JPH096182A - Recorder provided with fixing device - Google Patents

Abstract

PURPOSE: To provide a recorder provided with an inexpensive fixing device which is capable of preventing the occurrence of irregularities in fixing, the wrinkles and curling of a recording paper, etc., without lamitations on a heat generating means, at a low cost. CONSTITUTION: The recorder provided with the fixing device thermally fixing an image formed on the recording paper is provided with the heat generating means 2 for heating a heating roller 1, a temperature detecting means 3 detecting a temp. in the pivotal part of the heating roller 1 or the vicinity of the pivotal part, an energizing control part 4 for supplying power to the heat generating means 2 only for a specified time T1 , after the temperature detecting means 3 detects a prescribed temp. t1 , when the temp. drops, at the time of keeping the pivotal part of the heating roller 1 at a nearly fixing temp. and a temperature cycle counter means 5 counting a temperature cycle time T2 until the temperature detecting means 3 detects the prescribed temp. t1 when the temp. drops next, after the means 3 detects the prescribed temp. t1 when the temp. drops.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus provided with a fixing device used in an electrophotographic image forming apparatus such as a copying machine, a facsimile machine and a printer, and more particularly to a temperature ripple when a heating roller is kept at a fixing temperature. The present invention relates to a recording device that can reduce the size.

[0002]

2. Description of the Related Art A large number of electrophotographic recording devices are used in copying machines, facsimile machines, printers and the like. In the electrophotographic recording device, the toner image formed on the recording paper is thermally fixed by the fixing device. The temperature of the main part of the fixing device is kept at the preheating temperature in the standby state as shown in FIG. The fixing temperature is maintained during fixing. When the temperature rises to the fixing temperature, an inrush temperature higher than the fixing temperature occurs, and as a result, when the temperature ripple at the time of fixing shown by r in FIG. 7 becomes large, uneven fixing, wrinkles and curls of the recording paper occur. In order to solve the above problems, in the fixing device disclosed in Japanese Patent Laid-Open No. 5-297758, a large amount of power is supplied when the fixing temperature is raised, and a small amount of power is supplied when the fixing temperature is maintained. Suggesting a way to do it. However, if two kinds of power supplies are provided for that purpose, the cost will increase. Therefore, in the above-mentioned Japanese Patent Laid-Open No. 5-297758, the power is supplied repeatedly by turning on and off in detail, and the ratio of the on time and the off time is set. We propose a method to reduce or increase the power supply by changing the.

[0003]

SUMMARY OF THE INVENTION
The method of changing the on / off time ratio of energization, which is disclosed in Japanese Patent Laid-Open No. 5-297758, cannot be easily realized when a halogen heater is used as a heat generating means, as also disclosed in the above publication. Therefore, there is a problem that the heating means is limited to a resistance heating element or the like.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems of the prior art as described above and to reduce the temperature ripple when holding at the fixing temperature to prevent uneven fixing, wrinkling and curling of recording paper. An object of the present invention is to provide a recording apparatus that includes a fixing device that can be manufactured at low cost and that has no limitation of heat generating means.

[0005]

[Means for Solving the Problems] To achieve the above object,
A first means is a recording apparatus provided with a fixing device for thermally fixing an image formed on a recording sheet, and a heat generating means for heating a heating roller and a temperature of a main part of the heating roller or a temperature in the vicinity of the main part. When the temperature detecting means for detecting and the main part of the heating roller are kept at substantially the fixing temperature, when the temperature detecting means detects the predetermined temperature t 2 when the temperature is lowered, the heat generating means is energized for a predetermined time T ₁ from that time. a power supply controller for a temperature cycle count said temperature detecting means counts the temperature cycle time T ₂ of the from the detection of the predetermined temperature t ₁ at the temperature lowered to detecting a predetermined temperature t ₁ of the next temperature drop And means. The second means is characterized in that, in the above, the energization time adjusting means for comparing the temperature cycle time T ₂ with a predetermined value and adjusting the predetermined time T _{1 according} to the comparison result is provided. Third means, in the above, the predetermined time T _1, which is adjusted when it becomes smaller than the Tmin, and when it becomes larger than Tmax, characterized by comprising abnormality detecting means for determining an abnormal state.

