JPH0429171A - Heating device and temperature controller and temperature control system for developer - Google Patents

Abstract

PURPOSE:To always hold a developer in an optimum state even if a developer having temperature dependency for which its deterioration is intensified at a low temperature is used by heating the developer by means of a heater. CONSTITUTION:The heater 1021 composed of a plane heater is directly attached on the outside surface of a housing bottom part extending from a second stirring path 1011 to a paddle wheel 1012. On the other hand, a pair of a thermostat for the low temperature 1022 and a thermostat for a high temperature 1023 are provided on three places in the shaft direction of a second auger 1008, at the inside surface of the bottom part of the housing of the second stirring path 1022. Then, the developer is heated by the heater 1021. Then, the deterioration of the developer is relaxed, and the developer is held in the optimum state. Developing properties are improved, and simultaneously, the life of the developer is prolonged.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a heating device for heating a developer used in an image forming apparatus, and a temperature control device for controlling the temperature of the developer. and a temperature control method for controlling the temperature of the developer.

[Prior Art] Generally, in a copying machine, an image is formed as an electrostatic image on a latent image carrier, and this electrostatic image is made visible by a developing machine. In that case, a developer is used by a developing machine to create a visible image. Various types of developers have been considered for this developer, but they can be broadly classified into two-component developers consisting of toner and carrier, and one-component developers consisting only of toner.

Incidentally, in recent years, research and development of even higher speed development has been actively conducted in copying machines, etc., and in this case, among the two types of developers mentioned above, the high speed development Two-component developers are often used because they are suitable for However, this two-component developer has a problem in that it deteriorates (particularly the carrier deteriorates), and this deterioration causes a reduction in copy image density, toner fog, etc., and reduces developability. Therefore, maintenance work has conventionally been performed to replace the carrier at predetermined intervals.

[Problems to be Solved by the Invention] Among such two-component developers, there are some developers whose deterioration progress, that is, life span, is affected by temperature. For example, as shown in FIG. 10, there is a temperature-dependent developer in which the rate of deterioration is small at relatively high temperatures, but the rate of deterioration is large at relatively low temperatures. That is, when the temperature of this developer is lower than 43° C., ΔTP/10KC, which is an index of developer deterioration, changes greatly, and at low temperatures, the developer deteriorates more rapidly. Further, when the temperature of this developer is higher than 43° C., ΔTP/10KC, which is an index of developer deterioration, hardly changes, and when the temperature is high, the developer hardly deteriorates. In addition, ΔT
When P/l0KC is copied 10KC (10,000 times) on A4 paper, it becomes Tribo Prod.
uct; Tp: = toner concentration T, Cx indicates the amount by which the toner charge amount Trjbo#Con5t) decreases, and represents the progress of deterioration of the developer.

Humidity is also considered to be a factor in the influence of the surrounding environment on this developer, but the first
As is clear from FIG. 1, there is almost no change in the charge amount Tribo of the toner between 85% and 30% humidity, indicating that this developer is not significantly affected by humidity.

The following may be considered as the reason why the deterioration of the developer changes depending on the temperature. First, let's consider the thick edge of developer deterioration. One possible cause of the deterioration of the developer is that when the number of copies is increased, toner sticks to the carrier, that is, a thin layer of toner is infiltrated onto the surface of the carrier. The reason why this thin layer invasion occurs is that, as shown in FIG. 12, when the carrier C8 and the toner TN come into contact with each other during the relocation of the toner and carrier during the flow and compaction of the developer,
Toner TN receives shearing force F from carrier C9. As a result, shear stress is generated on the surface layer of toner TN. It is considered that the surface layer of the toner TN undergoes shear fracture due to this shear stress τ, and the fractured portion of the toner TN adheres to the surface of the carrier C9, thereby causing thin layer invasion.

In that case, the shear stress is expressed as τ" F H (shear force)/A (contact area between toner and carrier). Shear force F8 is the process speed, DR3-
Developer parameters such as TG and carrier C8 that is attracting attention
and the positional relationship of the toner TH in the entire developer, but these factors are not influenced by the surrounding environment such as temperature or humidity.

