JP2015072318A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus configured to provide a high-quality image in any environment.SOLUTION: An image forming apparatus includes: an image carrying section which carries a developer image according to image information; a transfer member which comes into contact with the image carrying section so as to transfer the developer image carried on the image carrying section to a recording material; transfer bias application means which applies a transfer bias to the transfer member to electrostatically transfer the developer image to the recording material; application transfer voltage determination control which controls the transfer voltage application means in constant current control so as to achieve a constant current value which is set in advance in the transfer member at a timing in a non-image area, and determines a transfer voltage to be applied to the image area of the recording material on the basis of an application voltage value corresponding to the constant current at that time; and environment detection means which detects atmospheric environment. The application voltage value corresponding to the constant current value is detected in the application transfer voltage determination control, and the environment is detected by the environment detection means, thereby determining an application transfer bias according to the above detection results.

Description

  The present invention relates to an image forming apparatus and an image forming method of an electrophotographic system or an electrostatic recording system such as a copying machine or an LBP (laser beam printer).

  In an image forming apparatus (image recording apparatus) using an image forming process such as an electrophotographic system or an electrostatic recording system, an electrostatic latent image is formed on a photosensitive drum or the like as an image carrier, and the latent image is developed by a developer. The toner image is visualized as a toner image, and the toner image is transferred onto a recording material such as paper. Thereafter, the recording material onto which the toner image has been transferred is transferred to a fixing roller and a pressure roller provided in the fixing device. The toner image is heated and fixed as a permanent image on the recording material.

FIG. 18 is a schematic side view of a main part showing a typical example of such an image forming apparatus. The surface of a photoconductor 1001 (hereinafter referred to as a photoconductive drum) that extends in the direction perpendicular to the paper surface and rotates in the direction of the arrow is uniformly charged by a charging roller 1002 connected to a high-voltage power source and charged by a laser scanner 1003. A laser beam L modulated by an image signal is applied to the surface to form an electrostatic latent image. This latent image from the developing device 1004 toner arrives at the transfer nip N _t becomes supplied toner image.

Transfer nip N _t consists nip between the conductive transfer roller 1005 in contact thereto with the photosensitive drum 1001, in conjunction with the timing at which the toner image portion on the photosensitive drum 1001 arrives at the transfer nip N _t, the recording The material P is supplied and passes through the nip portion. At this time, a transfer bias is applied to the transfer roller 1005 by the high voltage power source 1006, and the toner image on the photosensitive drum 1001 side is transferred to the recording material P. Thereafter, the recording material P carrying the toner image leaves the transfer nip portion _NT and is conveyed to the fixing device 1009.

  In the transfer roller, the resistance value is adjusted to a value of about 1 × 10 6 to 1 × 10 10 (Ω), an elastic layer is provided on the outer peripheral surface of the conductive metal core, and the elastic layer has conductivity. These have been proposed in recent years.

  In general, it is known that the resistance value of the transfer roller is likely to vary according to the temperature and humidity of the atmospheric environment. When the resistance value of the transfer roller fluctuates, the transfer drum is generated due to the low electrical holding power of the toner on the paper, and the photosensitive drum is charged to the same polarity as the transfer because the transfer voltage is too strong. As a result, there is a concern that a phenomenon called “strengthening” occurs in which the toner is retransferred to the drum. Therefore, in order to prevent the occurrence of transfer bulge and strong omission caused by fluctuations in the resistance value of the transfer roller, the resistance value of the transfer roller is measured, and the transfer voltage applied to the transfer roller is appropriately set according to the measurement result. “Applied transfer voltage control” is used. As such an applied transfer voltage control means, there is an ATVC control (Active Transfer Voltage Control) disclosed in JP-A-2-123385.

  In the ATVC control, the voltage applied to the transfer roller when the toner image is transferred to the recording material is optimized, and control is performed so as to prevent the occurrence of a strong drop and a transfer lever. In ATVC control, a desired constant current is applied from the transfer roller to the photosensitive drum during the pre-multi-rotation process of the image forming apparatus, and the resistance value of the transfer roller is measured by holding the voltage value at that time, and a toner image is recorded. By transferring a transfer current corresponding to the resistance value to the transfer roller when transferring to the material, it is possible to transfer the toner to the recording material satisfactorily.

Next, the fixing device 1009 will be described with reference to FIG. In recent years, there has been proposed a film heating type fixing device using a fixing method that does not supply power during standby and suppresses power consumption as much as possible (see, for example, Patent Documents 1 to 4). 19, the fixing device 1009 has a heater (heating body) 1022 as a fixing body, a heat-resistant film (fixing film) 1023 that slides on the heater, and a heater holder 1021 that supports the heater 1022 and guides the fixing film 1023. and, have a this film 1023 pressing member made of an elastic body 1026 and the core 1025 to form the fixing nip portion N _F pressed against the heater 1022 via (pressure roller) 1024 as pressurizer and the heat from the fixing nip portion N _F of the film 1023 and the pressure member heater 1022 is awarded an unfixed image to a recording material having an unfixed image is formed is nipped and conveyed through the film 1023 between the 1024 the pressure of the fixation nip N _F is a device for fixing a toner T as a permanent image on the recording material. Such a film heating type fixing device can use a low heat capacity linear heating element as a heater and a thin film with a low heat capacity as a heater, so that it can save power and shorten the wait time (quick start). is there.

