JP2002139952A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device in which the temperature detection of a heating roller can stably be performed by a non-contact temperature detecting means. SOLUTION: The image forming device includes a heating roller 19 having a heat source 19a within and a pressure roller 21 press-contacting the heating roller 19, and is provided with a fixing device 13 to fix a toner image transferred on a transfer material P, and a thermopile 23 to detect the temperature of the heating roller 19. In a laser printer 1 which controls the temperature of the heating roller 19 on the basis of a temperature detected by the thermopile 23, the thermopile 23 is installed below the axis line of the heating roller 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, and the like.

[0002]

2. Description of the Related Art For example, in a laser printer,
The transfer image on the sheet (transfer material) is fixed by a fixing device (fixing device). As a means for detecting the temperature during the fixing, a contact-type thermistor or the like is used to contact a heating roller of the fixing device. And a contact-type temperature detecting means for detecting the temperature.

However, in the contact-type temperature detecting means, toner adheres to the contact surface of the temperature detecting means with the heating roller, and the surface of the heating roller is worn to shorten its life, or toner adheres too much. Then, since the temperature of the heating roller is detected via the toner, there is a problem that the detected temperature deviates from the actual temperature and the control temperature changes.

For this reason, it has been considered to use a non-contact type temperature detecting means. As the non-contact temperature detecting means, a means using a thermopile can be used (for example, Japanese Patent Application Laid-Open No. 7-77888).

[0005]

However, the non-contact temperature detecting means described above is generally weak against heat and does not have a high usable temperature. There is a problem that the temperature of the contact temperature detecting means rises and exceeds the usable temperature of the non-contact temperature detecting means, and the temperature detection of the heating roller by the non-contact temperature detecting means becomes unstable.

Accordingly, it is an object of the present invention to provide an image forming apparatus capable of stably detecting the temperature of a heating roller by a non-contact temperature detecting means.

[0007]

According to a first aspect of the present invention, there is provided a heating roller having a heat source therein and a pressure roller which is in pressure contact with the heating roller, and is transferred from an image carrier to a transfer material. An image forming apparatus comprising: a fixing device for fixing a transferred image; and a non-contact temperature detecting unit for detecting a temperature of the heating roller, wherein a temperature of the heating roller is controlled based on a temperature detected by the non-contact temperature detecting unit. The detecting means is provided below the axis of the heating roller.

According to the first aspect of the present invention, the fixing device applies heat and pressure by a heating roller and a pressure roller to the transfer material carrying the toner image to transfer the transfer image to the transfer material. The non-contact temperature detecting means detects the temperature of the heating roller, and controls the temperature of the heating roller based on the detected temperature so that the temperature of the heating roller does not rise more than necessary.

The non-contact temperature detecting means is disposed below the axis of the heating roller, and the heat from the heating roller is hardly transmitted to the non-contact temperature detecting means. Temperature can be prevented,
The failure of the non-contact temperature detecting means can be prevented, and the temperature of the non-contact temperature detecting means can be stably detected. Further, since the non-contact temperature detecting means is not in contact with the heating roller, it does not damage the heating roller and can extend the life of the heating roller.

According to a second aspect of the present invention, there is provided a fixing device which includes a heating roller having a heat source therein and a pressure roller which presses against the heating roller to fix a transfer image transferred from an image carrier to a transfer material. An image forming apparatus that includes a device and a non-contact temperature detecting unit that detects a temperature of the heating roller, and controls a temperature of the heating roller based on a temperature detected by the non-contact temperature detecting unit. It is installed near the exterior part of the apparatus main body, and the exterior part is formed with a ventilation hole communicating with the outside air at a position corresponding to the installation part of the non-contact temperature detecting means.

According to the second aspect of the present invention, the non-contact temperature detecting means is provided near the exterior part having the air hole, and the non-contact temperature detecting means is always in contact with the outside air through the air hole. Since the temperature rise of the non-contact temperature detecting means can be prevented, the failure of the non-contact temperature detecting means can be prevented, and the temperature of the non-contact temperature detecting means can be stably detected. Also, since the non-contact temperature detecting means is not in contact with the heating roller, it does not damage the heating roller,
The life of the heating roller can be extended.

[0012] The invention according to claim 3 is the invention according to claim 1 or 2.
The non-contact temperature detecting means is attached to a portion other than the fixing device in the image forming apparatus main body.

