JP2965232B2 - Fixing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device, and more particularly, to a structure of a fixing unit in a laser printer or a copying machine and a method of controlling a temperature of a heater of the fixing unit.

[0002]

2. Description of the Related Art A fixing device heats a toner image transferred onto a transfer sheet and fuses the toner image onto the transfer sheet. There is a method in which heating is performed by bonding or non-adhering a heating means to the transfer sheet. Generally, a heat roller fixing method is employed. The heat roller fixing method has a heater on a shaft, a fixing roller heated to a constant temperature by the heater, and a pressure roller that rotates while being pressed against the fixing roller in an axis parallel to the fixing roller. This is a fixing method in which the sheet is nipped between the fixing roller and the pressure roller, heated, and transported.

[0003] Conventionally, halogen lamps have generally been used as heaters. The halogen lamp has a quartz tube having a tungsten filament inside and an inert gas containing a trace amount of halogen sealed therein, and uses Joule heat as a heat source by energizing the high melting point tungsten filament.

FIG. 9 is a view showing a partial vertical cross-sectional structure of a conventional halogen lamp heater. A halogen lamp 30 has a sealing portion 34 made of molybdenum foil at each opening end of a quartz tube 31 having both ends opened. A double coil-shaped tungsten filament 32 is stretched around the terminal portion 33, and a gas such as the above-mentioned halogen gas is sealed in the sealed quartz tube 31. A lead wire 35 electrically connected to the tungsten filament 32 is connected to the terminal portion 33, and the halogen lamp 30 is heated by an external power supply via the lead wire 35.

The heating portion H of the halogen lamp 30 is a portion where the tungsten filament 32 forms a coil. However, the temperature also becomes high in the section A near the terminal portion 33 due to heat conduction. The molybdenum foil 34 is a material having a thermal expansion coefficient selected to prevent the halogen gas and the like in the quartz tube 31 from leaking outside between the quartz tube 31 and the terminal portion 33 due to thermal expansion. At this temperature, oxidation starts and the sealability deteriorates. For this reason, the sealing portion 3
No. 4 had been treated so that the temperature did not rise.

FIGS. 10 and 11 are views showing a heat radiation structure of a sealing portion 34 of a conventional tungsten lamp 30. FIG.
Then, the entire terminal portion 33 including the seal portion 34 is exposed to the outside air to radiate heat, the quartz tube 31 inside the seal portion 34 is inserted between the heat roller portion 36 and heat shielded by the heat shield plate 37 made of a heat insulating material. Thus, the temperature of the heat roller unit 36 is prevented from dropping.

The heat dissipating structure shown in FIG.
Is inserted into the heat roller portion 36, and a heat shield plate 38 of a heat insulating material having a diameter smaller than the inner diameter of the heat roller portion 36 is attached to the outer end of the seal portion 34. Heat dissipating prevent temperature rise of the sealing portion as in this order from the gap 36 a between the heat shielding plate 38 and the heat roller 36 arrow Q.

The above-mentioned halogen lamp 30 has an expensive tungsten filament, and a sealing gas such as a halogen gas is sealed in a quartz tube 31. However, if the heater is made of a nichrome wire, it is inexpensive and a special gas is used. Since there is no need to perform encapsulation, the size can be reduced. However, since a thick nichrome wire is used, the heat capacity is large and the thermal response is poor, so that the conventional temperature control device cannot be applied.

Conventionally, the fixing temperature is maintained at a constant temperature by detecting the temperature of the surface of the fixing roller with a temperature sensor such as a thermistor and controlling the heater lamp current in the fixing roller based on the detected temperature. Specifically, the following ON-OFF control is performed. If the measured temperature is lower than the set temperature, the heater is turned on, and if it is higher, the heater is turned off. For example, Table 1 below shows a control method for controlling the temperature to a constant value of 165 ° C.

