JPH08305210A - Image forming apparatus - Google Patents

Abstract

PURPOSE: To provide an image forming apparatus, by which glossiness suiting to a user's taste can be obtained while good fixability is ensured according to the thickenss of a recording material without damaging high speed performance even if the rubber layer of the surface layer of a fixing roller is made thick by making both the fixing roller and a pressure roller as a three-layer structure in which the surface layer and the lowermost layer are formed by silicon rubber and the intermediate layer is formed by an oil resistant layer of fluorine-contained rubber. CONSTITUTION: As shown in the drawing (A), the glossiness of an output image is displayed on a display 130 of a console panel to be selected by a user according to the user's taste. In the case where the glossiness is selected on the screen, as shown in the drawing (B), the kind of paper to be copied is displayed to be selected so as to enable a user to select the kind of paper. Further, the fixing speed by which the selected glossiness can be obtained in the paper of the selected kind is determined from a prepared table to control a fixing device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine.

[0002]

2. Description of the Related Art Various image forming apparatuses are known. Among them, an electrophotographic image forming apparatus is often used, in which an image is exposed on a photoconductor with a laser beam and developed to obtain an image. There is. Such an image forming apparatus has advantages such as high image quality and high speed, and is widely used as an output device such as a copying machine, a color laser beam printer and the like.

For example, as an example of a copying machine, there is an apparatus as shown in FIG. The color copying machine shown in FIG. 7 has a document reading system I provided on the upper part thereof, a latent image forming section II provided below the document reading system I, and a latent image forming section II close to the latent image forming section II. The developing means provided, that is, the rotary developing device III, and the recording material conveying system IV provided from the right side of the apparatus main body 1 to substantially the center of the apparatus main body are roughly divided.

The structure of the image forming apparatus will be described below. First, the document reading system I will be described with reference to FIGS. FIG. 8 is a schematic configuration diagram of the document reading system I. In FIG. 8, 101 is a document and 102 is a platen. This platen 102 is provided immovably with respect to the apparatus main body 1, and an optical system unit 107 provided below the platen 102 moves in the direction of the arrow, so that the originals 101 placed on the platen 102 are sequentially placed. To scan. That is, when the copy key (not shown) of the operation unit (not shown) is pressed, the irradiation from the irradiation light source 103 is performed along with the movement in the arrow direction, and the original 1
The reflected light from 01 passes through the image forming element array 104 and the infrared cut filter 105 and is formed as an original image on a CCD (contact type CCD color sensor) 106.

As shown in FIG. 9, red (R), green (G), and blue (B) filters are regularly attached to the CCD 106 for each pixel, and as the original 101 is scanned. When a document image is formed on the CCD 106, an electric signal is output from the CCD 106, and the electric signal is processed by the signal processing circuit shown in FIG.

In FIG. 10, 106B, 106G, 1
06R represents electric signals from the B, G, and R elements on the CCD 106 shown in FIG. This 106B, 106
The respective signals of G and 106R are converted into digital signals B, G and R by the A / D conversion circuit 111, and the density conversion circuit 11
2, Y ₁ , M which are density signals in digital signal form
₁ , converted to C ₁ .

The Y ₁ , M ₁ and C ₁ signals are input to a circuit 113 which performs black extraction and UCR (under color removal) processing,
By the calculation processing as shown in the following equation, Y ₂ , M ₂ , C ₂ ,
It is generated as a Bk ₂ signal.

Y ₂ = Y ₁ −k ₃ min (Y ₁ , M ₁ , C ₁ ) M ₂ = M ₁ −k ₃ min (Y ₁ , M ₁ , C ₁ ) C ₂ = C ₁ −k ₃ min (Y ₁ , M ₁ , C ₁ ) Bk ₂ = k ₁ min (Y ₁ , M ₁ , C ₁ ) + k ₂

Where min (Y ₁ , M ₁ , C ₁ ) is
It is the smallest signal among the signals of Y ₁ , M ₁ , and C ₁ , and k
₁ , k ₂ and k ₃ are predetermined coefficients.

Next, the Y ₂ , M ₂ , C ₂ , and Bk ₂ signals are used by the color correction circuit 11 to correct the spectral distribution of the color material used by the color separation filter of the CCD 106 or the image forming means.
4 and is subjected to the arithmetic processing shown by the following equation.

[0011]

[Equation 1]

Here, a _{11 to} a ₄₄ are masking coefficients for color correction.

Then, the calculation results Y ₃ , M ₃ , C
₃ , latent image forming section II described below based on Bk ₃ signals
The laser beam is irradiated to visualize the image.
The latent image forming section II will be described below with reference to FIG.

The latent image forming section II is provided with a photosensitive drum 19 which is a latent image carrier which is rotatable in the direction of arrow B in FIG. Above the photosensitive drum 19, in the vicinity of the outer peripheral surface thereof, a charge eliminating charger 20, a cleaning means 21, and a primary charger 23 are sequentially arranged from the upstream side to the downstream side in the rotation direction of the photosensitive drum 19, and further. An image exposure means 24 such as a laser beam scanner for forming an electrostatic latent image and an image exposure reflection means 25 such as a mirror are arranged on the outer peripheral surface of the photosensitive drum 19.

Therefore, the image exposing means 24 is provided with the above Y ₃ , M 2.
_When the laser beam E is irradiated on the basis of ₃ , C ₃ , and Bk ₃ signals, the laser beam E is irradiated by the image exposure reflection means 25.
Is radiated onto the photosensitive drum 19 via the primary charger 23
An electrostatic latent image is formed on the photosensitive drum 19 that is uniformly charged by the above, and is visualized as a developer image by the next rotary developing device III. The rotary developing device III will be described below.

