JP4821777B2 - Printing device - Google Patents

Description

  The present invention relates to a fixing device including an external heating unit that selectively heats a heating member or conveyed paper, and a printing device including the above-described fixing device.

  In order to thermally fix the toner on the paper by the heat fixing device, it is necessary to raise the surface temperature of the fixing roller to a heating temperature suitable for heat fixing. Conventionally, since this heating temperature is set high, it takes a long time to heat the fixing roller.

Therefore, the heating temperature is lowered by selectively heating the sheet in advance (hereinafter referred to as “preheating”) and heating the fixing roller by one external heating unit. Thus, a technology that can shorten the rise time (hereinafter referred to as “warm-up time”) for raising the temperature to the heating temperature is disclosed (for example, see Patent Document 1).
Japanese Utility Model Publication No. 56-85853

  However, in the above-described technique, when the fixing roller is heated by an external heating means, heat easily escapes from both ends in the longitudinal direction of the fixing roller, so that there is a problem that temperature unevenness occurs at the center and both ends. It was.

  The present invention has been made to solve the above-described problems. When the heating member is heated by an external heating means, both ends in the longitudinal direction of the heating member are heated, thereby causing uneven temperature of the heating member. It is an object of the present invention to provide a fixing device capable of suppressing the occurrence and a printing apparatus including the above-described fixing device.

In order to achieve this object, the printing apparatus according to claim 1 radiates heat, and a heat fixing unit that sandwiches the paper between the heating member and the pressure member and thermally fixes the printing agent on the paper. An external heating means having an opening for forming the heating member, wherein the heating member is configured to be movable between a heating position where the opening faces the heating member and a paper position where the opening faces the paper. Alternatively, the fixing device includes an external heating unit that selectively heats the paper from the outside, and both end portions are heated by the external heating unit more than the central portion in the longitudinal direction of the heating member. and fixing device that is configured as that provided with the fixing device therein, comprising a main body portion which one surface is opened, and a lid for covering the opened said one surface of said main body portion so as to be opened and closed, and
The external heating device is moved to the heating position when the lid is opened.

  The fixing device according to claim 2 is characterized in that the heating member has an internal heating means inside.

  The fixing device according to claim 3, further comprising a heat shield portion that shields between a central portion in a longitudinal direction of the heating member and the external heating means, and the heating member by the external heating means is provided by the heat shield portion. It is characterized in that the heating of is shielded.

  According to a fourth aspect of the present invention, there is provided the fixing device further comprising a temperature detection unit that detects a temperature of the heating member between the heating member and the heat shield portion.

Further, the fixing device according to claim 5 is provided with a heat shield part that shields between a central portion in the longitudinal direction of the heating member and one end thereof and the external heating means, and the heating member and each of the heat shields. Temperature detecting means for detecting the temperature of the heating member is provided between each of the parts.

According to the printing apparatus of the first aspect, when the heating member is heated by the external heating means, it is possible to suppress the occurrence of temperature unevenness of the heating member. Moreover, it is possible to avoid that a user touches an external heating means directly.

  According to the fixing device of the second aspect, the warm-up time is further shortened by having the internal / external heating means.

  According to the fixing device of the third aspect, it is possible to use an external heating means having a simple configuration.

  According to the fixing device of the fourth aspect, since the temperature detecting means can be prevented from being directly heated by the external heating means, it is possible to accurately measure the temperature of the heating member.

  According to the fixing device of the fifth aspect, the temperature detecting means provided at the longitudinal end of the heating member can be prevented from being directly heated by the external heating means, so that the temperature of the heating member can be more accurately set. It is possible to measure.

<Overall configuration of printing apparatus>
FIG. 1 is a side sectional view showing a schematic configuration of a printer 1 as an example of a printing apparatus of the present invention. The overall configuration of the printer 1 will be described with reference to FIG. For convenience of explanation, the X axis is taken in the horizontal direction in the figure, and the Y axis is taken in the vertical direction in the figure.

  Note that the printing apparatus of the present invention can be applied not only to a printer but also to a widely known printing apparatus such as a copying machine or a multi-function machine having a fixing unit 7 described later.

