JPS6336507B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat fixing device for a copying machine, and particularly to control of power supplied to the device.

In copying machines, the fixing methods for permanently adhering the toner image formed on the transfer paper can be roughly divided into a pressure roller method that uses pressure, a heat fixing method that uses heat to fuse the toner, and a heat roll method that combines both. There is. Each of the above-mentioned methods is individually selected depending on the image quality, copy speed, warm up time (the time required for the temperature of the fixing section to reach a state where fixing is possible), the type and width of the transfer paper used, and other factors.

The fixing method according to the present invention relates to heat fixing, and is intended to provide a fixing device that has a short warm-up time and can quickly respond to changes in the surrounding environment.

To achieve the objects of the present invention, the warm-up time is shortened by variable control of the power applied to the heating element based on the operation of the high power consumption load of the copying machine. However, in general offices and the like where copying machines are used, the rated voltage is 100 (V) and the maximum is 15 A, and it is necessary to operate the copying machine within this power (1500 [W]). Therefore, the above
The problem is how to make full use of the power consumption below 1500 [W].

In view of the above-mentioned points, it is an object of the present invention to effectively use limited electric power and shorten warm-up time. Copying machines charge, expose, develop, transfer,
A single copy is completed after going through each fixing process.
In each of the above steps, the power consumption load is different. In particular, a halogen lamp or the like with a high power consumption load is used as a light source during exposure. The power consumption load of the other processes is not a problem compared to the above-mentioned exposure process, and can be considered to be more or less constant. Therefore, during the above-mentioned exposure, it is necessary to set the maximum power consumption load of the heating element in the fixing process and perform power control so that the power consumption is 1500 [W] or less.

Before explaining the present invention, a conventional example will be explained. FIG. 1 is a time chart showing a conventional power consumption waveform. In the figure, 1 indicates the standard power consumption of the copying machine, which is considered to be constant due to the power supplied to the power supply for the LSI control circuit, the motor, the fan, etc., which is activated when the power is turned on. 2 indicates the power consumption of a halogen lamp as a light source that is turned on during exposure, and 3 indicates the power consumption of a heating element during the fixing process. That is, conventionally, the power supplied to the heating element in the fixing process was always constant, and the power consumption was constant not only when lighting a halogen lamp or the like. Further, 4 indicates the cumulative power consumption of the entire copying machine. Note that the fixing device is additionally equipped with a temperature adjustment device, and this adjustment device controls the power supplied to the heating element in order to maintain the temperature of the fixing section within an allowable range.

From the above, when the power is turned on, the power consumption 3 of the heating element is set so that it stays within 1500 [W] when the halogen lamp is turned on, as shown in the figure.
Since this is always constant, the warm-up time becomes long. This means that the cumulative power consumption 4 was always kept below 1500 [W], and the effective use of power was not planned.

FIG. 2 is a time chart showing the power consumption waveform in the present invention. In the figure, numerals 1 to 4 correspond to those in FIG. 1 for ease of understanding. In other words, the power 3 supplied to and consumed by the heating element is
It decreases in sync with the application of high power consumption loads. FIG. 3 shows the blinking control signal waveform of the high power consumption load, for example, the light source (halogen lamp) during exposure. The power consumption 3 of the heating element is adjusted by this blinking control signal. Therefore, when the power is turned on, more power is consumed by the heating element, the fixing temperature of the fixing section increases quickly, and the warm-up time can be shortened. This is the cumulative power consumption of 4
As shown in the figure, effective power usage within the specified power can be measured.

FIG. 4 is a circuit diagram showing a specific example according to the present invention. In the figure, reference numerals 5 and 6 indicate heaters of the fixing unit which are connected in series and connected to a power source AC. Note that a temperature adjustment circuit is connected to the heater circuit, but is omitted for the sake of simplicity. The temperature adjustment circuit is generally used to keep the temperature of the fixing section constant. For example, if the temperature of the fixing section exceeds a set temperature that allows fixing, it stops the power supply to the heaters 5 and 6, and stops the power supply to the heaters 5 and 6. When the temperature falls below the set temperature, power is supplied to the heaters 5 and 6 to maintain the temperature of the fixing section at the set temperature. In addition to supplying power to the heaters through this temperature control, the circuit shown in FIG. 4 also supplies power to the heaters 5 and 6.

On the other hand, the heaters 5 and 6 are arranged on the upper and lower rollers of, for example, a heat fixing roller, and are connected in series with each other as shown in FIG. In particular, the heater 6 is arranged to face the toner in order to fix the toner on the paper. A relay switch 7 is connected in parallel to the circuit of the heaters 5 and 6.
Halogen lamp which is a high power consumption load through 8
is connected. The relay switch 7 is normally connected to the contact a side, and switches to the contact b side when the relay is operated, and the contact a is connected to the heaters 5 and 6.
A contact point b is connected to the halogen lamp 8 at the connection point. Furthermore, the relay (not shown) is controlled based on a control signal for driving the halogen lamp 8, which is a high power consumption load, as shown in the time chart of FIG.

Therefore, the signal to turn on the halogen lamp 8 is
The relay is energized (during operation) and relay switch 7 is switched to contact b. Also, halogen lamp 8
With the OFF signal, the relay stops energizing and relay switch 7 switches to contact a. As a result, power is supplied through the series circuit connection of the heaters 5 and 6, or power is supplied to the heater 6 alone. Moreover, the temperature control device controls the power supply to both heaters accordingly.