[0013] According to the third aspect of the present invention, the first aspect is provided.
Or the same effect as the invention described in 2 above, and the non-contact temperature detecting means is arranged at a portion other than the fixing device, so that the non-contact temperature detecting means is separated from the heating roller, and the non-contact temperature detecting means is separated from the heating roller. Since heat is less likely to reach the non-contact temperature detecting means, it is possible to further prevent the temperature of the non-contact temperature detecting means from rising, and to stably detect the temperature of the non-contact temperature detecting means.

The invention described in claim 4 is the first to third aspects of the present invention.
In the invention described in any one of the above, the image carrier is located below the fixing device, and the transfer of the transfer material is performed from below to above.

[0015] According to the fourth aspect of the present invention, the first aspect is provided.
According to the third aspect of the present invention, when the non-contact temperature detecting unit is disposed below the heating roller, the transfer material is conveyed in the horizontal direction. By the pressure rollers being arranged side by side in the vertical direction, the transfer material passes between the non-contact temperature detecting means and the heating roller during paper passing, thereby shielding between the non-contact temperature detecting means and the heating roller. In some cases, the temperature cannot be detected by the non-contact temperature detecting means, and it becomes difficult to arrange the non-contact temperature detecting means below the heating roller.

However, if the transfer material is conveyed upward (conveyed vertically) from below, the heating roller and the pressure roller of the fixing device are arranged side by side (in a direction intersecting the conveyance direction). Since the transfer material does not shield between the non-contact temperature detecting means and the heating roller even when the paper is passed, the non-contact detecting means can be easily arranged below the heating roller, and the non-contact temperature detecting means Temperature detection of the heating roller can always be performed.

[0017]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a sectional view schematically showing a laser printer to which the present invention is applied. A laser printer (image forming apparatus) 1 includes a photosensitive member 3 serving as an image carrier, a charging device 4 for charging the photosensitive member 3, and writing on the charged photosensitive member 3 an electrostatic latent image corresponding to a document image. A developing device 7 for developing the electrostatic latent image of the photoconductor 3 as a toner image; a transfer device 9 for transferring the toner image (transfer image) of the photoconductor 3 to transfer paper (transfer material) P; A cleaning device 11 for removing toner remaining on the photoconductor 3 later, a fixing device 13 for fixing the toner image of the transfer paper P to the transfer paper P, and a paper feeding device for feeding the transfer paper P toward the photoconductor 3 15 is provided. In addition, the code | symbol 17 in a figure is:
This is a manual paper feed tray for manually feeding paper.

In this embodiment, the laser printer 1
As shown in FIG. 1, the paper feeding device 17 is located at the lower portion of the printer main body 2, the fixing device 13 is located at the upper portion of the printer main body 2, and the photoconductor 3 is located between the paper feeding device 17 and the fixing device 13. The transfer sheet P from the sheet feeding device 17 is conveyed vertically downward in FIG. 1 from below. That is, the laser printer 1 shortens the transfer path of the transfer sheet P by forming the transfer path of the transfer sheet P upward from below in order to reduce the size and shorten the first print time.

FIG. 2 is an enlarged sectional view showing the vicinity of the fixing device. As shown in FIG. 2, the fixing device 13 includes a heating roller 19 having a heat source 19 a such as a heater therein, and a pressure roller 21 pressed against the heating roller 19.
Heat and pressure are applied to the transfer paper P passing through the nip between the heating roller 19 and the pressure roller 21 to fix the toner image on the transfer paper P.

A thermopile (non-contact temperature detecting means) 23 for detecting the temperature of the surface of the heating roller 19 is located outside the fixing device 13 between the heating roller 19 and the photosensitive member 3. That is, the thermopile 23 is
The heating roller 19 is disposed below a horizontal line H passing through the axis of the heating roller 19. The temperature of the heating roller 19 is controlled to about 180 ° by temperature detection by the thermopile 23.
The thermopile 23 detects the temperature of the surface of the heating roller 19 by detecting the amount of infrared radiation radiated from the surface of the heating roller 19, and the temperature control unit (not shown) of the fixing device 13 Based on this temperature detection, the heat source 1
The temperature of 9a is adjusted.