[0010]

[Table 1]

Table 1 shows the heater control according to the prior art.
FIG. FIG. 13 is a diagram showing a usage example of FIG. In FIG. 12, first, it is determined whether or not the detected temperature is 165 ° C. or higher (S1), 165
If it is not higher than ℃, the heater is turned on (S2), 165 ℃
If so, the heater is turned off (S3). By repeating this operation, the temperature of the fixing unit is controlled to a constant temperature. In FIG. 13, first, the temperature control is started,
It is checked whether one second has elapsed (S1). If one second has not elapsed, other processing other than the heater control is performed. If one second has elapsed, heater control is performed (S2).

[0012]

As described above, the length and position of the heating section H are determined by the maximum width of the sheet required for fixing. However, in the conventional halogen lamp heater,
If the position of the seal portion 34 having the molybdenum foil is designed to be 350 ° C. or lower, the lamp is inevitably elongated, and A, B, and C of the non-heated portions in FIGS. 9 to 11 are elongated (for example, 30 mm or more). . As a result, there is a disadvantage that the fixing unit becomes large, and accordingly, the machine width becomes large. In addition, heaters with large heat capacities, such as nichrome wires, which do not enclose halogen gas and thus do not require molybdenum foil, can be used in devices with severe operating temperature range conditions, such as laser printers and copier fixing units. When used, the conventional temperature control method has a problem that the temperature is difficult to be constant and fluctuates greatly above and below the set temperature.

The present invention has been made in view of such circumstances, and does not require the filling of a gas such as a halogen gas. Therefore, the present invention provides a lamp heater using an inexpensive nichrome wire heater which does not require a sealing material. It is another object of the present invention to provide a temperature control method that stabilizes a control temperature near a set temperature and stabilizes the fixability of a laser printer or a copying machine.

[0014]

In order to achieve the above object, the present invention provides: (1) a cylindrical heat roller body which is open at both ends and is rotatably supported; and heats the heat roller body. that Do from the lamp and body, a support for lamp holders to the lamp body located inside the heat roller body
In the fixing device, said lamp body includes a cylindrical quartz tube open at both ends, and stretched a nichrome wire to the quartz tube, a crimping terminal portion for fixing each of the ends of the nichrome wire, the heat
The outer circumference has a flange with an outer diameter approximately equal to the diameter of the roller body.
A cylindrical body, the supporting portion of the caulking terminal portion and the flange portion;
There it comprising a holder portion for each fits into the openings of both ends of the quartz tube as well as stretches integrally molded and, the nichrome wire and supports the caulking terminal portions of the respective, further, (2 In the above (1), the holder portion may be formed of a material having a high heat insulating effect.
(3) In the above (1), the holder portion is an integrally molded body made of ceramic. (4) In the above (1), a temperature detecting means for detecting the temperature of the surface of the heat roller body at regular intervals. And temperature control means for determining a time for turning on and off the lamp body based on a difference between a current temperature detected by the temperature detection means and a temperature before the current temperature and a predetermined time before. It was done.

[0015]

A fixing device in which a highly heat-insulating ceramic holder having caulking terminals is fitted at both ends of a quartz tube having both ends open, and is fixed in a rotatable heat roller as a heater having a nichrome wire stretched between the caulking terminals. Structure.
On the other hand, temperature control of a nichrome wire heater with a large heat capacity
The surface temperature of the heat roller is detected at regular intervals, and the heater ON / OFF ratio is determined based on the detected temperature. At this time, the heater ON / OFF is determined by determining the heater ON time from two factors of the difference between the current temperature and the temperature a fixed time ago and the current temperature. This makes it possible to use inexpensive nichrome wire heaters even in equipment with strict control conditions for setting the temperature range.

[0016]

An embodiment will be described below with reference to the drawings. FIG. 1 is a structural view for explaining an embodiment of a fixing device according to the present invention. In the drawing, 1 is a drive gear, 2, 3 are bearings, 4 is a frame, 5, 5 are lamp holders, and 7 is a lamp. (Heater part), 8 is a quartz tube, 9 and 10 are ceramic holders, 11 and 12 are caulking terminals, 13 and 14 are lead wires, 15 is a nichrome wire, and 16 is a heat roller.