  The printer 1 prints on a sheet 2 based on image data received from a host device (not shown) such as a personal computer or a server, or an external storage device (not shown) such as a digital camera or a USB memory.

  The printer 1 includes a main body 3 as a main body portion of the present invention. A lid 4 is provided as a lid portion of the present invention on the front side (+ X side) of the main body 3 and covers an entrance for a user to access the inside of the main body. A paper feed tray 5 is provided at the bottom (−Y side) of the main body 3, and the paper 2 is stacked and accommodated in the paper feed tray 5.

  In the main body 3, a conveyance path for conveying the paper 2 taken out from the paper feed tray 5 to the outside of the main body 3 (the paper discharge tray 8) is provided, and the printing unit 6 is sequentially arranged on the conveyance path from the upstream side. The fixing units 7 constituting the fixing device of the present invention are arranged. A paper discharge tray 8 is formed on the upper side (+ Y side) of the main body 3, and the printed paper 2 is conveyed on the conveyance path and discharged onto the paper discharge tray 8.

  A paper feed roller 9, a registration roller 10, and a paper discharge roller 11 are arranged on the transport path to transport the paper 2. The paper feeding roller 9, the registration roller 10, and the paper discharge roller 11 constitute a conveying unit.

  A paper feed roller 9 as a paper feed unit is disposed at the front end (+ X side) of the paper feed tray 5, picks up the paper 2 stored in the paper feed tray 5, and sends it out to the registration roller 10. The registration roller 10 is disposed on the upstream side of the printing unit 6, corrects the skew of the paper 2, and sends it to the printing unit 6. In the conveyance path, the paper feed tray 5, the paper feed roller 9, and the registration roller 10 constitute a paper feed unit.

  A paper discharge roller 11 as a paper discharge unit is disposed on the downstream side of the printing unit 6 and discharges the paper 2 to the paper discharge tray 8. In the conveyance path, the paper discharge roller 11 and the paper discharge tray 8 constitute a paper discharge unit.

  The printing unit 6 includes a charger 12, a photosensitive drum 13, a scanner unit 14, a toner cartridge 15, a toner 16, and a transfer roller 17, and is on the sheet 2 based on input image data. An image is formed on.

  The charger 12 is disposed in the vicinity of the photosensitive drum 13, and the surface of the photosensitive drum 13 charged by the charger 12 is irradiated with a laser from the scanner unit 14 to form an electrostatic latent image. The photosensitive drum 13 is supplied with toner 16 from the toner cartridge 15, and the electrostatic latent image on the photosensitive drum 13 is visualized (hereinafter referred to as “toner image”).

  A transfer roller 17 is disposed opposite to the photosensitive drum 13, and a toner image is transferred by the photosensitive drum 13 and the transfer roller 17 onto the sheet 2 conveyed from the registration roller 10 between the photosensitive drum 13 and the transfer roller 17. Transcribed.

  A fixing unit 7 is disposed on the downstream side of the photosensitive drum 13 so that the image transferred onto the paper 2 is thermally fixed.

  An open / close sensor 18 for detecting the open / closed state of the lid 4 is disposed on the upper side (+ Y side) of the front side (+ X side) of the main body 3.

  Further, the printer 1 is provided with an operation unit (not shown) as an input unit and a display unit (not shown) as a display unit, and serves as an interface with a user.

  The main body 3 is provided with a power switch (not shown) for starting or stopping the power supply of the printer 1.

Note that the printer 1 of the present embodiment has only one toner cartridge 15 installed and can only perform printing with the monochromatic toner 16, but the printing apparatus of the present invention is not limited thereto. In other words, the present invention is also applicable to a printer in which a plurality of toner cartridges 15 are configured in the printing unit 6 and printing with a plurality of color toners 16 (for example, printing with yellow, magenta, cyan, and black toners 16) is possible. .
<Overall configuration of heat fixing device>
FIG. 2 is a perspective view showing the overall configuration of the fixing unit 7. FIG. 2 shows a state where an external heating unit 20 described later is heating the paper 2. For convenience of explanation, XYZ axes are taken in FIG. 2 corresponding to FIG.