Therefore, we will further consider the reason why developer deterioration is affected by temperature. As shown in FIG. 13, when the developer is at a high temperature, the toner TN tends to be elastically deformed, and the shear stress τ becomes small. Furthermore, due to the strain caused by the elastic deformation of the toner TN, the energy due to shearing from the carrier C7 is effectively absorbed, thereby preventing the toner TN from being damaged by shearing. On the other hand, when the developer is at a low temperature,
Elastic deformation of the toner TN becomes less likely to occur, and the contact area A between the toner TN and the carrier C9 becomes smaller. Therefore, from the above equation, the shear stress τ becomes large, so that shear failure of the surface layer of the toner TN is likely to occur, and the above-described thin layer invasion of the toner TNO onto the surface of the carrier 08 occurs. Thus, the developer tends to deteriorate at low temperatures.

When the lifespan of the developer is affected by temperature in this way,
Developability is also affected by temperature, making it impossible to obtain high-quality images. In addition, since the life of the carrier is shortened, carriers must be replaced within a short period of time, which not only makes maintenance complicated, but also makes maintenance difficult.
There is a problem in that the cost is high.

The present invention was made in view of these problems, and its purpose is to improve the constant developing performance even with temperature-dependent developers, and to extend the life of the developer. It is an object of the present invention to provide a developer heating device, a developer temperature control device, and a developer temperature control method that enable the developer to perform the following steps.

[Means for Solving the Problems and Their Effects] In order to solve the above-mentioned problems, the invention according to claim 1 includes a heater in an image forming apparatus that develops and visualizes a latent image on a latent image carrier. A heater is provided to heat the developer. This heating reduces the deterioration of the developer.
Since the developer is maintained in an optimal state, developing performance is improved and the life of the developer is extended.

According to the invention of claim 2, by providing the heater on the outer surface of the housing 71 of the image forming apparatus corresponding to the developer stirring path, the developer can be heated efficiently, and the installation of the heater, Easy to remove.

Furthermore, as in the third aspect of the invention, by forming at least the portion of the housing where the heater is provided from a material with good thermal conductivity, the heat loss of the heater can be reduced and heating can be performed more effectively. Furthermore, by covering at least the portion with good thermal conductivity and the heater with a heat insulating material, not only is the heat of the heated developer prevented from escaping to the outside, but the developer is almost unaffected by external temperature. Therefore, the developer is kept in an even more optimal state.

According to a fourth aspect of the invention, a heater is provided in a housing of an image forming apparatus, and the developer is heated within the housing. Therefore, since almost no heat from the heater escapes to the outside, the developer can be heated efficiently without waste.

In this case, by providing a heater on the inner surface of the housing forming the developer stirring path, the developer can be directly heated, and
Since the heated developer is stirred, the developer is heated evenly.

In the sixth aspect of the invention, the temperature of the developer is detected by a temperature sensor, and the drive of the heater is controlled based on the temperature information of the developer detected by the control device.

In this case, the actual temperature of the uniformly heated developer can be detected by providing a temperature sensor on the inner surface of the housing that forms the developer stirring path. Become.

According to the eighth aspect of the invention, the developer temperature control device constantly maintains the developer at a high set temperature when the image forming apparatus is powered on, and maintains the developer at a high set temperature when the image forming apparatus is powered off. The temperature is controlled to be maintained at a low set temperature lower than this high set temperature.

By controlling the temperature of the developer in this way, the developer can be kept at a high set temperature that is in the optimum state for a long period of time (for example, several days).
Solidification of the developer that would otherwise occur if the developer is kept held is prevented. Also, by keeping the image forming apparatus at a predetermined temperature when the power is turned off.

When the power of the image forming apparatus is turned on, the temperature of the developer can be quickly brought to the optimum high temperature setting. As a result, the developer is always maintained in an optimal state and good developing performance can be obtained.

[Example code] Embodiments of the present invention will be described below with reference to the drawings.

Here, in one rotation of the drum, Black and Co1or
Although an example is shown in which two colors are developed and transferred once, the conventional case where one color is developed and transferred in one rotation of the drum is exactly the same. In that case, the black developer can be either a -component or a two-component developer, but in this embodiment, a case will be described in which a two-component developer is used.