  Further, in this type of film fixing and heating type fixing device, a fixing film is driven by a pressure roller as a pressure member while applying tension using a dedicated roller and a driven roller for conveying the film. There are a system for conveying the fixing film between them and a tensionless system in which the cylindrical fixing film is driven by the conveying force of the pressure roller by rotationally driving a pressure roller as a pressure member. The former has the advantage that the transportability of the fixing film can be increased, and the latter has the advantage that the apparatus configuration can be simplified and a low-cost apparatus can be realized.

JP-A-63-313182 (page 5 Fig. 2) Japanese Patent Laid-Open No. 2-157878 (page 10 Fig. 1) JP-A-4-44075 (page 15 Fig. 1) JP-A-4-204980 (page 11 Fig. 1)

  Incidentally, in recent years, image forming apparatuses have been used in various parts of the world, and there is a demand for image quality that does not change even when used in various environments. Therefore, it is necessary to detect the environment, perform control suitable for the environment, and maintain the same image quality in any environment. In order to maintain image quality, it is necessary to maintain the same level of developer transfer to the recording material regardless of the environment.

  However, although the current ATVC control has high accuracy in detecting the resistance value of the transfer member, it includes elements of both the resistance value variation of the transfer member and the environmental variation of the resistance value. In the case of “humid environment (hereinafter referred to as H / H environment) / high resistance transfer roller” and “room temperature and normal humidity environment (hereinafter referred to as N / N environment) / low resistance transfer roller”, the same resistance value may be detected. Yes, the same transfer bias may be applied even in different environments. For paper that is left in an H / H environment and paper that is left in an N / N environment, the moisture content changes and the resistance value of the paper is not the same. Therefore, problems such as “transfer edge” and “strong omission” occur.

  Therefore, an object of the present invention is to detect the use environment of the image forming apparatus main body in any environment, and in particular, by performing transfer control according to the recording material left in the use environment, a high-quality image can be obtained. An image forming apparatus is provided.

The invention according to the present invention for achieving the above object is as follows:
An image carrier that carries a developer image according to image information;
A transfer member in contact with the image carrier to transfer the developer image carried on the image carrier to a recording material;
A transfer bias applying means for applying a transfer bias for electrostatically transferring the developer image to the recording material on the transfer member;
In the timing in the non-image area, the transfer voltage applying means is controlled to be a constant current control so that the transfer member has a constant current value set in advance, and an applied voltage value corresponding to the constant current at this time is set. An applied transfer voltage determination control for determining an applied transfer voltage to the image area of the recording material,
An environmental detection means for detecting the atmospheric environment;
In an image forming apparatus having
An applied voltage value corresponding to a constant current value in the applied transfer voltage determination control;
By detecting the environment by the environment detection means,
An image forming apparatus is characterized in that an applied transfer bias is determined according to a detection result of both.

  As described above, after detecting the applied voltage value corresponding to the constant current value by ATVC control, by detecting the atmospheric environment by the environment detection means, the environment detection that produced an error only by ATVC control can be accurately performed without error. Therefore, transfer control according to the actual use environment can be performed, and a good image can be provided regardless of the environment in which the image forming apparatus exists.

Schematic configuration diagram of an image forming apparatus according to an embodiment of the invention Diagram showing transfer roller resistance measurement method Diagram showing V-I characteristics of transfer roller R2 Diagram showing V-I characteristics of transfer rollers R2, R1, and R3 Relationship between temperature and resistance value of transfer roller R2 Diagram of V-I characteristics of transfer roller R2 at H / H and L / L 1 is an equivalent circuit diagram showing an electrical path of a fixing device, a recording material P, a transfer roller, and a transfer power source according to an embodiment of the invention. FIG. 1 is a schematic cross-sectional view of a fixing device of an image forming apparatus according to an embodiment of the invention. Schematic longitudinal view of a fixing device of an image forming apparatus according to an embodiment of the invention The figure showing the rise temperature change of the heating body thermistor concerning Example 2 of embodiment of invention The figure showing the relationship between V0 and the applied transfer current according to the embodiment of the invention The figure showing the relationship between V0 and the applied transfer constant current concerning Example 1 of embodiment of invention The figure showing the relationship between V0 and the applied transfer constant current concerning Example 1 of embodiment of invention The figure showing the result of the comparative example 1 of embodiment of invention The figure which expressed the result when outputting an image in 3 environments of Example 1 of an invention The rise of the thermistor detection temperature of the embodiment of the invention The rise of the thermistor detection temperature of the embodiment of the invention The figure showing the result of Example 2 of the invention Schematic configuration diagram of an image forming apparatus Schematic configuration diagram of fixing device

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As described above, in the conventional image forming apparatus, the resistance value of the transfer roller is detected by the ATVC control of the transfer, and the applied transfer current is determined according to the resistance value of the transfer roller. As a result, there was an error in the applied transfer current, so that proper transfer control suited to the surrounding environment could not be performed.

