JPH05297745A - Fixing device - Google Patents

Abstract

PURPOSE:To prevent a person's hand from touching a high-temperature fixing roller by deforming a lock member by heat so that a fixing cover may be locked when temperature in a fixing device is high, and restoring the lock member to an initial state so that locking may be released when the temperature becomes low. CONSTITUTION:When a heater 30 is turned off, that means, a heating roller 31 is not heated, the lock member 35 becomes vertical and a hook 37 is disengaged from the hole 34 of a fixing cover 28. However, when the heater 30 is turned on and the roller 31 is heated, the lock member 35 is deformed by heat because it is bimetal, and the hook 37 is fitted in the hole 34 as shown by a chain line when the temperature becomes equal to or higher than specified temperature. In such a state, the cover 28 is locked by the lock member 35 and is not opened. When the heater 30 is turned off and the temperature is lowered to temperature that is safe enough even when the person's hand touches the cover 28, the lock member 35 is restored to the initial state and the hook 37 is disengaged from the hole 34, and the cover 28 is opened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device in a laser printer, a laser facsimile, a copying machine or the like.

[0002]

2. Description of the Related Art In general, a fixing device for fixing a transferred image by pinching a transfer paper by a heating roller having a built-in heating means and a pressure roller which is rotated in pressure contact with the heating roller is generally used for heat retention and safety. The heat fixing portion composed of the heating roller and the pressure roller is covered with a fixing cover, and the fixing cover can be opened and closed for maintenance and jam processing. FIG. 8 shows a type in which the fixing cover 1 is screwed and removed when it is opened as shown in FIG. 9, and FIG. 10 is a type in which the fixing covers 1 and 2 are hinged and can be opened and closed as shown in FIG. is there. In addition, 3 is a heating roller and 4 is a pressure roller.

However, in the former fixing device, if the fixing cover 1 is removed as shown in FIG. 9 at the time of maintenance, it is dangerous because the high temperature heating roller is easily touched by the hand. Further, in the latter fixing device, as shown in FIG. 11, the fixing covers 1 and 2 can be opened and closed easily in the first place, and there are many occasions when the fixing covers are opened for jam clearance, and the risk of touching the high temperature heating roller is much higher. ..

Therefore, in the fixing device disclosed in Japanese Patent Laid-Open No. 1-285972, a warning indicating that the temperature is high is displayed. Also, in Japanese Utility Model Laid-Open No. 2-5771,
When the temperature of the fixing device is lower than a predetermined temperature, the upper fixing case is automatically opened by a spring when the upper case of the image forming device main body is opened, and when the temperature is higher than the predetermined temperature, the upper case of the image forming device main body is opened. Even if this happens, the upper fixing case is kept closed.

[0005]

However, merely displaying a warning that the temperature is high is not enough to call attention and is not a sufficient countermeasure. Further, when the upper case of the image forming apparatus main body is opened, the upper fixing case can be artificially opened even if the upper fixing case is held in the closed state when the fixing device has a predetermined temperature or higher. Therefore, it is unavoidable to open the upper fixing case of the fixing device in a high temperature state for maintenance or jam processing.

It is an object of the present invention to lock the fixing cover when the fixing device is at a high temperature so as to prohibit the fixing cover from being opened so that the fixing cover can be opened after the temperature becomes low.

[0007]

In the fixing device according to the present invention, a position constituted by a temperature-sensitive displacement material that is displaced according to a temperature change is engaged with a locking portion of a fixing cover of the fixing device when the temperature is higher than a predetermined temperature. A locking member is provided which locks the fixing cover by displacing the fixing cover. The locking is performed with the locking portion and a part of the locking member in a male and female fitting relationship. For example, the locking portion is a hole, a part of the lock member is a pin, and the pin is guided by a pin guide member to be fitted into the hole.

In addition to the above structure, it is preferable to provide a high-temperature display member outside the fixing cover, the high-temperature display member indicating that the color changes in accordance with the temperature change and is in a high temperature state. The high temperature display member is attached to the surface of the fixing cover in the form of a label, for example.

In order to cool the fixing device in advance before opening the fixing cover, the switch for turning on / off by the displacement of the lock member and the main body cover (or the upper unit) of the image forming apparatus main body have been opened. It is preferable to include a cover open detection circuit for detecting and a fan motor that is on / off controlled by the cover open detection circuit and the switch.

[0010]

When the temperature inside the fixing device is high, the lock member is displaced by heat and engages with the locking portion of the fixing cover,
The fixing cover is in a locked state where it cannot be opened. When the temperature inside the fixing device decreases, the lock member returns to its original position and disengages from the locking portion, and the lock is released, so that the fixing cover can be opened.

It is not easy to confirm whether the lock member is in the locked state or the unlocked state, but if a high temperature display member for discoloring according to the temperature change and notifying that the temperature is high is provided outside the fixing cover. The color of the high temperature display member can be used as a guide for confirming unlocking.

