Image formation device

Abstract

To determine the kind of a fixation unit without any specific detection part.SOLUTION: An image formation device 1 has an image formation unit 12 which develops and transfers an electrostatic latent image to a medium P to form an image, and a fixation unit 17 which is provided with a fixation belt 30 heating the medium P and a pressure roller 44 pressing the medium P, and the fixation unit 17 consists of a normal fixation unit 17a and an edge-less print fixation unit 17b different from the normal fixation unit 17a, and is provided with a contacting / leaving member 45 which switches between a nip state in which the fixation belt 30 and pressure roller 44 are in contact and a release state in which they are separate, a contacting / leaving state detection sensor 52 which detects a pressure roller support member 46 of the contacting / leaving member 45 in the process of switching between the nip state and release state, a contacting / leaving time measurement part 74 which determines the kind of the fixation unit 17 based upon the detection result of the contacting / leaving state detection sensor 52, and a fixation kind determination part 76.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to an image forming apparatus, and is suitable for application to an electrophotographic printer that discriminates the type of a fixing device, for example.

Background Art

[0002] Conventionally, as an image forming apparatus, based on an image supplied from a computer device or the like, a developer image is formed by an image forming unit using a developer, transferred to a medium such as paper, and fixed by applying heat and pressure thereto, whereby a printing process is performed, and such an apparatus has been widely spread. In such an image forming apparatus, a normal printing fixing device used during normal printing in which an image is formed on a medium with margins and a borderless printing fixing device used during borderless printing in which an image is formed on the entire surface of the medium without margins may be selectively used. Further, in an image forming apparatus, by reading information of an identification unit provided in a fixing device with a discrimination unit which is a detection unit, there has been one that discriminates whether the type of the fixing device currently installed in the image forming apparatus is a normal printing fixing device or a borderless printing fixing device (for example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in order to discriminate the type of the fixing device in such an image forming apparatus, it has been necessary to provide a specific detection unit.

[0005] The present invention has been made in consideration of the above points, and intends to propose an image forming apparatus capable of discriminating the type of a fixing device without providing a specific detection unit.

Means for Solving the Problems

[0006] In order to solve such problems, the image forming apparatus of the present invention includes an image forming unit that develops an electrostatic latent image, transfers it to a medium, and forms an image, a heating unit that heats the medium, and a fixing unit provided with a pressing unit that presses the medium. The fixing unit is composed of a first fixing unit and a second fixing unit different from the first fixing unit, and includes a separating and contacting member that switches between a contacting state where the heating unit and the pressing unit are in contact and a separating state where they are separated, a detecting unit that detects the separating and contacting member during the process of switching between the contacting state and the separating state, and a discriminating unit that discriminates the type of the fixing unit based on the detection result of the detecting unit.

[0007] Accordingly, the present invention can discriminate the type of the fixing unit only by detecting a separating and contacting member that switches between a contacting state and a separating state with a conventionally existing detecting unit.

Advantages of the Invention

[0008] According to the present invention, it is possible to discriminate the type of the fixing unit only by detecting a separating and contacting member that switches between a contacting state and a separating state with a conventionally existing detecting unit, and to realize an image forming apparatus capable of discriminating the type of the fixing unit without providing a specific detecting unit.

Brief Description of the Drawings

[0009]

Figure 1

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Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments for carrying out the invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

[0011] [1. First Embodiment] [1-1. Overall Configuration of Image Forming Apparatus] As shown in FIG. 1, the image forming apparatus 1 is a printer using, for example, an electrophotographic method, and forms a black-and-white image or a color image on a medium P such as paper or film by performing an image forming operation using a developer such as toner. The entire image forming apparatus 1 is comprehensively controlled by a control unit 64 composed of a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). Hereinafter, a position close to the media storage tray 2 or a direction toward the media storage tray 2 as viewed from an arbitrary position on the conveyance path along which the media P is conveyed is referred to as the upstream. Also, a position close to the media stacking tray 18 where the media P is discharged and stacked or a direction toward the media stacking tray 18 as viewed from an arbitrary position on the conveyance path is referred to as the downstream. Further, the direction from the upstream to the downstream is referred to as the conveyance direction G.

[0012] This image forming apparatus 1 is composed of a main body 11 and an openable and closable top cover 20. The top cover 20 is opened with respect to the main body 11 when a jammed medium P is removed, or when the transfer belt 7, the image forming units 12 (image forming units 12K, 12C, 12M, and 12Y), and the fixing unit 17 are replaced.

[0013] The media storage tray 2 is detachably mounted at the lower part inside the main body 11 and stores the media P in a stacked state. The pickup roller 4 separates and takes out the media P stored in the media storage tray 2 one by one from the topmost part thereof, and feeds it out along the media conveyance path 3 toward the conveyance roller pair 5a located downstream thereof. The conveyance roller pairs 5a and 5b sandwich and convey the media P fed out from the pickup roller 4 and convey it along the conveyance direction G toward the transfer unit 6.

[0014] The transfer unit 6 includes a transfer belt 7, a belt support roller 8, a belt drive roller 9, and a transfer roller 10 corresponding to each image forming unit 12. The transfer belt 7 is an endless belt and is stretched by the belt drive roller 9 and the belt support roller 8. The belt drive roller 9 is rotated by a motor (not shown) and rotates the transfer belt 7 counterclockwise in FIG. 1. The belt support roller 8 is a driven roller and rotates following the transfer belt 7. Thereby, while the toner image is transferred onto the medium P by the image forming units 12 (12K, 12C, 12M, and 12Y), the transfer unit 6 rotates the transfer belt 7 to convey the medium P conveyed along the medium conveyance path 3 to the fixing unit 17 along the medium conveyance path 3.

[0015] The image forming units 12K, 12C, 12M, and 12Y are arranged in order along the conveyance direction G from the upstream side to the downstream side, and form developer images (toner images) on the medium P using toners (developers) of different colors. Specifically, the image forming units 12K, 12C, 12M, and 12Y form toner images of black, cyan, magenta, and yellow colors using toners of black (K), cyan (C), magenta (M), and yellow (Y), respectively. The image forming units 12K, 12C, 12M, and 12Y have the same configuration except that they form toner images using toners of different colors of black, cyan, magenta, and yellow, respectively. Hereinafter, the image forming units 12K, 12C, 12M, and 12Y are also collectively referred to as the image forming unit 12.

[0016] The transfer rollers 10 are provided one by one according to each of the image forming units 12K, 12C, 12M, and 12Y, and a plurality of them are arranged so as to face each of the photosensitive drums 19 of the image forming units 12K, 12C, 12M, and 12Y with the transfer belt 7 interposed therebetween. The plurality of transfer rollers 10 have substantially the same configuration. This transfer roller 10 electrostatically transfers the toner images of each color formed in the image forming units 12K, 12C, 12M, and 12Y onto the medium P. In addition, the image forming units 12C, 12M, and 12Y each including a photosensitive drum 19 other than the image forming unit 12K are separated from the transfer rollers 10, that is, from the transfer unit 6, by a certain distance upward by moving upward from the transfer rollers 10 during monochrome printing.

[0017] The toner image formed on the photosensitive drum 19 is transferred to the medium P conveyed by the transfer belt 7 on the medium conveyance path 3. The fixing device 17 applies heat and pressure to the toner image on the medium P conveyed from the transfer belt 7, fixes the toner image to the medium P, and feeds it out along the medium conveyance path 3 toward the conveyance roller pair 5c. The conveyance roller pairs 5c, 5d, and 5e sandwich the medium P and convey it through the medium conveyance path 3, and discharge and accumulate it in the medium stacking tray 18 formed on the upper surface of the main body 11. Hereinafter, the conveyance roller pairs 5a, 5b, 5c, 5d, and 5e are collectively referred to as the conveyance roller pair 5.

[0018] On the medium conveyance path 3, a writing sensor 21 and a discharge sensor 22, which are sensors for detecting the presence or absence of the medium P, are provided. The writing sensor 21 is installed near the upstream side of the image forming unit 12K, detects the medium P reaching the image forming unit 12K, and notifies the control unit 64 of the detection result. The discharge sensor 22 is installed near the downstream side of the fixing device 17, detects the medium P discharged from the fixing device 17, and notifies the control unit 64 of the detection result. The control unit 64 recognizes various timings such as the exposure timing and the timing for applying a high voltage based on the detection results obtained from the writing sensor 21 and the discharge sensor 22.

[0019] In the vicinity of the top cover 20 in the closed state, a top cover sensor 23 is provided. The top cover sensor 23 detects the top cover 20 and notifies the detection result to the control unit 64. The control unit 64 recognizes the open / closed state of the top cover 20 based on the detection result obtained from the top cover sensor 23.

[0020] [1-2. Configuration of the fixing device] The fixing device 17 is a belt heating type device, and either the normal fixing device 17a shown in Fig. 2(A) or the borderless printing fixing device 17b shown in Fig. 2(B) is used. The same reference numerals are assigned to the same components in the normal fixing device 17a (Fig. 2(A)) and the borderless printing fixing device 17b (Fig. 2(B)). Hereinafter, the normal fixing device 17a and the borderless printing fixing device 17b are collectively referred to as the fixing device 17.

[0021] [1-2-1. Configuration of the normal fixing device] As shown in Fig. 2(A), the normal fixing device 17a includes a fixing belt 30, a fixing roller 32, a guide roller 34, a plate heater 36, a pressure pad 38, a guide member 40, a fixing belt temperature detection sensor 42, a pressure roller 44, a normal fixing device contact / separation member 45a, a pressure roller temperature detection sensor 50, and a contact / separation state detection sensor 52.

[0022] The fixing belt 30 is a belt member disposed above the medium conveyance path 3, is stretched by the plate heater 36 and the pressure pad 38, and is guided by the fixing roller 32, the guide roller 34, the plate heater 36, and the guide member 40. This fixing belt 30 rotates following the fixing roller 32 by the friction at the contact surface with the fixing roller 32 while being heated by the plate heater 36.

[0023] The fixing roller 32 is arranged at the front end of the lower end part on the inner peripheral surface side of the fixing belt 30, and is composed of a core metal part made of a pipe or a shaft and a heat-resistant elastic layer provided on the outer peripheral side of the core metal part. Both ends of the core metal part are supported by a sheet metal (not shown) via a rotary bearing (not shown). An activation gear (not shown) is provided at one end of the core metal part, and the fixing roller 32 rotates when a driving force is transmitted from the activation gear.