  A feature of the present invention is that, after performing the transfer ATVC control, the environment detection unit detects the surrounding environment, and performs transfer control suitable for the resistance of the transfer roller and the environment without error.

<Image forming apparatus body configuration>
FIG. 1 shows a main part of a laser beam printer as an image forming apparatus according to an embodiment of the present invention. In the image forming apparatus 1000 of FIG. 1, 101 is an organic photosensitive drum as an image carrier, 102 is a charging roller as a charging member, 103 is a laser exposure device, 104 is a developing sleeve and a developing blade, and a development composed of a one-component magnetic toner or the like. 105, a cleaning blade, 106 a transfer roller, and 107 a fixing device. The organic photosensitive drum 101 is uniformly charged to a negative charge by the charging roller 102, and an electrostatic latent image is formed on the organic photosensitive drum 101 by the laser beam from the laser exposure device 103. Next, the toner T charged in the developing device 104 adheres to the electrostatic latent image on the organic photosensitive drum 101 to become a visible image, is transferred onto the transfer material P on the transfer roller 106, and is fixed by the fixing device 107. The The cleaning blade 105 removes the toner remaining on the organic photosensitive drum 101. An image is formed by the function of each unit described above.

<Transfer configuration>
The transfer roller 106 as a contact transfer member contacts the surface of the photosensitive drum 101 with a predetermined pressing force, and is transferred to a transfer nip portion Ntr between the photosensitive drum 101 and the transfer roller 106 by a transfer voltage applied from the transfer high-voltage power supply 11. A bias is applied to transfer the toner image on the surface of the photosensitive drum 101 to the recording material P.

  In this embodiment, when the developer is transferred to the recording material P, constant current control is performed as a control method. There is constant voltage control as a transfer bias, but in the case of constant voltage control, the voltage is set according to a certain recording material P. Depending on the current, the current may flow too much and the strength may become severe. Therefore, constant current control is employed in this embodiment. The occurrence of strong omission changes depending on the type of developer and the configuration of the image forming apparatus, so that the level of occurrence of strong omission changes. Therefore, an image forming apparatus that has a margin to this phenomenon may naturally perform constant voltage control.

  The transfer roller 106 used in the present embodiment is configured by forming an elastic layer made of a conductive rubber material on the surface of the core metal, and the resistance value of the transfer roller 106 is 10 ^ 6 to 10 ^ 10Ω. The resistance is adjusted.

  As shown in FIG. 2, the transfer roller resistance is measured by applying a voltage of 2 kV while rotating the transfer roller against an aluminum drum connected in series with a 1 KΩ resistor in a 20 ° C./50% RH environment. Since R is sufficiently larger than 1, the resistance value R can be obtained by the following equation (A).

R = 2 / V-1 ≒ 2 / V (A)
In the present embodiment, the range of 1 × 10 ^ 8 to 6 × 10 ^ 8 is set by the above measuring method. In this embodiment, the transfer roller has an outer diameter of 14 mm, a core diameter of 6 mm, a rubber thickness t = 4 mm, and an NBR rubber having ionic conductivity as the rubber material.

<Transcription ATVC control>
The resistance value of the transfer roller 106 varies depending on whether it is a single unit or the environment, and the voltage at which the above-described strong omission or transfer lever is generated changes each time. It becomes possible to make full use by applying.

  The ATVC control applies a constant current value to the transfer roller 106 during non-sheet feeding, and the resistance value of the transfer roller can be determined by detecting the voltage at that time, and the applied transfer current to the recording material P corresponding to the resistance is determined. It is a decision.

  FIG. 3 is a conceptual diagram showing the relationship between the voltage applied to the transfer roller and the current (V-I). FIG. 3 shows the measurement with an R2 transfer roller at 20 ° C./50% R.H (hereinafter referred to as N / N environment). When the same current value I0 is applied to the transfer roller having the resistance value r2 of the transfer roller R2, the voltage value is V0 (2) as shown in FIG.

  V0 has the same meaning as the resistance value of the transfer roller because the voltage and current are known. That is, the resistance value of the transfer roller is known. When V0, which has the same meaning as the resistance value of the transfer roller, is known, transfer control is performed by applying an appropriate transfer current It that matches this V0. This determined one correct It for one V0 value.

  On the other hand, the resistance value of the transfer roller naturally has a variation due to the difference in the composition of the components at the time of manufacture or rubber. FIG. 4 is a diagram showing V-I in the N / N environment due to differences in resistance values r1, r2, and r3 of the transfer rollers R1, R2, and R3. The relationship between the resistance values is r1 <r2 <r3. At R3 having a higher resistance value, V0 (3) also increases, and at R1 having a lower resistance value, V0 (1) also decreases.