The cover open detection circuit detects that the main body cover (or upper unit) of the main body of the image forming apparatus is opened, and from that point on, the fan motor is activated to start cooling the fixing device and locks when the temperature drops. If the fan motor is stopped when the member is displaced toward the original position and the switch is turned off or on, the fixing device can be cooled before the fixing cover is unlocked.

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is an example of an image forming apparatus, and shows the internal structure of the apparatus with the upper unit 10a of the apparatus main body being opened with respect to the lower unit 10b (that is, with the cover open). In the figure, 11 is a shield plate, 12 is a toner overflow sensor, 13 is a type sensor, and 14 is a type sensor.
Is a charging voltage terminal, 15 is a reset lever, 16 is an ozone filter, 17 is a fan motor, 18 is a fixing device according to the present invention, 19 is an OPC magazine (cleaning unit), 20 is an interlock switch, 21 is a developing unit, and 22 is Image forming case, 23 is a total counter, 2
4 is a main motor, 25 is a toner end sensor, 26 is a developing bias voltage terminal, 27 is a laser beam shutter,
Reference numeral 28 is a fixing cover that can be opened and closed in the fixing device 18, and 29 is a high-temperature display label attached to the upper surface of the fixing cover 28.

FIG. 2 is a perspective view of the fixing device 18. The fixing device 18 heat-fixes an image by sandwiching a transfer sheet with an upper heating roller 31 having a heater 30 and a lower pressure roller 32. The fixing cover 28 covers the heating roller 31 from the upper side, and has a structure in which it is opened and closed vertically by a hinge 33. The high-temperature display Laval 29 attached to the upper surface of the fixing cover 28 is made of a thermo film and is red at a high temperature, but changes color to blue at a temperature that can be touched by a person.

Holes 34 serving as locking portions are provided in, for example, two side wall portions of the fixing cover 28, and locking members 35 corresponding to the holes 34 are fixed on a substrate 36 as shown in FIG. ing. The lock member 35 is made of an L-shaped bimetal, and has a hook 37 at its upper end that fits into the hole 34.

When the heater 30 is off, that is, when the heating roller 31 is not heated, the lock member 35 is in a vertical state as shown by the solid line in FIG.
Is out of the hole 34 of the fixing cover 28, the heater 3
When 0 is turned on and the heating roller 31 is heated, since the lock member 35 is a bimetal, it is thermally deformed, and when it reaches a temperature higher than a predetermined temperature, the hook 37 is provided with a hole 34 as shown by a chain line.
Mate with. In this state, the fixing cover 28 is locked by the lock member 35 and cannot be opened. Also,
In the high temperature state, the high temperature display label 29 turns red.

The heater 30 is turned off and the fixing cover 28 is turned on.
When the temperature falls to a safe level even if a person touches it, the lock member 35 returns to the original state, the hook 37 disengages from the hole 34, and the fixing cover 28 can be opened. The high temperature display label 29 is designed to turn blue after the temperature further decreases. That is, the lock member 35 and the high-temperature display member 29 are delayed in time after the lock member 35 returns to its original state and the hook 37 is disengaged from the hole 34.
9 has been selected for the thermal reaction relationship such that the color changes from red to blue.

FIG. 4 shows a structure in which the fixing device 18 is cooled in addition to the structure described above. That is, the L-shaped electrodes 38 face each other so that the vertical portions thereof face each other so as to form a switch in cooperation with the lock member 35, and the insulating material 39 is interposed between the horizontal portions of the plastic screws 40. Are fixed on the substrate 36 together. Then, the lock member 35
When the fixing cover 28 is thermally deformed and the fixing cover 28 is locked as shown by the chain line, the locking member 35 comes into contact with the electrode 38 to switch on, and a fixing cover lock signal is obtained. That is, the signal level at this time is L
become.

On the other hand, the upper unit 10 of the image forming apparatus main body
The opening / closing of a is detected by the cover open detection circuit 41, and a cover open signal is output from the cover open detection circuit 41. When the upper unit 10a is opened, the level of the cover open signal becomes L. The cover open signal and the fixing cover lock signal are input to the gate circuit 42. The output of the gate circuit 42 drives the transistor 4 for driving the fan motor 43.
4 is turned on and off.

Therefore, when the fixing cover 28 is locked as described above, when an operator or a service person opens the upper unit 10a for jam clearance or maintenance, the fixing cover lock signal becomes L. Since the cover open signal also becomes L, the transistor 44 is turned on, the fan motor 43 rotates, and the fixing device 18 is cooled.

After that, when the temperature inside the fixing device 18 is lowered to a level touched by a person, the lock member 35 is unlocked and separated from the electrode 38, the switch is turned off and the fixing cover lock signal becomes H. , The transistor 44 is turned off and the phone motor 43 is stopped.

