JP2007264167A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus allowing design man-hour of a neutralization device for a photoreceptor drum used in an electrophotographic process to be reduced. <P>SOLUTION: The image forming apparatus includes: an image forming section which develops an electrostatic latent image formed on the photoreceptor drum, with toner and transfers and fixes the developed image to recording paper, thereby forming the image on the recording paper; and a neutralization heating part 37 which turns on a light emitting diode LED attached to one side 371a of a substrate 371 and irradiates the photoreceptor drum with light, thereby removing electricity from the photoreceptor drum. In addition, electrode pats P1 and P2 for attaching a resistance element R that heats the photoreceptor drum are attached to the other side 371b of the substrate 371. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that performs image formation by an electrophotographic process.

  In an image forming apparatus using an electrophotographic process such as a copying machine, a printer, or a facsimile, an electrostatic latent image is formed on the surface of a photosensitive drum, and this image is developed with toner and visualized. In this type of image formation, there is an image forming apparatus that includes a charge removing device that discharges light by projecting light onto the surface of the photosensitive drum for the purpose of erasing unnecessary charging, latent images, and the like.

  This static eliminator is configured by, for example, a plurality of LEDs (Light Emitting Diodes) as light sources, which are linearly attached at substantially equal intervals on a substrate. The surface of the photosensitive drum is irradiated with the light for discharging from the LED, so that unnecessary charging, latent images, and the like are removed (see, for example, Patent Document 1).

  In addition, a photosensitive drum, particularly a photosensitive drum using amorphous silicon as a photosensitive member, easily adsorbs moisture in the air. When the photosensitive drum absorbs moisture, the surface resistance of the photosensitive drum decreases, and particularly electrostatic discharge. It is known that a so-called image flow phenomenon in which the image quality is lowered occurs due to the surface potential being lowered at the edge of the latent image.

Therefore, there is known an image forming apparatus that suppresses the occurrence of a so-called image flow phenomenon by heating the photosensitive drum with a heater and evaporating moisture on the surface of the photosensitive drum to suppress moisture absorption (for example, (See Patent Document 2).
JP 2003-76234 A JP 2004-191790 A

  By the way, it is difficult to predict the occurrence of the above-described image flow phenomenon in advance at the design stage, and the image flow phenomenon may not occur without necessarily providing a heater for suppressing image flow. In such a case, if a heater for suppressing image flow is provided, the cost increases. Therefore, conventionally, when designing an image forming apparatus that performs image formation by an electrophotographic process using a photosensitive drum, first, an image is formed. Designed with a configuration that does not have a heater for suppressing flow, and, based on the results of an evaluation test using a prototype, a new heater for suppressing image flow may be designed and added when an image flow phenomenon occurs. It was.

  However, if a heater for suppressing image flow is added as a result of an evaluation test using a prototype, there is an inconvenience that the design man-hour for newly designing a heater for suppressing image flow is increased. There was a disadvantage that the increase in design cost was large.

  The present invention has been made in view of such problems, and provides an image forming apparatus capable of reducing the number of man-hours for designing a heater for suppressing image flow of a photosensitive drum used in an electrophotographic process. With the goal.

  An image forming apparatus according to the present invention develops an electrostatic latent image formed on a photosensitive drum and transfers the image to a recording paper, thereby forming an image on the recording paper, and an image forming unit on one surface of the substrate. A neutralization unit for neutralizing the photosensitive drum by emitting light from the attached light emitting element and irradiating the photosensitive drum with light, and heating the photosensitive drum on the other surface of the substrate An attachment portion for attaching the heating element is provided.

  According to this configuration, the electrostatic latent image formed on the photosensitive drum is developed and transferred to the recording paper to form an image. Then, the light emitting element attached to one surface of the substrate in the charge eliminating portion emits light, and the photosensitive drum is irradiated with light, and the photosensitive drum is discharged. Further, since the mounting portion for mounting a heating element for heating the photosensitive drum is provided on the other surface of the substrate in the static eliminating portion, the photosensitive drum is mounted in order to reduce the occurrence of the so-called image flow phenomenon. When it is necessary to heat, it is only necessary to attach a heating element to the mounting part, and it is not necessary to design a new image flow suppression heater to reduce the occurrence of image flow phenomenon. It is possible to reduce the number of man-hours for designing the heater for suppressing the image flow of the photosensitive drum used.