The lamp 7, each high heat insulating effect, the ceramic holders 9, 10 are fitted for example in the openings of both ends of the quartz tube 8 at both ends are opened, the ceramic holders 9,1
The crimping terminals 11 and 12 made of stainless steel etc.
Is press-fitted, and the crimping terminal 1 is inserted in the axial direction inside the quartz tube 8.
A nichrome wire 15 fixed to 1 and 12 is stretched. Further, lead wires 13 and 14 that are connected to a heating power supply are connected to outer ends of the caulking terminals. The illustrated ceramic holders 9 and 10 have the same cylindrical shape, and have a flange 10a having an outer diameter substantially equal to the outer diameter of the quartz tube.

The ceramic holders 9 and 10 are fixed to one ends 5b and 6b of lamp holders 5 and 6 having an L-shaped cross section.
The other ends 5a and 6a are fixed to the frame 4 having a U-shaped cross section. The frame 4 is a support member for arranging the quartz tube 8 on the axis and rotatably supporting the heat roller 16 via the bearings 2 and 3. Both ends of the heat roller 16 are open, and a drive gear 1 is fixed coaxially near one of the openings, and a motor (not shown) is driven via the drive gear 1.

FIG. 2 is a view for explaining another embodiment of the fixing device according to the present invention. In the figure, reference numerals 17 and 18 denote ceramic holders, and the same portions as those in FIG. Numbered.

The fixing device of FIG. 2 has the same structure as the fixing device of FIG. 1 except for the ceramic holders 17 and 18. Ceramic holder 17, 18
Have the same shape, and flange portions 17a and 18a are formed integrally with the cylindrical body. The flanges 17a and 18a have outer diameters substantially equal to the diameter of the heat roller 16.

The lamp 7 of the fixing device constructed as shown in FIGS. 1 and 2 has a simple structure in which a nichrome wire 15 is stretched in the axial direction of the quartz tube 8 and a special gas is filled inside. Therefore, an unstable sealing material is not required, and the ratio of the length of the heat generating portion H to the entire length can be increased.
The heat roller 16 is uniformly rotated around the lamp 7. The temperature of the heat roller 16 of the fixing device having the above configuration is set within the sheet width up to the end of the fixing paper.
It is necessary to set the same temperature as that of the central part of No. 6, and this point will be compared between the fixing device of the present invention and the conventional fixing device.

FIGS. 3 (a), 3 (b) and 3 (c) show experimental results comparing the lamp end length of the fixing device of the present invention with that of the present invention and the fixing paper end. FIG. 3 (a) is shown in FIG. FIGS. 1 (b) and 1 (c) show the conventional example shown in FIGS. 1 and 2, wherein the vertical axis is the temperature axis and the horizontal axis is the length axis. A, B, and C are the distances from the end of the heater to the end of the terminal 33 shown in FIGS.
The distance between the five ends and the caulking terminal 12, A "is the distance between the end of the nichrome wire 15 and the caulking terminal 12 in FIG.

According to FIG. 3, the distance between the end of the fixing paper having a constant temperature and the end of the lamp is [I] of the conventional example shown in FIG.
Assuming that (b) and (c) of the present invention are [II] and [III], [III] <[II] <[I] in the figure. Further, the size (width) of the apparatus main body is (c) <(b) <(a), and the apparatus of the present invention is smaller than the conventional apparatus.

FIG. 4 is a block diagram for explaining an embodiment of the temperature control device of the fixing device according to the present invention.
Denotes a power supply, 22 denotes a heater (Nichrome wire), 23 denotes a temperature detecting device, and 24 denotes a control device (CPU). First, the current heater temperature is detected by the temperature detecting device 23. The control device 24 generates a control signal from the difference between the current temperature and the temperature a predetermined time ago. The control signal is input to the power supply 21 and turns on and off the heater to control the temperature to the set temperature.

FIG. 5 is a time chart for explaining the temperature control method according to the present invention. The heater ON / OFF is determined by determining the heater ON time from two factors of the difference between the current temperature and the temperature before the predetermined time and the current temperature. Set temperature and number of set temperature items, temperature difference and number of temperature difference items, O
The optimum ratio of N may be determined by experiment according to the control system. For example, when it is desired to set to 165 ° C., the heater is turned on / off as shown in Table 2 below.