  Next, FIG. 5 shows a conceptual diagram of how the resistance value of the transfer roller changes depending on the environment. FIG. 5 shows a change in the resistance value of the transfer roller R2 when the temperature is changed at the same humidity. From this figure, the resistance value tends to decrease as the temperature increases and increase as the temperature decreases. That is, the resistance value of the transfer roller changes with temperature. Since the transfer roller of the present embodiment is ion and has a large temperature dependency, the temperature is explained. However, the influence of humidity becomes large for electrons.

  Furthermore, the relationship between the voltage and current applied to the transfer roller in a 10 ° C 10% environment (hereinafter referred to as L / L environment) and 30 ° C and 90% environment (hereinafter referred to as H / H environment) (VI) ) Is represented by the conceptual diagram of FIG. As a comparison, the relationship of V-I at N / N of the transfer roller of R2 is also shown. V0 (2H), V0 (2), and V0 (2L) have a relationship of V0 (2H) <V0 (2) <V0 (2L). From FIG. 6, if R2 is in the H / H environment, V0 (2) is detected in the direction as small as V0 (2H), that is, the resistance value is small and shifts in the H / H arrow direction. V0 (2) is detected in a direction larger than V0 (2L), that is, in a direction in which the resistance value is large, and shifts in the L / L arrow direction. This indicates that the resistance value of the transfer roller also changes when the environment changes as described above. For example, when R2 overlaps R3, the same value is detected as V0. Therefore, the same V0 is detected in the N / N environment of R3 and the H / H environment of R2, and the same transfer current is applied in different environments.

  The current It is determined based on a transfer roller having a resistance value determined by N / N. For this reason, if R3 and R1 are the upper and lower limits of the resistance value considering the manufacturing variation, it changes depending on the resistance value of the transfer roller. Or, the same It may be applied in different environments.

  By the way, the recording material P to which the developer is transferred is, for example, a paper left in H / H, N / N, L / L, naturally the humidity of the environment is different, so the water absorption varies depending on the environment, and the absolute moisture in the atmosphere environment The larger the amount of paper, the smaller the resistance value. Therefore, when H / H with a high absolute moisture content and N / N with a lower absolute moisture content than H / H and an appropriate It are applied to N / N, the paper resistance at H / H is smaller than N / N. There is a possibility that a transfer lever will be generated due to a shortage of transfer current. In addition, when L / L and N / N with low absolute moisture content and proper It are applied to N / N, the paper resistance at L / L is greater than N / N, and the transfer current becomes excessive, causing strong loss. May occur.

  The resistance of the recording material P is easily affected by humidity, and this phenomenon occurs because the transfer performance varies depending on the magnitude of the applied transfer current.

  On the other hand, the resistance of the transfer roller, R1, R2, and R3 described above, will be described. Since r1 <r2 <r3, r3 having a large resistance is not easily affected by H / H, and r1 is easily affected. There is a difference in how L / L is affected. Therefore, the optimum current value differs between the three transfer rollers.

  Therefore, the present invention obtains the transfer roller resistance value under the same environment of r1, r2, and r3, and performs optimum transfer control in consideration of the environment.

  In the ATVC control method of this embodiment, when application of transfer current is controlled, as shown in FIG. 7, during non-image formation (time from exposure device 103 to image exposure on photosensitive drum 101 and writing of image information) In addition, a voltage is applied to the transfer roller 106 by a transfer output value (digital value 0 to 255) output from the control device (CPU) 10 to the transfer high-voltage power supply 11 via the D / A converter 12 in the paper interval. The The current flowing at this time is detected by the current detection means 14, the detected current value is fed back to the control device 10 via the A / D converter 13, and the current value flowing through the transfer roller 106 is determined to determine a constant current value I0 ( Constant current control is performed at 2 to 4 μA). In this embodiment, I0 = 3 μA.

  Then, the resistance value of the transfer roller 106 is substantially detected by detecting the voltage V0 generated in the transfer roller 106 during the constant current control, and the recording material P is then detected according to the resistance value and data of the atmospheric environment described later. An applied transfer current It, which is constant current control in the paper when the developer is transferred, is applied in an appropriate range based on this voltage V0.

<Fixer configuration>
FIG. 8 is a schematic cross-sectional view of a tension fixing film heating type heat fixing apparatus of the present embodiment. Reference numeral 301 denotes a resin heater holder that serves as an inner surface guide member of the fixing film 302 described later.

  302 is an endless heat-resistant film, and a stay 301 including a heating body 303 is circumscribed. A thermistor 304 detects the temperature of the heater 303. The inner peripheral length of the endless heat resistant film 302 and the outer peripheral length of the stay 301 including the heating body 303 are about 3 mm larger than that of the stay 302 including the heating body 303. The circumference is circumscribing loosely.

  FIG. 9 is a schematic longitudinal view of the fixing device. The fixing flanges 201 and 204 support the inner peripheral surface of the end portion of the fixing film 2 with support portions 202 and 205, and restrict movement in the longitudinal direction with end portion restricting members 203 and 206.