[0006]

With the above construction, the first means
The temperature ripple corresponds to the predetermined energization time T ₁ , and the temperature cycle time corresponds to the temperature ripple. Moreover, since the temperature cycle time of the temperature ripple can be acquired, the temperature ripple at the time of fixing can be reduced by adjusting the predetermined energization time T ₁ as necessary. In the second means, the temperature ripple during fixing can be reduced by automatically adjusting the predetermined energization time T ₁ . With the third means, it is possible to prevent the situation in which the electricity is continuously supplied to the heat generating means despite the occurrence of the abnormal state.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration block diagram of a recording apparatus including a fixing device according to a first embodiment of the present invention. As shown in the figure, in the recording apparatus of this embodiment, a heating means 2 for heating the heating roller 1, a temperature detecting means 3 for detecting the temperature of a main part of the heating roller 1 (for example, a recording paper pressure contact part) or the vicinity thereof,
An energization control unit 4 that controls energization of electric power supplied from the power source 7 to the heat generating unit 2, a temperature cycle counting unit 5 that counts a temperature cycle time, and a temperature as an analog signal detected by the temperature detecting unit 3 is converted into a digital value. A / D converter 6, a control unit 10 for controlling the entire recording apparatus, a recording unit 11 such as an electrophotographic system for recording on recording paper, an operation unit 12,
An image memory 13 and the like are provided.

The power source 7 is, for example, a commercial power source, and is connected to the heating means 2 via a switch 8 which is turned on / off by a HETON signal from the energization control section 4. The heat generating means 2 is, for example, a halogen heater, and the temperature detecting means 3
Is, for example, a thermistor, and the switch 8 is an SSR, a triac, or the like. Normally, the switches 8 are provided on both sides of the heat generating means 2, but only one is shown for simplification. Energization control unit 4 and temperature cycle counting unit 5
Is provided in the control unit 10 as illustrated, for example. Control unit 10
Is composed of a CPU, a ROM containing a program, a RAM, a logic circuit, and the like.

In the temperature detecting means 3 such as a thermistor, the resistance value decreases when the temperature around it rises and increases when the temperature decreases, so that the resistance value of the temperature detecting means 3 is r _t and the resistance of the resistance R is a value input voltage Vt = rV / to the AD converter 6 when the r (r _t + r) varies in response to the temperature around. Therefore, this input voltage Vt is AD
By supplying the data converted into a digital value by the converter 6 to the energization controller 4 in the controller 10, it becomes possible to control the energization of the heating means 2 according to the temperature of the main part of the heating roller 1 or the vicinity thereof. That is why.

FIG. 2 shows the temperature detected by the temperature detecting means 3 after the power is turned on. As shown in the figure, when the power is turned on, the energization control unit 4 closes the switch 8 to energize the heat generating means 2, thereby raising the temperature and eventually reaching the preheating temperature. Then, the energization control unit 4 causes the heating unit 2 to operate.
The energization to and from is repeatedly turned on and off, and the temperature is maintained almost at the preheating temperature. When a recording request occurs in such a state, the energization control unit 4 continues energizing the heat generating means 2 until it detects a predetermined temperature t ₀ that is lower than the fixing temperature. As a result, the temperature rises, and when the predetermined temperature t ₀ is detected, the energization control unit 4 cuts off the energization to the heating means 2. Then, the temperature once reaches the maximum ripple rush temperature, rises above the fixing temperature, and then starts to fall. When a temperature t ₁ slightly lower than the fixing temperature is detected, the energization control unit 4 energizes the heat generating means 2 for T ₁ hours from that point. Thus, the temperature rises and falls again after the temperature has dropped slightly from the start of the energization time T ₁ . After that, the same energization control is repeated, and the temperature is maintained almost at the fixing temperature. In FIG. 2, T ₂ is a temperature cycle, which is the time from the detection of the predetermined temperature t ₁ at the time of temperature decrease to the detection of t ₁ at the next temperature decrease. In FIG. 2, the HETON signal when the fixing temperature is maintained is shown in association with the temperature. Further, r in the figure shows a temperature ripple.