FIG. 2 is a perspective view showing an example of a copying machine to which an embodiment of the present invention is applied, and FIG. 3 is a schematic sectional view of the copying machine.

As shown in FIGS. 2 and 3, the copying machine 1 includes a main body 2, a platen 3 provided on the top side of the main body 2 and on which a document (not shown) is placed, and a platen 3 provided below the platen 3. An image information reading section 4 that reads image information of a document, an image forming device 5 that receives signals from the image information reading section 4 and forms a predetermined image, and transfers the image formed by the image forming device 5 to a transfer medium. It is composed of a transfer section 7 that transfers the image onto the paper 6, and a paper supply section 8 and a paper transport section 9 that supply and transport the paper 6.

The paper supply unit 8 is composed of three paper trays 81, 82 and 83, which respectively accommodate paper 6 according to the size, a large capacity tray 84, a double-sided tray 85, and a manual feed tray 86. The paper transport section 9 also includes a paper reversing chute 91 and a paper 6 sent out from each tray 81 to 86.
The first sheet conveying path 92 conveys the copied sheet 6 to the image forming apparatus 5, and the second sheet conveying path 93 conveys the copied sheet 6 to the image forming apparatus 5 again.

Further, the paper 6 on which the toner image has been transferred by the image forming device 5 is sent to the fixing device 10 through the discharge side conveyance path 94.
After the toner image is fixed by the pressure roll 101 and heating roll 102 of the fixing device 10, it is conveyed to the discharge tray 87.

As shown in FIG. 4, the image forming apparatus 5 includes a photosensitive drum 5
1, a charger 52, a first latent image forming means 53, and a first developing means 5, which are sequentially arranged along the outer periphery of the photosensitive drum 51.
4, a second latent image forming means 55, a second developing means 56, and a pre-transfer charger 57. The photosensitive drum 5
The visible image formed on the paper 6 is transferred to the paper 6 in the transfer section 7.

In the image forming apparatus 5 configured as described above, when recording a color image, when the mode of the console panel 21 of the main body 2 is switched to the color mode, the charger 52 is activated as shown in FIG. 5(a). The surface of the photosensitive drum 51 is uniformly charged, and the surface potential of the photosensitive drum 51 is charged to one polarity. In this state, after a first latent image is formed on the photosensitive drum 51 by the first latent image forming means 53 as shown in FIG. By applying a predetermined developing bias voltage to the first toner image, a first toner image is formed by a reversal phenomenon. Next, as shown in FIG. 5D, a second latent image is formed on the photosensitive drum 51 by the second latent image forming means 55. By applying a predetermined developing bias voltage to the second developing means 56, , a toner image is formed on the photosensitive drum 51 by regular development, as shown in FIG. Then, as shown in FIG. 5(f), after the polarities of both toner images are aligned by the pre-transfer charger 57, the transfer section 7 transfers both toner images onto the paper 6 at once, thereby creating a color image. Recording is now taking place.

In this case, the first and second latent image forming means 53 and 55 are formed by laser diodes, and write a predetermined latent image on the photosensitive drum 51 in response to a signal from the image information reading section 4. It has become. Note that the first latent image forming means 53 is of a type that writes an image area, and the second latent image forming means 55 is of a type that writes a background area. However, these first and second latent image forming means 53.
55 does not necessarily have to be these methods; conversely, it may be a method in which the first latent image forming means 53 writes the background part, and a method in which the second latent image forming means 55 writes the image part; The dual-temperature image forming means 53 and 55 may be of a type that writes a co-image area or a background area.

The first developing means 54 has a two-component developer for color (red), and includes a developing roll 541 disposed on the photosensitive drum 51 side and a partition 542 on the back side of this developing roll 541. A first auger 543a and a second auger 543b installed together, and these augers 543a, 54
3b, a third auger 543C provided via a receiving plate 544 on the upper side of the housing 54a, a sealing member 545 on the film attached to the upstream side of the opening of the housing 54a and in contact with the photosensitive drum 51, and a back side of the housing 54a. A toner conveying coil auger 547a and a toner conveying auger 5 disposed in a toner box 547 attached to the
47b. In this case, the developing roll 541 is made of a non-magnetic conductive member such as aluminum alloy or stainless steel.