[0026]

[Table 2]

The temperature is measured at intervals of about one second, and the heater is turned ON / OFF as shown in FIG. In Table 2, from 165 ° C to 1
When the inclination at 60 ° C. is 0, the previous state is continued. For example, 166 ° C. → 165 ° C. → 165 ° C. → 164 ° C. → 165
When the temperature changes to ℃, 0% → 9% → 9% → 18% →
0%. If the temperature is 166 ° C., the heater is turned off at 166 ° C. because the difference between the current temperature and the temperature a predetermined time ago is 0%. Next, when the temperature reaches 165 ° C., the difference between the current temperature and the temperature a predetermined time ago becomes −1 because the previous temperature is 166 ° C., and the control value becomes 9% from the intersection of 165 ° C. and −1 in Table 2. Now the heater is 90ms
ON only for ec (milliseconds). Next, when the temperature reaches 165 ° C again, the difference between the current temperature and the temperature a predetermined time ago becomes 0 since the previous temperature is 165 ° C, and the control value becomes 9% from the intersection of 165 ° C and 0 in Table 2. Now the heater is 90ms again
ec is turned ON. Next, when the temperature reaches 164 ° C., the difference between the current temperature and the temperature a predetermined time ago becomes −1 because the previous temperature is 165 ° C., and the control value becomes 18% from the intersection of 164 ° C. and −1 in Table 2. The heater is now 180mSec O
N. Next, when the temperature reaches 165 ° C again, the previous temperature becomes 1
Since the temperature is 64 ° C., the difference between the current temperature and the temperature a predetermined time ago is +1
And the control value is 0% from the intersection of 165 ° C. and +1 in Table 2.
Becomes

FIGS. 6 and 7 are flowcharts showing the heater control. Hereinafter, the steps will be sequentially described. First, it is determined whether the detected temperature is 166 ° C. or higher (S1). If the detected temperature is 166 ° C. or higher, the control value is set to 0% (S2), and the heater is turned off (S2).
3). In S1, if it is not 166 ° C. or higher, then it is determined whether it is 165 (S4). If it is 165 ° C., it is determined whether or not the gradient is 1 or more (S5).
If so, go to S2. If the inclination is not equal to or greater than 1, it is determined whether the inclination is equal to or less than -1 (S6). If the inclination is not equal to or less than -1, it is determined whether the previous control value was 0% (S7). If the control value is 0%, R
ETURN. If the slope is not more than -1 in S6, the control value is set to 9% (S8). If the previous control value is not 0% in S7, the control value is set to 9%.
Set (S8), and turn on the heater.

In S4, if it is not 165.degree. C., it is determined whether it is 164.degree. C. (S9). If it is 164.degree. C., it is determined whether or not the gradient is 0 (S10). For example, it is determined whether the inclination is equal to or less than −1 (S1).
1) If the inclination is not less than −1, it is determined whether the inclination is 1 (S12).
Go to S2. In S10, if the inclination is 0, it is determined whether the previous control value is 9% (S13). If the control value is 9%, the heater is turned on. If the control value is not 9%, the control value is determined. Is set to 18% (S14), and the heater is turned on. If the inclination is not more than −1 in S11, the control value is set to 18% (S14), and the heater is turned on.
I do. If the inclination is 1 in S12, the control value is set to 9% (S8), and the heater is turned on.

Next, in step S9, if the temperature is not 164 ° C., it is determined whether the temperature is 163 ° C. (S15).
, It is determined whether the inclination is 0, and the inclination is 0
If not, it is next determined whether or not the inclination is -1 or less (S17). If the inclination is not -1 or less, it is determined whether or not the inclination is 1 (S18). If not, go to S2. If the inclination is 0 in S16, it is determined whether or not the previous control value is 18% (S1).
9) If the control value is 18%, the heater is turned on. If the control value is not 18%, the control value is set to 27% (S2).
0), turn on the heater. In S17, the inclination is -1.
If not, the control value is set to 27% (S20), and the heater is turned on. In S18, if the inclination is 1,
The control value is set to 18% (S14), and the heater is turned on.