FIG. 3 is an external view of the fixing unit 7 and shows a positional relationship among a thermistor 23 described later, a heat shield member 24 described later, and a sheet 2 to be conveyed described later. 3 is a view seen from the + X direction of FIG. For convenience of explanation, the Y-axis and the Z-axis are taken corresponding to FIGS. Moreover, in FIG. 3, it has illustrated in the state except the external heating apparatus 20 mentioned later.

  Further, FIGS. 4A and 4B are cross-sectional views showing a state in which an external heating unit 20 described later heats a heating roller 21 and a sheet 2 described later. For convenience of explanation, the X-axis and the Y-axis are taken corresponding to FIGS.

  The overall configuration of the fixing unit 7 will be described with reference to FIGS. 2, 3, 4 (A), and 4 (B).

  The fixing unit 7 includes an external heating unit 20 that is an external heating unit of the present invention, a heating roller 21 and a pressure roller 22 that are a thermal fixing unit of the present invention, a thermistor 23 that is a temperature detection unit of the present invention, It is comprised by the heat-insulating member 24 which is the heat-insulating part of invention. The heating roller 21 and the pressure roller 22 correspond to the heating member and the pressure member in the present invention, respectively.

  The external heating unit 20 is long like the heating roller 21, and includes a single halogen heater 25, a reflecting plate 26, and a condenser lens 27. The heat generated by the halogen heater 25 is radiated in the opening direction of the reflecting plate 26. The condenser lens 27 is disposed so as to cover the opening of the reflecting plate 26 and radiates heat from the halogen heater 25 that diffuses from the opening of the reflecting plate 26 in a certain direction. The condenser lens 27 also serves to protect the user from touching the halogen heater 25 directly.

  Further, the external heating unit 20 is rotatably supported in order to selectively heat either the heating roller 21 or the paper 2 being conveyed. Specifically, the reflecting plate 26 and the condenser lens 27 are supported so as to be rotatable about the longitudinal direction, and are driven to rotate by a motor 34 (see FIG. 4). The halogen heater 25 is fixed and is not driven to rotate.

  In addition, the external heating part 20 in this embodiment is a structure already known, and is implement | achieved by the simple structure.

  The heating roller 21 is provided with an internal heating unit 28 that is an internal heating means of the present invention, and the internal heating unit 28 heats the heating roller 21 from the inside.

  The pressure roller 22 sandwiches the paper 2 with the heating roller 21 and heat-fixes the toner on the paper 2.

  The thermistor 23 is for measuring the temperature of the surface of the heating roller 21, and is disposed in contact with the heating roller 21 at the longitudinal center and the right end (+ Z direction) of the heating roller 21. In this embodiment, the contact type thermistor 23 is used, but a non-contact type thermistor may be used.

  If the paper 2 to be transported is a paper 2 of a size that can be transported, it is transported so that the central portion of the paper 2 passes through the central portion in the longitudinal direction of the heating roller 21, and the thermistor 23 at the right end (+ Z direction) is As shown in FIG. 3, the sheet 2 is provided outside the maximum sheet width W of the sheet 2 conveyed to the fixing unit 7.

That is, the thermistor 23 provided at the center measures the temperature of the heating roller 21 at the portion where the paper 2 is conveyed, and the thermistor 23 provided at the right end (+ Z direction) is the portion where the paper 2 is not conveyed. The temperature of the heating roller 21 is measured. By providing the thermistor 23 in this way, the temperature of the heating roller 21 taken from the heating roller 21 to the paper 2 conveyed can be accurately measured.

  The arrangement of the thermistor 23 is not limited to this arrangement. Therefore, the thermistor 23 provided at the right end (+ Z direction) may measure the temperature of the heating roller 21 in the portion where the paper 2 is conveyed. In this case, highly accurate temperature measurement is possible by measuring the temperature of the heating roller 21 at two locations.

  Needless to say, the thermistor 23 provided at the right end (+ Z direction) may be provided at the left end (−Z direction) or may be provided at both ends.