[0024] The guide roller 34 is arranged at the rear end of the lower end part on the inner peripheral surface side of the fixing belt 30, and is composed of a core metal part made of a pipe or a shaft and a heat-resistant elastic layer provided on the outer peripheral side of the core metal part. This guide roller 34 rotates following the rotation of the fixing belt 30.

[0025] The plate-shaped heater 36 is arranged closer to the upper side on the inner peripheral surface side of the fixing belt 30, and is a heat source that generates heat by passing an electric current through a resistance wire in a plate-shaped substrate and heats the fixing belt 30. This plate-shaped heater 36 is configured such that a power source and a control circuit are connected to the resistance wire by a connector (not shown), enabling heat generation at an arbitrary timing. Further, the plate-shaped heater 36 is pressed upward by a biasing member such as a compression coil spring with a pressing force f1, and generates heat while diffusing the heat.

[0026] The pressure pad 38 is arranged to contact the inner peripheral surface of the fixing belt 30 closer to the lower side on the inner peripheral surface side of the fixing belt 30, and is composed of a support base material, a heat-resistant elastic material adhesively fixed to the support base material, and a sliding layer formed on the surface of the heat-resistant elastic material. This pressure pad 38 is pressed downward by a biasing member such as a compression coil spring with a pressing force f2, and presses the fixing belt 30 toward the pressing roller 44.

[0027] The guide member 40 is arranged closer to the rear side on the inner peripheral surface side of the fixing belt 30, and guides the driving of the fixing belt 30 together with the fixing roller 32, the guide roller 34, and the plate-shaped heater 36.

[0028] The fixing belt temperature detection sensor 42 is arranged on the inner peripheral surface side of the fixing belt 30, is composed of a thermistor or the like, detects the temperature near the fixing belt 30, and notifies the detection result to the control unit 64 (Fig. 1). In this embodiment, the image forming apparatus 1 is provided with the fixing belt temperature detection sensor 42 on the inner peripheral surface side of the fixing belt 30, but it may be provided on the outer peripheral surface side of the fixing belt 30.

[0029] The pressure roller 44 is arranged below the medium conveyance path 3, and is composed of a core metal part made of a pipe or a shaft and a heat-resistant elastic layer provided on the outer peripheral side of the core metal part. Both ends of the core metal part are supported by a pressure roller support member 46 via a rotation bearing (not shown). This pressure roller 44 is pressed toward the fixing roller 32 with the fixing belt 30 interposed therebetween, and rotates following the fixing belt 30.

[0030] The normal fixing device contact / separation member 45a is composed of a pressure roller support member 46 and a normal fixing device cam member 47a. The pressure roller support member 46 as a shielding member and a pressure part support member is formed with a pressure roller support part 46h and a contact part 46t as schematically shown by a broken line, and is configured to be rotatable about a pressure roller support member rotation center 46x provided at the lower end of the front end. The pressure roller support part 46h is formed below the pressure roller support member 46 and supports the rotation shaft of the pressure roller 44. The contact part 46t extends linearly upward from the pressure roller support part 46h and contacts the normal fixing device cam 48a. The front end of a compression spring (not shown) whose rear end is fixed to the frame is fixed to the contact part 46t. This compression spring biases the contact part 46t with a pressing force f3 so that the pressure roller support member 46 rotates in the pressing rotation direction which is clockwise in Fig. 2 about the pressure roller support member rotation center 46x. Therefore, the compression spring biases the pressure roller support member 46 in the direction of pressing the pressure roller 44 supported by the pressure roller support member 46 toward the fixing roller 32.

[0031] Normally, the fixing cam member 47a is composed of a fixing cam 48a and a camshaft 48s for normal fixing. The fixing cam 48a for normal fixing is provided at a position facing the compression spring with the contact portion 46t of the pressure roller support member 46 interposed therebetween. The fixing cam 48a for normal fixing is supported by a frame (not shown) with the camshaft 48s inserted and fixed in the cam rotation shaft hole 48h, and is configured to be rotatable about the camshaft 48s by driving a camshaft drive motor based on the control of the fixing separation control unit 72 (FIG. 5). Further, the fixing cam 48a for normal fixing has its rotation angle switched when the camshaft drive motor rotates the camshaft 48s. Furthermore, the fixing cam 48a for normal fixing has a protruding portion 48p protruding on one side (front lower side in FIG. 2) about the cam rotation shaft hole 48h, and a non-protruding portion 48d that does not protrude more than the protruding portion 48p on the other side (other than the front lower side in FIG. 2) about the cam rotation shaft hole 48h, and is an eccentric cam centered on the cam rotation shaft hole 48h as a whole.

[0032] When the fixing cam 48a for normal fixing is in the rotation position shown in FIG. 2(A), the non-protruding portion 48d faces the contact portion 46t of the pressure roller support member 46, and the fixing cam 48a for normal fixing is separated from the contact portion 46t. In this state, the pressure roller 44 is pressed against the fixing roller 32 and the pressure pad 38, and a fixing nip portion N is formed between the pressure roller 44, the fixing roller 32, and the pressure pad 38. Hereinafter, the state where the pressure roller 44 is pressed toward the fixing roller 32 and the pressure pad 38 in this way is also referred to as a nip state. In this nip state, the distance between a predetermined position at the contact portion 46t of the pressure roller support member 46 and the center of the cam rotation shaft hole 48h, which is the distance between the support member and the cam shaft hole, is shorter than that in the release state (described later).

[0033] On the one hand, as shown in FIG. 3(A), when the cam 48a for the normal fixing device is in a rotational position rotated, for example, 180 degrees from FIG. 2(A), the protruding portion 48p faces the contact portion 46t of the pressure roller support member 46, and the cam 48a for the normal fixing device is in contact with the contact portion 46t, compressing the compression spring and rotating the pressure roller support member 46 in the separation rotation direction opposite to the pressing rotation direction from the nip state. In this state, compared with the nip state, the pressure roller 44 moves in a direction away from the fixing roller 32 and the pressure pad 38, and the nip formation between the pressure pad 38 and the pressure roller 44 is released. Hereinafter, the state where the pressure roller 44 is separated from the pressure pad 38 and there is no pressing from the pressure roller 44 to the pressure pad 38 is also referred to as the release state. When the separation operation is thus performed and the state shifts from the nip state to the release state, the distance between the support member cam shaft holes becomes longer than that in the nip state.

[0034] The pressure roller temperature detection sensor 50 is arranged on the outer peripheral surface side of the pressure roller 44, is composed of a thermistor or the like, detects the temperature near the pressure roller 44, and notifies the control unit 64 (FIG. 1) of the detection result.

[0035] The contact / separation state detection sensor 52 is arranged near the contact portion 46t of the pressure roller support member 46, is, for example, an optical sensor, and is composed of a light emitting portion that emits detection light and a light receiving portion that receives the detection light. This contact / separation state detection sensor 52 notifies the control unit 64 (FIG. 1) of the light receiving result of the detection light. Specifically, when the release state is reached and the pressure roller support member 46 crosses the detection light, the contact / separation state detection sensor 52 notifies the control unit 64 (FIG. 1) of a light receiving result (that is, the L level) indicating that the detection light is blocked by the pressure roller support member 46 and the detection light is not received. On the other hand, when the nip state is reached and the pressure roller support member 46 does not cross the detection light, the contact / separation state detection sensor 52 notifies the control unit 64 (FIG. 1) of a light receiving result (that is, the H level) indicating that the detection light is received. Based on this light receiving result, the control unit 64 determines whether the current pressure state of the fixing nip portion N is in the nip state or the release state.

[0036] In this way, in the fixing device 17, in the nip state, the pressure roller 44 presses the fixing roller 32 and the pressure pad 38 via the fixing belt 30 to form a fixing nip portion N. In the fixing nip portion N, heat and pressure are applied when the medium P onto which the toner image has been transferred passes through, and the fixing of the toner image is performed. On the other hand, in the release state of the fixing device 17, the pressure roller 44 does not press the fixing roller 32 and the pressure pad 38, and the deformation of the fixing belt 30 due to the continuous pressing of the pressure roller 44 on the fixing belt 30 is prevented.

[0037] [1-2-2. Configuration of the edge-less printing fixing device] As shown in Fig. 2(B) in which the same components as those in Fig. 2(A) are given the same reference numerals, the edge-less printing fixing device 17b is different from the normal fixing device 17a in that an edge-less printing fixing device separating and contacting member 45b is provided instead of the normal fixing device separating and contacting member 45a, and a fixing belt cleaning roller 54 and a pressure roller cleaning roller 56 are added. However, in other respects, it is similarly configured. The edge-less printing fixing device separating and contacting member 45b is different from the normal fixing device separating and contacting member 45a in that an edge-less printing fixing device cam member 47b is provided instead of the normal fixing device cam member 47a. However, in other respects, it is similarly configured. The edge-less printing fixing device cam member 47b is different from the normal fixing device cam member 47a in that an edge-less printing fixing device cam 48b is provided instead of the normal fixing device cam 48a. However, in other respects, it is similarly configured. Hereinafter, the normal fixing device separating and contacting member 45a and the edge-less printing fixing device separating and contacting member 45b are collectively referred to as the separating and contacting member 45, and the normal fixing device cam 48a and the edge-less printing fixing device cam 48b are collectively referred to as the cam 48.

[0038] The edge-less printing fixing device cam 48b has a different shape from the normal fixing device cam 48a, and the details will be described later. The fixing belt cleaning roller 54 cleans the residual toner attached to the fixing belt 30. The pressure roller cleaning roller 56 cleans the residual toner attached to the pressure roller 44.

[0039] When the cam 48b for the borderless printing fixing device is in the rotational position shown in Fig. 2(B), the non-projecting portion 48d faces the contact portion 46t of the pressure roller support member 46, and when the cam 48b for the borderless printing fixing device separates from the contact portion 46t, it is in the nip state. On the other hand, as shown in Fig. 3(B), when the cam 48b for the borderless printing fixing device is in the rotational position rotated, for example, 180 degrees from Fig. 3(A), the projecting portion 48p faces the contact portion 46t of the pressure roller support member 46, and the cam 48b for the borderless printing fixing device is in contact with the contact portion 46t. By compressing the compression spring and rotating the pressure roller support member 46 in the separating rotation direction from the nip state, it is in the release state.