The rotary developing device III comprises the photosensitive drum 1 described above.
It is arranged at a position opposed to the outer peripheral surface of 9, and is constructed by mounting four kinds of developing devices at four positions in the circumferential direction in a rotatable housing (hereinafter referred to as “rotating body”) 26. There is. The four types of developing devices are yellow developing devices 27, respectively.
Y, magenta developing device 27M, cyan developing device 27C, and black developing device 27Bk, and the above Y ₃ , M ₃ ,
In response to an electrostatic latent image based on the signal of the C _3, Bk _3, thereby performing the development by each color developer. Then, the developed visible image on the photosensitive drum 19 is transferred onto the recording material conveyed by the next recording material conveying system IV. The recording material conveying system IV will be described below.

The recording material conveying system IV has the following structure. First, an opening is formed in the right wall of the apparatus main body 1, and removable recording material supply trays 2 and 3 are disposed in the opening so as to partially project outside the machine. Paper feed rollers 4 and 5 are arranged substantially directly above the trays 2 and 3, and arrow A is arranged on the left side of the paper feed rollers 4 and 5.
A paper feed roller 6 and paper feed guides 7 and 8 are provided so as to communicate with a transfer drum 15, which is a transfer means rotatable in any direction. In the vicinity of the outer peripheral surface of the transfer drum 15, a contact roller 9, a gripper 10, a recording material separating charger 11 and a separating claw 12 are sequentially arranged from the upstream side to the downstream side in the rotation direction. A transfer charger 13 and a recording material separating charger 14 are provided on the inner peripheral side of the transfer drum 15. The transfer drum 15 has a transfer sheet (not shown) made of polyvinylidene fluoride or the like attached to a portion around which the recording material is wound. The recording material is electrostatically adhered to the transfer sheet. It has become. Further, a conveying belt means 16 is arranged on the upper right side of the transfer drum 15 in the vicinity of the separating claw 12, and a fixing device 18 is arranged at the end (right) end of the conveying belt means 16 in the recording material conveying direction. ing. Further, a discharge tray 17 that extends to the outside of the apparatus main body 1 and is detachable from the apparatus main body 1 is disposed downstream of the fixing device 18 in the transport direction.

The sequence of the entire image forming apparatus having the above-mentioned configuration will be briefly described by taking the case of the full color mode as an example. When the photosensitive drum 19 described above rotates in the direction of arrow B in FIG. 7, the photosensitive member on the photosensitive drum 19 is uniformly charged by the primary charger 23. Note that FIG.
In the apparatus shown in (1), the operating speed of each part (hereinafter referred to as process speed) is 160 mm / sec. When the primary charger 23 uniformly charges the photoconductor, image exposure is performed by the laser beam E modulated by the yellow image signal Y ₃ of the original 101, and an electrostatic latent image is formed on the photoconductor drum 19. Then, the electrostatic latent image is developed by the yellow developing device 27Y which is previously fixed at the developing position by the rotation of the rotating body 26.

On the other hand, the recording material conveyed through the paper feed guide 7, the paper feed roller 6, and the paper feed guide 8 is held by the gripper 10 at a predetermined timing and brought into contact with the contact roller 9 in a corresponding manner. It is electrostatically wound around the transfer drum 15 by the use roller 9 and the opposing electrode. The transfer drum 15 is rotating in the direction of arrow A in FIG. 7 in synchronization with the photosensitive drum 19, and the visible image developed by the yellow developing device 27Y is the outer peripheral surface of the photosensitive drum 19 and the outer periphery of the transfer drum 15. Transfer charger 13 at the portion where the surface is in contact with
Transcribed by The transfer drum 15 continues to rotate and is ready for transfer of the next color (magenta in FIG. 7).

The photosensitive drum 19 is destaticized by the decharging charger 20, is cleaned by a cleaning means 21 by a conventionally known blade method, is charged again by the primary charger 23, and is recharged by the next magenta image signal. Receive image exposure like. The rotary developing device III rotates while the electrostatic latent image based on the magenta image signal is formed on the photosensitive drum 19 by the image exposure to set the magenta developing device 27M at the predetermined developing position. Magenta development is performed. Then,
When the above-described processes are carried out for cyan and black, respectively, and when the transfer of four colors is completed, the four-color visible image formed on the recording material is discharged by the chargers 20 and 14, respectively. The gripping of the recording material by the gripper 10 is released, and the recording material is separated from the transfer drum 15 by the separating claw 12 and sent to the fixing device 18 by the conveyor belt 16 and fixed by heat and pressure to perform a series of full-color printing. The sequence is completed, and the required full-color print image is formed.

As described above, since a color image has two to four layers of multicolor toners, the toner in an electrophotographic apparatus capable of forming a color image is different from that of a black and white apparatus. It has different characteristics.

In other words, since this toner is required to have good melting property and color mixing property when heat is applied, a sharp melting property toner having a low softening point and a low melt viscosity is used. By using the sharp melt toner, a color copy having a wide color reproduction range can be obtained.

Such a sharp melt toner includes a binder resin such as polyester resin or styrene-acrylic ester resin, a colorant (dye, sublimable dye),
It is produced by melt-kneading, pulverizing and classifying a toner forming material such as a charge control agent. If necessary, an external addition step of adding various external additives (for example, hydrophobic colloidal silica) to the toner may be added. As such a color toner, it is particularly preferable to use a polyester resin as the binder resin in consideration of the fixability and the sharp melt property. As the sharp melt polyester resin, a polymer compound having an ester bond in the main chain of a molecule synthesized from a diol compound and a dicarboxylic acid is exemplified.