  The heat shield member 24 shields the heating from the external heating unit 20, and between the heating roller 21 and the external heating unit 20, as shown in FIG. It arrange | positions so that it may cover the thermistor 23 arrange | positioned at the center part and the right end part (+ Z direction), respectively. By disposing the heat shield member 24 in this way, the heating of the thermistors 23 at the center in the longitudinal direction and the right end (+ Z direction) of the heating roller 21 is shielded, and only the left and right ends of the heating roller 21 are heated. It becomes possible to do.

  Since the surface of the heating roller 21 easily escapes heat from the left and right end portions in the longitudinal direction due to its shape, the heating at the center portion in the longitudinal direction of the heating roller 21 is high when only the internal heating portion 28 is heated. The temperature is lowered and temperature unevenness occurs. However, as shown in FIG. 3 and FIG. 4A, the left and right ends in the longitudinal direction of the heating roller 21 are heated by the external heating unit 20, so that the occurrence of uneven temperature in the heating roller 21 can be suppressed. Is possible. Therefore, since the temperature of the entire heating roller 21 is uniform, it is possible to perform heat fixing with good quality.

Further, the heating roller 21 is heated by the two heating units, that is, the external heating unit 20 and the internal heating unit 28, whereby the warm-up time can be shortened.
<Control block configuration>
FIG. 5 is a control block diagram of the printer 1.

  The printer 1 is controlled by the control unit 30. The control unit 30 is a known computer, and a ROM 32 and a RAM 33 are connected to the CPU 31. The ROM 32 stores a printing program for printing by the printer 1 and a heating program for operating the external heating unit 20, and the CPU 31 executes the program stored in the ROM 32.

  The CPU 31 is connected to an open / close sensor 18 to detect the open / closed state of the lid 4 with respect to the main body 3.

  Further, a motor 34 is connected to the CPU 31, and the reflection plate 26 and the condenser lens 27 of the external heating unit 20 are driven to rotate about the longitudinal direction by the CPU 31 according to the state of the printer 1.

  In addition, the halogen heater 25 of the external heating unit 20 and the internal heating unit 28 are connected to the CPU 31, and the halogen heater 25 and the internal heating unit are processed by the CPU 31 according to the temperature value obtained from the thermistor 23 connected in the same manner. The heating by 28 is controlled.

Note that the CPU 31 is connected to the printing unit 6 and various rollers, which are omitted in FIG.
<Description of Operation of Fixing Unit 7>
FIG. 6 is a flowchart showing a warm-up operation (to be described later) and a preheating operation (to be described later) of the fixing unit 7 constituting the fixing device of the present invention. Further, FIG. 7 is a flowchart showing the operation of the fixing unit 7 when the lid 4 is opened. The operation of the fixing unit 7 will be described with reference to FIGS. 4A, 4B, 6, and 7. FIG.

  First, when a power switch (not shown) is turned on by the CPU 31 in step 101 (hereinafter abbreviated as “S”) 101 in FIG. 6, or when the printer 1 starts up from a state where printing is not performed for a long time to a state where a printing operation is possible. (Hereinafter referred to as “rising from the power saving mode”) (S101: Y), the printer 1 starts a warm-up operation. Note that the warm-up operation is preparation so that the printer 1 can execute the printing operation. At this time, the surface of the heating roller 21 of the fixing unit 7 is heated to a heating temperature necessary for heat fixing.

  During the warm-up operation, the motor 34 is driven by the CPU 31 in S102, and the external heating is performed toward the position where the opening direction of the reflection plate 26 of the external heating unit 20 faces the heating roller 21 as shown in FIG. The unit 20 is rotationally driven. In step S <b> 103, the surface of the heating roller 21 is heated by the halogen heater 25 of the external heating unit 20.

  At this time, the heating roller 21 is rotationally driven (rotated) to uniformly heat the circumferential direction, and the internal heating unit 28 also heats the surface of the heating roller 21 from the inside. Further, both the left and right ends in the longitudinal direction of the heating roller 21 are heated by the external heating unit 20 and the heat shield member 24, and the heating roller 21 is heated from the inside by the internal heating unit 28. The surface has a uniform temperature distribution, and the occurrence of temperature unevenness is suppressed.