  Moreover, it is preferable that a plurality of the attachment portions are provided to attach the plurality of heating elements.

  According to this configuration, when it is necessary to heat the photosensitive drum in order to reduce the occurrence of a so-called image flow phenomenon, a plurality of heating elements can be attached to the plurality of attachment portions. The heating value necessary for heating can be shared by multiple heating elements, and the heating value per heating element can be reduced, so parts that have a small heating value and are easily available are used as heating elements. Easy to do.

  In addition, the light emitting element and the heating element are surface mounting chip components, the attachment portion is an electrode pad formed of a wiring pattern formed on the other surface of the substrate, and one surface of the substrate is Preferably, the same wiring pattern as the wiring pattern formed on the other surface of the substrate is formed, and the light emitting element is attached to an electrode pad in the wiring pattern formed on the one surface of the substrate.

  According to this configuration, since the wiring pattern formed on one side of the substrate is the same as the wiring pattern formed on the other side of the substrate, there is no need to individually design the wiring pattern on both sides of the substrate, Wiring pattern design man-hours can be reduced.

  Further, the static elimination unit includes a power receiving terminal for receiving a power supply voltage, the light emitting element emits light by a power supply voltage received by the power receiving terminal, and the attachment portion is configured to generate heat from the heating element. It is preferable that the power supply voltage received by the power receiving terminal is supplied.

  According to this configuration, since the power supply voltage received by the power receiving terminal is supplied to the light emitting element and the heating element, the power supply voltage for causing the light emitting element to emit light and the power supply voltage for causing the heating element to generate heat are the same. As a result of using the voltage, the power supply voltage supply circuit can be simplified.

  Moreover, it is preferable that the said heat generating body is attached to the attachment part in the other surface of the said board | substrate.

  According to this configuration, since the photosensitive drum can be heated by the heating element attached to the other surface of the substrate in the static elimination unit to reduce the occurrence of a so-called image flow phenomenon, an image is separately provided in addition to the static elimination unit. It is not necessary to provide a heater for suppressing the flow, and it becomes easy to reduce the occurrence of the image flow phenomenon.

  In the image forming apparatus having such a configuration, the electrostatic latent image formed on the photosensitive drum is developed using toner, transferred to a recording sheet, and fixed to form an image on the recording sheet. Then, the light emitting element attached to one surface of the substrate in the charge eliminating portion emits light, and the photosensitive drum is irradiated with light, and the photosensitive drum is discharged. Further, since the mounting portion for mounting a heating element for heating the photosensitive drum is provided on the other surface of the substrate in the static eliminating portion, the photosensitive drum is mounted in order to reduce the occurrence of the so-called image flow phenomenon. When it is necessary to heat, it is only necessary to attach a heating element to the mounting part, and it is not necessary to design a new image flow suppression heater to reduce the occurrence of image flow phenomenon. It is possible to reduce the number of man-hours for designing the heater for suppressing the image flow of the photosensitive drum used.

  Embodiments according to the present invention will be described below with reference to the drawings. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted. FIG. 1 is a cross-sectional view showing an internal configuration of a printer as an example of an image forming apparatus according to an embodiment of the present invention. A printer 100 shown in FIG. 1 is a tandem color printer, and includes a paper feeding unit 10 that stores paper 11, a paper transport unit 20 that transports paper 11, and a predetermined toner image on the paper 11 by an electrophotographic process. Image forming units 30C, 30M, 30Y, and 30B, a fixing unit 40 that fixes the toner image on the paper 11, and a DC power supply voltage of, for example, 24V DC as operating power to each unit in the printer 100. And a power supply unit 50 to be supplied.

  The sheet feeding unit 10 feeds a bundle of sheets 11 stacked in the sheet feeding cassette 13 one by one to the outlet side (right side in FIG. 1) of the sheet feeding cassette 13 by rotating the sheet feeding roller 12. Paper is fed to the transport unit 20.