In particular, the following equation

[0025]

Embedded image

(Wherein R is an ethylene or propylene group, x and y are positive integers of 1 or more, and the average value of x + y is 2 to 10) or a bisphenol derivative thereof. A carboxylic acid component consisting of a diol component as a substituent and a divalent or higher carboxylic acid or an acid anhydride thereof or a lower alkyl ester thereof (for example, fumaric acid, maleic acid, maleic anhydride, phthalic acid, terephthalic acid, trimellitic acid). , Pyromellitic acid, etc.) are more preferable because they have a sharp melting property.

The softening point of the polyester resin is 75 to 15
0 degreeC, Preferably 80-120 degreeC is good.

FIG. 11 shows an example of softening characteristics of a sharp melt toner containing this polyester resin as a binder resin. The measurement conditions are as follows.

A flow tester CFT-500A type (manufactured by Shimadzu Corporation) was used, and the diameter of the die (nozzle) was 0.2 mm.
A thickness of 1.0 mm, an extrusion load of 20 kg, an initial set temperature of 70 ° C., a preheating time of 300 seconds, and a constant temperature increase at a rate of 6 ° C./min. Hereinafter, a softened S-shaped curve) was obtained. As the sample toner, fine powder precisely weighed from 1 to 3 g is used, and the cross-sectional area of the plunger is 1.0 cm ² . Figure 1 shows the softened S-curve
It becomes a curve like 1. As the temperature rises at a constant rate, the toner is gradually heated and begins to flow (plunger descending A → B). When the temperature is further raised, the melted toner largely flows out (B → C → D), and the plunger lowering is stopped and completed (D → E).

The height H of the S-shaped curve indicates the total outflow amount, and H /
The temperature T ₀ corresponding to point C of 2 indicates the softening point of the toner.

Whether or not the toner and the binder resin have a sharp melting property can be determined by measuring the apparent melt viscosity of the toner or the binder resin.

Toner having such a sharp melt property
-Or a binder resin has an apparent melt viscosity of 10³ Poi
T is the temperature at which₁ 5 x 10²  Showing poise
The temperature of the mushroom is T₂ And then T₁ = 90 to 150 ° C | ΔT | = | T₁ -T₂ │ = 5 to 20 ° C. means the one satisfying the condition.

The sharp-melting resin having these temperature-melt viscosity characteristics is characterized by extremely sharply decreasing the viscosity when heated. Such a decrease in viscosity causes a proper mixing of the uppermost toner layer and the lowermost toner layer, and further sharply increases the transparency of the toner layer itself, thereby causing good color-reducing mixing.

Therefore, as the fixing device 18, as shown in FIG. 12, a fixing roller 29 as a fixing member having a halogen heater 36 as a heat generating means and a pressure roller 30 as a fixing member also having a heater 37 are added. The pressure of a total pressure of about 40 kg is applied by a pressure mechanism (not shown), the temperature of the pressure roller 30 is detected by the thermistor 38 in contact with the pressure roller 30, and the controller 39 is based on the detected temperature. By controlling the halogen heaters 36 and 37 so that the temperature of the fixing roller 29 and the temperature of the pressure roller 30 are both kept constant at about 150 ° C., the sharp melt toner transferred onto the recording material P is removed. The developer t is favorably heated and fixed on the recording material P.

However, since such a sharp-melting color toner has a large affinity and is easily offset to the fixing roller, in the fixing device, a high releasability is obtained for a long period of time. Need to be shown.

Therefore, the apparatus shown in FIG. 12 is provided with an oil applying device O as a releasing agent applying means, a cleaning device C, a cleaning blade C1 for removing oil and dirt from the pressure roller 30, and further releasing property. We are trying to improve

The oil applying device O is a dimethyl silicone oil 41 (KF963 manufactured by Shin-Etsu Chemical Co., Ltd.) in an oil pan 40.
00 cs) is applied to the fixing roller 29 after the oil application amount is adjusted by the oil application amount adjusting blade 44 through the oil pumping roller 42 and the oil application roller 43. The amount of 0.08 g / A4 is applied according to the measuring method. The oil applying roller 43 can be brought into contact with and separated from the fixing roller 29, and is 5 mm from the front end of the recording material to 5 mm from the rear end.
Oil is applied up to mm.

The amount of silicone oil applied by the oil applying device O is determined as follows.

First, the weight of 50 sheets of A4 size blank paper is A
₁ (g), without transferring the image onto the blank sheet and without applying silicone oil to the rubber layer of the fixing roller,
Blank sheet 50 after passing between the fixing roller and the pressure roller
Let the weight of the sheet be B (g). Next, similarly, the weight of another 50 sheets of A4 size paper is set to A ₂ (g), and the image is not transferred onto this white paper, but the silicone oil is applied to the rubber layer of the fixing roller. Let C (g) be the weight of 50 blank sheets after passing between the fixing roller and the pressure roller. When the above A ₁ , B, A ₂ and C are used, the amount of silicone oil applied per white sheet of A4 size X (g)
Is calculated by the following equation.

X = (C + A ₁ −B−A ₂ ) / 50

On the other hand, in the fixing device shown in FIG. 12, the cleaning device C performs cleaning by pressing the non-woven fabric web 46 made of Nomex (product name) against the fixing roller 29 by the pressing roller 45. The web 46 is appropriately wound by a winding device (not shown) so that toner or the like does not accumulate on the contact portion.