[0040] [1-3. Configuration of the cam member] [1-3-1. Configuration of the cam member for the normal fixing device] As shown in Fig. 4(A), when the cam 48a for the normal fixing device is set to 0[°] with the direction straight down as the reference when viewed in the rotation angle range, the projecting portion 48p is formed in the rotation angle range from 0[°] to 90[°] in the counterclockwise direction, and the non-projecting portion 48d is formed in the rotation angle range from 90[°] to 360[°](0[°]) in the counterclockwise direction. Therefore, during one rotation (i.e., 360[°] rotation) of the cam 48a for the normal fixing device, the rotation angle range of 90[°] is in the release state, and the remaining rotation angle range of 270[°] is in the nip state for the normal fixing device 17a.

[0041] [1-3-2. Configuration of the cam member for the borderless printing fixing device] On the other hand, as shown in FIG. 4(B), for the cam 48b for the borderless printing fixing device, when the direction straight down is taken as 0[°] with respect to the rotation angle range, the protruding portion 48p is formed over the rotation angle range from 0[°] to 105[°] in the counterclockwise direction, and the non-protruding portion 48d is formed over the rotation angle range from 105[°] to 360[°](0[°]) in the counterclockwise direction. Therefore, in the borderless printing fixing device 17b, within one rotation of the cam 48b for the borderless printing fixing device, the rotation angle range of 105[°] is in the release state, and the remaining rotation angle range of 255[°] is in the nip state.

[0042] [1-4. Control Configuration of Image Forming Apparatus] As shown in FIG. 5, the image forming apparatus 1 includes a receiving unit 62, a control unit 64, and an operation display unit 79, and the control unit 64 performs overall control. The receiving unit 62 receives the print data transmitted from the PC (Personal Computer) 60 and notifies the control unit 64. The control unit 64 includes an image control unit 66, a conveyance control unit 68, a fixing temperature control unit 70, a fixing contact / separation control unit 72, a contact / separation time measurement unit 74, a fixing type determination unit 76, and a mounting check unit 78.

[0043] The image control unit 66 forms an image on the medium P by controlling the image forming unit 12 and the transfer belt 7. The conveyance control unit 68 conveys the medium P by controlling the pickup roller 4 and the pair of conveyance rollers 5. The fixing temperature control unit 70 fixes the toner image on the medium P by controlling the fuser 17. The fixing separation contact control unit 72 controls the pressure state of the fixing nip portion N by driving the camshaft drive motor to rotate the camshaft 48s and the cam 48. The separation contact time measurement unit 74 measures the time during which the L level (release state) or the H level (nip state) continues in the detection result of the separation contact state detection sensor 52 when the cam 48 makes one rotation. The fixing type determination unit 76 discriminates the shape of the cam 48 based on the measurement result of the separation contact time measurement unit 74, and determines whether the fixing type of the fuser 17 is the normal fuser 17a or the edge-free printing fuser 17b. The mounting check unit 78 as the mounting confirmation unit checks whether the fuser 17 is correctly mounted on the image forming apparatus 1 when the power of the image forming apparatus 1 is turned on or when the top cover 20 is opened and closed.

[0044] The operation display unit 79 is an operation panel composed of an input unit such as an operation button for receiving an input operation of an operator and a display unit such as a display, displays the operation state of the image forming apparatus 1, and provides an interface for menu operations to the user.

[0045] [1-5. Method for Determining Fixing Device Type] When the image forming apparatus 1 measures the release time, which is the time during which the release state continues when the cam 48 is rotated one full circle (0[°] to 360[°]) (i.e., rotated once) in the fuser mounting check processing procedure SRT1 (Figs. 8 and 9) described later, and compares the measured release time with a predetermined release time threshold, if the release time is equal to or greater than the release time threshold, the edge-free printing fuser 17b is detected as the fuser 17, that is, it is determined that the fixing device type is the edge-free printing fuser 17b. On the other hand, when the release time of the image forming apparatus 1 is less than the release time threshold, the normal fuser 17a is detected as the fuser 17, that is, it is determined that the fixing device type is the normal fuser 17a.

[0046] Also, in the fixing device mounting check processing procedure SRT1 (Figs. 8 and 9) described later, when the image forming apparatus 1 measures the nip time, which is the time during which the nip state continues when the cam 48 is rotated once, the measured nip time is compared with a predetermined nip time threshold. If the nip time is equal to or greater than the nip time threshold, it is determined that the fixing device type is the normal fixing device 17a. On the other hand, if the nip time is less than the nip time threshold, the image forming apparatus 1 determines that the fixing device type is the borderless printing fixing device 17b.

[0047] Here, the nip time threshold and the release time threshold will be described. Fig. 6 shows the output waveforms of the detection results of the contact / separation state detection sensor 52 in the normal fixing device 17a and the borderless printing fixing device 17b when the cam 48 rotates once. The contact / separation state detection sensor 52 outputs a high-level signal in the nip state and a low-level signal in the release state.

[0048] As described above, the normal fixing device 17a (Fig. 2(A)) is provided with a normal fixing device cam 48a (Fig. 4(A)), and the borderless printing fixing device 17b (Fig. 2(B)) is provided with a borderless printing fixing device cam 48b (Fig. 4(B)). Regarding the rotation angle range of the cam 48, the normal fixing device 17a is in the release state in the range of (0° to 90°), and the borderless printing fixing device 17b is in the release state in the range of (0° to 105°). In the present embodiment, since the cam 48 is rotated one full turn in a predetermined cam one-rotation time (for example, 2700 [ms]), in the normal fixing device 17a, during one rotation of the normal fixing device cam 48a, the release state continues for 675 [ms], and the nip state continues for 2025 [ms]. Therefore, the normal fixing device 17a has a release time of 675 [ms] and a nip time of 2025 [ms]. Similarly, for the borderless printing fixing device 17b, during one rotation of the borderless printing fixing device cam 48b, the release state continues for 787 [ms], and the nip state continues for 1913 [ms]. Therefore, the borderless printing fixing device 17b has a release time of 787 [ms] and a nip time of 1913 [ms].

[0049] Therefore, the image forming apparatus 1 sets the average value of the release time of the normal fixing device 17a and the release time of the borderless printing fixing device 17b as the release time threshold. That is, the release time threshold = (675 [ms] + 787 [ms]) / 2 = 731 [ms]. Further, the image forming apparatus 1 sets the average value of the nip time of the normal fixing device 17a and the nip time of the borderless printing fixing device 17b as the nip time threshold. That is, the nip time threshold = (2025 [ms] + 1913 [ms]) / 2 = 1969 [ms].

[0050] [1-6. Printing process] Regarding the specific processing procedure of the printing process by the image forming apparatus 1, it will be described using the flowchart of FIG. 7. When the power of the image forming apparatus 1 is turned on, the control unit 64 reads out a printing process program from a storage unit (not shown) and executes it to start the printing process procedure RT1, and moves to step SP1.

[0051] In step SP1, the control unit 64 checks whether the top cover 20 is opened or closed by the mounting check unit 78, and determines whether the top cover 20 has been opened or closed when the power of the image forming apparatus 1 is OFF. Note that the control unit 64 operates even when the power of the image forming apparatus 1 is OFF if the image forming apparatus 1 is connected to a commercial power supply. If an affirmative result is obtained here, this indicates that it is necessary to check the mounting of the fixing device 17 because the top cover 20 may have been opened or closed and the fixing device 17 may have been detached. At this time, the control unit 64 moves to step SP2. In step SP2, the control unit 64 performs a fixing device mounting check process by executing a fixing device mounting check process procedure SRT1 (described later) shown in FIGS. 8 and 9, and moves to step SP3.

[0052] In step SP3, the control unit 64 determines whether there is a fixing device mounting error indicating that the fixing device 17 is not correctly mounted on the image forming apparatus 1 through the fixing device mounting check process in the fixing device mounting check process procedure SRT1. If an affirmative result is obtained here, this indicates that there is a fixing device mounting error, and at this time, the control unit 64 moves to step SP4. In step SP4, the control unit 64 notifies the user that there is a fixing device mounting error by displaying a fixing device mounting error screen indicating that there is a fixing device mounting error on the display unit of the operation display unit 79, then moves to step SP12, and ends the printing process procedure RT1.

[0053] On the other hand, if a negative result is obtained in step SP3, this indicates that there is no fixing device mounting error, and at this time, the control unit 64 moves to step SP5. Also, if a negative result is obtained in step SP1, this indicates that since the top cover 20 is not opened or closed and there is no possibility of detaching the fixing device 17, there is no need to check the mounting of the fixing device 17, and at this time, the control unit 64 moves to step SP5. In step SP5, the control unit 64 waits for the reception unit 62 to receive print data from the PC60, and when the print data is received, it moves to step SP6.

[0054] In step SP6, the control unit 64 performs printing preparation by changing the fixing device 17 from the release state to the nip state by the fixing release contact control unit 72, and then moves to step SP7. In step SP7, the control unit 64 executes the fixing control process procedure SRT2 (described later) shown in FIG. 10 to perform different fixing control processes according to the fixing device type to make the fixing device 17 in a printable state, and then moves to step SP8.

[0055] In step SP8, the control unit 64 starts conveyance control by the conveyance control unit 68, feeds only one sheet of the medium P from the medium storage tray 2, and sends it out to the medium conveyance path 3, then proceeds to step SP9. In step SP9, the control unit 64 starts image control by the image control unit 66. When the leading edge of the medium P passes the writing sensor 21, it controls the transfer belt 7 and the image forming unit 12 to start image formation, and then proceeds to step SP10.

[0056] In step SP10, the control unit 64 determines whether there is still print data for a plurality of pages to be printed. If an affirmative result is obtained here, at this time the control unit 64 returns to step SP8 and repeats the above-described steps SP8 and SP9 until there is no more print data. When there is no more print data, the control unit 64 obtains a negative result in step SP10 and proceeds to step SP11.

[0057] In step SP11, the control unit 64 releases the fixing device 17 by the fixing separation contact control unit 72 to complete printing, then proceeds to step SP12 and ends the printing process procedure RT1.

[0058] [1-6-1. Fixing Device Mounting Check Process] Next, the specific process procedure of the fixing device mounting check process by the image forming apparatus 1 will be described using the flowcharts shown in FIGS. 8 and 9. The control unit 64 starts the fixing device mounting check process procedure SRT1 (FIG. 8) in step SP2 of the printing process procedure RT1 (FIG. 7) and proceeds to step SP21.