The second developing means 56 is a developing device having a black two-component developer, and is used to develop the second latent image formed on the photosensitive drum 51. As shown in Figure 1, this second
The developing means 56 includes a developing roll 1002 (developer carrier) having a part of its outer peripheral surface exposed outside the housing 1001 through an opening provided at one end inside the housing 1001;
A developer stirring means 1003 disposed inside the housing 1001 on the back side of the developing roll 1002 and the developing roll 10
Do not attach it to the housing 1001 top plate above the 02.
It is composed of a trimmer plate 1004 (trimmer) that regulates the height of the magnetic brush of the developer formed on the developing roll 1002.

Further, the developing roll 1002 includes a cylindrical sleeve 1 that is rotatable concentrically so as to cover the outer periphery of a fixedly supported substantially cylindrical magnetic member (mag roll) 1005.
006, a magnetic brush of developer is formed on the sleeve 1006 by the magnetic force of the mag roll 1005, and as the sleeve 1006 rotates, the magnetic brush is conveyed to the developing area facing the photosensitive drum 51. It looks like this. Magroll 1005 includes a peeling pole N1,
Adsorption pole N2, transport pole S3゜N3, and main development pole Sl, S2
A plurality of magnetic poles are provided in this order counterclockwise. The repelling pole of the main developing pole S1, 52 is formed by, for example, embedding a sintered ferrite group ferromagnetic material in the roll body.

A developing roll 100 having such a magnetic pole arrangement
In 2, magnetic poles of different magnetic properties are alternately successive: attraction pole N2→transport pole S3−transport pole N3−main developing pole 31, 32
→The developer is held on the surface of the sleeve 1006 between the attraction poles N1, while the stripping poles N1 have adjacent magnetic poles of the same magnetic property.
The developer is peeled off from the sleeve 1006 between 1 and the suction electrode N2.

By the way, in such a developing roll 1002,
A depressed part of the magnetic force is formed between the main developing poles Sl and S2.
Due to this depressed portion of the magnetic force, a repulsive magnetic field is formed between the main developing poles S1 and S2. In this repulsive magnetic field, Sl, N2
The magnetic force acting on the developer spreads out at a predetermined angle and acts between the two magnetic poles S1 and 32, and the magnetic force acting on the developer is temporarily weakened. Therefore, in this repulsive magnetic field, the carrier jumps out from the developing roll 1002 and is disturbed, so that the developer is transferred to the photosensitive drum 50 with high efficiency.
You will be able to rub it against the surface. This improves developability.

Both of these developing means 54 and 56 are arranged correspondingly to each other or are connected to the photosensitive drum 5 by a tract mechanism 58.
It is moved in the direction toward and away from 1. These retract mechanisms 58 are operated by a drive source (not shown).

Tracking rolls (not shown) are rotatably provided outside both ends of the developing roll 1002, and the gap between the developing roll 1002 and the photosensitive drum 51 is maintained by the tracking rolls coming into contact with the photosensitive drum 51. It looks like this.

On the other hand, the stirring means 1003 includes a first auger 1007 and a second auger arranged so that the axial direction coincides with that of the developing roll 1002.
It consists of an auger 1008 and a partition plate 1009 erected on the housing so as to separate these two augers. The rotational directions of the first auger 1007 and the second auger 1008 are determined so that the developer conveyance directions are opposite to each other. Further, at both ends of the partition plate 1009, an area where the first auger 1007 is arranged (hereinafter the first auger
An opening is provided that communicates the area where the second auger 1008 (referred to as the stirring path 1010) and the second auger 1008 is provided (hereinafter referred to as the second stirring path 1011), so that the first stirring path 1010 → the second stirring path The developer is circulated from path 1011 to first stirring path 101O.