  The paper transport unit 20 transports the paper 11 fed from the paper feed unit 10 to the paper transport belt 27 by the feed roller pair 22 and the registration roller pair 23 via the reverse guide 24. A belt driving roller 62 and a belt driven roller 61 are attached to the sheet conveying belt 27, and the sheet conveying belt 27 travels when the belt driving roller 62 and the belt driven roller 61 rotate. The sheet 11 is conveyed from the upstream image forming unit 30C toward the downstream image forming unit 30B.

  The four image forming units are provided according to toners of cyan, magenta, yellow, and black, respectively. From the upstream side, the image forming unit 30C having cyan toner, the image forming unit 30M having magenta toner, and yellow are provided. An image forming unit 30Y having toner and an image forming unit 30B having black toner are arranged in series. These image forming units 30C, 30M, 30Y, and 30B are rotated around cylindrical photosensitive drums 31C, 31M, 31Y, and 31B each formed using, for example, an amorphous silicon (a-Si) photosensitive member. In order along the direction, chargers 32C, 32M, 32Y, 32B, exposure devices 33C, 33M, 33Y, 33B, developing devices 34C, 34M, 34Y, 34B, transfer rollers 35C, 35M, 35Y, 35B, static elimination heating unit 37C. , 37M, 37Y, and 37B (static elimination unit) and cleaners 36C, 36M, 36Y, and 36B are disposed.

  In the following description, alphabetical subscripts are omitted when generically referring to each component provided according to toner of each color of cyan (C), magenta (M), yellow (Y), and black (B). Reference numerals are used to indicate individual configurations, and reference numerals with alphabetic suffixes are used.

  FIG. 2 is a schematic diagram illustrating an example of the positional relationship between the photosensitive drum 31 and the static elimination heating unit 37 illustrated in FIG. As shown in FIG. 2, the static elimination heating unit 37 includes a substrate 371 that is a printed wiring board, and a light-emitting diode LED (light-emitting element) that is attached to one surface 371 a of the substrate 371 that faces the photosensitive drum 31. The substrate 371 includes a resistance element R (a heating element) attached to the other surface 371b which is the back surface of the one surface 371a.

  FIG. 3 is a schematic diagram illustrating an example of a detailed configuration of the static elimination heating unit 37 illustrated in FIG. 1. FIG. 3A shows the one surface 371 a side of the static elimination heating unit 37, and FIG. 3B shows the other side 371 b side of the static elimination heating unit 37. 3 is received on one surface 371a of the substrate 371 by the power receiving terminals 372 and 373 and through the power receiving terminals 372 and 373 which are through holes for receiving a power supply voltage of, for example, 24V DC from the power source 50. Light-emitting diodes LED1 to LED18 (light-emitting elements) that emit light according to a power supply voltage and current-limiting resistors R1 to R3, and a resistive element that generates heat on the other surface 371b of the substrate 371 due to the power supply voltage received by the power receiving terminals 372 and 373 R11 to R31 are provided.

  The power receiving terminals 372 and 373 are not limited to through holes, and may be connectors. As the light emitting diodes LED1 to LED18 and the resistance elements R11 to R31, for example, substantially box-shaped surface mounting chip components are used. Hereinafter, the light emitting diodes LED1 to LED18 are collectively referred to as a light emitting diode LED, and the resistance elements R11 to R31 are collectively referred to as a resistance element R.

  More specifically, the static elimination heating unit 37 includes, on one surface 371a, a series circuit of light emitting diodes LED1 to LED6 and a current limiting resistor R1, a series circuit of light emitting diodes LED7 to LED12 and a current limiting resistor R2, and a light emitting diode. A series circuit of the LEDs 13 to 18 and the current limiting resistor R3 is connected in parallel, a power receiving terminal 372 is connected to one end of the parallel circuit, and a power receiving terminal 373 is connected to the other end. Accordingly, power is supplied from the power supply unit 50 to the light emitting diodes LED1 to LED18 via the power receiving terminals 372 and 373, and light for discharging the photosensitive drum 31 is emitted from the light emitting diodes LED1 to LED18. ing.