FIG. 5 shows a buzzer 45 in addition to the configuration of FIG.
Further, a buzzer drive transistor 46 for driving the same is provided so that the buzzer 45 sounds at the same time as the rotation of the fan motor 43, and the buzzer 45 also stops at the same time as the fan motor 43 stops.

6 and 7 show another example of the lock mechanism. In the lock member 35 of this example, a pin 47 that fits into the hole 34 of the fixing cover 28 is provided at the center of the upper end of the lock member 35, and a pin guide member 48 is made to face the lock member 35 so as to face the substrate 3
A guide hole 49 for guiding the pin 47 by penetrating the pin 47 is provided in the pin guide member 48 so as to stand upright. In this case, when the lock member 35 is thermally deformed, the pin 47 is guided by the guide hole 49 and fitted into the hole 34 of the fixing cover 28,
The fixing cover 28 is locked.

[0024]

The effects corresponding to each claim of the present invention are as follows. (Claim 1) When the temperature inside the fixing device is high, the lock member is displaced by heat to lock the fixing cover, and when the temperature inside the fixing device decreases, the lock member returns to the original state and unlocks. , I.e., opening of the fixing cover is prohibited until the temperature of the fixing roller is touched by people.
It is possible to reliably prevent an operator or a service person from touching the high-temperature fixing roller with the hands, and it is possible to provide a fixing device with high safety.

(Claim 2) Since the locking portion on the fixing cover side and a part of the locking member have a male and female fitting relationship, the fixing cover can be reliably locked.

(Claim 3) Since the pin of the lock member is fitted into the hole of the fixing cover to be locked, and the pin guide member for guiding the pin is provided, the locking and unlocking operations can be accurately performed.

(Claim 4) Since the high temperature display member which changes color according to the temperature change is provided outside the fixing cover, be careful that the fixing device is at high temperature when the upper unit or cover of the image forming apparatus main body is opened. In addition, when the lock member is inside the fixing device, it is not possible to directly confirm that the lock is released, but the release of the lock can be indirectly confirmed outside the fixing device by the color of the high temperature display member.

(Claim 5) Since the high-temperature display member is attached to the surface of the fixing cover in the form of a label, it is easy to visually check the temperature change and the lock and unlock.

(Claim 6) Since the fixing device can be cooled by the fan motor until the fixing cover is unlocked after the cover of the main body of the image forming apparatus is opened, it is possible to shorten the waiting time until the temperature is lowered to the temperature at which it can be touched by hand.

[Brief description of drawings]

FIG. 1 is a perspective view of an example of an image forming apparatus.

FIG. 2 is a perspective view of an example of a fixing device according to the present invention provided in the image forming apparatus.

FIG. 3 is a side view of a part that is a main part of the present invention in the identification and attachment device.

FIG. 4 is a diagram in which a fan motor control circuit is added to the configuration of FIG.

FIG. 5 is a diagram in which a buzzer control circuit is added to the configuration of FIG.

FIG. 6 is a side view showing another example of the lock mechanism.

FIG. 7 is a perspective view of the same.

FIG. 8 is a schematic view of a conventional fixing device of a type in which a fixing cover can be removed and opened.

FIG. 9 is a schematic diagram of a state in which a fixing cover is opened in the identification fixing device.

FIG. 10 is a schematic view of a conventional fixing device in which a fixing cover is a double-open type.

FIG. 11 is a schematic diagram of a state in which a fixing cover is opened in the identification fixing device.

[Explanation of symbols]

 18 Fixing Device 28 Fixing Cover 29 High Temperature Display Label 34 Hole (Locking Part) 35 Lock Member 37 Hook 41 Cover Open Detection Circuit 43 Fan Motor 45 Buzzer 47 Pin 48 Pin Guide Member

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location B41J 29/13 G03G 15/00 103

Claims (6)

[Claims] 1. A fixing device provided with a fixing cover that can be opened and closed to cover a heat fixing portion, and is made of a temperature sensitive displacement material that is displaced according to a temperature change, and engages with a locking portion of the fixing cover when the temperature is higher than a predetermined temperature. A fixing device, comprising: a lock member that is displaced to a matching position to lock the fixing cover. 2. The fixing device according to claim 1, wherein the locking portion and a part of the locking member are in a male and female fitting relationship. 3. The fixing device according to claim 2, wherein the locking portion is a hole, a part of the lock member is a pin, and a pin guide member for guiding the pin is provided. 4. The fixing device according to claim 1, further comprising a high-temperature display member provided outside the fixing cover, the high-temperature display member changing color in response to a temperature change and indicating a high temperature state. 5. The fixing device according to claim 4, wherein the high temperature display member is attached to the surface of the fixing cover in the form of a label. 6. A switch that is turned on / off by the displacement of the lock member, a cover open detection circuit that detects that the main body cover of the image forming apparatus main body is opened, and a switch that is turned on / off by the cover open detection circuit and the switch. The fixing device according to claim 1, further comprising a fan motor controlled to be turned off.