JPH0570822B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention [Field of Industrial Application] The present invention relates to an image forming apparatus such as an electrophotographic copying apparatus or an electrostatic recording apparatus.

More specifically, the developing device containing the developer of the desired color can be used interchangeably with the image forming apparatus, and the image fixing device is a heat roller fixing device, and the surface of the fixing roller is The present invention relates to an image forming apparatus in which rotation of a fixing roller is started when the temperature reaches a first surface temperature setting value.

The above-mentioned developing device may be in the form of a process cartridge that incorporates the developing device and can be freely replaced with respect to the main image forming apparatus.

[Conventional technology]

Image forming apparatuses using the above-mentioned developing device exchange system are in practical use, and a plurality of developing devices each containing a developer of a different color, such as black, blue, red, or brown, are installed on the user side. A developing device containing developer of a desired color is prepared and used by replacing it with the main image forming apparatus.For example, a developing device containing black developer is used to copy a document.
It can be used to copy photographs and drawings using a developing device containing blue developer. It is also possible to perform multicolor copying in which images are formed using developers of two or more colors on the same transfer paper.

[Problem that the invention seeks to solve]

By the way, when considering the fixability of images to transfer paper, generally speaking, developers of colors other than black generally have lower fixing performance than those of black. Even if this is not the case, it is inevitable that there will be differences in fixing performance depending on the color. For this reason, in an image forming apparatus using a developing device replacement system as described above, when copies of two or more colors are obtained by replacing the developing device, there are differences in the fixing performance of each developer, so it is difficult to determine which colors will fix well. However, the drawback was that some colors were difficult to fix.

This is particularly likely to occur in low-temperature environments, and is generally referred to as the first copy in the morning. This problem was most likely to occur when copying was performed immediately after the wait was started after the main power of the device was turned on. This is largely due to the fact that the inside of the image forming apparatus, especially the fixing device, is not sufficiently warmed up.

One way to counter this is to change the surface control temperature of the fixing roller (usually during copying) depending on the type of developer used in the fixing device, but this may be difficult depending on the capacity of the fixing roller heater. Ta. In addition, when replacing a developer with a higher control temperature with a developer with a lower control temperature, the fixing roller control temperature does not drop immediately, so the releasability of the transfer paper from the fixing roller decreases and curls. There were also drawbacks such as increased opacity and differences in gloss.

The present invention eliminates the drawbacks of conventional devices as described above. Particularly in the first copy in the morning, it eliminates the difference in fixing performance depending on the color type of the developer used, thereby ensuring stable copy quality. Further, in the present invention, the fixing control temperature does not need to be changed depending on the developer, so that curling and differences in gloss do not occur due to replacement of the developing device (developer).

B. Structure of the Invention [Means for Solving Problems] In the present invention, the timing at which the fixing roller starts rotating before fixing is changed depending on the color type of the developer used.

[Effect]

In other words, depending on the color type of developer stored in the developing device used, that is, the difference in fixability depending on the color type of developer, the start time of the rotation period of the fixing roller is set earlier for developer with lower fixability. (in the case of time control, the rotation time is lengthened; in the case of temperature control, the set temperature (for starting rotation) is lowered), and as a result, when a developer with low fixing properties is used, the fixing roller is The waiting time for the surface temperature to reach the surface temperature set value at the time of fixing or at the end of standby wait becomes longer, and more heat is applied to the entire fixing device, resulting in the development of a developer with poor fixing properties. In this case, the image fixability first thing in the morning is substantially the same as in the case of a developer with good fixability, and it is possible to obtain an image formed product with no difference in fixability for all color developers.

In addition, since the surface temperature setting value of the fixing roller, that is, the fixing control temperature value, is the same temperature for all color developers even if it is not changed, the curling property of the image bearing material such as transfer paper or the image surface may be affected by replacing the developing device. No difference in gloss occurs.

〔Example〕

FIG. 1 shows an example of a developing device. Since this developing device 1 itself is well known, its explanation will be kept brief. That is, this developing device uses a magnetic one-component toner as the developer T, coats the toner in a thin layer with a magnetic blade 3 on the surface of 2 rotating developing sleeves in which a magnet is arranged, and then coats the toner-coated surface with a magnetic blade 3. This is a system in which a latent image is developed facing the D surface of an electrostatic latent image carrier such as a rotating photosensitive drum. 4 is a developing device case that accommodates the toner T, 5 is a toner stirring member, 6 is a toner remaining amount detection device, and 7 is a toner replenishment port, and normally a toner cartridge is inserted into this port to open the case 4.
Replenish toner inside. 8 is a handle portion for handling the developing device. Reference numeral 9 denotes an exposure device that performs so-called blank exposure on the surface of the latent image carrier D before the developing process, and in this example, the exposure device 9 is integrally attached to and supported by the developing device 1.