By using the thermopile 23 that is not in contact with the heating roller 19, the life of the heating roller 19 can be extended since the thermopile 23 does not damage the surface of the heating roller 19. In this embodiment, the heat-resistant temperature of the thermopile 23 is about 80 °. Further, the non-contact temperature detecting means is not limited to the thermopile 23 but may be any as long as it can detect the temperature of the heating roller 19 in a non-contact state.

Next, the operation of the present embodiment will be described based on the above configuration. The transfer sheet P fed by the sheet feeding device 15 is conveyed toward the photosensitive member 3 located above the sheet feeding device 15 and the transfer device 9. The photoconductor 3 has a developing device 7
The transfer device 9 transfers the toner image of the photoconductor 3 to the transfer paper P passing between the photoconductor 3 and the transfer device 9. Transfer paper P on which toner image has been transferred
Is transported toward the fixing device 13 located above the photoconductor 3, and the heating roller 19 and the pressure roller 21 of the fixing device 13 fix the toner image on the transfer paper P by heat and pressure.

At this time, the heat radiated from the heating roller 19 is easily transmitted upward, and the temperature above the heating roller 19 increases. Further, since the transfer paper P passes through the fixing device 13, the transfer paper P itself becomes hot after passing.
For this reason, since the transfer paper P which has become hot is transported downstream of the fixing device 13 (upper side of the heating roller 19), the transport guide 22 and the surrounding atmosphere are also upstream (heating roller 1).
9 below).

Here, since the thermopile 23 uses electronic components, its heat-resistant temperature is not so high and may break down if it exceeds about 80 ° C. If the thermopile 23 breaks down, the temperature of the heating roller 19 cannot be detected. Therefore, the temperature of the heating roller 19 cannot be controlled, and the temperature of the heating roller 19 may be abnormally high.

However, in the present embodiment, the heating roller 1
The thermopile 23 is installed below the axis of the transfer roller 9 so that the heat from the heat roller 19 is less affected by heat and the heat roller 19 is moved in the transfer direction of the transfer paper P.
, The influence of heat from the heated transfer paper P is also reduced, so that the temperature of the thermopile 23 can be prevented from rising, and the thermopile 23 can be prevented from malfunctioning. Temperature detection can be performed stably.

In this embodiment, the transfer paper P is transported upward from below, and the transfer paper P is transported in the vertical direction in FIG.
9 and the pressure roller 21 are arranged side by side, so that the thermopile 23 can be easily installed below the heating roller 19.

On the other hand, in a configuration in which the transfer paper P is transported in the horizontal direction, when the heating roller and the pressure roller are arranged in the vertical direction and the heating roller is located on the upper side, the thermopile is placed below the heating roller. When the transfer roller 23 is provided, the transfer paper passes between the heating roller and the thermopile 23 in the paper passing state, and the temperature of the heating roller cannot be detected during that time. Therefore, it is difficult to install the thermopile 23 on the heating roller 19.

However, in the present embodiment, the transfer paper P is transported in the vertical direction, and the heating roller 19 and the pressure roller 2
1 are arranged in the horizontal direction, so that even if the thermopile 23 is installed below the heating roller 19, it is possible to prevent the transfer paper P from blocking between the thermopile 23 and the heating roller 19 during paper passing, and 23 can always detect the temperature of the heating roller 19.

Next, another embodiment will be described. In the description, the same parts as those described above are denoted by the same reference numerals, and the description thereof will be omitted.

FIG. 3 is an enlarged sectional view showing the vicinity of the fixing device according to the second embodiment. In the second embodiment, as shown in FIG. 3, the thermopile 23 is arranged beside the heating roller 19 and near the exterior part 2a of the printer main body 2, and as shown in FIG. The first embodiment differs from the first embodiment in that a ventilation hole 2b for taking in air is formed. The vent 2b may be as shown in FIG.

In the second embodiment, since the thermopile 23 is arranged near the ventilation hole 2b of the exterior part 2a in which the ventilation hole 2b is formed, the outside air always comes into contact with the thermopile 23, and the temperature of the thermopile 23 rises. Can be prevented. In the second embodiment, the same operation and effect can be obtained even when the present invention is applied to not only the vertical transport printer 1 but also a horizontal transport printer.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. For example, in the first embodiment, the thermopile 23 is provided immediately below the heating roller 19, but is not limited thereto, and may be provided obliquely below the heating roller 19 in the fixing device 13. What is necessary is just to arrange | position below the horizontal line H which passes through an axis.