FIG. 3 shows an enlarged temperature curve and HETON signal. The temperature curve 1 is a temperature curve when the power supply voltage is high or the ambient temperature is high, and the temperature rises sharply, and the temperature curve 2 is the opposite case. As shown in the figure, when the temperature rises sharply, the temperature ripple r also increases (r ₁ > r ₂ ). Since the temperature gradient during the temperature decrease is almost constant regardless of the steep rise, the larger the temperature ripple r, the larger the temperature cycle T ₂ . That is, if the temperature cycle T ₂ is kept within a predetermined value, the temperature ripple r can be kept within a predetermined value. The present invention has been made in view of such a point, and the temperature cycle T _{2 is set} to an appropriate value by adjusting the energization time T _1, and thus the temperature ripple r is suppressed within a predetermined value. .

In the first embodiment, each time one temperature cycle ends, the control unit 10 acquires the temperature cycle T ₂ from the T ₂ register and records it in a logging file (not shown). And at the time of regular maintenance,
The service person outputs the contents of the above-mentioned file to the recording paper of the recording unit 11 to know the value of the temperature cycle T ₂ , and instructs the operation unit 12 as necessary to display it in a predetermined area of the RAM in the control unit 10. The set predetermined time T ₁ (time to energize the heat generating means) is updated.

FIG. 4 is a block diagram showing the configuration of the main part of a recording apparatus having a fixing device according to the second embodiment of the present invention. As shown in the drawing, the recording apparatus of this embodiment has a configuration in which the controller 10 of the recording apparatus of the first embodiment shown in FIG. When the temperature cycle T ₂ is larger than a predetermined value T ₃ , the energization time adjusting means 14 sets the time shorter than the predetermined energization time T ₁ by dT as the energization time,
When T ₂ is smaller than the predetermined value T ₄ , the energization time is set to be larger than T ₁ by dT.

In the third embodiment shown in FIG. 5, an abnormality detecting means 15 is further added to the control unit 10 of the recording apparatus of the second embodiment. The abnormality detecting means 15 is an energization time adjusting means.
When the energization time T ₁ adjusted by 14 is larger than the predetermined energization time Tmax and smaller than Tmin, it is determined as an abnormal state. Then, the subsequent energization to the heating means 2 is stopped, the operation of the recording unit 11 is stopped, and the operation unit 12
The abnormal status is displayed. In this way, damage such as burnout and fire due to abnormal operation can be prevented.

FIG. 6 shows an operation flow of the third embodiment. The operation flow of the first and second embodiments is shown in FIG.
It becomes a part of the operation flow shown in. The operation flow will be described below with reference to FIG. When in the preheating state, as shown in FIG. 6, the energization control unit 4 receives a recording request from the control unit 10.
Turns on the HETON signal (S1) and closes the switch 8 to start energizing the heating means 2. On the other hand, the control unit 10 issues a recording request to the recording unit 11 to start recording.

Thereafter, the energization controller 4 periodically reads the output value of the AD converter 6 (S2), and when the acquired detected temperature t reaches a predetermined temperature t ₀ lower than the fixing temperature (S3), HE
The TON signal is turned off (S4), and the power supply to the heating means 2 is cut off. Then, the energization control unit 4 periodically reads the detected temperature t thereafter (S5), and if the temperature is an abnormally high temperature exceeding a predetermined temperature (S6), the process proceeds to the abnormality processing. When the temperature is not an abnormally high temperature and once the detected temperature exceeds t ₁ , the temperature starts lowering, and when a temperature lower than t ₁ is detected (S7), the energization control unit 4 starts the timer in the temperature cycle counting means 5. (S8, start timing of times T ₁ and T ₂ ). Next, the energization control unit 4 reads a predetermined energization time T ₁ preset by the user from the operation unit 12 from the T ₁ register in the energization control unit 4 (S9), and measures the read time T ₁ with a timer. The HETON signal is turned on (S10) only for the period, and the heating means 2 is energized. Then, the process proceeds to the fixing temperature maintaining mode.

When the fixing temperature maintaining mode is entered, the energization control section 4 monitors whether or not the temperature at the time of the temperature drop after the energization for T ₁ hours becomes equal to or lower than t ₁ , and if an abnormally high temperature is detected during that time, it is abnormal. Proceed to the processing (S11 to S13). Eventually when the detected temperature t is lower than t ₁ (S13), to stop the timer (S14), a temperature cycle counting means 5 reads the timer value T ₂ of the case that the built-in timer (S15). Then, the energization time adjustment means 14 acquires the timer value T _2, when T ₂ is larger than the predetermined value T ₃ (S16), only a small time dT than a predetermined energization time T ₁ and the energization time T ₁ (S17 ), When T ₂ is smaller than the predetermined value T ₄ (S1
8), the time that is larger than T ₁ by dT is the energization time (S19).