[0059] In step SP21, the control unit 64 starts the rotation of the cam 48 for one revolution by the fixing separation control unit 72 and proceeds to step SP22. This is to confirm whether the fixing device 17 is correctly installed in the image forming apparatus 1. When the fixing device 17 is correctly installed in the image forming apparatus 1, the pressure roller support member 46 rotates due to the rotation of the cam 48, and the pressure state of the fixing nip portion N based on the detection result of the separation / detection sensor 52 changes from the nip state to the release state, or from the release state to the nip state. On the other hand, when the fixing device 17 is not correctly installed in the image forming apparatus 1, the gear that rotates the cam 48 idles and the cam 48 does not rotate, so the detection result of the separation / detection sensor 52 does not change.

[0060] In step SP22, the control unit 64 checks the current state of the fixing device 17 by the mounting check unit 78 based on the detection result of the separation / detection sensor 52 and determines whether it is in the release state or the nip state. When the current fixing device 17 is in the release state, the control unit 64 proceeds to step SP23.

[0061] In step SP23, the control unit 64 determines by the mounting check unit 78 whether or not a cam one-rotation time (for example, 2700 [ms]), which is the time required for the cam 48 to make one rotation after starting the rotation of the cam 48, has elapsed. If a negative result is obtained here, this indicates that the cam one-rotation time has not yet elapsed since the start of the rotation of the cam 48. At this time, the control unit 64 proceeds to step SP24.

[0062] In step SP24, the control unit 64 determines by the mounting check unit 78 whether or not the fixing device 17 has changed from the release state to the nip state. If a negative result is obtained here, this indicates that the fixing device 17 has not changed from the release state to the nip state and remains in the release state. At this time, the control unit 64 returns to step SP23.

[0063] After starting the rotation of the cam 48, if one rotation time of the cam elapses before the fixing device 17 changes from the release state to the nip state, this indicates that the pressure roller support member 46 does not rotate even when the camshaft drive motor is driven because the fixing device 17 is not properly installed in the image forming apparatus 1. At this time, the control unit 64 obtains an affirmative result in step SP23 and moves to step SP43 (FIG. 9).

[0064] On the other hand, if the fixing device 17 changes from the release state to the nip state before one rotation time of the cam elapses after starting the rotation of the cam 48, the control unit 64 obtains an affirmative result in step SP24 and moves to step SP25. In step SP25, the control unit 64 starts measuring the nip time by the contact / separation time measurement unit 74 and moves to step SP26.

[0065] In step SP26, the control unit 64 determines whether one rotation time of the cam has elapsed since starting the rotation of the cam 48 by the mounting check unit 78. If a negative result is obtained here, this indicates that one rotation time of the cam has not elapsed since starting the rotation of the cam 48. At this time, the control unit 64 moves to step SP27.

[0066] In step SP27, the control unit 64 determines whether the fixing device 17 has changed from the nip state to the release state by the mounting check unit 78. If a negative result is obtained here, this indicates that the fixing device 17 has not changed from the nip state to the release state and remains in the nip state. At this time, the control unit 64 returns to step SP26.

[0067] After starting the rotation of the cam 48, if the fixing device 17 once changes from the release state to the nip state and then one rotation time of the cam elapses before changing from the nip state to the release state, this indicates that the pressure roller support member 46 does not rotate even when the camshaft drive motor is driven because the fixing device 17 is not properly installed in the image forming apparatus 1. At this time, the control unit 64 obtains an affirmative result in step SP26 and moves to step SP43 (FIG. 9).

[0068] On the other hand, before the elapse of the time for one rotation of the cam 48 after starting the rotation of the cam 48, when the fixing device 17 once changes from the release state to the nip state and then changes from the nip state to the release state, the control unit 64 obtains an affirmative result in step SP27 and moves to step SP28. In step SP28, the control unit 64 ends the measurement of the nip time by the contact / separation time measurement unit 74 and moves to step SP35.

[0069] On the other hand, in step SP22, when the current fixing device 17 is in the nip state, the control unit 64 moves to step SP29.

[0070] In step SP29, the control unit 64 determines by the mounting check unit 78 whether or not the time for one rotation of the cam has elapsed after starting the rotation of the cam 48. If a negative result is obtained here, this indicates that the time for one rotation of the cam has not yet elapsed after starting the rotation of the cam 48. At this time, the control unit 64 moves to step SP30.

[0071] In step SP30, the control unit 64 determines by the mounting check unit 78 whether or not the fixing device 17 has changed from the nip state to the release state. If a negative result is obtained here, this indicates that the fixing device 17 has not changed from the nip state to the release state and remains in the nip state. At this time, the control unit 64 returns to step SP29.

[0072] When the time for one rotation of the cam elapses before the fixing device 17 changes from the nip state to the release state after starting the rotation of the cam 48, this indicates that the pressure roller support member 46 does not rotate even when the camshaft drive motor is driven because the fixing device 17 is not correctly mounted on the image forming apparatus 1. At this time, the control unit 64 obtains an affirmative result in step SP29 and moves to step SP43 (FIG. 9).

[0073] On one hand, if the fixing device 17 changes from the nip state to the release state before the elapse of the time for one rotation of the cam 48 after starting the rotation of the cam 48, the control unit 64 obtains an affirmative result in step SP30 and moves to step SP31. In step SP31, the control unit 64 starts measuring the release time by the contact separation time measurement unit 74 and moves to step SP32.

[0074] In step SP32, the control unit 64 determines whether or not the time for one rotation of the cam 48 has elapsed since starting the rotation of the cam 48 by the mounting check unit 78. If a negative result is obtained here, this indicates that the time for one rotation of the cam 48 has not yet elapsed since starting the rotation of the cam 48. At this time, the control unit 64 moves to step SP33.

[0075] In step SP33, the control unit 64 determines whether or not the fixing device 17 has changed from the release state to the nip state by the mounting check unit 78. If a negative result is obtained here, this indicates that the fixing device 17 has not changed from the release state to the nip state and remains in the release state. At this time, the control unit 64 returns to step SP32.

[0076] After starting the rotation of the cam 48, if the fixing device 17 once changes from the nip state to the release state, and then the time for one rotation of the cam elapses before it changes from the release state to the nip state, this indicates that the pressure roller support member 46 does not rotate even when the camshaft drive motor is driven because the fixing device 17 is not correctly mounted on the image forming apparatus 1. At this time, the control unit 64 obtains an affirmative result in step SP32 and moves to step SP43 (FIG. 9).

[0077] On the other hand, before the time for one rotation of the cam 48 elapses after starting the rotation of the cam 48, when the fixing device 17 once changes from the nip state to the release state and then changes from the release state to the nip state, the control unit 64 obtains an affirmative result in step SP33 and moves to step SP34. In step SP34, the control unit 64 ends the measurement of the release time by the contact separation time measurement unit 74 and moves to step SP35.

[0078] When the measurement of the nip time or the release time is completed, in step SP35, the control unit 64 stops the rotation of the cam 48 by the fixing contact control unit 72 and moves to step SP36 (FIG. 9). In step SP36, the control unit 64 determines by the fixing type determination unit 76 whether the nip time or the release time was measured. When the release time was measured, the control unit 64 moves to step SP37.

[0079] In step SP37, the control unit 64 determines by the fixing type determination unit 76 whether the release time is equal to or greater than the release time threshold (731 [ms]). When an affirmative result is obtained here, the control unit 64 moves to step SP38. In step SP38, the control unit 64 detects the edge-less printing fixing device 17b as the fixing device 17, that is, the fixing type determination unit 76 determines that the fixing device type is the edge-less printing fixing device 17b, moves to step SP44, ends the fixing device mounting check processing procedure SRT1, and moves to step SP3 in the printing processing procedure RT1 (FIG. 7).

[0080] On the other hand, when a negative result is obtained in step SP37, the control unit 64 moves to step SP39. In step SP39, the control unit 64 detects the normal fixing device 17a as the fixing device 17, that is, the fixing type determination unit 76 determines that the fixing device type is the normal fixing device 17a, moves to step SP44, ends the fixing device mounting check processing procedure SRT1, and moves to step SP3 in the printing processing procedure RT1 (FIG. 7).

[0081] On the one hand, when it is determined in step SP36 that the nip time has been measured, the control unit 64 proceeds to step SP40. In step SP40, the control unit 64 determines whether the nip time is equal to or greater than the nip time threshold value (1969 [ms]) by means of the fixing type determination unit 76. If an affirmative result is obtained here, the control unit 64 proceeds to step SP41. In step SP41, the control unit 64 detects the normal fixing unit 17a as the fixing unit 17, that is, the fixing type determination unit 76 determines that the fixing unit type is the normal fixing unit 17a, and then proceeds to step SP44, terminating the fixing unit mounting check processing procedure SRT1 and proceeding to step SP3 in the printing processing procedure RT1 (Fig. 7).

[0082] On the other hand, if a negative result is obtained in step SP40, the control unit 64 proceeds to step SP42. In step SP40, the control unit 64 detects the edge-free printing fixing unit 17b as the fixing unit 17, that is, the fixing type determination unit 76 determines that the fixing unit type is the edge-free printing fixing unit 17b, and then proceeds to step SP44, terminating the fixing unit mounting check processing procedure SRT1 and proceeding to step SP3 in the printing processing procedure RT1 (Fig. 7).

[0083] Furthermore, on the other hand, in step SP43, the control unit 64 determines that there is a fixing unit mounting error by means of the mounting check unit 78, and then proceeds to step SP44, terminating the fixing unit mounting check processing procedure SRT1 and proceeding to step SP3 in the printing processing procedure RT1 (Fig. 7).

[0084] [1-6-2. Fixing Control Processing] Next, the specific processing procedure of the fixing control processing by the image forming apparatus 1 will be described with reference to the flowchart shown in Fig. 10. The control unit 64 starts the fixing control processing procedure SRT2 (Fig. 10) in step SP7 of the printing processing procedure RT1 (Fig. 7) and proceeds to step SP51.

[0085] In step SP51, the control unit 64 sets the target temperatures of the fixing belt 30 and the pressure roller 44 by the fixing temperature control unit 70 in order to perform the fixing operation during printing, and then proceeds to step SP52. The fixing temperature control unit 70 sets, for example, the target temperature of the fixing belt 30 to 150 [°C] and the target temperature of the pressure roller 44 to 10 [°C] or higher.

[0086] In step SP52, the control unit 64 determines by the fixing temperature control unit 70 whether the fixing device type is the normal fixing device 17a or the borderless printing fixing device 17b. If the fixing device type is the normal fixing device 17a, the control unit 64 proceeds to step SP53. In step SP53, the control unit 64 corrects the normal fixing device 17a by setting the correction value of the normal fixing device 17a by the fixing temperature control unit 70, and then proceeds to step SP55.