Next, in step S15, if the temperature is not 163 ° C., it is determined whether the temperature is 162 ° C. (S21).
If the temperature is ° C, it is determined whether the gradient is 0 (S22). If the gradient is not 0, it is determined whether the gradient is not more than -1 (S23). This time, it is determined whether or not the inclination is 1 (S24). If the inclination is not 1, the flow proceeds to S2. If the inclination is 0 in S22, it is determined whether or not the previous control value is 27% (S25). If the control value is 27%, the heater is turned off.
N. If the control value is not 27%, the control value is set to 36% (S26), and the heater is turned on. If the inclination is not more than -1 in S23, the control value is set to 36% (S26), and the heater is turned on. If the inclination is 1 in S24, the control value is set to 27% (S20), and the heater is turned on.

Next, in step S21, if the temperature is not 162 ° C., it is determined whether the temperature is 161 ° C. (S27).
If the temperature is ° C, it is determined whether the inclination is 0 (S2).
8) If the inclination is not 0, then it is determined whether or not the inclination is not more than -1 (S29). This time, it is determined whether or not the inclination is 1 (S30). Go to S2. In S28, if the inclination is 0, it is determined whether the previous control value is 36% (S31). If the control value is 36%, the heater is turned on. If the control value is not 36%, the control is performed. The value is set to 54% (S32), and the heater is turned on.
N. If the inclination is equal to or smaller than −1 in S29, the control value is set to 54% (S32), and the heater is turned on.
I do. In S30, if the inclination is 1, the control value is set to 3
6% is set (S26), and the heater is turned on.

Next, in step S27, if the temperature is not 161 ° C., it is determined whether the temperature is 160 ° C. (S33).
If it is ° C, it is determined whether or not the inclination is 0 (S3).
4) If the inclination is not 0, then it is determined whether or not the inclination is -1 or less (S35). If the inclination is not -1 or less, it is determined whether or not the inclination is 1 (S36). If is not 1, go to S2. In S34, if the inclination is 0, it is determined whether the previous control value is 54% (S37), and if the control value is 54%, the heater is turned on,
If the control value is not 54%, the control value is set to 72% (S38), and the heater is turned on. If it is determined in S35 that the inclination is equal to or less than -1, the heater is set to 72% (S38), and the heater is turned on. If the inclination is 1 in S36, the control value is set to 54% (S32), and the heater is turned on.

Next, in S33, if the temperature is not 160 ° C., it is determined whether the temperature is 159 ° C. to 110 ° C. (S39).
If it is 159 ° C. to 110 ° C., it is determined whether the inclination is 2 or more (S40). If the inclination is 2 or more, the process goes to S2. If it is not 159 ° C. to 110 ° C. in S39, and if the inclination is not 2 or more in S40, the control value is set to 100% (S41), and the heater is turned on.
(S42).

FIG. 8 is a diagram showing a main routine using the temperature control method according to the present invention. The temperature control is started, and it is first determined whether or not 1 second has elapsed (S1).
If one second has elapsed, the heater control is performed (S
2). If one second has not elapsed in S1, then
The time of the ratio set by the heater control is determined, and it is determined whether or not the control time has elapsed (S3). If the control time has elapsed, the heater is turned off (S4), and S3
If the control time has not elapsed, the process returns to S1.

[0036]

The present invention is configured as described above, and has the following effects. (A) Nichrome wire heater structure shall be a simple structure in which a nichrome wire is stretched through a crimp terminal such as stainless steel in a quartz tube, and a seal structure using molybdenum foil without the need for halogen gas etc. shall be taken. Since there is no heater, an inexpensive heater can be provided. (B) Since it is a crimped terminal made of stainless steel or the like, it has high thermal stability, and can be used at a temperature higher than 350 ° C., which has been conventionally restricted by molybdenum foil. it can. (C) In the conventional halogen lamp, sufficient heat insulation could not be obtained due to the temperature of the molybdenum foil even if a heat insulating material was provided at the heat roller end in order to prevent heat release at the heat roller end. In the present invention, by performing the same treatment, the temperature gradient at the end of the heat roller can be easily obtained, so that the size can be reduced (for example, the size can be reduced by about 20 mm as compared with a halogen lamp). (D) When the temperature is detected at regular intervals and the rate at which the heater is turned on / off at the detected temperature is determined, the heater is determined based on two factors, namely, the difference between the current temperature and the temperature a predetermined time ago and the current temperature. Since the ON time is determined, even an inexpensive heater having a large heat capacity, such as a nichrome wire heater, can perform temperature control with high accuracy, and cost reduction can be achieved.