Further, the abnormality detecting means 15 obtains the energizing time T ₁ adjusted by the energizing time adjusting means 14 and compares the T ₁ with a preset minimum value Tmin and maximum value Tmax of the energizing time. , T ₁ is smaller than Tmin (S20), and when T ₁ is larger than Tmax (S21), it is determined that an abnormality has occurred, and an abnormality process is performed. In the above abnormality processing,
The subsequent energization to the heat generating means 2 is stopped, the operation of the recording unit 11 is stopped, and an abnormal state is displayed on the operation unit 12. On the other hand, if the value of T ₁ is within the normal range and the fixing is not completed (S22), the timer is started again (S22).
23), HET for the duration of the adjusted T ₁ hour by monitoring the timer
The ON signal is turned on (S24), and the heating means 2 is energized. After that, it repeats from S11.

As described above, according to the present invention, the temperature ripple at the time of holding at the fixing temperature can be reduced, and therefore wrinkles and curls of the recording paper can be prevented. In the above description, the case where the recording apparatus is of the electrophotographic type has been described, but the present invention can be implemented even in the case where the recording apparatus uses ink and the ink after recording is dried.

[0020]

As described above, according to the present invention,
When maintaining at the fixing temperature, the temperature cycle T ₂ can be adjusted by adjusting the predetermined energizing time T ₁ manually or automatically to energize, and thus the temperature ripple at the time of fixing can be reduced, so that fixing unevenness and recording The occurrence of wrinkles and curls of paper can be prevented, the CPU and ROM of the control unit can be shared, and the cost can be reduced, and there is no restriction on the heating means.

Further, it is possible to prevent the situation where the electricity is continuously supplied to the heating means despite the occurrence of the abnormal state, so that the safety is improved.

[Brief description of drawings]

FIG. 1 is a configuration block diagram of a recording apparatus showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a temperature of a main part of a recording apparatus showing an embodiment of the present invention.

FIG. 3 is another explanatory diagram of the temperature of the main part of the recording apparatus showing the embodiment of the present invention.

FIG. 4 is a configuration block diagram of a main part of a recording apparatus showing an embodiment of the present invention.

FIG. 5 is another configuration block diagram of a main part of the recording apparatus showing the embodiment of the present invention.

FIG. 6 is an operation flowchart of a main part of the recording apparatus showing the embodiment of the present invention.

FIG. 7 is an explanatory diagram illustrating a problem of the conventional technique.

[Explanation of symbols]

1 ... Heating roller, 2 ... Heat generating means, 3 ... Temperature detecting means, 4
... energization control unit, 5 ... temperature cycle counting unit, 6 ... AD converter, 7 ... power supply, 8 ... switch, 10 ... control unit, 11 ... recording unit, 14 ... energization time adjusting unit, 15 ... abnormality detecting unit.

Claims (3)

[Claims] 1. A recording apparatus including a fixing device for thermally fixing an image formed on a recording sheet, wherein a heating means for heating a heating roller and a temperature of a main part of the heating roller or a temperature near the main part is detected. When the temperature detecting means detects the predetermined temperature t ₁ while the temperature of the heating roller and the main part of the heating roller is kept at substantially the fixing temperature when the temperature decreases, the heat generating means is turned on for the predetermined time T ₁ from the detection time point. temperature cycling for counting the power supply controller to energize the temperature cycle time T ₂ of the from the temperature detecting means detects a predetermined temperature t ₁ at the temperature lowered to detecting a predetermined temperature t ₁ of the next temperature drop A recording apparatus having a fixing device, comprising: a counting unit. 2. The recording apparatus according to claim ₁ , further comprising energization time adjusting means for comparing the temperature cycle time T ₂ with a predetermined value and adjusting the predetermined time T _{1 according} to the comparison result. 3. An abnormality detecting means for determining an abnormal state when the adjusted predetermined time T ₁ becomes smaller than Tmin and becomes larger than Tmax, respectively. Item 2 recording device.