[0087] On the other hand, in step SP52, if the fixing device type is the borderless printing fixing device 17b, the control unit 64 proceeds to step SP54. In step SP54, the control unit 64 corrects the borderless printing fixing device 17b by setting the correction value of the borderless printing fixing device 17b by the fixing temperature control unit 70, and then proceeds to step SP55.

[0088] Fig. 11 shows the target temperature correction table TB for each fixing device type. In the case of the normal fixing device 17a, the fixing temperature control unit 70 corrects, for example, the target temperature of the fixing belt 30 by +5 [°C] and continues the correction for 1000 [ms], and does not correct the pressure roller 44. On the other hand, in the case of the borderless printing fixing device 17b, since heat is taken away by the fixing belt cleaning roller 54 and the pressure roller cleaning roller 56, the heat capacity becomes larger than that of the normal fixing device 17a, and the characteristics such as temperature rise are different from those of the normal fixing device 17a. Therefore, different corrections are required. For this reason, the fixing temperature control unit 70 corrects so as to increase the target temperature more than that of the normal fixing device 17a. The fixing temperature control unit 70 corrects, for example, the target temperature of the fixing belt 30 by +8 [°C], continues the correction for 2000 [ms], and corrects the target temperature of the pressure roller 44 by +30 [°C].

[0089] In the case of this embodiment, the pressure roller 44 has no heat source and is heated by the fixing belt 30. Therefore, the image forming apparatus 1 does not set the time for continuing the correction for the pressure roller 44. If the image forming apparatus 1 has a heat source for the pressure roller 44 and the temperature of the heat source can be controlled, the time for continuing the correction of the pressure roller 44 may be set.

[0090] In step SP55, the control unit 64 determines whether the fixing belt 30 and the pressure roller 44 have reached the target temperature by the fixing temperature control unit 70, and performs a heating operation until the fixing belt 30 and the pressure roller 44 reach the target temperature. When the fixing belt 30 and the pressure roller 44 reach the target temperature, in step SP55, the control unit 64 obtains an affirmative result and moves to step SP56.

[0091] In step SP56, the control unit 64 performs constant temperature control by the fixing temperature control unit 70 so as to maintain the target temperature, and moves to step SP57. At this time, when the fixing belt 30 is higher than the target temperature, the fixing temperature control unit 70 does not energize the plate heater 36, while when the fixing belt 30 is lower than the target temperature, the fixing temperature control unit 70 energizes the plate heater 36 to keep the fixing belt 30 near the target temperature.

[0092] In step SP57, the control unit 64 waits by the fixing temperature control unit 70 until the correction time of the fixing belt 30 for each fixing device type set in step SP53 or SP54 elapses. When the correction time of the fixing belt 30 elapses, in step SP57, the control unit 64 obtains an affirmative result and moves to step SP58. In step SP58, the control unit 64 removes the correction of the fixing belt 30, moves to step SP59, ends the fixing control processing procedure SRT2, and moves to step SP8 in the printing processing procedure RT1 (FIG. 7).

[0093] Note that in this embodiment, the image forming apparatus 1 adjusts the correction of the target temperature based on the fixing device type. However, the present invention is not limited to this, and other parameters related to printing, such as correction of error conditions, change of conveyance speed, and change of printing range, may be adjusted based on the fixing device type.

[0094] [1-7. Effects, etc.] In the above configuration, when there is a possibility that the fixing device 17 has been replaced, the image forming apparatus 1 rotates the cam 48 to rotate the pressure roller support member 46. The cam 48 includes a normal fixing device cam 48a for the normal fixing device 17a and a borderless printing fixing device cam 48b for the borderless printing fixing device 17b, and the rotation angle ranges in which the protrusions 48p corresponding to the release state are formed are different. When the fixing device 17 is in the release state when starting to rotate the cam 48, the image forming apparatus 1 rotates the cam 48 to switch the fixing device 17 from the release state to the nip state, and then measures the nip time as the non-shielding time, which is the time during which the nip state continues until the release state is reached. Subsequently, the image forming apparatus 1 determines that the fixing device type is the normal fixing device 17a when the nip time is equal to or greater than the nip time threshold, and determines that the fixing device type is the borderless printing fixing device 17b when the nip time is less than the nip time threshold.

[0095] On the other hand, when the fixing device 17 is in the nip state when starting to rotate the cam 48, the image forming apparatus 1 rotates the cam 48 to switch the fixing device 17 from the nip state to the release state, and then measures the release time as the shielding time, which is the time during which the release state continues until the nip state is reached. Subsequently, the image forming apparatus 1 determines that the fixing device type is the borderless printing fixing device 17b when the release time is equal to or greater than the release time threshold, and determines that the fixing device type is the normal fixing device 17a when the release time is less than the release time threshold.

[0096] In this way, the image forming apparatus 1 rotates the cam 48 to measure the nip time or the release time, and determines whether the fixing device type is the normal fixing device 17a or the borderless printing fixing device 17b according to whether the nip time or the release time is equal to or greater than a predetermined threshold. Subsequently, the image forming apparatus 1 starts the process operation and performs a fixing control process including corrections different according to the determined fixing device type to make the fixing device 17 in a printable state.

[0097] On the other hand, when the fixing device 17 does not switch between the nip state, the release state, and the nip state, or between the release state, the nip state, and the release state from when the cam 48 starts to rotate until the cam 48 makes one full rotation, the image forming apparatus 1 determines that a fixing device mounting error has occurred because the fixing device 17 is not correctly mounted on the image forming apparatus 1.

[0098] Here, Japanese Patent Laid-Open No. 2007-232899 describes an image forming apparatus as a comparative example in which cleaning rollers are detachably provided for a fixing roller and a pressure roller, respectively, and the type of fixing device is determined according to the detection result of a cleaning roller state detection sensor that detects the detachment state. In the image forming apparatus of this comparative example, since cleaning rollers are detachably provided for the fixing roller and the pressure roller, respectively, a cleaning roller state detection sensor for detecting the detachment state is provided. However, in the case of the image forming apparatus of the comparative example, a cleaning roller state detection sensor is provided even though it is not necessary for a normal fixing device without a cleaning roller. Also, like the image forming apparatus 1 according to the present embodiment, when the fixing belt cleaning roller 54 and the pressure roller cleaning roller 56 are not detachably provided with respect to the fixing belt 30 and the pressure roller 44, respectively, a sensor for detecting the detachment state is not necessary. Furthermore, in the case of the image forming apparatus of the comparative example, it is necessary to perform an abnormality detection operation for detecting whether the cleaning roller state detection sensor is malfunctioning by checking whether the output result of the cleaning roller state detection sensor changes.

[0099] Also, the image forming apparatus of the comparative example is provided with a fixing and pressure roller state detection sensor for detecting the detachment state between the fixing roller and the pressure roller. However, although the image forming apparatus of the comparative example determines whether the cleaning roller state detection sensor is malfunctioning and whether the contact and separation mechanism for separating the fixing roller and the pressure roller is malfunctioning using the detection result of the fixing and pressure roller state detection sensor, it does not determine the type of fixing device.

[0100] In contrast, the image forming apparatus 1 can determine the type of fixing device simply by rotating the cam 48 without separately providing a specific detection unit such as a sensor for determining the fixing device type or adding a special member. Further, since the image forming apparatus 1 does not use a special sensor for determining the fixing device type, there is no need to perform an abnormality detection operation for detecting whether the sensor is operating normally. Therefore, the image forming apparatus 1 can determine the fixing device type without deteriorating the printing efficiency.

[0101] Also, when there is a possibility that the fixing device 17 has been replaced, the image forming apparatus 1 determines whether a fixing device mounting error has occurred by rotating the cam 48 once during the first operation after that. Therefore, the image forming apparatus 1 can determine the fixing device type simply by performing the rotation operation of the cam 48 that has been conventionally performed when there is a possibility that the fixing device 17 has been replaced, without performing an additional operation. As a result, the image forming apparatus 1 can prevent the deterioration of the printing efficiency by not performing an additional operation for determining the fixing device type.

[0102] As described above, the image forming apparatus 1 can determine the fixing device type without adding a specific detection unit or a special member and without adding a new operation, simply by making the normal fixing device cam 48a and the edge-free printing fixing device cam 48b have different shapes from each other.

[0103] According to the above configuration, the image forming apparatus 1 includes an image forming unit 12 as an image forming unit that develops an electrostatic latent image, transfers it to the medium P, and forms an image, a fixing belt 30 as a heating unit that heats the medium P, and a fixing device 17 provided with a pressure roller 44 as a pressure unit that pressurizes the medium P. The fixing device 17 is composed of a normal fixing device 17a as a first fixing device and a borderless printing fixing device 17b as a second fixing device different from the normal fixing device 17a. A separating member 45 that switches between a nip state where the fixing belt 30 and the pressure roller 44 are in contact and a release state where they are separated, and a separating state detection sensor 52 that detects a pressure roller support member 46 of the separating member 45 during the process of switching between the nip state and the release state are provided. A separating time measurement unit 74 and a fixing type determination unit 76 that determine the type of the fixing device 17 based on the detection result of the separating state detection sensor 52 are provided.

[0104] Thus, the image forming apparatus 1 can determine the type of the fixing device 17 only by detecting a separating member 45 that switches between the nip state and the release state with a separating state detection sensor 52, which is a conventionally existing detection unit.

[0105] [2. Second Embodiment] [2-1. Overall Configuration of Image Forming Apparatus] As shown in FIG. 1, the image forming apparatus 101 according to the second embodiment is different from the image forming apparatus 1 according to the first embodiment in that it has a control unit 164 in place of the control unit 64 and a fixing device 117 in place of the fixing device 17, but is otherwise configured in the same manner.

[0106] [2-2. Configuration of Fixing Device] Either the normal fixing device 117a shown in FIG. 12(A) or the borderless printing fixing device 117b shown in FIG. 12(B) is used as the fixing device 117. The same reference numerals are assigned to the same components in the normal fixing device 117a (FIG. 12(A)) and the borderless printing fixing device 117b (FIG. 12(B)). Hereinafter, the normal fixing device 117a and the borderless printing fixing device 117b are collectively referred to as the fixing device 117.