The above-mentioned developing device 1 can be freely inserted into and removed from the main image forming apparatus (not shown) in the direction perpendicular to the plane of the paper. A mechanical power transmission/reception mechanism such as a gear provided opposite to the machine side and an electrical signal transmission/reception connector are connected to each other, and the developing sleeve 2 and toner stirring member 5 are driven by the drive source of the machine side.
becomes ready to drive. Also, the control circuit on this machine side,
The developing sleeve 2 is electrically connected to the developing device side.
It becomes possible to apply bias to the remaining toner amount detection device 6, feed back the detection signal to the remaining toner amount detection device 6, and supply power to the exposure device 9.

The present invention includes means for detecting the color type of developer contained in the developing device 1 installed in the image forming apparatus. Various such detection means can be considered. In the case of this embodiment, the connector portions that are connected to each other when the developing device 1 is installed in the machine are provided with a group of terminals for detecting the type of developer color contained in the installed developing device. That is, in FIG. 2, 10 is a connector on the developing device 1 side, and is provided with four terminals 10a, 10b, 10c, and 10d shown in FIGS. 1 to 4. 11 is a connector receiver on the side of this machine, and the first to
Fourth four terminals 11a, 11b, 11c, 11
d is provided. When the developing device 1 is attached to the machine, the connector 10 is connected to the connector receiver 11, and the first to fourth terminals 1 on the connector 10 side are connected to each other.
0a to 10d are the first to the connector receiver 11 side, respectively.
It comes into contact with the fourth terminals 11a to 11d.

Therefore, for convenience, black toner, blue toner,
The developing devices containing red toner are 1 _BK and 1 BK, respectively.
_BL , 1 _R , for device 1 _BK , the first and second terminals 1 of the four terminals of the connector 10
0a and 10b are electrically connected (closed) 12 in advance (the remaining terminals 10c and 10d are open). Similarly, for devices _1BL and _1R , the first and third terminals 10a and 10c and the first and fourth terminals 10a and 10d are connected, respectively.

Then, when device 1 _BK is attached to this machine, the first and second terminals 11 on the connector receiver 11 side
a and 11b become conductive. As a result, it is detected that the installed developing device contains black toner, and the detected information is input to the main control circuit 18 (FIG. 3) of the machine. Similarly, in the case of devices 1 _BL and 1 _R , the first and third terminals 11a, 11c and the first and fourth terminals 11a, 11b on the connector receiver 11 side are selectively brought into conduction state, and the devices are not attached. The color type of developer contained in the developing device is detected and input to the main control circuit 18.

FIG. 3 is a block diagram of the heat roller fixing device 13 and its control system. 14 is a fixing roller, 15
1 is a pressure roller, 16 is a heater built into the fixing roller 14, and 17 is a thermistor for detecting the surface temperature of the fixing roller 14.

When the main power supply of this machine is turned on, a heater energization start signal is issued from the main control circuit 18 to the heater control circuit 19, and the heater 16 is energized.
As a result, the temperature of the fixing roller 14 is increased from a cold state at room temperature by the heat of the heater. The heated surface temperature of the fixing roller is measured by the thermistor 17, and the temperature increase state is fed back to the main control circuit 18 via the temperature detection circuit 20.

When the surface temperature of the fixing roller 14 reaches the first surface temperature set value _T1 , a drive start signal is issued from the main control circuit 18 to the fixing roller/pressure roller drive circuit 21, and the rollers 14, 15 is in a rotationally driven state. The rotational driving of the rollers 14 and 15 is for the purpose of preventing deformation due to the heating of both rollers while being in pressure contact with each other, and for heating the fixing roller and the like evenly and uniformly.

The temperature of the fixing roller 14 is increased by subsequently applying electricity to the heater 16 . And the surface temperature is the second
When the surface temperature set value T ₂ , that is, the fixing control set temperature is reached, the main control circuit 18 issues an off signal to the heater control circuit 19 and roller drive circuit 21, and the power to the heater 16 is cut off. The rotation of the rollers 14 and 15 is stopped, the wait is completed, and a standby state is entered in which image formation can be started. Thereafter, the surface temperature of the fixing roller 14 is adjusted to the raised second surface temperature set value _T2 by controlling the power supply to the heater 16 on and off by the automatic temperature control system of the thermistor 17 and circuits 20, 18, and 19. Almost maintained. Depending on the image forming device, this temperature T ₂ and
In some cases, the temperature is slightly different from the temperature during the actual image forming process. In this embodiment, for convenience, it is assumed that both are at the same temperature _T2 .