Further, in the fixing device 18, as shown in FIG. 12, as the fixing roller 29, the HTV (high temperature vulcanization type) silicone rubber layer 3 is provided on the core metal 31 made of aluminum.
2 and an RTV (room temperature vulcanization type) silicone rubber layer 33 as a heat resistant elastic layer on the outside thereof, and having a thickness of 3 mm and a diameter of 40
On the other hand, as a pressure roller 30, a 1 mm thick HTV layer 35a and a fluororesin layer 35b were provided on the surface of the pressure roller 30 to form a pressure roller 30 having a diameter of 40 mm. A roller is used, and by combining the fixing roller 29 and the pressure roller 30 having such a configuration, the releasability with respect to the sharp melt toner is further enhanced.

However, with the spread of color copying machines in recent years, the speed and convenience of color copying machines are comparable to those of black and white copying machines, that is, automatic double-sided copying, or use of paper from postcard to large size, thin paper to thick paper, Has been required to meet various needs such as OHP film and pack print film.

Therefore, in order to meet such needs,
The above-described improvement of the fixing device 18 has been proposed. For example, in order to fix a double-sided image, not only the fixing roller 29 but also the surface layer of the pressure roller 30 has a high toner releasing effect RTV.
Or LTV silicone rubber has come to be used. At the same time, in order to satisfy the high speed of color fixing, it is necessary to increase the nip, and the diameter of the roller can be increased (for example, 60 mm or 80 mm). Furthermore, since thick paper is used, fixing is performed. In addition, the fixing temperature must be increased.

However, the silicone rubber of the surface layer which is originally used to maintain the releasability and the silicone rubber of the lower layer which forms the nip for wrapping the sharp melt toner are both used in the silicone oil used. Therefore, a large amount of silicone rubber enters the rubber depending on the durability, and especially the lowermost layer of silicone rubber contains a large amount of silicone oil and peels off between the core metal interface during heating. This could happen.

Therefore, in a copying machine which is required to make a large number of copies at a high speed, in order to prevent the peeling, both the fixing roller and the pressure roller are provided between the lower layer silicone rubber and the surface layer silicone rubber. However, it has become common to use fluororubber having an oil resistant layer that does not absorb or pass silicone oil.

[0047]

However, according to the above-mentioned conventional example, both the fixing roller and the pressure roller have a three-layer structure in which the surface layer and the lowermost layer are made of silicone rubber and the middle portion is made of fluororubber having an oil resistant layer. By using a roller, the following phenomenon occurs in the currently required high-speed color fixing.

This is a phenomenon of fixing property which occurs when the discharge property is improved when paper is used as the recording material. Originally, when the toner is not transferred onto the paper and the fixing roller and the pressure roller have the same curvature, the paper is discharged straight after passing through the nip.

However, once the toner is deposited, the toner is melted when passing through the nip, and therefore the paper is also pulled and wound around the fixing roller due to its adhesive force. Therefore,
In a conventional black-and-white copying machine, a separating roller is brought into contact with a fixing roller to mechanically separate the paper from the roller. However,
In color copiers, the image ratio is often high, and the toner is a sharp melt, so when the separating claw comes into contact with the fixing roller, the marks by the separating claw may appear on the image. Since the roller is not a roller but a soft roller made of silicone rubber, the roller may be scratched due to the contact of the separation claw, which may cause an image defect or peeling when the roller is used for a long period of time.

Therefore, in the color copying machine, a soft rubber roller is used as the fixing roller, and a fluororesin roller having a thinner layer and a harder surface layer than the fixing roller is used as the pressure roller, and a lower paper discharge nip as shown in FIG. By providing the pressure roller with the separation claw 100, the paper is discharged in the direction A to prevent the paper from being wound around the fixing roller, and even when the paper is wound around the pressure roller, the paper is separated by the lower separation claw 100 and the toner-laden paper is attached. The dischargeability of was increased.

However, as described above, since the fixing roller and the pressure roller have the three-layer structure in which the surface layer and the bottom layer are the silicone rubber and the middle is the fluorine rubber having the oil resistant layer, the pressure roller is also deformed. In some cases, the nip as shown in FIG. 13 cannot be formed and the paper cannot be discharged in the A direction.

Therefore, in such a combination of the fixing roller and the pressure roller having the three-layer structure, it is conceivable to make the silicone rubber layer of the fixing roller thick in order to make the fixing roller easily deformed. By increasing the thickness, the fixability may be deteriorated.

For example, the lowermost silicone rubber layer of the fixing roller remains 1 mm, and the surface silicone rubber layer is 1.
When the temperature is increased from 5 mm to 2.5 mm, for example, when the roller temperature is adjusted to 150 ° C. and the paper is passed through, when the wall thickness is 1.5 mm as shown in FIG. Since the temperature is transmitted relatively efficiently, the temperature recovers quickly, and the roller temperature nadir is above the fixing nadir temperature (cold offset lower limit temperature), indicating good fixing performance.
When the roller is 2.5 mm, the heat of the heater is hard to be transferred to the surface, and the fixing property may be deteriorated as shown by the shaded area in FIG.

Therefore, in order to prevent the deterioration of the fixing property, it is conceivable to raise the temperature adjustment point before passing the sheet by that amount so as to enter the temperature lowest point fixing zone.
The lowermost fixing temperature increases as the thickness of thick paper increases. Therefore, in the image forming apparatus using thick paper of plain paper (64 to 80 g / m ² ) or more, the temperature adjustment point is the maximum thickness of paper that can be passed. It is necessary to set it according to the fixing temperature, and when trying to fix thin paper, the amount of heat applied becomes excessive, which may cause hot offset.