[0107] [2-2-1. Configuration of Normal Fuser] As shown in FIGS. 12(A) and 13(A) in which the same reference numerals are given to the same components as those in FIGS. 2(A) and 3(A), the normal fuser 117a has a normal fuser separation / connection member 145a instead of the normal fuser separation / connection member 45a compared with the normal fuser 17a. Although the separation / connection state detection sensor 52 is omitted and the density sensor 80 is added, it is otherwise configured in the same manner. The normal fuser separation / connection member 145a is different from the normal fuser separation / connection member 45a in that it has a normal fuser cam member 147a instead of the normal fuser cam member 47a, but is otherwise configured in the same manner. The normal fuser cam member 147a is different from the normal fuser cam member 47a in that a normal fuser rotating plate 82a is added, but is otherwise configured in the same manner.

[0108] The density sensor 80 is, for example, an optical sensor arranged near the normal fuser rotating plate 82a, and includes a light emitting part that emits detection light and a light receiving part that receives the reflected light obtained by reflecting the detection light from the measurement object. The density sensor 80 notifies the control unit 164 of the light reception result of the reflected light. Specifically, in the case of the normal fuser 117a, the density sensor 80 notifies the control unit 164 of a light reception result (for example, 1 [V]) indicating that it is in the release state (FIG. 13(A)) and receiving the reflected light reflected by the black low-reflection part 82w (described later) on the normal fuser rotating plate 82a. On the other hand, in the case of the borderless printing fuser 117b, the density sensor 80 notifies the control unit 164 of a light reception result (for example, 2 [V]) indicating that it is in the release state (FIG. 13(B)) and receiving the reflected light reflected by the gray medium-reflection part 82m (described later) on the borderless printing fuser rotating plate 82b. Also, on the other hand, in the case of the nip state (FIGS. 12(A) and 12(B)), the density sensor 80 notifies the control unit 164 of a light reception result (for example, 3 [V]) indicating that it is receiving the reflected light reflected by the white high-reflection part 82s (described later) on the rotating plate 82. Based on this light reception result, the control unit 164 determines whether the current pressure state of the fixing nip portion N is in the nip state or the release state.

[0109] [Configuration of the borderless print fuser] As shown in FIGS. 12(B) and 13(B) in which the same reference numerals are given to the same components as those in FIGS. 2(B) and 3(B), the borderless print fuser 117b has a borderless print fuser disengagement member 145b in place of the borderless print fuser disengagement member 45b as compared with the borderless print fuser 17b, and the disengagement state detection sensor 52 is omitted and the density sensor 80 is added. Although it is different in these points, it is configured in the same manner in other respects. The borderless print fuser disengagement member 145b is different in that it has a borderless print fuser cam member 147b in place of the borderless print fuser cam member 47b as compared with the borderless print fuser disengagement member 45b, but is configured in the same manner in other respects. The borderless print fuser cam member 147b is different in that a rotation plate 82a for the normal fuser is added and a normal fuser cam 48a is provided in place of the borderless print fuser cam 48b as compared with the borderless print fuser cam member 47b, but is configured in the same manner in other respects. For this reason, the borderless print fuser 117b (FIG. 12(B)) is different in that a rotation plate 82b for the borderless print fuser is provided in place of the rotation plate 82a for the normal fuser as compared with the normal fuser 117a (FIG. 12(A)), but is configured in the same manner in other respects. Thus, the borderless print fuser 117b is provided with the same normal fuser cam 48a as that of the normal fuser 117a. Hereinafter, the normal fuser disengagement member 145a and the borderless print fuser disengagement member 145b are collectively referred to as the disengagement member 145 as well.

[0110] [2-3. Configuration of the cam member] [2-3-1. Configuration of the cam member for the normal fuser] As shown in FIG. 14(A), the rotary plate 82a for the normal fixing device has a disk shape, and the camshaft 48s is inserted and fixed in the hole at the center, and rotates together with the camshaft 48s. When the rotary plate 82a for the normal fixing device is viewed in the rotation angle range with the camshaft 48s as the central axis and the direction downward is taken as the reference 0[°], a low reflection portion 82w is formed in the rotation angle range from 0[°] to 90[°] in the counterclockwise direction, and a high reflection portion 82s is formed in the rotation angle range from 90[°] to 360[°](0[°]) in the counterclockwise direction. Thus, the low reflection portion 82w is formed in the same rotation angle range as the protruding portion 48p of the cam 48a for the normal fixing device, and the high reflection portion 82s is formed in the same rotation angle range as the non-protruding portion 48d of the cam 48a for the normal fixing device. The low reflection portion 82w is constituted by, for example, a black member, and the light reflectance is low. The high reflection portion 82s is constituted by, for example, a white member, and the light reflectance is higher than that of the low reflection portion 82w.

[0111] [2-3-2. Configuration of Cam Member for Edge-Free Printing Fixing Device] As shown in FIG. 14(B) in which the members corresponding to those in FIG. 14(A) are given the same reference numerals, the rotating plate 82b for the edge-less print fixing device has a disk shape, and the camshaft 48s is inserted and fixed in the hole at the central part, and rotates together with the camshaft 48s. When the direction directly downward is taken as 0[°] as a reference when viewed in the rotation angle range with the camshaft 48s as the central axis, the middle reflection part 82m is formed over the rotation angle range from 0[°] to 90[°] in the counterclockwise direction, similar to the low reflection part 82w (FIG. 14(A)). The high reflection part 82s is formed over the rotation angle range from 90[°] to 360[°] (0[°]) in the counterclockwise direction. Thus, the middle reflection part 82m is formed in the same rotation angle range as the protruding part 48p of the cam 48a for the normal fixing device, similar to the low reflection part 82w, and the high reflection part 82s is formed in the same rotation angle range as the non-protruding part 48d of the cam 48a for the normal fixing device. The middle reflection part 82m is constituted by, for example, a gray member, and has a light reflectance higher than that of the low reflection part 82w but lower than that of the high reflection part 82s. The high reflection part 82s is constituted by, for example, a white member similar to the rotating plate 82a for the normal fixing device, and has a light reflectance higher than that of the middle reflection part 82m. Hereinafter, the rotating plate 82a for the normal fixing device and the rotating plate 82b for the edge-less print fixing device are collectively referred to as the rotating plate 82 as well.

[0112] [2-4. Control Configuration of Image Forming Apparatus] As shown in FIG. 15 in which the functions corresponding to those in FIG. 5 are given the same reference numerals, the image forming apparatus 101 is different in that a control unit 164 is provided instead of the control unit 64 compared with the image forming apparatus 1, but is configured similarly in other respects. The control unit 164 is different in that it has a rotating plate control unit 84 instead of the contact / separation time measurement unit 74 and a fixing type determination unit 176 instead of the fixing type determination unit 76 compared with the control unit 64, but is configured similarly in other respects.

[0113] The rotary plate control unit 84 measures the density of the rotary plate 82 by the density sensor 80 when the cam 48 makes one rotation. The fixing type determination unit 176 discriminates the type of the rotary plate 82 based on the measurement result of the rotary plate control unit 84, and determines whether the fixing device type of the fixing device 117 is either the normal fixing device 117a or the borderless printing fixing device 117b.

[0114] [2-5. Method for Determining Fixing Device Type] When the image forming apparatus 101 rotates the cam 48 one round (0[°] to 360[°]) (that is, rotates it once) in the fixing device mounting check processing procedure SRT101 (FIG. 17) described later, it compares the dynamic range (described later) of the measured density measurement value with a predetermined normal fixing device threshold and a borderless printing fixing device threshold. When the dynamic range is less than the normal fixing device threshold and equal to or greater than the borderless printing fixing device threshold, the borderless printing fixing device 117b is detected as the fixing device 117, that is, it is determined that the fixing device type is the borderless printing fixing device 117b. On the other hand, when the dynamic range is equal to or greater than the normal fixing device threshold, the normal fixing device 117a is detected as the fixing device 117, that is, it is determined that the fixing device type is the normal fixing device 117a.

[0115] Here, the normal fixing device threshold and the borderless printing fixing device threshold will be described. As described above, the normal fixing device 117a (FIG. 12(A)) is provided with a normal fixing device rotary plate 82a (FIG. 14(A)), and the borderless printing fixing device 117b (FIG. 12(B)) is provided with a borderless printing fixing device rotary plate 82b (FIG. 14(B)). FIG. 16 shows the output waveforms of the measurement results of the density sensor 80 in the normal fixing device 117a and the borderless printing fixing device 117b when the cam 48 makes one rotation. The vertical axis represents the detection voltage of the density sensor 80. When the density sensor 80 detects white, it outputs a detection voltage of 3[V] or more. When it detects gray, it outputs a detection voltage of about 2[V]. When it detects black, it outputs a detection voltage of less than 1[V].

[0116] In the case of the rotating plate 82a for the normal fixing device of the normal fixing device 117a, it is composed of a white highly reflective portion 82s and a black low reflective portion 82w. Therefore, the detection voltage of the density sensor 80 is 3 [V] or more when detecting the white highly reflective portion 82s, and less than 1 [V] when detecting the black low reflective portion 82w. On the other hand, in the case of the rotating plate 82b for the borderless printing fixing device of the borderless printing fixing device 117b, it is composed of a white highly reflective portion 82s and a gray medium reflective portion 82m. Therefore, the detection voltage of the density sensor 80 is 3 [V] or more when detecting the white highly reflective portion 82s, and about 2 [V] when detecting the gray medium reflective portion 82m.

[0117] Also, on the rotating plate 82a for the normal fixing device, a black low reflective portion 82w is provided over the rotation angle range corresponding to the release state, and a white highly reflective portion 82s is provided over the other rotation angle range. On the other hand, on the rotating plate 82b for the borderless printing fixing device, a gray medium reflective portion 82m is provided over the rotation angle range corresponding to the release state, and a white highly reflective portion 82s is provided over the other rotation angle range.

[0118] Therefore, the image forming apparatus 101 sets the voltage difference (dynamic range) between the white detection voltage and the black detection voltage in the density sensor 80 as the normal fixing device threshold. That is, the normal fixing device threshold = (3 [V] - 1 [V]) = 2 [V]. Also, the image forming apparatus 101 sets the voltage difference (dynamic range) between the white detection voltage and the gray detection voltage in the density sensor 80 as the borderless printing fixing device threshold. That is, the borderless printing fixing device threshold = (2 [V] - 1 [V]) = 1 [V].