In the second embodiment, the thermopile 23 is arranged beside the heating roller 19, but may be arranged below or above the heating roller 19, for example. In particular, when the thermopile 23 is disposed below the heating roller 19, the temperature of the thermopile 23 can be further prevented from rising.

Although the present invention has been applied to the laser printer 1, the present invention is not limited to this. For example, the present invention can be applied to an image forming apparatus such as a copier, a facsimile, or a multifunction peripheral including the same. Get.

[0035]

According to the first aspect of the present invention, the non-contact type temperature detecting means is disposed below the axis of the heating roller, so that heat from the heating roller is not easily transmitted to the non-contact temperature detecting means. With this configuration, it is possible to prevent the temperature of the non-contact temperature detecting means from rising above the temperature, so that the failure of the non-contact temperature detecting means can be prevented and the temperature of the non-contact temperature detecting means can be detected stably. Further, since the non-contact temperature detecting means is not in contact with the heating roller, it does not damage the heating roller and can extend the life of the heating roller.

According to the second aspect of the present invention, since the non-contact temperature detecting means is always in contact with the outside air through the vent, the temperature rise of the non-contact temperature detecting means can be prevented. In addition to preventing failure of the means,
The temperature detection by the non-contact temperature detecting means can be performed stably. Further, since the non-contact temperature detecting means is not in contact with the heating roller, it does not damage the heating roller and can extend the life of the heating roller.

According to the third aspect of the present invention, the same effect as the first or second aspect of the present invention is obtained, and the non-contact temperature detecting means is disposed at a portion other than the fixing device. Since the contact temperature detecting means is separated from the heating roller and the heat from the heating roller is less likely to reach the non-contact temperature detecting means, the temperature rise of the non-contact temperature detecting means can be further prevented, and the temperature detection of the non-contact temperature detecting means is stabilized. You can do it.

According to the fourth aspect of the present invention, the same effects as those of the first to third aspects of the invention are obtained, and the transfer material is conveyed upward from below, so that the fixing device can be used. The heating roller and the pressure roller are arranged side by side in the horizontal direction, and the transfer material does not shield between the non-contact temperature detecting means and the heating roller even during paper passing, so that the non-contact detecting means can be easily positioned below the heating roller. The temperature of the heating roller can always be detected by the non-contact temperature detecting means.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a laser printer to which the present invention is applied.

FIG. 2 is an enlarged sectional view showing the vicinity of a fixing device.

FIG. 3 is an enlarged sectional view showing the vicinity of a fixing device according to a second embodiment.

FIG. 4 is a perspective view showing an exterior part having a ventilation hole according to a second embodiment.

FIG. 5 is a perspective view showing an exterior part having a ventilation hole according to a modification of the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser printer (image forming apparatus) 2 Printer main body (image forming apparatus main body) 2a Exterior part 2b Ventilation hole 3 Photoconductor (image carrier) 13 Fixing device 19 Heating roller 19a Heat source 21 Pressure roller 23 Thermopile (non-contact temperature detection means)

Claims (4)

[Claims] A fixing device for fixing a transfer image transferred from an image bearing member to a transfer material, the fixing device including a heating roller having a heat source therein and a pressure roller pressed against the heating roller; A non-contact temperature detecting means for detecting the temperature of the heating roller based on the temperature detected by the non-contact temperature detecting means, wherein the non-contact temperature detecting means is installed below the axis of the heating roller. An image forming apparatus, comprising: A fixing device for fixing a transfer image transferred from an image carrier to a transfer material, the fixing device including a heating roller having a heat source therein and a pressure roller pressed against the heating roller, and a temperature of the heating roller. A non-contact temperature detecting means for detecting the temperature of the heating roller based on the temperature detected by the non-contact temperature detecting means. An image forming apparatus, wherein a ventilation hole is provided in the exterior part, the ventilation part communicating with the outside air at a position corresponding to an installation part of the non-contact temperature detecting means. 3. The image forming apparatus according to claim 1, wherein the non-contact temperature detecting unit is attached to a portion other than the fixing device in the image forming apparatus main body. 4. The image forming apparatus according to claim 1, wherein the image carrier is located below the fixing device, and the transfer of the transfer material is performed from below to above. apparatus.