Further, a paddle wheel 1012 having a plurality of blades 1012a parallel to the axial direction is provided between the developing roll 1002 and the stirring means 1003. As the paddle wheel 1012 rotates, the developer separated from the developing roll 1002 is forcibly conveyed toward the stirring means 1003, and the developer mixed and stirred by the stirring means 1003 is continuously transferred to the developing roll 1002. supply.

Further, the bottom shape of the housing 1001 is such that the developer is not transported and does not stagnate.

That is, from the developing roll 1002 to the roller wheel 1
The bottom of the housing from 012 to 012 is the developing roll 100.
Guide surface 1 that guides the developer adsorbed on 2 to the peeling area
017 and a guide surface 1018 that guides the peeled developer to the paddle wheel 1012.

By determining the intersection of the guide surface 1017 and the guide surface 1018 from the relationship between the separation pole N1 and the adsorption electrode N2, the flow of the developer after separation from the developing roll 1002 is promoted.

A toner supply device 1020 is disposed above the first auger 1007 in the housing 1001 . This toner supply device 1020 is a toner supply device of a cartridge leaving type that is used with a cartridge filled with toner attached to the main body 2.

The developer used in this example consists of a toner using styrene normal butyl acrylate as a binder and a carrier made of ferrite or iron powder. It has a temperature dependence similar to the temperature dependence.

Furthermore, as shown in FIGS. 1 and 6, a second stirring path 10
On the outer surface of the bottom of the 71 Uzing from 11 to the paddle wheel 1012, there is a heater consisting of a plain heater! 021 is directly attached. By attaching the heater 1021 to the outer surface of the housing in this manner, attachment and detachment of the heater 1021 becomes easy. Further, on the inner surface of the bottom of the housing of the second stirring path +011, a pair of low-temperature thermostats 1022 and high-temperature thermostats 1023 are provided at three locations in the axial direction of the second auger 1008. As shown in FIG. 7, the low-temperature thermostat 1022 is set at a low temperature of 30°C, and the high-temperature thermostat 1023 is set at a low temperature of 30°C.
The temperature is set at a high temperature of 3°C.

This high set temperature is a temperature at which the rate of deterioration of the developer used in this embodiment is small, the developer is maintained in an optimal state, and is lower than the glass transition temperature. Therefore, the high-temperature thermostat 1023 is not limited to a thermostat with a set temperature of 43° C., but may be a thermostat set at an optimum temperature depending on the temperature-dependent characteristics of various developers. In addition, the low set temperature is a temperature that will prevent the developer from solidifying when the copier is not used for a long period of time (for example, several days) while the developer is kept at the high set temperature, and when the developer is not used for long periods of time (for example, several days), and when the developer is not used for developing when using the copier. The temperature is such that the agent can be raised to the high set temperature relatively quickly. Therefore, the low-temperature thermostat 1022 is not limited to a thermostat with a set temperature of 30° C., but any thermostat set at an appropriate temperature can be used.

As is clear from FIG.
This relay 1024 is connected to heater 1
It is connected to a control device 1025 that drives and controls the 021.

In addition, the relay 1024 is connected to the main switch 10 of the copying machine.
26.

The heater 1021 constitutes a developer heating device in this embodiment of the present invention.
021, low temperature and high temperature thermostat 10221
023, the relay 1024, and the control device 1025 constitute a developer temperature control device and a developer temperature control method in this embodiment of the present invention.

In this embodiment configured in this manner, the main switch 1026 is turned off when the copying machine is not used, such as at night, and the relay 1024 switches the thermostat to the low temperature thermostat 1022 side.

Therefore, the temperature information of the developer detected by the low mixing thermostat 1022 is sent to the control device 1025 via the relay 1024. Based on this temperature information, the control device 1025 controls when the developer temperature is higher than 30°C.
The driving of the heater 1021 is stopped and the temperature of the developer is lowered. Further, the control device 1025 controls the temperature of the developer to be 30°C.
When the temperature is lower, the heater tozt is driven to heat the developer and raise its temperature. In this way, the control device 1025 controls the developer temperature to always be maintained at 30° C. when the main switch 1026 is off.