  Next, in S104, the thermistor 23 determines whether the surface temperature of the heating roller 21 has been heated to the heating temperature. At this time, the condition for determining that the heating roller 21 has been heated to the heating temperature is to detect that the thermistors 23 arranged at the center and the right end (+ Z direction) have reached the heating temperature.

  When the heating roller 21 is heated, the external heating unit 20 and the internal heating unit 28 are controlled so as to suppress the occurrence of temperature unevenness at the center and the end in the longitudinal direction of the heating roller 21. Specifically, when the thermistor 23 at the center reaches the heating temperature and the thermistor 23 at the right end (+ Z direction) does not reach the heating temperature, the heating of the internal heating unit 28 is stopped and only the external heating unit 20 is used. The heating roller 21 is heated. Needless to say, in the opposite case, heating is performed only by the internal heating unit 28.

  Here, if it is determined that the heating roller 21 has not reached the heating temperature (S104: N), the external heating unit 20 and the internal heating unit 28 heat the heating roller 21 by the above-described control until the heating roller 21 reaches the heating temperature. Continued.

  If it is determined that the surface temperature of the heating roller 21 has reached the heating temperature (S104: Y), then in S105, it is determined whether a printing operation has been executed. The printing operation is an operation for printing an image on the paper 2 by the printer 1. Further, the printing operation is executed in response to a print command from a host device (not shown) and an operation unit (not shown) by the user.

  Here, if it is determined that the printing operation is not executed (S105: N), the warm-up operation is continued in S103 and S104 in order to keep the temperature of the heating roller 21 constant. While the warm-up operation is continued, the temperature of the heating roller 21 is kept uniform, and the heat fixing of the toner 16 on the paper 2 is performed well.

On the other hand, if it is determined in S105 that the printing operation has been executed (S105: Y), then in S106, the motor 34 is driven by the CPU 31, and the reflection of the external heating unit 20 shown in FIG. The external heating unit 20 is rotationally driven toward the position where the opening direction of the plate 26 faces the conveyance path of the paper 2. In step S107, the sheet 2 conveyed by the halogen heater 25 of the external heating unit 20 is preheated. The preheat is synchronized with the conveyance of the paper 2 in the printing operation, and the halogen heater 25 of the external heating unit 20 is controlled so that the heat of the preheat is applied to each of the conveyed paper 2.

  The sheet 2 is preheated before the heat fixing by the heating roller 21 and the pressure roller 22, so that the heating temperature of the heating roller 21 necessary for the heat fixing can be set low. Therefore, it is possible to shorten the warm-up time.

  Thereafter, when it is determined in S108 whether the printing operation is completed, the process returns to S102 and the warm-up operation is executed.

  When the power switch is turned off by the user, the operation of the printer 1 is forcibly stopped. In addition, when the time during which the warm-up operation is performed passes a predetermined time for shifting to the power saving mode, the warm-up operation is stopped, and the heating of the external heating unit 20 and the internal heating unit 28 is stopped.

  Next, the operation when the lid 4 of the printer 1 is opened will be described.

  When the power switch (not shown) of the printer 1 is turned on, if it is determined in S201 of FIG. 7 that the lid 4 has been opened by the open / close sensor 18 of the printer 1 (S201: Y), in S202, the external heating unit It is determined whether the heating is performed by the 20 halogen heaters 25 and the internal heating unit 28.

  Here, when it is determined that the heating is performed by the halogen heater 25 and the internal heating unit 28 of the external heating unit 20 (S202: Y), the halogen heater 25 and the internal heating unit 28 of the external heating unit 20 are determined in S203. The heating of is stopped. Next, when the process of S203 is completed or it is determined in S202 that heating is not performed by the halogen heater 25 and the internal heating unit 28 of the external heating unit 20 (S202: N), in S204, the external It is determined whether the heating unit 20 is located in the direction facing the heating roller 21 shown in FIG.

  Here, if it is determined that the external heating unit 20 is not positioned in the direction facing the heating roller 21 (S204: N), in S205, the CPU 31 drives the motor 34 to move the external heating unit 20 to the heating roller 21. Rotate to the position facing you. This position corresponds to the retracted position of the present invention.