When the image formation start signal is input to the main control circuit after the above-mentioned wait is completed, the rollers 14 and 15 are driven to rotate, and the unfixed toner image bearing member (transfer paper, etc.) from the image forming mechanism is transferred to the fixing roller 14. The toner image is introduced and passed between the roller and the pressure roller 16, and the toner image is fixed by heat and pressure.

In the present invention, the first surface temperature setting value _T1 of the fixing roller 14 is changed in height depending on the color type of the developer stored in the developing device installed in this machine, that is, the difference in fixability depending on the color type of the developer. It is something that makes you

For example, among black toner, blue toner, and red toner, the fixability of blue and red toners is generally inferior to that of black toner. The reason for this is thought to be that blue and red toners have poorer heat absorption than black toner. Therefore, appropriate first surface temperature setting values T _1BK , T _1BL , and T _1R of the fixing roller 14 are determined corresponding to the differences in the fixing properties of each toner.

In this embodiment, these values are set in advance in the main control circuit 18 as T _1BK >> _{T 1BL} >T _1R . When a developing device containing black toner is installed in this machine, the color type is detected as described above and input to the main control circuit 18, and the first color of the fixing roller 14 is detected. Surface temperature set value T ₁ is T _1BK
The heating and driving control of the fixing roller described above is executed. In the case of a developing device containing blue toner and red toner, T ₁ = T _1BL and T ₁ = T _1R , respectively.
Then, heating and driving control of the fixing roller is executed.

FIG. 4 is a graph of changes in the surface temperature of the fixing roller during the wait-up operation first thing in the morning when a developing device containing black toner is used and when a developing device containing blue toner is used. .

The temperature T _R is the surface temperature of the fixing roller before the power is turned on, and is approximately room temperature. The surface temperature of the fixing roller for black toner is a after turning on the power.
When it reaches the first surface temperature set value T _1BK for black toner, it moves on the straight line b, and after t _BK seconds, it reaches the second surface temperature set value T ₂ , and the weight increases. It will be completed. The reason why the slope of straight line b is smaller than that of straight line a is because the heater 16 is continuously turned on during these periods, but the fixing roller 14 and pressure roller 15 rotate.

In the case of blue toner, the curve changes along a straight line a after the power is turned on, but when the first surface temperature setting value T _1BL for blue toner is reached, the curve shifts to a straight line c. Line c has the same slope as line b. In the case of blue toner, the transition to straight line c is faster than that of black toner (because T _{1BK≫T 1BL} ), and the time until the weight increases is correspondingly longer, which is after t _BL seconds.

The longer the wait-up time, the more heat is given to the fixing device, which means that even in the case of blue toner, which has poor fixing properties, the image fixing properties will be better first thing in the morning.
Almost the same fixing properties as with black toner can be obtained.

Note that in the above embodiment, the temperature was set rather than controlled by time, but when the start of rotation of the roller is controlled by temperature or time (e.g., elapsed time after turning on the main power),
Any combination of controlling the end of rotation by temperature or time (time elapsed after turning on the main power or starting rotation, etc.) may be used, and the present invention includes all of these. This is to variably control the

In addition, the above control effect is particularly effective not only when first thing in the morning, but also when the main power of the device is turned off, such as during a lunch break, the device is stopped for a relatively long period of time, and then the main power is turned back on. There is. Further, the difference in wait up time depending on the color type of toner occurs when the fixing roller surface temperature T is T< _T1BK , and does not occur after normal jam processing or after a slight power off. At this time, since the entire machine is warm, there is almost no difference in fixing performance depending on the toner, so there is no problem.

The developer may be determined manually, by an instruction signal from a cartridge, or by a signal based on toner determination from the main body of the apparatus.

C. Effects of the Invention As described above, according to the present invention, it is possible to eliminate the difference in fixing performance depending on the color type of developer, and to obtain an image with no problems in fixing performance for any of the images made with toner of each color. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an example of a developing device, FIG. 2 is a configuration diagram of an example of contained developer color type detection means, FIG. 3 is a block diagram of a fixing device and its control system, and FIG.
The figure is a graph of changes in the surface temperature of the fixing roller during the first weight-up operation in the morning for both black toner and blue toner. 1 is a developing device, 13 is a fixing device, and 10 and 11 are connectors and connector receivers.

Claims (1)

[Scope of Claims] 1. A developing device having a developing device and a fixing device, a developer of a desired color can be used interchangeably with the image forming apparatus, and the surface temperature of the fixing roller is set at a first surface temperature setting. When the time corresponding to the value is reached, the rotation of the fixing roller is started, and when the fixing roller has a second surface temperature higher than the first surface temperature setting value, the developer is heated and fixed on the recording material. The image forming apparatus is characterized in that the color type of the developer used in the image forming apparatus is determined, and the rotation start timing of the fixing roller is changed according to the type. Forming device.