[0119] [2-6. Printing Process] Regarding the specific processing procedure of the printing process by the image forming apparatus 101, it will be described using the flowchart of FIG. 7. When the power of the image forming apparatus 101 is turned ON, the control unit 164 starts the printing process procedure RT101 by reading and executing a printing process program from a storage unit (not shown), and moves to step SP1.

[0120] The printing process procedure RT101 is configured in the same way as the printing process procedure RT1, except that a fixing unit mounting check process procedure SRT101 (FIG. 17) is provided instead of the fixing unit mounting check process procedure SRT1 (FIG. 8). Therefore, hereinafter, the fixing unit mounting check process procedure SRT101 (FIG. 17) will be mainly described, and the description of other processes will be omitted.

[0121] When an affirmative result is obtained in step SP1, the control unit 164 then moves to step SP102. In step SP102, the control unit 164 performs a fixing unit mounting check process by executing the fixing unit mounting check process procedure SRT101 (described later) shown in FIG. 17, and then moves to step SP3.

[0122] [2-6-1. Fixing Unit Mounting Check Process] Next, the specific process procedure of the fixing unit mounting check process by the image forming apparatus 101 will be described using the flowchart shown in FIG. 17. The control unit 164 starts the fixing unit mounting check process procedure SRT101 (FIG. 17) in step SP102 of the printing process procedure RT101 (FIG. 7), and then moves to step SP61.

[0123] In step SP61, the control unit 164 starts the rotation of the cam 48 for one rotation by the fixing separation connection control unit 72, and then moves to step SP62. This is to confirm whether the fixing unit 117 is correctly mounted on the image forming apparatus 101. When the fixing unit 117 is correctly mounted on the image forming apparatus 101, the cam 48 and the rotating plate 82 rotate due to the rotation of the camshaft 48s, and the pressure state of the fixing nip portion N based on the detection result of the density sensor 80 changes from the nip state to the release state, or from the release state to the nip state. On the other hand, when the fixing unit 117 is not correctly mounted on the image forming apparatus 101, the gear that rotates the cam 48 idles and the camshaft 48s does not rotate, so the cam 48 and the rotating plate 82 do not rotate either, and the detection result of the density sensor 80 does not change.

[0124] In step SP62, the control unit 164 starts measuring the density of the rotating plate 82 by the rotating plate control unit 84 based on the detection result from the density sensor 80, and then moves to step SP63. At this time, the rotating plate control unit 84 reads the density by the density sensor 80 at intervals of, for example, 10 [ms], and calculates the average value of three measurements after removing the maximum value and the minimum value from the density measurement values, which are the most recent five density measurement values.

[0125] In step SP63, the control unit 164 determines whether the time for one rotation of the cam 48 (for example, 2700 [ms]) has elapsed since the start of the rotation of the cam 48 by the mounting check unit 78. If a negative result is obtained here, this indicates that the time for one rotation of the cam 48 has not elapsed since the start of the rotation of the cam 48. At this time, the control unit 164 continues to measure the rotating plate 82. When the time for one rotation of the cam 48 has elapsed since the start of the rotation of the cam 48, since the measurement of the rotating plate 82 in the cam 48 that rotates at a speed of one rotation in 2700 [ms] has been performed for one rotation of the cam 48, the control unit 164 obtains an affirmative result in step SP63 and moves to step SP64. In step SP64, the control unit 164 ends the density measurement of the rotating plate 82 by the rotating plate control unit 84 and stops the rotation of the cam 48 by the fixing contact control unit 72, and then moves to step SP65.

[0126] In step SP65, the control unit 164 analyzes the density measurement value by the fixing type determination unit 176 and then moves to step SP66. At this time, the fixing type determination unit 176 reads the density measurement value every 10 [ms] for 2700 [ms]. When the average processing as described above is performed, the data becomes valid after 50 [ms] have elapsed, so 265 data can be collected. The fixing type determination unit 176 sorts the 265 data in descending order, sets the average value of 10 data from the larger values as the average value A, and sets the average value of 10 data from the smaller values as the average value B. The difference between the average value A and the average value B is the voltage difference (dynamic range) between white and black or gray.

[0127] In step SP66, the control unit 164 determines whether the dynamic range is equal to or greater than the normal fixing device threshold value (2 [V]) by the fixing type determination unit 176. If an affirmative result is obtained here, the control unit 164 proceeds to step SP67. In step SP67, the control unit 164 detects the normal fixing device 117a as the fixing device 117, that is, the fixing type determination unit 176 determines that the fixing device type is the normal fixing device 117a, and then proceeds to step SP71, terminates the fixing device mounting check processing procedure SRT101, and proceeds to step SP3 in the printing processing procedure RT101 (Fig. 7).

[0128] On the other hand, if a negative result is obtained in step SP66, the control unit 164 proceeds to step SP68. In step SP68, the control unit 164 determines whether the dynamic range is equal to or greater than the edge-free printing fixing device threshold value (1 [V]) by the fixing type determination unit 176. If an affirmative result is obtained here, this indicates that the dynamic range is less than the normal fixing device threshold value (2 [V]) and equal to or greater than the edge-free printing fixing device threshold value (1 [V]). At this time, the control unit 164 proceeds to step SP69. In step SP69, the control unit 164 detects the edge-free printing fixing device 117b as the fixing device 117, that is, the fixing type determination unit 176 determines that the fixing device type is the edge-free printing fixing device 117b, and then proceeds to step SP71, terminates the fixing device mounting check processing procedure SRT101, and proceeds to step SP3 in the printing processing procedure RT101 (Fig. 7).

[0129] On the other hand, if a negative result is obtained in step SP70, this indicates that there is a problem with the mounting state of the fixing device 117 because the dynamic range is less than the edge-free printing fixing device threshold value (1 [V]), and it means that the rotating plate 82 is not rotating. At this time, the control unit 164 proceeds to step SP70. In step SP70, the mounting check unit 78 determines that there is a fixing device mounting error, then proceeds to step SP71, terminates the fixing device mounting check processing procedure SRT101, and proceeds to step SP3 in the printing processing procedure RT101 (Fig. 7).

[0130] [2-7. Effects, etc.] In the above configuration, when there is a possibility that the fixing device 117 has been replaced, the image forming apparatus 101 rotates the camshaft 48s (that is, the cam 48) once to rotate the rotating plate 82 provided on the camshaft 48s once. At this time, the image forming apparatus 101 irradiates light on the rotating plate 82 and measures the density of the reflected light. The cam 48 is provided with the same normal fixing device cam 48a for the normal fixing device 117a and the edge-free printing fixing device 117b. The rotating plate 82 as a reflecting member has different densities (that is, light reflectivities) of the low reflection portion 82w and the medium reflection portion 82m formed in the rotation angle range corresponding to the release state between the normal fixing device rotating plate 82a of the normal fixing device 117a and the edge-free printing fixing device rotating plate 82b of the edge-free printing fixing device 117b. Subsequently, when the dynamic range of the measured density measurement value is equal to or greater than the normal fixing device threshold, the image forming apparatus 101 determines that the fixing device type is the normal fixing device 117a, and when the dynamic range is less than the normal fixing device threshold and equal to or greater than the edge-free printing fixing device threshold, it determines that the fixing device type is the edge-free printing fixing device 117b.

[0131] In this way, the image forming apparatus 101 rotates the camshaft 48s once to measure the density of the rotating plate 82, and determines whether the fixing device type is the normal fixing device 117a or the edge-free printing fixing device 117b based on the dynamic range of the density measurement value. Subsequently, the image forming apparatus 101 starts the process operation and performs a fixing control process including corrections different according to the determined fixing device type to bring the fixing device 117 into a printable state.

[0132] On the other hand, when the dynamic range of the density measurement value is less than the edge-free printing fixing device threshold, the image forming apparatus 101 determines that a fixing device mounting error has occurred in that the fixing device 117 is not correctly mounted on the image forming apparatus 101.

[0133] Therefore, the image forming apparatus 101 can determine the fixing device type only by rotating the camshaft 48s without separately providing a specific detection unit such as a sensor for determining the fixing device type or adding a special member. Further, since the image forming apparatus 101 does not use a special sensor for determining the fixing device type, it is not necessary to perform an abnormality detection operation for detecting whether the sensor is operating normally. For this reason, the image forming apparatus 101 can determine the fixing device type without degrading the printing efficiency.

[0134] Also, when there is a possibility that the fixing device 117 has been replaced, the image forming apparatus 101 determines whether a fixing device mounting error has occurred by rotating the camshaft 48s once during the first operation after that. For this reason, the image forming apparatus 101 can determine the fixing device type only by performing the rotation operation of the camshaft 48s, which has been conventionally performed when there is a possibility that the fixing device 117 has been replaced, without performing an additional operation. Thereby, the image forming apparatus 101 can prevent the degradation of the printing efficiency by not performing an additional operation for determining the fixing device type.

[0135] Furthermore, since the image forming apparatus 101 can use the same normal fixing device cam 48a for both the normal fixing device 117a and the edge-free printing fixing device 117b, compared with the image forming apparatus 1, it is possible to eliminate the need to make the cams 48 have different shapes from each other, such as the normal fixing device cam 48a and the edge-free printing fixing device cam 48b. For this reason, the image forming apparatus 101 can determine the fixing device type at a lower cost compared with the image forming apparatus 1 without adding a specific detection unit or a special member and without adding a new operation, just by making the low reflection portion 82w of the normal fixing device rotating plate 82a and the medium reflection portion 82m of the edge-free printing fixing device rotating plate 82b have different densities (colors).

[0136] In other respects as well, the image forming apparatus 101 according to the second embodiment can achieve the same operational effects as the image forming apparatus 1 according to the first embodiment.

[0137] [3. Other Embodiments] In the first embodiment described above, for the image forming apparatus 1, the normal fixing device 17a has the protruding portion 48p (release state) in the rotation angle range of the normal fixing device cam 48a of (0° to 90°), and the borderless printing fixing device 17b has the protruding portion 48p (release state) in the rotation angle range of the borderless printing fixing device cam 48b of (0° to 105°). The present invention is not limited to this. For the image forming apparatus 1, as long as the protruding portions 48p (release state) of the normal fixing device cam 48a and the borderless printing fixing device cam 48b are in different rotation angle ranges from each other, the rotation angle ranges of the protruding portions 48p (release state) of the normal fixing device cam 48a and the borderless printing fixing device cam 48b may be various other values.