  In S204, if it is determined that the external heating unit 20 is positioned in the direction facing the heating roller 21 (S204: Y), the external heating unit 20 is not rotationally driven.

Therefore, when the user accesses the inside of the main body 3 of the printer 1, direct contact with the external heating unit 20 can be avoided.
<Description of modification>
The fixing device and the printing device of the present invention are not limited to the above configuration.

  For example, in the fixing device of the present invention, the internal heating unit 28 does not exist, the heating roller 21 is heated from the outside, and the fixing unit 7 has a new external heating unit that has the same effect as the internal heating unit 28 described above, The present invention can also be applied to the fixing unit 7 that can perform surf fixing.

  In that case, even when the heating roller 21 is heated uniformly from the outside in the longitudinal direction of the heating roller 21, heat at the end in the longitudinal direction easily escapes from the shape of the heating roller 21, and temperature unevenness similarly occurs. Similar effects can be obtained.

  The thermistor 23 can also be applied to one fixing unit 7. In this case, when the thermistor 23 is disposed at the center in the longitudinal direction of the heating roller 21, the heat shield member 24 disposed at the right end (+ Z direction) in the longitudinal direction of the heating roller 21 in the above embodiment is not necessary. The heat shield member 24 may be configured to shield only the central portion in the longitudinal direction of the heating roller 21.

  Needless to say, the present invention can also be applied to the fixing unit 7 using the heating roller 21 without the internal heating unit 28 and the thermistor 23 having one thermistor 23.

Furthermore, the external heating means of the present invention may have a configuration in which two external heating units 20 are arranged one at each of the left and right ends of the heating roller 21 in the longitudinal direction.

1 is a side sectional view showing a schematic configuration of a printer 1 which is a printing apparatus of the present invention. FIG. 2 is a perspective view showing an overall configuration of a fixing unit 7 according to the present invention. 4 is an external view for illustrating a positional relationship between a heat shield member 24 and a thermistor 23. FIG. (A) is sectional drawing explaining when the external heating part 21 is heated by the external heating part 20, (B) is description when the paper 2 conveyed by the external heating part 20 is heated. FIG. 2 is a control block diagram of the printer 1. FIG. 5 is a flowchart illustrating a warm-up operation and a preheating operation of the fixing unit 7. 6 is a flowchart showing the operation of the fixing unit 7 when the lid 4 is opened.

Explanation of symbols

2 paper 3 body 4 lid 7 fixing unit 18 open / close sensor 20 external heating unit 21 heating roller 22 pressure roller 23 thermistor 24 heat shield member 28 internal heating unit

Claims (5)

A heat fixing unit that sandwiches a sheet between a heating member and a pressure member and thermally fixes the printing agent on the sheet; and an external heating unit in which an opening for radiating heat is formed, the opening being External heating means for selectively heating the heating member or the paper from the outside by being configured to be movable between a heating position facing the heating member and a paper position where the opening faces the paper ; a fixing device comprising, by the external heating means, said compared to the central portion in the longitudinal direction of the heating member, and fixing device that is configured such that both end portions are heated more,
A main body portion provided with the fixing device therein and having one surface open;
A cover that covers the open surface of the main body so as to be openable and closable,
The printing apparatus according to claim 1, wherein the external heating unit moves to the heating position when the lid is opened. The printing apparatus according to claim 1, wherein the heating member includes an internal heating unit. A heat-shielding part that shields between the longitudinal center of the heating member and the external heating means is provided, and the heating of the heating member by the external heating means is shielded by the heat-shielding part. The printing apparatus according to claim 1 or 2. The printing apparatus according to claim 3, further comprising a temperature detection unit configured to detect a temperature of the heating member between the heating member and the heat shield. A heat shield part that shields between the central part in the longitudinal direction of the heating member and one end thereof and the external heating means, respectively,
3. The printing apparatus according to claim 1, wherein temperature detection means for detecting the temperature of the heating member is provided between the heating member and each of the heat shielding portions.