  In addition, the power receiving terminals 372 and 373 penetrate the substrate 371 from one surface 371a and reach the other surface 371b. A series circuit of .about.R24 and a series circuit of resistance elements R25 to R31 are connected in parallel, a power receiving terminal 372 is connected to one end of the parallel circuit, and a power receiving terminal 373 is connected to the other end. As a result, electric power is supplied from the power supply unit 50 to the resistance elements R11 to R31 via the power receiving terminals 372 and 373, the resistance elements R11 to R31 generate heat, and the photosensitive drum 31 is heated, so-called image flow phenomenon. The occurrence of is reduced.

  FIG. 4 is a diagram illustrating an example of an attachment portion 374 for attaching the light emitting diode LED and the resistance element R to the substrate 371. In the drawing, a wavy line P indicates the outline of the light emitting diode LED and the resistance element R, and indicates the mounting position of the light emitting diode LED and the resistance element R. As shown in FIG. 4, when the light emitting diode LED and the resistance element R are placed at the mounting position indicated by the wavy line P, the mounting portion 374 contacts the electrodes formed at both ends of the light emitting diode LED and the resistance element R, respectively. In addition, electrode pads P1 and P2 are formed by a wiring pattern. The plurality of electrode pads P1 and P2 for mounting the light emitting diode LED are provided on one surface 371a in correspondence with the outer dimensions of the light emitting diode LED, for example, 2.0 mm × 1.2 mm, and for mounting the resistance element R The plurality of electrode pads P1 and P2 are provided on the other surface 371b so as to correspond to the outer dimensions of the resistance element R, for example, 3.2 mm × 1.6 mm.

  A wiring pattern for power supply is connected to the electrode pads P1 and P2, and the light emitting diode LED and the resistance element R are placed at the attachment position indicated by the broken line P, and are formed at both ends of the light emitting diode LED and the resistance element R. The light emitting diode LED and the resistance element R are attached to the substrate 371 by soldering the formed electrodes to the electrode pads P1 and P2.

  The electrode pads P1 and P2 have a shape corresponding to the outer dimensions of both the light emitting diode LED and the resistance element R, and the same wiring pattern is formed on the one surface 371a and the other surface 371b, thereby There is no need to individually design wiring patterns on both sides of 371, and the number of man-hours for designing the wiring pattern can be reduced, or the number of masks used in the exposure process of the substrate 371 can be reduced, thereby reducing the cost of the mask. In this case, the power receiving terminals 372 and 373 for the one surface 371a and the power receiving terminals 372 and 373 for the other surface 371b may be provided individually. For example, the power receiving terminals 372 and 373 are provided in the center in the longitudinal direction of the substrate 371. Thus, by aligning the positions of the power receiving terminals 372 and 373 on the one surface 371a with the power receiving terminals 372 and 373 on the other surface 371b, both the light emitting diode LED and the resistance element R can be obtained by the pair of power receiving terminals 372 and 373. You may make it supply a power supply voltage to.

  The heat generation amount of the static elimination heating unit 37 is 3 W, for example. Then, since the plurality of resistance elements R, for example, 21 resistance elements R are attached to the static elimination heating unit 37, the heat generation amount per resistance element R is reduced to 0.14 W, and the resistance element R As a result, it becomes easy to use a surface mount chip component having a small power rating.

Moreover, in the static elimination heating part 37, since the series circuit with which seven resistance elements R were connected in series is made into 3 parallel, it becomes 1W per series circuit of resistance elements R. When the power supply voltage supplied from the power supply unit 50 to the power receiving terminals 372 and 373 is, for example, DC 24 V, the current I flowing per series circuit line of the resistor elements R
I = P / V
= 1/24
= 41.7 [mA].

The resistance value r per series circuit of the resistance element R is
r = V / I
= 24 / 41.7 × 10 ⁻³
= 576 [Ω].

Since seven resistance elements R are in series, the resistance value r _{1 of} one resistance element R is:
r ₁ = 576/7
= 82.3 [Ω], and a resistance of about 82Ω can be used as the resistance elements R11 to R31.

  In this case, by using a resistance of about 82Ω as the resistance elements R11 to R31, the power supply voltage received by the power receiving terminals 372 and 373 is supplied to the light emitting diode LED and the resistance element R so that the light emitting diode LED emits light. As a result, the power supply unit 50 need only output a single DC 24V, and the circuit of the power supply unit 50 can be simplified. Can do.