  Grease is present on the inner peripheral surface side of the fixing film 302 in order to improve slidability. In the present embodiment, 500 mg of grease is uniformly applied on the heating resistor. 303 is a heater as a heating element. The heater 303 is formed by applying an electric resistance material such as Ag / Pd (silver palladium) as a heating element to a thickness of about 10 μm and a width of 1 to 3 mm by screen printing or the like along a substantially central portion of a substrate made of alumina or the like. Then, the sliding surface with the fixing film 302 is coated with insulating glass, fluorine resin or the like as a protective layer. In this example, a glass coat layer having a thickness of about 50 μm was provided. A heating body thermistor 304 is provided on the opposite surface of the heating body to the fixing film, and the temperature of the heating body 303 is controlled by the temperature detected by the thermistor.

  The pressure roller 306 is formed by coating a silicone foam having a length of 240 mm and a thickness of 3 mm as a heat-resistant elastic layer on an aluminum core having an outer diameter of 13 mm connected to a driving device. A fixing nip portion is formed with the film sandwiched between and a rotating body that drives the film, and is connected to the driving device by a core metal such as iron, stainless steel, or aluminum. The pressure roller 306 is rotated by transmitting a driving force from a driving motor of a driving device.

  The recording material P as a heated body is conveyed and passed through a fixing nip portion N formed by sandwiching a film between the pressure roller 306 and the heater 303, whereby the toner image T is heated and pressed to record the recording material P. It is supposed to be fixed on the top.

  The film 302 has a total thickness of about 100 μm or less in order to reduce the heat capacity and improve the quick start property, and has PTFE, PFA, FEP having heat resistance, releasability, strength, durability, etc. Single layer of polyimide, polyamide imide, PEEK, PES, PPS base layer, outer layer surface of the base layer, primer layer as an adhesive layer, release layer mainly composed of PTFE, PFA on the outer surface. It is formed from a mold layer. In order to increase the thermal conductivity of the film 302 itself, a filler such as boron nitride, aluminum nitride, or carbon fiber is blended. A heat conductive filler can be mix | blended with any layer or all the layers of a base layer, a primer layer, or a top layer. The film according to the embodiment of the present invention has an outer diameter of 18 mm, polyimide is used for the base layer, the thickness is 60 μm, and carbon-based fibers are dispersed in the filler in consideration of improvement in thermal conductivity. The primer layer has a three-layer structure of 6 μm made of fluororesin and carbon, the top layer is 15 μm made of PFA and PTFE, and the total film thickness is 81 μm.

<Transfer Control of Embodiment of the Present Invention>
Next, characteristic transfer control in the present embodiment will be described. In the transfer control according to the present embodiment, after the transfer ATVC control is performed and the resistance value of the transfer roller is measured, in order to obtain information on the surrounding environment that cannot be understood only by the transfer ATVC control, the environment detection unit detects the surrounding environment, and the transfer control is performed. It is to be back-backed to the control.

  Here, since the transfer ATVC control is as described above, the description thereof is omitted. After the transfer ATVC control is completed, the environment sensor detects the surrounding environment to determine the transfer voltage applied to the recording material.

<Example 1>
Using the transfer control, image comparison was performed at different environments and transfer rollers. As Comparative Example 1, it is assumed that the image forming apparatus is not changed, and the feedback control is performed only by the same ATVC control as before.

(Consideration conditions)
● Image forming device body:
HP Laserjet P1006 with process speed 160mm / s and changed to 25ppm ● Environment:
L / L (low temperature and low humidity) environment 10 ℃ / 10% RH (absolute water content 0.941g / m ^ 3)
N / N (room temperature and humidity) environment 20 ℃ / 50% RH (absolute water content 8.655g / m ^ 3)
H / H (high temperature and high humidity) environment 30 ° C / 90% RH (Absolute water content 24.304g / m ^ 3)
CS680 manufactured by Canon Marketing Japan
Use paper that has been left in the environment for 3 days in each environment and open paper that is opened just before the examination.
Continuous passage of up to 100 photographs and text images alternately ● Transfer roller resistance standard:
1 × 10 ^ 8 ～ 6 × 10 ^ 8Ω in N / N environment
● Roller resistance value:
When the resistance value is measured in N / N environment, 1 × 10 ^ 8Ω resistance value lower limit product, 3 × 10 ^ 8Ω resistance value center product, 6 × 10 ^ 8Ω resistance value upper limit product, resistance 3 level transfer roller Confirm with.

● Ambient environment detection method of Example 1:
The environment is detected by the environment detection sensor. A device capable of measuring temperature and humidity is installed.

  The environment detection sensor is installed inside the front exterior of the image forming apparatus main body.

● Relationship between V0 determined by ATVC control of Comparative Example 1 and applied transfer current:
As shown in FIG. I0 = 3 μA and the relationship between V0 and the applied transfer voltage at that time. The control is determined using a transfer roller having a central resistance value of N / N. FIG. 11 shows the V0 detection result in three environments of the transfer roller having a resistance value of three levels.

● Relationship between V0 determined by ATVC control and environment detection in Example 1 and applied transfer voltage:
FIG. 12 shows the relationship between the absolute water content at the middle and lower limits and the optimum transfer current value Itr on the transfer roller resistance value.