[Brief description of the drawings]

FIG. 1 is a structural diagram for explaining an embodiment of a fixing structure according to the present invention.

FIG. 2 is a view for explaining another embodiment of the fixing device according to the present invention.

FIG. 3 is a diagram illustrating a comparison between a lamp end length of a fixing device according to the related art and a fixing device end according to an experiment.

FIG. 4 is a configuration diagram for explaining an embodiment of a temperature control device according to the present invention.

FIG. 5 is a time chart for explaining a temperature control method according to the present invention.

FIG. 6 is a flowchart (part 1) of a heater control according to the present invention.

FIG. 7 is a flowchart (part 2) of the heater control of the present invention.

FIG. 8 is a diagram showing a main routine using the present invention.

FIG. 9 is a view showing a partial vertical cross-sectional structure of a conventional halogen lamp heater.

FIG. 10 shows a seal portion 3 of a conventional tungsten lamp 30.
FIG. 4 is a view showing a heat dissipation structure of FIG.

FIG. 11 shows a seal portion 3 of a conventional tungsten lamp 30.
FIG. 4 is a view showing a heat dissipation structure of FIG.

FIG. 12 is a flowchart of a conventional heater control.

FIG. 13 is a diagram showing a usage example of FIG. 12;

[Explanation of symbols]

1 ... drive gear, 2, 3 ... bearing, 4 ... frame, 5, 6 ...
Lamp holder, 7 Lamp (heater part), 8 Quartz tube, 9, 10 Ceramic holder, 11, 12 Caulking terminal, 13, 14 Lead wire, 15 Nichrome wire, 1
6 Heat rollers 17, 18 Ceramic holder, 21 Power supply, 22
Heater, 23: Temperature detection device, 24: Control device (CP
U).

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideki Goto 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Toshihide 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Sharp Corporation (72) Inventor Yuhi Akakawa 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Takashi Sugito 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Sharp Corporation (72) Inventor Mitsuru Terada 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Inside Sharp Corporation (72) Inventor Yoshinobu Tateishi 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Inside Sharp Corporation (72) Yoshikazu Kondo Osaka City, Osaka Prefecture 22-22 Nagaikecho, Abeno-ku Inside Sharp Corporation (72) Inventor Naoyuki Yamane Nagaikecho, Abeno-ku, Osaka-shi, Osaka No. 22-22 Inside Sharp Corporation (56) References JP-A-62-165891 (JP, A) JP-A-2-82281 (JP, A) JP-A-58-185865 (JP, U) JP-A-2-185 −131 262 (JP, U) Actually open 1986-193472 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 13/20 G03G 15/20

Claims (4)

(57) [Claims] 1. A cylindrical heat roller body having both ends opened and rotatably supported, a lamp body for heating the heat roller body, and a lamp body positioned so as to be located inside the heat roller body. Ru fixation instrumentation name from a lamp holder for supporting
The lamp body includes a cylindrical quartz tube having both ends opened, a nichrome wire stretched in the quartz tube, a caulking terminal portion for fixing both ends of the nichrome wire, and a diameter of the heat roller body.
A cylindrical body having a flange portion having substantially the same outer diameter on the outer periphery,
The supporting portion of the caulking terminal portion and the flange portion are integrally formed.
And a holder for supporting the respective caulking terminal portions, stretching the nichrome wire, and fitting the opening portions at both ends of the quartz tube. 2. The fixing device according to claim 1, wherein said holder portion is formed of a material having a high heat insulating effect. 3. The fixing device according to claim 2, wherein said holder portion is formed as an integral molded body made of ceramic. Wherein said from the difference of the temperature detecting means for detecting the temperature at regular intervals of the heat roller surface, current and temperature detected by the temperature detection means, the current temperature and the predetermined time before the temperature ramp 2. A temperature control means for determining a time for heating the body on and off.
The fixing device as described in the above.