  In addition, although the example which uses a resistance element as a heat generating body was shown, various heat generating bodies, such as a thermistor and a heating wire, can be used. Further, the light emitting diode LED and the resistance element R are not limited to the surface mounting chip parts, but may be lead parts. And the attachment part is not restricted to an electrode pad, For example, a through hole and a connector may be sufficient.

  Next, the operation of the printer 100 configured as described above will be described. First, the surfaces of the photosensitive drums 31C, 31M, 31Y, and 31B are charged by the chargers 32C, 32M, 32Y, and 32B, respectively, and light corresponding to a desired image is emitted from the exposure devices 33C, 33M, 33Y, and 33B. As a result, the surface potentials of the photosensitive drums 31C, 31M, 31Y, and 31B are selectively attenuated, and electrostatic latent images corresponding to the respective colors are formed. Subsequently, toner of each color is appropriately supplied from the respective toner tanks 39C, 39M, 39Y, 39B to the developing units 34C, 34M, 34Y, 34B, and the photosensitive drums 31C, 31M are developed by the developing units 34C, 34M, 34Y, 34B. , 31Y and 31B are developed with respective color toners to form respective color toner images. Next, the toner images of the respective colors are transferred onto the paper 11 conveyed by the paper conveying belt 27 by the transfer rollers 35C, 35M, 35Y, and 35B, thereby forming a color toner image. Thereafter, in the fixing unit, the paper 11 on which the color toner image has been transferred is sandwiched between the heating roller 41 and the pressure roller 42 to apply heat and pressure, and the color toner image is fixed. An image is formed. Further, the paper 11 on which the color image is formed is discharged onto the discharge tray 26 by the discharge roller pair 25.

  On the other hand, after the toner images are transferred from the photosensitive drums 31C, 31M, 31Y, and 31B onto the paper 11, the surface of the photosensitive drums 31C, 31M, 31Y, and 31B is removed by the static elimination heating units 37C, 37M, 37Y, and 37B. Each of the photosensitive drums 31C, 31M, 31Y, and 31B is irradiated with light to neutralize the surface charges, and the photosensitive drums 31C, 31M, 31Y, and 31B are heated to evaporate surface moisture, thereby suppressing moisture absorption. This suppresses the occurrence of a so-called image flow phenomenon.

  Next, the surfaces of the photosensitive drums 31C, 31M, 31Y, and 31B are cleaned by cleaners 36C, 36M, 36Y, and 36B configured by using, for example, a fur brush or a rubber blade, and the photosensitive drums 31C, 31M, 31Y, and 31B are cleaned. The toner remaining on the surface of 31B, its additive, and the like are removed.

  Conventionally, in an image forming apparatus using an electrophotographic process, a charging device, an exposure device, a developing device, a transfer roller, a static elimination device, and a cleaner are opposed to each other without any gap around the photosensitive drum. Therefore, there is no extra space, and it is difficult to dispose a heater for suppressing image flow around the photosensitive drum. Therefore, a heater for suppressing image flow is disposed at a position away from the photosensitive drum, or an intermediate transfer member that rotates while contacting the photosensitive drum as in the image forming apparatus described in Patent Document 2, for example, is heated. As a result, the photosensitive drum is indirectly warmed, and therefore, it is necessary to use a heater with a large calorific value as a heater for suppressing image flow.

  On the other hand, according to the static elimination heating unit 37 illustrated in FIG. 2, the resistance element R that is a heating element is provided on the other surface 371 b of the substrate 371 in the static elimination heating unit 37 that is disposed in the vicinity of the photosensitive drum 31. Therefore, as compared with the case where the heater is disposed at a position away from the photosensitive drum as described above, or the intermediate transfer body is heated to indirectly warm the photosensitive drum, The calorific value can be reduced. Thereby, when the conventionally used heater as described above is 15 W, for example, the amount of heat generated by the resistance elements R11 to R31 in the static elimination heating unit 37 is reduced to, for example, about 3 to 4 W, which is about 1/4. Becomes easy.