[0138] Also, in the first embodiment described above, for the image forming apparatus 1, the contact / separation state detection sensor 52 is arranged such that in the nip state, the detection light is not crossed by the pressure roller support member 46 and the light receiving result is at the H level, and in the release state, the detection light is crossed by the pressure roller support member 46 and the light receiving result is at the L level. The present invention is not limited to this. For the image forming apparatus 1, the contact / separation state detection sensor 52 may be arranged such that in the release state, the detection light is not crossed by the pressure roller support member 46 and the light receiving result is at the H level, and in the nip state, the detection light is crossed by the pressure roller support member 46 and the light receiving result is at the L level. In that case, the image forming apparatus 1 may appropriately change the release time threshold and the nip time threshold.

[0139] Also, in the second embodiment described above, for the image forming apparatus 101, the normal fixing device rotating plate 82a of the normal fixing device 117a is composed of a white high-reflection portion 82s and a black low-reflection portion 82w, and the borderless printing fixing device rotating plate 82b of the borderless printing fixing device 117b is composed of a white high-reflection portion 82s and a gray medium-reflection portion 82m. The present invention is not limited to this. For the image forming apparatus 101, as long as the dynamic ranges based on the measurement results of the density sensor 80 are different between the normal fixing device rotating plate 82a and the borderless printing fixing device rotating plate 82b, the high-reflection portion 82s, the low-reflection portion 82w, and the medium-reflection portion 82m may be composed of various other colors.

[0140] Furthermore, in the second embodiment described above, the image forming apparatus 101 has been described for the case where the low reflection portion 82w of the rotating plate 82a for the normal fixing device and the medium reflection portion 82m of the rotating plate 82b for the borderless printing fixing device are formed over the rotation angle range (0[°] to 90[°]) of the cam 48. The present invention is not limited to this, and the image forming apparatus 101 may form the low reflection portion 82w of the rotating plate 82a for the normal fixing device and the medium reflection portion 82m of the rotating plate 82b for the borderless printing fixing device over other various rotation angle ranges of the rotation angle range of the cam 48.

[0141] Furthermore, in the first embodiment described above, the image forming apparatus 1 has been described for the case where, in the release state, the nip between the pressure pad 38 and the pressure roller 44 is released. The present invention is not limited to this, and in the release state, the pressure pad 38 and the pressure roller 44 may be in contact with each other. In short, in the release state, the pressing force from the pressure roller 44 to the pressure pad 38 may be weaker than in the nip state. The same applies to the second embodiment.

[0142] Furthermore, in the first embodiment described above, the image forming apparatus 1 has been described for the case where it is determined whether the fixing device type of the fixing device 17 is the normal fixing device 17a or the borderless printing fixing device 17b. The present invention is not limited to this, and the image forming apparatus 1 may determine other fixing devices, such as a fixing device for envelopes. The same applies to the second embodiment.

[0143] Furthermore, in the above-described embodiments, the case where the present invention is applied to the image forming apparatus 1 or 101 having the fixing device 17 of the belt heating method that heats a part of the fixing belt 30 by the plate-shaped heater 36 has been described. The present invention is not limited to this, and the present invention may be applied to an image forming apparatus having various other types of fixing devices, such as a fixing device that heats the entire fixing belt 30 and the pressure roller 44, as long as it is a fixing device in which the nip state and the release state can be switched.

[0144] Furthermore, in the first embodiment described above, in the case of the borderless printing fuser 17b, the case where one fixing belt cleaning roller 54 is provided on the fixing belt 30 and one pressure roller cleaning roller 56 is provided on the pressure roller 44 has been described. The present invention is not limited to this. In the case of the borderless printing fuser 17b, the image forming apparatus 1 may omit either the fixing belt cleaning roller 54 or the pressure roller cleaning roller 56, or may provide various other numbers of the fixing belt cleaning roller 54 and the pressure roller cleaning roller 56. The same applies to the second embodiment.

[0145] Furthermore, in the embodiment described above, the case where the present invention is applied to the image forming apparatus 1 or 101 which is a single-function printer has been described. The present invention is not limited to this. For example, the present invention may be applied to an image forming apparatus having various other functions, such as an MFP (Multi Function Peripheral) having functions of a copier and a facsimile machine.

[0146] Furthermore, the present invention is not limited to the above-described embodiments and other embodiments. That is, the present invention applies to embodiments in which any one or more of the above-described embodiments and other embodiments are arbitrarily combined. Also, the present invention applies to embodiments in which a part of the configuration described in any of the above-described embodiments and other embodiments is extracted and replaced or diverted with a part of the configuration of any of the above-described embodiments and other embodiments, or embodiments in which a part of the extracted configuration is added to any of the above-described embodiments and other embodiments.

[0147] Furthermore, in the first embodiment described above, the image forming apparatus 1 as an image forming apparatus is configured by the fixing device 17 as a fixing device, the contact separation member 45 as a contact separation member, the contact separation state detection sensor 52 as a detection unit, and the contact separation time measurement unit 74 and the fixing type determination unit 76 as determination units. In the second embodiment described above, the case where the image forming apparatus 101 as an image forming apparatus is configured by the fixing device 117 as a fixing device, the contact separation member 145 as a contact separation member, the density sensor 80 and the rotating plate 82 as detection units, and the rotating plate control unit 84 and the fixing type determination unit 176 as determination units was described. The present invention is not limited to this, and an image forming apparatus may be configured by a fixing device, a contact separation member, a detection unit, and a determination unit having various other configurations.

Industrial Applicability

[0148] The present invention can be used when printing an image on a medium using an electrophotographic image forming apparatus.

Explanation of Signs

[0149] 1, 101... Image forming apparatus, P... Medium, 2... Medium storage tray, 3... Medium conveyance path, 4... Pickup roller, 5a, 5b, 5c, 5d, 5e... Conveyor roller pair, 6... Transfer section, 7... Transfer belt, 8... Belt support roller, 9... Belt drive roller, 10... Transfer roller, 11... Main body section, 12... Image forming unit, 17a, 117a... Normal fuser, 17b, 117b... Borderless printing fuser, 18... Medium stacking tray, 19... Photosensitive drum, G... Conveyance direction, 20... Top cover, 21... Writing sensor, 22... Discharge sensor, 23... Top cover sensor, 30... Fusing belt, 32... Fusing roller, 34... Guide roller, 36... Plate heater, 38... Pressing pad, 40... Guide member, 42... Fusing belt temperature detection sensor, 44... Pressing roller, 45a, 145a... Normal fuser contact / separation member, 45b, 145b... Borderless printing fuser contact / separation member, 46... Pressing roller support member, 46x... Rotation center of pressing roller support member, 46h... Pressing roller support section, 46t... Contact section, 47a, 147a... Cam member for normal fuser, 47b, 147b... Cam member for borderless printing fuser, 48a... Cam for normal fuser, 48b... Cam for borderless printing fuser, 48p... Protruding portion, 48d... Non-protruding portion, 48h... Cam rotation shaft hole, 48s... Cam shaft, 48a... Cam for normal fuser, 48b... Cam for borderless printing fuser, 48p... Protruding portion, 48d... Non-protruding portion, 48s... Cam shaft, 48h... Cam rotation shaft hole, 50... Pressing roller temperature detection sensor, 52... Contact / separation state detection sensor, 54... Fusing belt cleaning roller, 56... Pressing roller cleaning roller, N... Fusing nip section, f1, f2, f3... Pressing force, 60... PC, 62... Receiver, 64, 164... Control section, 66... Image control section, 68... Conveyance control section, 70... Fusing temperature control section, 72... Fusing contact / separation control section, 74... Contact / separation time measurement section, 76, 176... Fusing type determination section, 78... Mounting check section, 79... Operation display section, 80... Density sensor, 82a... Rotating plate for normal fuser, 82b... Rotating plate for borderless printing fuser, 82s... High reflection section, 82w... Low reflection section, 82m... Medium reflection section, 84... Rotating plate control section, TB... Target temperature correction table.

Claims

1. An image forming apparatus having an image forming unit that develops an electrostatic latent image, transfers it to a medium, and forms an image, a fixing device provided with a heating unit that heats the medium and a pressing unit that presses the medium, The fixing device is composed of a first fixing device and a second fixing device different from the first fixing device, A separating and contacting member that switches between a contacting state in which the heating unit and the pressing unit are in contact and a separating state in which they are separated, A detecting unit that detects the separating and contacting member during the process of switching between the contacting state and the separating state, A discriminating unit that discriminates the type of the fixing device based on the detection result of the detecting unit An image forming apparatus characterized by comprising the same.

2. A mounting confirmation unit that confirms the mounting state of the fixing device with respect to the image forming apparatus based on the detection result of the detecting unit The image forming apparatus according to claim 1, further comprising the same.

3. The separating and contacting member Has a shielding member capable of shielding the detecting unit, The discriminating unit Discriminates the type of the fixing device based on at least one of the shielding time during which the shielding member shields the detecting unit and the non-shielding time during which the shielding member does not shield the detecting unit in the detection result of the detecting unit The image forming apparatus according to claim 1, characterized by the same.

4. The shielding member Is a pressing unit support member that moves to separate the pressing unit from the heating unit to switch between the contacting state and the separating state, shields the detecting unit in either the contacting state or the separating state, and does not shield the detecting unit in the other of the contacting state or the separating state The image forming apparatus according to claim 3, characterized by the same.

5. The separating and contacting member It has a reflecting member that reflects the light from the detection unit as reflected light. The discrimination unit discriminates the type of the fixing device based on the reflected light detected by the detection unit. The image forming apparatus according to claim 1, characterized in that.

6. The contact-separation member has a pressure unit support member that moves to separate and contact the pressure unit from the heating unit to switch between the contact state and the separated state, and a cam that contacts the pressure unit support member and moves the pressure unit support member. and has The reflecting member rotates together with the cam, and a high-reflection part with a high light reflectivity irradiated with the light from the detection unit and a low-reflection part with a lower reflectivity than the high-reflection part irradiated with the light from the detection unit are formed. The discrimination unit discriminates the type of the fixing device based on the difference between the detection value of the reflected light from the high-reflection part detected by the detection unit and the detection value of the reflected light from the low-reflection part detected by the detection unit. The image forming apparatus according to claim 5, characterized in that.

7. The cam in the first fixing device and the cam in the second fixing device have the same shape. The image forming apparatus according to claim 6, characterized in that.

8. A control unit that starts the operations of the image forming unit and the fixing device based on the type of the fixing device discriminated by the discrimination unit. The image forming apparatus according to claim 1, further comprising.

Images