
A zero-cross signal determining step of invalidating the zero-cross signal input during the invalid period and detecting the zero-cross signal input during a period other than the invalid period as a normal waveform zero-cross signal; and
Based on the zero-cross signal of the normal waveform, a control signal output step of outputting a control signal for controlling the power supply of the heater to the heater drive unit;
A heater control method comprising: In the computer provided in the image forming apparatus,
A power supply voltage peak detection step for detecting the peak value of the power supply voltage of the AC power supply that feeds the heater;
A zero cross signal generating step of detecting a zero cross point of the power supply voltage and generating a zero cross signal indicating the detected zero cross point;
According to the peak value of the power supply voltage detected by the power supply voltage peak detection step, after the falling timing of the zero cross signal that changes the timing in accordance with the change of the peak value of the power supply voltage , the zero cross An invalid period determining step for determining an invalid period for invalidating detection of the zero-cross signal in a period including a rising edge of the signal;
A zero-cross signal determining step of invalidating the zero-cross signal input during the invalid period and detecting the zero-cross signal input during a period other than the invalid period as a normal waveform zero-cross signal; and
Based on the zero-cross signal of the normal waveform, a control signal output step of outputting a control signal for controlling the power supply of the heater to the heater drive unit;
Heater control program for executing

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