Therefore, it is conceivable to change the temperature adjustment point depending on the type of paper, as in a black-and-white copying machine. In a color copying machine, especially in a double-sided copying machine, as described above, the paper in the sequence is changed. If the temperature control point was changed by controlling the heater after detecting the type of, the response would be slow due to the wall thickness, which may have a large effect on the copy speed. In addition, even if the user specified it or tried to change the temperature by some method before copying, it sometimes took a considerable time before the copy could be made.

Further, as described above, in the roller in which the heat of the heater is hard to be transmitted, the phenomenon that the gloss changes occurs. The gloss (glossiness) is an index indicating the image quality of a copy, and is a term that corresponds to gloss and silk in a photograph, and the gloss value is JIS Z8105-4003, Z.
As defined by 8741 and the like, a large image gives a glossy and glossy image, and a small image gives a matte matte image. Since this gloss is almost proportional to the surface temperature of the fixing roller, as shown in FIG. 14, at the beginning and the end of the sheet passing, when the thickness of the roller has a considerable difference in the surface temperature of the fixing roller, the beginning of copying. At the end, the gross difference was great, which sometimes complained to users.

Furthermore, this gloss influences the impression of the output image, and it depends on the user what kind of gloss is preferred. However, in the conventional apparatus, the gloss is as described above. In some cases, it may be difficult to obtain the gloss according to the user's preference.

Further, such a phenomenon applies not only to the gloss but also to the density, and there are cases where it is difficult to obtain the density desired by the user because the density differs at the beginning and the end of copying.

Therefore, in the present invention, both the fixing roller and the pressure roller are rollers having a three-layer structure in which the surface layer and the lowermost layer are the silicone rubber and the middle is the fluorine rubber having the oil resistant layer to improve the fixing property. Even when the thickness of the rubber layer on the surface of the fixing roller is increased, it is possible to satisfactorily fix recording materials of various thicknesses without causing hot offset and without losing high speed, and at the beginning of copying. It is an object of the present invention to provide an image forming apparatus capable of obtaining an output image in a state according to a user's preference without a large change in gloss at the end.

[0060]

According to the first invention of the present application, the above-mentioned object is achieved by a fixing member having at least a plurality of heat-resistant elastic layers and oil-resistant layers, and a developer in which a plurality of colors are melt-mixed. An image forming unit that forms an image on a recording material,
In the image forming apparatus, the recording material conveying length between the image forming unit and the fixing member is equal to or longer than the maximum recording material length, and the image forming apparatus has a driving unit capable of continuously varying the driving speed of the fixing member, and the state of the output image is appropriately selected. This is achieved by having a selecting means, and the driving means being set to determine the driving speed of the fixing member based on the state selected by the selecting means.

According to the second invention of the present application,
The above object is achieved in the first aspect of the present invention, in which the state of the output image is glossiness or density.

Further, according to the third invention of the present application, in the above-mentioned object, the recording material is nipped before being fed and conveyed to the image forming section in the first invention or the second invention. A detection unit that has at least a pair of recording material pinching rollers that convey the recording material, and a detection unit that detects the amount of radial displacement of at least one roller when the recording material is sandwiched between the pair of recording material pinching rollers. And a comparing means for comparing both the driving speed of the fixing member determined on the basis of the state selected by the above and the appropriate speed determined by the detection content of the detecting means, the driving means being selected by the comparing means. This is achieved by setting that the proper speed is prioritized when it is determined that the speed determined based on the state is different from the proper speed.

According to the fourth invention of the present application,
The above object can be achieved by providing warning means for displaying a warning when the comparison means determines that the speed determined by the selected state is different from the proper speed in the third aspect of the invention.

Further, according to a fifth invention of the present application, in the above-mentioned first invention or the second invention, the recording material is nipped before the recording material is fed and conveyed to the image forming section. A detection unit that has at least a pair of recording material pinching rollers that convey the recording material, and a detection unit that detects the amount of radial displacement of at least one roller when the recording material is sandwiched between the pair of recording material pinching rollers. The comparing means for comparing both the driving speed of the fixing member determined on the basis of the state selected by and the proper speed determined by the detection content of the detection means, and the comparison means for determining the selected state. This is achieved by providing a means for stopping the image forming operation when it is determined that the speed is different from the appropriate speed, and a warning means for displaying a warning together with the stop.

[0065]

According to the first aspect of the present invention, when the user appropriately selects the state of the output image by the selecting means, the driving means determines the driving speed of the fixing member based on the state selected by the selecting means. Then, the fixing is performed at the determined speed. Therefore, the amount of heat corresponding to the selected output image state is applied to the recording material and the image on the recording material without changing the fixing temperature, and the output image state is the one selected by the user.

According to the second invention of the present application,
When the user appropriately selects the glossiness or density of the output image by the selection means, the drive means determines the driving speed of the fixing member based on the glossiness or density selected by the selection means, and the fixing is performed at the determined speed. Done. Therefore, the amount of heat corresponding to the glossiness or density of the selected output image is applied to the recording material and the image on the recording material without changing the fixing temperature, and the glossiness or density of the output image is selected by the user. Becomes

Further, according to the third invention of the present application, similarly to the first invention, the user selects the state of the output image, and the driving speed of the fixing member is determined based on the selection. When the recording material is nipped and conveyed by the recording material nip roller before the recording material is fed and conveyed to the image forming unit, and the recording material is nipped between the recording material nip rollers,
The means for detecting the displacement amount of the roller in the radial direction detects the displacement amount of at least one of the rollers in the radial direction to detect the thickness of the recording material. Then, during the image forming sequence, the appropriate speed determined by the detection content of the recording material thickness and the speed determined based on the selected state are compared by the comparing means, and if this speed is different from the appropriate speed. When the judgment is made, the proper speed is prioritized and the fixing is performed at the proper speed. Therefore, even if the user makes an inappropriate selection, an output image in a proper state is obtained.