When the main switch 1026 of the copying machine is turned on for copying, the relay 1024 switches the thermostat to the high temperature thermostat 1023 side. Therefore, the temperature information of the developer detected by the high temperature thermostat 1022 is sent to the control device 1025 via the relay 1024. Based on this temperature information, when the temperature of the developer is lower than 43° C., the control device 1025 drives the heater 1021 to heat the developer and raise its temperature. Further, the control device 1025 indicates that the temperature of the developer is 43°C.
When the temperature is higher, the drive of the heater 1021 is stopped,
Lower the developer temperature.

In this way, the control device 1025 controls the main switch 1
When 026 is off, the temperature of the developer is controlled to be maintained at 43° C. at all times. In that case, since the temperature of the developer is maintained at 30° C. when the main switch 1026 is turned off, the temperature of the developer will change after the main switch 1026 is turned on.
It can be raised to 43°C relatively quickly. Further, the heater 1021 is connected to the first and second stirring paths 1011 for the developer.
．． Since the developer is installed at a location corresponding to heater 1010, the developer can be heated efficiently and uniformly by heater 1021.

In this way, when the main switch 1026 is on, the developer is always maintained in an optimal state with a low rate of deterioration.

The transfer unit 7 includes a transfer corotron 73 in which a wire electrode 72 is stretched in a shelf 1 having a U-shaped cross section that opens toward the photosensitive drum 51 side, and a transfer corotron 73 disposed downstream of the transfer corotron 73 and a photosensitive drum. Two wire electrodes 75 and 76 are placed inside the shelf 4, which has a U-shaped cross section and opens toward 51.
and a peelable corotron 76 which are stretched parallel to each other.

On the downstream side of the transfer section 7, there is a peeling claw 2 for peeling off the paper 6 adhering to the photosensitive drum 51 from the photosensitive drum 51 after the transfer.
00 is arranged. Furthermore, a cleaning device 300 for removing residual toner adhering to the photosensitive drum 51 is disposed downstream of the peeling claw 200. in this case,
The cleaning device 300 includes a cleaning blade 301 that scrapes toner adhering to the photosensitive drum 51, a rotating brush roll 302 provided upstream of this cleaning blade 301, and a toner receiver 303 provided upstream of this rotating brush roll 302. and a toner scattering prevention film seal 304 attached to the photosensitive drum 51 side of the toner receiver 303 and in contact with the photosensitive drum 51.

FIG. 8 is a sectional view similar to FIG. 1 showing another embodiment of the present invention. It should be noted that the same components as those in the above-mentioned embodiments are given the same reference numerals, and detailed explanations thereof will be omitted.

In this embodiment, the upper wall of the housing 1001 of the second developing means 56] 001a, the lower wall 1001b
and the right side wall (right side in FIG. 8) 1001c are made of a material with relatively good thermal conductivity, such as aluminum. Further, the front and rear walls (in the direction perpendicular to the drawing in FIG. 8) are made of a material that does not have high thermal conductivity, such as plastic. At least the portion of the housing 1001 made of a material with good thermal conductivity and the heater 1021 are covered with a heat insulating material 1027 made of, for example, flocked hair.

In this embodiment, since the housing 1001 is made of a material with good thermal conductivity, the heater 102
The heat of No. 1 can be quickly transferred to the developer with almost no loss. This allows the developer to be heated efficiently and quickly.

Moreover, at least the portion of the housing 1001 made of a material with good thermal conductivity and the heater 1021 are covered by the heat insulating material 1.
027, the amount of heat escaping to the outside is almost small, and the developer can be heated even more efficiently. Furthermore, the heat of the developer heated to the high set temperature of 43°C does not escape to the outside, and the developer is not affected by external temperature, ensuring that the developer is in the optimal state. While being held, the developing roll 1005
sent to.

FIG. 9 is a diagram showing still another embodiment of the present invention. Similarly, the same components as those in the above-mentioned embodiments include:
Explanation will be omitted by assigning the same reference numerals.

In this embodiment, the heater 1 consists of a plain heater.
Reference numeral 021 denotes a portion inside the housing 1001 where the developer is stirred and conveyed, that is, the inner wall surface of the right side wall 1001c, the first and second stirring paths 1010. It is provided over the inner surface of the roll, the wall surface of the partition wall 1009, and the guiding surface 1018.