  This is a product with a central resistance value. The optimum transfer constant current value is obtained according to the absolute water content of the environment and the moisture content obtained by the environment detection sensor, and the optimum constant current value is corrected according to the resistance value of the transfer roller. It is a thing.

  In this embodiment, the optimum current value is determined for each of the three levels of resistance values. FIG. 13 is a graph showing the relationship between the absolute moisture content of the environment and the optimum current value. The V0 detection result in the three environments of the transfer roller having the resistance value of 3 level is the same as that of the comparative example 1, and is as shown in FIG.

(Study results)
FIG. 14 shows the results when images are output in the three environments of Comparative Example 1 and FIG. First, Comparative Example 1 in FIG. 14 will be described. With respect to the resistance value center transfer roller of Comparative Example 1, images were output without any problem in all three environments. However, the upper limit transfer roller generates a left side paper in the N / N environment, the rectified paper in the L / L environment, and the left side paper. The lower limit transfer roller generates an open sheet in the L / L environment. Strong breakthrough occurred in paper and N / N open paper.

  First, the transfer lever generated in the resistance value upper limit transfer roller will be described. The transfer lever is a phenomenon in which, when the transfer bias is low, a portion where the toner cannot be peeled off from the photosensitive drum is generated, resulting in image unevenness in a solid image.

  From FIG. 11, in the H / H environment, V0 detected by ATVC is detected as 600 V, and the applied transfer current It is 4.69 μA obtained from the It formula. Since this current value is weak in the H / H environment, the transfer voltage is lowered particularly in the case of paper having a high resistance value and a low resistance value such as paper left in the H / H environment, and a transfer lever having a low level is generated. In addition, although the transfer voltage is larger than that of the left-sided paper, a slight transfer margin is generated even with the open paper. In the H / H environment, if the transfer current is not 4.91μA <It, the transfer current will be too weak and the transfer will be generated. However, the resistance value upper limit transfer roller detects V0 as 600V with ATVC. The transfer current applied in the N / N environment is applied in the H / H environment.

  In the N / N environment, V0 detected by ATVC is detected as 1200 V, and the applied transfer current It is 3.38 μA obtained from the It formula. In the N / N environment, it has been experimentally confirmed that the transfer current is appropriate and it is not generated when it is 4.0 μA, not limited to left paper and open paper. In case of It = 3.38μA In case of open paper, since the moisture is not absorbed, the resistance value is high and the applied transfer voltage becomes larger than the appropriate value in the N / N environment, and there is no transfer margin. Since the moisture content of the paper is higher than that of the open paper and the resistance value is low, the transfer voltage is slightly lowered and a slight transfer lever is generated.

  Next, the strong omission occurring in the resistance value lower limit transfer roller will be described. From FIG. 11, in the L / L environment, V0 detected by ATVC is detected as 1000 V, and the applied transfer current It is 3.82 μA obtained from the It formula. Since this current value is too strong in the L / L environment, especially in the case of a paper having a low resistance value such as L / L environment leaving paper, the transfer voltage is too high, and a strong loss of low level occurs. In addition, although the transfer voltage is smaller than that of the left-sided paper, a slight strong omission occurs. In the L / L environment, if it ≤ 2.29μA, the transfer current will be too strong and a strong drop will occur. However, the resistance lower limit transfer roller detects V0 as 1000V with ATVC, and as a result it is originally The transfer current applied in the N / N environment is applied in the L / L environment.

  In the N / N environment, V0 detected by ATVC is detected as 400 V, and the applied transfer current It is 5.13 μA obtained from the It formula. In the N / N environment, it is experimentally confirmed that the transfer current is appropriate and it does not cause a strong omission when it is 4.0 μA, not limited to left paper and open paper. When It = 5.13μA In the case of untreated paper, since moisture is absorbed in the N / N environment, the resistance value is low, and even if the applied transfer voltage is larger than the appropriate value in the N / N environment, there is no occurrence of strong omission. In the case of the open paper, the moisture content of the paper is less than that of the left paper and the resistance value is high, so that the transfer voltage becomes high and a slight strong drop occurs. In the N / N environment, if it is not originally It = 4.0μA, strong loss will occur. However, the resistance lower limit transfer roller detects V0 as 400V with ATVC, and as a result it is applied in the H / H environment. The transfer current to be applied is applied in an N / N environment.

  In other words, the resistance value of the transfer roller cannot be specified well only from the value of V0, so when the transfer roller with the upper and lower resistance values is inserted, it does not match the transfer current control determined by the center resistance value of N / N. An image defect occurs.

  Next, Example 1 in FIG. 15 will be described. In Example 1, in any of the three environments and the three-level transfer rollers, no image problem occurred and a high-quality image was obtained.

  By detecting V0 with ATVC, predicting the environment to some extent with the transfer roller, and then detecting the environment with the environment sensor in detail, the variation in resistance value of the transfer roller that could not be detected with ATVC, and even paper Since the error caused by the variation in resistance value can be corrected and the transfer control suited to the surrounding environment can be performed, image defects such as strong dropout and transfer edge that occurred in Comparative Example 1 did not occur. is there.