According to the fourth invention of the present application,
In the third aspect of the invention, when the speed determined based on the selected state is compared with the proper speed determined by the detection content of the recording material thickness, and it is determined that this speed is different from the proper speed. The warning means gives a warning to prevent a recurrence.

Further, according to the fifth invention of the present application, the state of the output image is selected by the user and the driving speed of the fixing member is determined based on the selection of the state of the output image by the user as in the first invention. When the recording material is nipped and conveyed by the recording material nip roller before the recording material is fed and conveyed to the image forming unit, and the recording material is nipped between the recording material nip rollers,
The means for detecting the displacement amount of the roller in the radial direction detects the displacement amount of at least one of the rollers in the radial direction to detect the thickness of the recording material. Then, during the image forming sequence, the appropriate speed determined by the detection content of the recording material thickness and the speed determined based on the selected state are compared by the comparing means, and if this speed is different from the appropriate speed. When judged, the image forming operation is stopped and the warning is displayed by the warning means. Therefore, even if the user makes an inappropriate selection, the state of the output image is not deteriorated and the recurrence is prevented.

[0070]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) First, a first embodiment of the present invention will be described with reference to FIG. The apparatus of the present embodiment is common to the conventional example shown in FIG. 7 except for the configuration described below, and the common portions are denoted by the same reference numerals and the description thereof will be omitted.

FIG. 1 shows a display of an operation panel of the image forming apparatus according to the first embodiment of the present invention. FIG.
As shown in (A), in this embodiment, the glossiness of the output image is displayed on the display 130 of the operation panel, which is a selection unit, so that the user can select the glossiness of the output image according to his / her preference. Then, when the glossiness is selected on this screen, next, as shown in FIG. 1B, the paper type to be copied is displayed so that the user can select it.

When the user selects the glossiness and the paper type in accordance with such a display, the contents are output to the control means (not shown), and the control means reduces the fixing property of any recording paper. Instead, the fixing speed is determined by referring to a table prepared in advance so that the fixing speed at which the selected glossiness is obtained is uniquely determined. An example of this table is shown in Table 1.

[0074]

[Table 1]

As described above, since the fixing speed is changed according to the gloss, standard, and matte gloss level selected by the user, both the fixing roller and the pressure roller are made of silicone rubber for the surface layer and the bottom layer, Even if the roller is a three-layer structure with an oil resistant layer made of fluororubber, and the surface rubber layer of the fixing roller is thick, the speed of copying of the image forming apparatus is not lost, and it can be adapted to the user's preference. Satisfactory image quality is obtained with excellent glossiness.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, a means for selecting a paper type as shown in FIG. 1B without adding a user's hand is added.

That is, in this embodiment, the user only needs to select FIG. 1A by automatically detecting the paper type. The configuration of the image forming apparatus of this embodiment will be described below.

In this embodiment, as shown in FIG. 2, the present invention is applied to a laser beam printer, and an image is formed by including a developing device and the like around a photosensitive drum which is a latent image carrier. There are provided four image forming stations as forming means, and the image on the photosensitive drum formed by each of the image forming stations moves and passes adjacent to the photosensitive drum. It is configured to be transferred to a recording material such as.

Image forming stations Pa and P for forming images of magenta, cyan, yellow and black, respectively.
b, Pc, and Pd respectively include photosensitive drums 19a and 19a.
b, 19c, 19d are arranged, and each photosensitive drum is rotatable in the arrow direction. Further, around the photosensitive drums 19a, 19b, 19c and 19d, chargers 23a, 23b, 23c and 23d as charging means, developing devices 27a, 27b, 27c and 27d, and cleaners 21a, 21b, 21c and 21d are provided. Are sequentially arranged along the rotation direction of the photosensitive drums, and a transfer belt 31, which is a transfer device, and transfer chargers 13a, 13b, 13c, and 13d are provided below the respective photosensitive drums. A laser beam scanner 24, which is an exposing unit, is arranged above each photosensitive drum.

In the apparatus of this embodiment, the recording paper P, which is a recording material, is housed in the paper cassette 61, and the recording paper P fed from the paper cassette 61.
Passes through the paper thickness detection unit 120 before reaching the registration roller pair 50, and then passes under the four-color station while being attracted to the transfer belt 31, and the image is transferred. Then, the recording paper P is conveyed on the pre-fixing conveyance section 62, is fixed by the fixing device 18 at a predetermined speed, and is ejected to the paper ejection tray 63.

The detailed image forming method in the apparatus of this embodiment is almost the same as the method described in the conventional example, and the fixing device 18 has the same structure as that of the conventional apparatus shown in FIG. Both the pressure roller and the pressure roller are rollers having a three-layer structure in which the surface layer and the lowermost layer are silicone rubber, and the middle is a fluorine rubber having an oil resistant layer, and the surface silicone rubber layer of the fixing roller is a thick device. , Detailed description is omitted.

Next, the paper thickness detection unit in the apparatus of this embodiment will be described with reference to FIG. Conventionally, a mechanical lever method or the like has been known for double feed detection, etc., but in the present invention, more accurate control is possible by using an amplifier output type displacement sensor using a position detection element (PSD) and an LED. Became.