By providing the heater 1021 in the housing 1001 in this manner, the developer can be heated even more efficiently.

The heater 1021 of the embodiment shown in FIGS. 8 and 9 also
Thermostats 1022, 10 shown in FIGS. 6 and 7
23 and a control device.

Note that the present invention is not limited to the above-mentioned embodiments,
Various design changes are possible.

For example, in the embodiments described above, thermostats 1002 and 1023 are used as means for detecting the temperature of the developer, but other temperature sensors such as thermocouples and thermistors may also be used. Moreover, it goes without saying that these temperature sensors can also be installed at other suitable locations.

Further, in the above-mentioned embodiments, a two-component developer is described as the developer, but the present invention provides a developing means using a one-component developer if the deterioration is temperature-dependent. It goes without saying that it can also be applied.

[Effects of the Invention] As is clear from the above description, according to the present invention, since the developer is heated by a heater, even if a temperature-dependent developer that deteriorates rapidly at low temperatures is used, The deterioration of the developer is alleviated, and the developer can be maintained in an optimal state at all times. Therefore, the developability of the developer can be significantly improved, and the life of the developer can be extended.

In addition, since the lifespan of the developer can be extended,
The period of carrier replacement becomes longer, maintenance becomes easier, and costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of a developing means used in an embodiment of the present invention, FIG. 2 is a perspective view showing an example of a copying machine to which the embodiment is applied, and FIG. 3 is a schematic diagram of this copying machine. 4 is an enlarged sectional view of the image forming device of this copying machine, FIG. 5 is a diagram explaining the image forming process in this image forming device, and FIG. 6 is taken along the line Vl-VI in FIG. 1. 7 is a block diagram of the temperature control of the developer in this embodiment; FIG. 8 is a diagram showing another embodiment of the present invention; FIG. 9 is a diagram showing still another embodiment of the present invention; FIG. 10 is an explanatory diagram illustrating the change in deterioration of the temperature-dependent developer with respect to temperature. FIG. 11 is an explanatory diagram illustrating the change in deterioration of the developer with respect to temperature and humidity. FIG. 13 is a diagram illustrating the influence of temperature on developer deterioration. 1... Copy seed 5... Image forming device, 51... Photosensitive drum, 54... First developing means, 56... Second developing means, 102 Heater (heating device), 1022.102
3...Thermostat (temperature sensor) Patent applicant Fuji Xerox Co., Ltd.

Claims (8)

[Claims] (1) A developer heating device characterized in that an image forming apparatus that develops a latent image on a latent image carrier into a visible image is provided with a heater that heats the developer. (2) The developer heating device according to claim 1, wherein the heater is provided on an outer surface of the housing of the image forming apparatus corresponding to the developer stirring path. (3) The housing is characterized in that at least a portion where the heater is provided is formed from a material with good thermal conductivity, and at least the portion with good thermal conductivity and the heater are covered with a heat insulating material. The developer heating device according to claim 2. (4) The developer heating device according to claim 1, wherein the heater is disposed within a housing of the image forming apparatus. (5) The developer heating device according to claim 4, wherein the heater is provided on an inner surface of the housing that forms the developer stirring path. (6) A developer temperature control device used in an image forming apparatus that develops and visualizes a latent image on a latent image carrier, which includes a heater that heats the developer, and a temperature control device for the developer. A developer temperature control device comprising: a temperature sensor that detects temperature of the developer; and a control device that controls driving of the heater based on temperature information of the developer from the temperature sensor. (7) The developer temperature control device according to claim 6, wherein the temperature sensor is provided on an inner surface of the housing that forms the developer stirring path. (8) A developer temperature control method for controlling the temperature of the developer by the developer temperature control device according to claim 6, wherein the temperature of the developer is always maintained at a high set temperature when the image forming apparatus is powered on. Further, a developer temperature control method characterized in that when the image forming apparatus is powered off, the temperature is maintained at a low set temperature lower than the high set temperature.