  In Comparative Example 1, the transfer margin generated in the H / H environment leaving paper, open paper, and N / N environment leaving paper in the upper resistance value product did not occur in Example 1 in the case of the upper resistance value product in ATVC. In the H / H environment, the N / N environment was erroneously detected due to the high resistance value, and the transfer current originally applied at N / N was applied at H / H. H / H was judged by environmental detection by an environmental sensor, and a transfer current suitable for H / H could be applied.

  Even with a transfer lever that has been generated on N / N paper, the generation of the transfer lever is eliminated by applying a more appropriate current value fixed at N / N. In addition, in the case of the resistance value lower limit product, ATVC does not cause the strong omission that occurred in the L / L environment left-handed paper, open paper, and N / N open paper that occurred in the lower resistance value product. In the L / L environment, the N / N environment was erroneously detected due to the low resistance value, and the transfer current originally applied at N / N was applied at L / L. L / L was judged by the environmental detection by the environmental sensor, and a transfer current suitable for L / L can be applied.

  Even with regard to strong omissions that have occurred in N / N open paper, the occurrence of omissions can be eliminated by applying a more appropriate current value than that fixed by N / N. That is, after the transfer ATVC, it is possible to perform transfer control that matches the resistance value of the transfer roller and the surrounding environment, and it is possible to provide a high-quality image in any environment.

  In this embodiment, the value of V0 and the value of It are listed, but the values are naturally changed depending on the configuration and the control method, and the present invention is not limited to this. Further, other numerical values are not limited to this.

<Example 2>
Next, characteristic transfer control in the second embodiment will be described. In the second embodiment, the control is performed at a temperature detected by a thermistor used for fixing without using an environmental sensor. By finding the temperature more accurately and with a high response, the detection accuracy is increased and the environmental detection accuracy is increased.

  In the transfer control of the present embodiment, after the transfer ATVC control is performed and the resistance value of the transfer roller is measured, in order to obtain information on the surrounding environment that cannot be understood only by the transfer ATVC control, the heating body of the fixing device is used instead of the environment sensor. The ambient temperature is detected by detecting the amount of change in temperature detected by the thermistor included in the printer, and fed back to the transfer control.

  Here, since the transfer ATVC control is as described above, the description thereof is omitted. After the transfer ATVC control is completed, the surrounding environment is predicted from the rising change amount of the temperature of the thermistor for the heating element in a certain time, but the rising change amount of the thermistor for the heating element and the prediction of the surrounding environment are set in advance. And The surrounding environment can be predicted by the temperature rise of the heating element thermistor because the fixing device of this embodiment raises the temperature of the heating element with a constant power, so the time to reach the target temperature varies depending on the surrounding environment. This is because the surrounding environment can be predicted by looking at the amount of change. It is particularly convenient for the ion conductive transfer roller that the “temperature information” can be accurately known because the resistance shift is mainly caused by temperature.

  FIG. 16 shows the relationship between the thermistor rising amount and the surrounding environment. From FIG. 16, the relationship between the amount of change of the thermistor and the surrounding environment is set as follows from the experimental results.

Thermistor rise variation Judgment environment
α: TH-TL / ta → judged as an environment above A ℃ β: TH-TL / tb → judged as an environment below B ℃ and below A ℃ γ: judged as an environment below TH-TL / tc → B ℃

ta <tb <tc ta <t1, t1 ≦ tb ≦ t2, t2 <tc
A> B
t1, t2, A, and B are constants for detecting the detailed surrounding environment that cannot be detected by the ATVC at the time when the surrounding environment is detected, and determining the transfer control to the recording material. The image was compared with Comparative Example 1 when the environment was changed using the transfer control.

(Consideration conditions)
● Image forming device body:
HP Laserjet P1006 with process speed 160mm / s and changed to 25ppm ● Environment:
L / L (low temperature and low humidity) environment 10 ℃ / 10% RH (absolute water content 0.941g / m ^ 3)
N / N (room temperature and humidity) environment 20 ℃ / 50% RH (absolute water content 8.655g / m ^ 3)
H / H (high temperature and high humidity) environment 30 ° C / 90% RH (Absolute water content 24.304g / m ^ 3)
CS680 manufactured by Canon Marketing Japan
Use paper that has been left in the environment for 3 days in each environment and open paper that is opened just before the examination.
Continuous continuous passage of photographic images and text images up to a total of 100 ● Relationship between V0 determined by ATVC control and applied transfer constant current:
As shown in FIG.

● Ambient environment detection method of Example 2:
As shown in FIG.

  The surrounding environment is predicted from the amount of change in the temperature rise of the thermistor for heating element over a certain period of time.

  The amount of rise change is the amount of change for a certain time until the thermistor detection temperature rises from 60 ℃ to 150 ℃.

  The following is the thermistor rising change amount and the corresponding ambient temperature. The relationship between the rising change amount of the thermistor and the ambient temperature is obtained experimentally in an environment where the temperature is varied, and the relationship is as follows.

Thermistor rise variation Judgment environment
α1: 36 or more → Judged as an environment of 25 ° C or higher β1: Judged as an environment of 30 ° C or higher and lower than 36 ° C → Judged as an environment of 20 ° C or higher and lower than 25 ° C The absolute water content is detected as follows.