Since the circuit configuration is as described above, when the power is turned on, power is supplied only to the heater 6 in the state shown in the figure.
AC is supplied. The power consumption of the heater circuit at this time is 100 ² /R ₂ [W], where the power supply AC is 100V and the load resistances of the heaters 5 and 6 are R ₁ and R ₂ . On the other hand, when the temperature of the fixing section reaches the permissible temperature range, a message indicating that copying is possible is displayed. At this time, if the copy switch is pressed, a control signal is output to turn on the halogen lamp 8 shown in FIG. Switch. As a result, the halogen lamp 8 is turned on, illuminating the document and starting exposure. The power consumption of the heater circuit at this time is 100 ² /R ₁ +R ₂ .

From the above, the power consumed by the heater circuit, that is, the heating element, differs depending on the operation of the halogen lamp 8. Therefore, more power is supplied during the warm-up time after power-on than when the high power consumption load is operating, so the warm-up time can be shortened. In other words, a lot of power is consumed by the heater 6 when the halogen lamp 8 is not operating.
Since the amount of heat generated is large, the time required for the fixing section to reach the set temperature, that is, the warm-up time, is shortened. Furthermore, since the amount of heat generated is increased, it is less susceptible to external influences, and the temperature of the fixing section can always be maintained at the set temperature with sufficient margin.

Therefore, when the halogen lamp 8 is turned on at the start of the copying operation, power is supplied to the heaters 5 and 6 in series. In this case, the power supplied to both heaters will decrease, and the amount of heat generated will also decrease. However, if both heaters are arranged separately, for example, with respect to the upper and lower rollers, then the toner Since the lower roller on the side not facing the fixing roller is also heated, the heat transferred from the upper roller to the lower roller due to the rotation of the fixing roller is extremely reduced. Therefore, even if the upper roller is heated by the heater 6 due to a power drop, a sudden temperature drop can be suppressed, and by preventing a temporary temperature drop, the temperature of the entire upper roller can be controlled uniformly to the set temperature. . Therefore, the temperature for fixing the toner can be maintained, and the fixability of the toner will not be reduced. Note that even if the fuser unit is heated by the heaters 5 and 6 when the power is low, if the temperature of the fuser unit exceeds the set temperature, the temperature adjustment device will stop supplying power to the heaters 5 and 6 to maintain the set temperature. Monkey.

As mentioned above, the load resistance R ₁ of the heaters 5, 6, etc.
The power consumed by R ₂ is determined by the power consumption of the halogen lamp 8, etc. In other words, when the halogen lamp 8 is turned off, all the remaining power except for the reference power consumption 1 shown in FIG. 2 can be supplied to the heater 6, so the load resistance _R2 of the heater 6 is:
If the above standard power consumption 1 is 100 [W], 1400≧
It can be determined using the formula V ² /R ₂ . The above V is
AC power voltage. For example, if AC is 100 [V], R ₂ ≧50/7 (Ω).

When the halogen lamp 8 is ON, if the load resistance of the halogen lamp 8 is R, then V ² / (R ₁ + R ₂ ) +
The load resistance R ₁ of the heater 5 can be determined by V ² /R≦1400. For example, if the power consumption V ₂ /R of a halogen lamp is 400 [W], R ₁ ≧10−R ₂
becomes. By setting as above, the integrated power value can be maintained within 1500 [W].

As described above, according to the power supply control circuit to the heating element of the fixing device of the present invention, the heating element is divided into a plurality of sections, the plurality of heating elements are connected in series, and the exposure lamp is connected. This is a configuration in which some of the heating elements connected in series are controlled to be short-circuited or non-short-circuited based on the drive control signal, and some of the heating elements are short-circuited when the exposure lamp is turned off. , the power consumption by the remaining heating elements increases, the temperature of the fixing section can be maintained at the set temperature with sufficient margin, and the warm-up time from turning on the power until copying is possible can be shortened.

In addition, when the exposure lamp is turned on, power is supplied to multiple heating elements connected in series, which reduces power consumption. It also heats other parts of the fuser, and very little heat is lost to that part during fusing, which helps prevent a sudden temperature drop in the fusing device, and keeps the entire fusing device at the set temperature without any temporary temperature drop. It can be maintained. Therefore, the fixability of the toner on the paper is not deteriorated.

[Brief explanation of the drawing]

Fig. 1 is a time chart showing the power consumption waveform of a conventional copying machine, Fig. 2 is a time chart showing the power consumption waveform of the copying machine according to the present invention, and Fig. 3 is a time chart showing the power consumption waveform of the copying machine according to the present invention. A time chart showing a load control signal, FIG. 4, is a circuit showing a specific example of the present invention. 1: Standard power consumption, 2: (Halogen lamp) load power consumption, 3: Power consumption of heating element, 4: Integrated power consumption, 5, 6: Heater, 7: Relay switch, 8: Halogen lamp.

Claims (1)

[Claims] 1. A device in which a plurality of divided heating elements provided in a fixing device are arranged in a distributed manner, and the supply of electric power to the heating elements is controlled in accordance with ON/OFF control of an exposure lamp. In the step, the plurality of heating elements are connected in series, and when the exposure lamp is turned on, power is supplied to the plurality of heating elements connected in series, and the inside of the plurality of heating elements connected in series is A power control circuit for a heating element in a fixing device, characterized in that the specific one is short-circuited when the exposure lamp is turned off, and the power is supplied to the remaining heating element.