As shown in FIG. 3, the paper thickness detection unit 120
Is an upper roller 121 and a lower roller 1 which are recording material holding rollers.
22 and an amplifier output type displacement sensor 123 which is a means for detecting the displacement amount of the roller. Inside the amplifier output type displacement sensor 123, an LED 1231 and a PSD are provided.
1232 is provided.

When the fed recording paper P is nipped between the upper roller 121 and the lower roller 122 as shown in FIG.
The light from 1231 is reflected by the upper roller 121 and the PSD
It is incident on 1232. At this time, the angles α ₁ and α _{2 of} the light incident on the PSD 1232 and the incident positions l ₁ and l ₂ are uniquely determined by the thickness d of the recording paper P. The thickness d of the recording paper P can be detected by detecting the angle and position of the incident light.

FIG. 4 shows the relationship between the upper roller 121, the lower roller 122 and the sensor 123. The upper roller 121 and the lower roller 122 are a pair of rollers longer than the maximum sheet passing width W. The sensor 123 is arranged at one position at a position where light from the LED 1231 can be emitted, and detects the displacement amount of the upper roller 121 by the above-described method.

At this time, since the roller pair 121, 122 has a role of conveying the recording paper to the image forming portion while detecting the thickness, a through roller in the axial direction (W direction) is usually used. If you try to detect the surface that is in direct contact, recording paper and dust accompanying it,
Foreign matter, paper dust, etc. adhere to the rollers, making it impossible to accurately detect the paper thickness. Therefore, as shown in FIG. 4, a recess is formed in the roller, and the light from the LED is applied to a place that does not directly contact the paper for detection.

Further, although usually metal rollers are used as the upper and lower rollers, since PSD detects diffused light, a method of appropriately roughening or painting the surface instead of a mirror surface is effective.

Next, the control content of this embodiment using the content selected on the display and the content detected as described above will be described with reference to FIG. 5 similarly to the first embodiment.
First, when glossiness is selected and copying is started on the display shown in FIG. 1A (step S10), the paper thickness detection unit 120 detects the paper thickness (step S11). ), The PSD element 1232 of the paper thickness detection unit 120 is an analog element, and this detection signal is A / D converted by the CPU (step S12). At this time, the resolution of the PSD in analog is 2 to 3 μm, so 8 to 8 depending on the difference in the paper thickness to be cut.
A / D conversion may be performed within 16 bits. For example, in the present invention, 64 g / m which is usually used in a plain paper copying machine.
^2, 80g / m ^2, and paper 105 g / m ^2, the fixing of the big difference ^{127g / m 2, 157g / m} 2, 209g /
Since I want to cut at least m ² of paper, I decided to use 10-bits A / D conversion. A / D at 10 bits
When converted, the resolution becomes 10 to 20 μm. The thickness you want to actually cut is 7 to 80 to 105 g / m ² of paper.
0 to 100 μm zone and 127 g / m ^{2 to} 157 g /
130-160 μm zone for m ² paper, 209
200-250 μm zone for g / m ² paper.

Then, based on the reference table of Table 1 described in the first embodiment, the fixing speed is selected according to the detected value and the selected glossiness (step S13), and the fixing motor is driven at the fixing speed. To the motor driver (step S14).

Here, the zone is divided into three, but if it is desired to divide the zone more finely, the A / D conversion is performed with 10 bits.
As described above, the resolution can be increased.

What is important here is that in applying the present invention, the recording material conveying section 62 between the image forming section and the fixing section as shown in FIG. 2 must be longer than the maximum sheet passing length. Is. Normally, the image forming unit, the transport unit, and the fixing unit are driven at the same speed, and the image forming unit has a constant speed even when the other drives are fast or slow, which is a necessary condition for obtaining a good image. Has become.

When the present invention is applied, if the length of the conveyance section is shorter than that of the sheet, when the sheet is gripped by the fixing section, the trailing edge of the sheet, which is still undergoing image formation, is pulled or stopped. However, the toner image on the paper is disturbed, which causes inconvenience. Therefore, the transport length is L, which is the maximum paper length.
The length is longer than DR (432 mm), and the recording material is conveyed on the recording medium in a free state to try to absorb the speed difference between the fixing unit and the image forming unit.

As described above, according to this embodiment, the user only needs to select the glossiness shown in FIG.
It is possible to obtain the image quality according to the taste.

(Third Embodiment) Next, a third embodiment of the present invention will be described. In this embodiment, even if the paper set by the user does not match the selected paper type, proper control is performed to obtain appropriate fixability and glossiness.

In this embodiment, as in the first embodiment, the paper thickness detecting unit of the second embodiment is provided in the device for selecting the paper type on the display.

As shown in Table 2, for example, if the user has 170
If you select the plain paper mode even though you have set ultra-thick paper of μm or more, you can use this plain paper mode (1
Standard fixing speed of less than 20 μm) is 150 mm / s
Since it is ec, a shortage of heat occurs.

[0097]

[Table 2]

As a result, cold offset occurs, and the image quality is remarkably deteriorated. If this continues, the releasability of the fixing roller will be reduced, and the machine body will be damaged.

Therefore, in the present invention, if the user sets thick paper and selects plain paper, the amount of heat in the matte mode and the like is minimized (170 mm / sec in Table 1).
When the mode is selected, the thickness of the paper fed by the method shown in the second embodiment is read, and the fixing speed is set within an appropriate range (60 to 100 mm / sec in the case of super paper thickness). As shown in FIG. 6 (A), the display 1 is used to select the mode in which the copied paper is passed when it is selected and output.
A warning message is displayed as shown in FIG. 30 and a warning message is displayed as shown in FIG. 6B so that the machine body can be protected from excessive use. As a result, better and more reliable image quality can be obtained.