25 ℃ or higher → 14.989g / m ^ 3 or higher
20 ℃ or more and less than 25 ℃ → 3.462 or more and less than 14.989g / m ^ 3
Less than 20 ℃ → 3.462g / m ^ 3 or less ● Roller roller resistance value standard:
1 × 10 ^ 8 ～ 6 × 10 ^ 8Ω in N / N environment
● Roller resistance value:
When the resistance value is measured in N / N environment, 1 × 10 ^ 8Ω resistance value lower limit product, 3 × 10 ^ 8Ω resistance value center product, 6 × 10 ^ 8Ω resistance value upper limit product, resistance 3 level transfer roller Confirm with.
● Relationship between V0 determined by ATVC control of Comparative Example 1 and applied transfer current:
As shown in FIG. I0 = 3 μA and the relationship between V0 and the applied transfer voltage at that time. The control is determined using a transfer roller having a central resistance value of N / N. FIG. 11 shows the V0 detection result in three environments of the transfer roller having a resistance value of three levels.

(Study results)
The result of Example 2 is shown in FIG. In Example 2, as in Example 1, in any of the three environments and the three-level transfer rollers, no image problem occurred and a high-quality image was obtained. This is because the ambient temperature can be detected with high accuracy by the temperature rising change amount of the thermistor for the heating element, which is an alternative to the environmental sensor, and accordingly, the absolute moisture content can be predicted with high accuracy.

  Finally, since an optimum transfer current depending on the resistance value of the transfer roller and the amount of moisture in the environment can be applied, the image defect that occurs in Comparative Example 1 does not occur.

  In other words, it is possible to accurately grasp the resistance value of the transfer roller, and by accurately grasping the moisture content of the surrounding environment, it becomes possible to perform appropriate transfer control according to the resistance value of the transfer roller and the environment. This makes it possible to provide high-quality images.

  In the present embodiment, the temperature rise change amount of the thermistor for the heating element is used in place of the environmental sensor. However, the present invention is not limited to this method because other configurations and controls are naturally conceivable.

  In addition, although the numerical value of the rise change amount of the thermistor is determined, naturally this is not limited to this numerical value because there is a possibility that it will change depending on the configuration and control.

5 Cleaning container 7 Transfer inlet guide 10 Controller 11 Transfer high voltage power supply
101 Photosensitive drum 102 Charging roller 103 Laser scanner 104 Developer
105 Cleaning blade 106 Transfer roller 107 Fixing device
301 Heater holder 302 Fixing film 303 Heater 304 Thermistor for heater
306 Pressure roller
1000 Laser beam printer
1001 Photosensitive drum 1002 Charging roller 1003 Laser scanner 1004 Developer
1005 Transfer roller 1009 Fixing device 1021 Heater holder 1022 Heater
1023 Fixing film 1024 Pressure member 2001 Aluminum drum

Claims (3)

An image carrier that carries a developer image according to image information;
A transfer member in contact with the image carrier to transfer the developer image carried on the image carrier to a recording material;
Transfer bias applying means for applying a transfer bias for electrostatically transferring the developer image to a recording material on the transfer member;
At the timing in the non-image area, the transfer voltage applying means is controlled to be in constant current control so that the transfer member has a preset constant current value, and an applied voltage value corresponding to the constant current at this time is set. An applied transfer voltage determination control for determining an applied transfer voltage to the image area of the recording material,
An environmental detection means for detecting the atmospheric environment;
In an image forming apparatus having
An applied voltage value corresponding to a constant current value in the applied transfer voltage determination control;
By detecting the environment by the environment detection means,
An image forming apparatus, wherein an applied transfer bias is determined according to a detection result of both. The image forming apparatus includes a heating member,
Heating member temperature detecting means for detecting the temperature of the heating member;
Fixing temperature control means for detecting the temperature of the heating member with the heating body temperature detection means, starting the heating member with a constant power to a predetermined temperature, and then adjusting the temperature;
A pressure fixing member that forms a nip portion with the heating member, and a heating and fixing device that heats an image on the recording material while nipping and conveying the recording material at the nip portion,
The image forming apparatus according to claim 1, wherein the environment detection unit detects an atmospheric environment from a change amount of a rising temperature detected by the heating member temperature detection unit that detects a temperature of the heating member. The image forming apparatus includes a heating body that heats the flexible member;
Heating body temperature detection means for detecting the temperature of the heating body;
Fixing temperature control means for adjusting the temperature of the heating body at a predetermined fixing temperature while detecting the temperature of the heating body with the heating body temperature detection means;
A support member that movably supports the flexible member;
A pressure rotator that forms a nip portion with the support member across the flexible member, and a heating and fixing device that heats an image on the recording material while nipping and conveying the recording material at the nip portion. ,
3. The image formation according to claim 1, wherein the environment detection unit detects an atmospheric environment from a change amount of a rising temperature detected by the heating member temperature detection unit that detects a temperature of the heating member. apparatus.