  In addition, according to the static elimination heating unit 37 shown in FIG. 2, the photosensitive drum 31 can be locally heated in the vicinity of the photosensitive drum 31, so a heater is disposed at a position away from the photosensitive drum. Compared to the case where the intermediate transfer member is heated and the photosensitive drum is indirectly heated, it is possible to reduce the heating of the constituent parts other than the photosensitive drum that are not required to be heated by the static elimination heating unit 37. In addition, adverse effects such as deterioration of characteristics due to heating of components other than the photosensitive drum are reduced.

  Further, according to the static elimination heating unit 37 shown in FIG. 2, a so-called image flow phenomenon should occur due to the result of the evaluation test using the prototype without the resistance elements R11 to R31 attached to the static elimination heating unit 37. If the so-called image flow phenomenon occurs, the resistance elements R11 to R31 are attached to the attachment portion 374 on the other surface 371b so that the photosensitive element can be exposed to light. The body drum 31 can be heated to suppress the occurrence of the image flow phenomenon.

  Therefore, according to the static elimination heating unit 37 shown in FIG. 2, even if it is necessary to add a heater for suppressing image flow as a result of an evaluation test using a prototype, the heater for suppressing image flow. Therefore, the design man-hour for suppressing the image flow of the photosensitive drum used in the electrophotographic process can be reduced.

  The image forming apparatus is not limited to a color, and may be a monochrome image forming apparatus. The image forming apparatus is not limited to a printer, and may be a variety of image forming apparatuses such as a copying machine, a facsimile, and a composite machine thereof. Also good.

1 is a cross-sectional view illustrating an internal configuration of a printer that is an example of an image forming apparatus according to an embodiment of the present disclosure. FIG. 2 is a schematic diagram illustrating an example of a positional relationship between a photosensitive drum and a static elimination heating unit illustrated in FIG. 1. It is a schematic diagram which shows an example of a detailed structure of the static elimination heating part shown in FIG. (A) shows the one surface side in the static elimination heating part, (b) has shown the other surface side in the static elimination heating part. It is a figure which shows an example of the attaching part for attaching a light emitting diode and a resistive element to a board | substrate.

Explanation of symbols

30C, 30M, 30Y, 30B Image forming unit 31, 31C, 31M, 31Y, 31B Photosensitive drum 32C, 32M, 32Y, 32B Charger 33C, 33M, 33Y, 33B Exposure unit 34C, 34M, 34Y, 34B Developer 35C , 35M, 35Y, 35B Transfer roller 36C, 36M, 36Y, 36B Cleaner 37, 37C, 37M, 37Y, 37B Static elimination heating unit 40 Fixing unit 41 Heating roller 42 Pressure roller 50 Power supply unit 100 Printer 371 Substrate 371a One side 371b Other Direction 372, 373 Power receiving terminal 374 Mounting portion LED, LED1 to LED18 Light emitting diode R, R11 to R3 Resistive element R1, R2, R3 Current limiting resistor P1, P2 Electrode pad

Claims (5)

An electrostatic latent image formed on the photosensitive drum is developed and transferred to a recording paper, thereby forming an image on the recording paper; and
A neutralization unit that neutralizes the photoconductive drum by emitting light from a light emitting element attached to one side of the substrate and irradiating the photoconductive drum with light.
An image forming apparatus, wherein an attachment portion for attaching a heating element for heating the photosensitive drum is provided on the other surface of the substrate. The image forming apparatus according to claim 1, wherein a plurality of the attachment portions are provided to respectively attach the plurality of heating elements. The light emitting element and the heating element are surface mount chip parts,
The mounting portion is an electrode pad made of a wiring pattern formed on the other surface of the substrate,
The same wiring pattern as the wiring pattern formed on the other surface of the substrate is formed on one surface of the substrate,
The image forming apparatus according to claim 1, wherein the light emitting element is attached to an electrode pad in a wiring pattern formed on one surface of the substrate. The static eliminator includes a power receiving terminal for receiving a power supply voltage,
The light emitting element emits light by a power supply voltage received by the power receiving terminal,
4. The image forming apparatus according to claim 1, wherein a power supply voltage received by the power receiving terminal is supplied to the mounting portion so as to cause the heating element to generate heat. The image forming apparatus according to claim 1, wherein the heating element is attached to an attachment portion on the other surface of the substrate.

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