Further, in the above embodiment, when it is determined that the speed is different from the proper speed, the operation of the apparatus may be stopped and a warning may be displayed.

In each of the above-described embodiments, the case of selecting the glossiness has been described, but the density of the output image may be selected by the same method. This is because the density of the output image, like the glossiness, changes depending on the amount of heat applied.

[0102]

According to the first invention of the present application, the driving speed of the fixing member is determined based on the state of the output image selected by the user, and the fixing is performed at the determined speed. It is possible to obtain an output image in a state desired by the user without depending on the response of the temperature change.

According to the second invention of the present application,
The driving speed of the fixing member is determined based on the glossiness or density of the output image selected by the user, and fixing is performed at the determined speed, so that the glossiness desired by the user does not depend on the responsiveness of the temperature change of the fixing member. An output image of degree or density can be obtained.

According to the third invention of the present application,
The driving speed of the fixing member determined based on the state of the output image selected by the user is compared with the appropriate speed determined based on the thickness of the recording material.If these are different, the appropriate speed is prioritized. Since the image is fixed by fixing, an output image in a good state can be obtained even when the user makes an inappropriate selection.

Further, according to the fourth invention of the present application, the driving speed of the fixing member determined based on the state of the output image selected by the user and the proper speed determined based on the thickness of the recording material are set. If these are different, the appropriate speed is prioritized, and the warning means gives a warning, so even if the user makes an inappropriate selection, the deterioration of the output image state is prevented, Recurrence can be prevented.

Further, according to the fifth invention of the present application, the driving speed of the fixing member determined based on the state of the output image selected by the user, and the appropriate speed determined based on the thickness of the recording material are set. If they are different, the image forming operation is stopped and a warning is displayed.Therefore, even if the user makes an improper selection, the deterioration of the output image state is prevented and a reoccurrence occurs. Can be prevented.

[Brief description of drawings]

FIG. 1 is a diagram showing a display according to a first embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of the image forming apparatus according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram of a paper thickness detection unit according to the first embodiment of the present invention.

FIG. 4 is a perspective view showing a positional relationship between a recording material pinching roller and a paper thickness detection unit in the first embodiment of the present invention.

FIG. 5 is a flow chart of fixing speed control in the first embodiment of the present invention.

FIG. 6 is a diagram showing a display according to a second embodiment of the present invention.

FIG. 7 is a vertical sectional view of a conventional image forming apparatus.

FIG. 8 is a diagram showing a configuration of a conventional document reading system.

FIG. 9 is a diagram showing a configuration of a CCD in a conventional document reading system.

FIG. 10 is a block diagram of an image processing circuit in a conventional document reading system.

FIG. 11 is a softening characteristic graph of a sharp melt toner.

FIG. 12 is a sectional view of a conventional fixing device.

FIG. 13 is a diagram illustrating a recording material discharge direction in a conventional example in which a soft roller is used as a fixing roller and a hard roller is used as a pressure roller.

FIG. 14 is a graph showing the relationship between the temperature of the fixing roller and the number of passed sheets in the conventional fixing device.

[Explanation of symbols]

29 fixing roller (fixing member) 30 pressure roller (fixing member) 121 upper roller (recording material holding roller) 122 lower roller (recording material holding roller) 123 amplifier output type displacement sensor (means for detecting the amount of roller displacement) 1231 LED (light emitting element) 1232 PSD sensor (position detecting element) 130 Display (selecting means) P Recording paper (recording material) t Developer

Claims (5)

[Claims] 1. A fixing member comprising at least a plurality of heat resistant elastic layers and a plurality of oil resistant layers, an image forming section for forming an image on a recording material by a developer in which a plurality of colors are melt-mixed, the image forming section and the fixing. An image forming apparatus having a driving means capable of continuously varying the driving speed of the fixing member, the recording material conveying length with the member being equal to or longer than the maximum recording material length, and having a selecting means for appropriately selecting a state of an output image, The image forming apparatus, wherein the driving unit is set so as to determine the driving speed of the fixing member based on the state selected by the selecting unit. 2. The image forming apparatus according to claim 1, wherein the state of the output image is glossiness or density. 3. At least a pair of recording material nipping rollers for nipping and conveying the recording material before the recording material is fed and conveyed to the image forming section, and when the recording material is interposed between the pair of recording material nipping rollers. In addition, the detection means for detecting the displacement amount of at least one roller in the radial direction, the drive speed of the fixing member determined based on the state selected by the selection means, and the appropriateness determined by the detection content of the detection means. The driving means is set to give priority to the appropriate speed when it determines that the speed determined based on the state selected by the comparing means is different from the appropriate speed. The image forming apparatus according to claim 1, wherein the image forming apparatus according to claim 1. 4. The image forming apparatus according to claim 3, further comprising warning means for displaying a warning when the comparing means determines that the speed determined by the selected state is different from the proper speed. 5. When at least a pair of recording material nipping rollers are provided for nipping and conveying the recording material before the recording material is fed and conveyed to the image forming section, when the recording material is interposed between the pair of recording material nipping rollers. In addition, the detection means for detecting the displacement amount of at least one roller in the radial direction, the drive speed of the fixing member determined based on the state selected by the selection means, and the appropriateness determined by the detection content of the detection means. Comparing means for comparing both speeds, means for stopping the image forming operation when the comparing means determines that the speed determined by the selected state is different from the proper speed, and a warning for displaying a warning together with the stop The image forming apparatus according to claim 1, further comprising: