JP2007218996A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve low noise by suppressing generation of noise in an image forming apparatus for forming an image by using a deflector that deflects a light beam with an oscillating deflection mirror face. <P>SOLUTION: A light beam from a laser light source 62 is made incident on the deflection mirror face 6511 (M1) of a deflector 65 through a beam shaping system 63 and deflected with the deflection mirror face 6511. This deflector 65 is provided with a separate movable member other than the one having the deflection mirror face 6511. These two movable members are serially arranged apart from each other along a driving axis and pivotally supported so as to freely oscillate around the driving axis by a torsion spring. Then, by receiving a driving force from an oscillation driving part, the movable members oscillate. The phase and amplitude of respective movable members are set in the manner that inertia torque generated therein is mutually negated. In other words, the deflector is configured so that the sum total of the inertia torque becomes zero. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus using a deflector that deflects a light beam by a deflecting mirror surface formed on a surface of a movable member that vibrates around a predetermined drive shaft.

  In image forming apparatuses such as laser printers, copying machines, and facsimile machines, image processing such as gradation reproduction processing is applied to image data related to a toner image to be formed on the surface of a latent image carrier such as a photosensitive drum. Thus, an image signal is formed. In this image forming apparatus, an exposure unit is provided, and the exposure unit forms a latent image corresponding to the image data on the latent image carrier. That is, in this exposure unit, a light source such as a semiconductor laser is used, and a light beam from the light source is modulated based on the image signal, and the modulated light beam is deflected by a deflector to be a light beam in the main scanning direction. Are scanned. In recent years, in order to reduce the size and increase the speed of a deflector, it has been proposed to vibrate a reflecting mirror and use it as a deflector (see Patent Documents 1 and 2). That is, in the deflector described in Patent Document 1, the reflecting mirror is pivotally supported by the ligament and is fixed to the frame via the ligament. Then, by applying a mirror drive signal to the drive coil, the reflection mirror sine vibrates and deflects the light beam emitted from the light source.

  In the deflector described in Patent Document 2, torsion springs are attached to the upper and lower ends of the scanning mirror, and the torsion springs pivotally support the scanning mirror with respect to the casing. Yes. Then, by applying a mirror drive signal to the electromagnet disposed opposite to the permanent magnet, the scanning mirror sine vibrates and deflects the light beam emitted from the light source.

JP-A 63-279220 (FIG. 3) Japanese Patent Laid-Open No. 08-146334 (FIG. 1)

  Since this type of deflector deflects a light beam by sine-vibrating a movable member such as a reflection mirror or a scanning mirror, the momentum changes greatly whenever the drive direction of the movable member changes. For this reason, the force generated by the vibrating movable member is applied to the external fixing member such as the frame or the case, and the case of the external fixing member or deflector vibrates at the same frequency or higher harmonics as the mirror drive frequency, resulting in large noise. Could cause. This is one of the main causes of noise generated in the image forming apparatus.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and suppresses the generation of noise in an image forming apparatus that forms an image using a deflector that deflects a light beam by a vibrating deflection mirror surface, thereby reducing noise. For the purpose.

  According to a first aspect of the present invention, an exposure unit scans a light beam in the main scanning direction to form a latent image on a latent image carrier, and the latent image is developed by a developing unit to form an image. In order to achieve the above object, the exposure unit includes (a) a light source that emits a light beam, and (b) a deflector that deflects the light beam from the light source in the main scanning direction. The container (b) includes (b-1) a plurality of movable members arranged in series apart from each other along a predetermined drive shaft, and (b-2) a plurality of movable members provided along the drive shaft. A plurality of torsion springs that are connected and pivotally supported; and (b-3) a vibration drive unit that generates a driving force for vibrating the plurality of movable members around the drive shaft. A deflection mirror surface is formed, and a plurality of movable members are vibrated to deflect the deflection mirror surface. It is characterized in that the phase and amplitude of each movable member are set so that inertial torques generated by each movable member when the light beam is further deflected and a plurality of movable members are vibrated cancel each other. .

  In the invention configured as described above, the plurality of movable members are spaced apart from each other along the drive shaft and connected by a plurality of torsion springs so as to be freely vibrated around the drive shaft. The plurality of movable members vibrate around the drive shaft in response to the driving force from the vibration driving unit. A deflecting mirror surface of one of these movable members is formed, and the light beam from the light source is deflected by the deflecting mirror surface. On the other hand, the remaining movable member does not directly participate in the deflection of the light beam, but vibrates around the drive axis together with the movable member having the deflection mirror surface. In the present invention, the phase and amplitude of each movable member are set so that the inertia torque generated in each movable member cancels each other. That is, the deflector is configured so that the sum of inertia torques becomes zero. As a result, the cause of the noise is removed from the deflector which is one of the noise generation sources in the image forming apparatus, and the image forming apparatus is reduced in noise.

  In the second aspect of the present invention, a light beam is scanned in the main scanning direction by the exposure unit to form a line latent image on the latent image carrier, and the latent image is developed by the developing unit to form an image. In order to achieve the above object, the exposure unit includes: (a) first and second light sources that emit light beams; and (b) light beams from the first and second light sources. A deflector that deflects in the scanning direction, and each time the light beam is scanned forward to form a line latent image, the light beam emission source is alternately switched between the first and second light sources, and the deflector (b (B-1) first and second movable members having the same configuration and arranged in series apart from each other along a predetermined drive shaft, and (b-2) provided along the drive shaft A plurality of twists that are coupled to and pivotally support the first and second movable members And (b-3) a vibration drive unit that generates a drive force for vibrating the first and second movable members around the drive shaft at the same drive frequency, and receives the drive force from the vibration drive unit. While the first and second movable members vibrate with the same amplitude and in the opposite phase, the first deflecting mirror surface formed on the first movable member deflects the light beam from the first light source, while the second movable member A light beam from the second light source is deflected by a second deflection mirror surface formed on the member.

  In the invention configured as described above, two movable members having the same configuration, that is, the first and second movable members are spaced apart from each other along the drive shaft and connected by a plurality of torsion springs around the drive shaft. It is pivotally supported. Then, the first and second movable members vibrate around the drive shaft in response to the driving force from the vibration driving unit. The first and second movable members are provided with first and second deflection mirror surfaces, respectively, and the light beam from the first light source is deflected by the first deflection mirror surface, while the second deflection mirror surface. The light beam from the second light source is deflected. In this way, two movable members are provided to deflect the light beam, and vibrate with the same amplitude and in opposite phases. Therefore, the sum of inertia torque becomes zero. As a result, the cause of the noise is removed from the deflector which is one of the noise generation sources in the image forming apparatus, and the image forming apparatus is reduced in noise. Further, since the light beam emission source is alternately switched between the first and second light sources each time the light beam is scanned forward to form a line latent image (forward writing), the light beam from the first light source is switched. The forward writing by, and the forward writing by the light beam from the second light source are performed during one vibration period (reciprocal of the mirror driving frequency) of the deflecting mirror surface, so that the resolution can be improved. In addition, since image formation is performed only by forward writing, the scanning pitch in the sub-scanning direction substantially orthogonal to the main scanning direction is constant, and density unevenness can be prevented.

  According to a third aspect of the present invention, a light beam is scanned in the main scanning direction for each of the N colors (N ≧ 2) different from each other by the exposure unit, and a latent image is formed on the latent image carrier. In order to achieve the above object, the exposure unit corresponds to (a) each of the N latent image carriers. N light sources provided to emit light beams, and (b) each of the light beams from the N light sources is reflected toward the latent image carrier corresponding to the light beams in the main scanning direction. The deflector (b) is provided corresponding to each of the (b-1) N light sources and is arranged in series spaced apart from each other along a predetermined drive axis. And (b-2) connecting N movable members provided along the drive shaft. A plurality of torsion springs that support the shaft, and (b-3) a vibration driving unit that generates a driving force for vibrating the N movable members around the driving shaft at the same driving frequency. A deflection mirror surface on which the light beam from the light source corresponding to the movable member is formed on the surface of the movable member by each of the N movable members while the N movable members vibrate with the same amplitude by receiving the driving force. The phase of each movable member is set such that the inertia torque generated by each movable member when the N movable members are vibrated and the N movable members are vibrated is mutually canceled.

  In the invention thus configured, each of the light beams from the N light sources is reflected by the deflector toward the latent image carrier and deflected in the main scanning direction. In this deflector, N movable members provided corresponding to each of the N light sources are arranged in series spaced apart from each other along the drive shaft and connected by a plurality of torsion springs around the drive shaft. It is pivotally supported. In response to the driving force from the vibration driving unit, the N movable members vibrate with the same amplitude around the driving shaft. Each of the N movable members deflects the light beam from the light source corresponding to the movable member by a deflection mirror surface formed on the surface of the movable member. In the present invention, the phases of the movable members are set so that the inertia torques generated by the movable members when the N movable members are vibrated cancel each other. That is, the deflector is configured so that the sum of inertia torques becomes zero. As a result, the cause of the noise is removed from the deflector which is one of the noise generation sources in the image forming apparatus, and the image forming apparatus is reduced in noise.

  Further, according to a fourth aspect of the present invention, an exposure unit scans each of the first to fourth latent image carriers in the main scanning direction to form a latent image on the latent image carrier. An image forming apparatus that forms an image by developing a latent image formed on each of the first to fourth latent image carriers with a color developing unit. To achieve the above object, the exposure unit includes: ) First to fourth light sources provided corresponding to the first to fourth latent image carriers, respectively, and emitting light beams; and (b) each of the light beams from the first to fourth light sources. A deflector that reflects toward the latent image carrier corresponding to the beam and deflects in the main scanning direction. The deflector (b) has the same configuration as (b-1), and has a predetermined drive shaft. Two movable members arranged in series apart from each other along (b-2) A plurality of torsion springs provided along the axis of movement to support and support two movable members; and (b-3) for vibrating the two movable members around the drive axis at the same drive frequency. A vibration drive unit that generates a drive force, and the two movable members are formed on one surface of the first movable member while receiving the drive force from the vibration drive unit and vibrating in the same amplitude and in opposite phases. The light beam from the first light source is deflected by the first deflecting mirror surface and at the same time the light beam from the second light source is deflected by the first deflecting mirror surface formed on the other surface. The light beam from the third light source is deflected by the formed third deflection mirror surface, and at the same time, the light beam from the fourth light source is deflected by the fourth deflection mirror surface formed on the other surface.

In the invention thus configured, each of the light beams from the four light sources is reflected by the deflector toward the latent image carrier and deflected in the main scanning direction. In this deflector, two movable members having the same configuration are arranged in series spaced apart from each other along the drive shaft, and are connected to each other by a plurality of torsion springs so as to vibrate freely around the drive shaft. In response to the driving force from the vibration driving unit, the two movable members vibrate with the same amplitude and the same amplitude around the drive shaft in the opposite phase to deflect the light beams emitted from the respective light sources. Therefore, the deflector is configured so that the sum of inertia torques becomes zero. As a result, the cause of the noise is removed from the deflector which is one of the noise generation sources in the image forming apparatus, and the image forming apparatus is reduced in noise. The light beams from the first to fourth light sources are scanned simultaneously as follows.
(1) The light beam from the first light source is deflected by a first deflection mirror surface formed on one surface of the first movable member.
(2) The light beam from the second light source is deflected by the second deflection mirror surface formed on the other surface of the first movable member.
(3) The light beam from the third light source is deflected by a third deflection mirror surface formed on one surface of the second movable member.
(4) The light beam from the fourth light source is deflected by the fourth deflection mirror surface formed on the other surface of the second movable member.
As described above, since the light beam can be scanned by the two movable members with respect to the four latent image carriers, the configuration of the apparatus can be simplified.

  The present invention aims to suppress noise by reducing the noise of a deflector which is one of noise generation sources in an image forming apparatus. Therefore, the inventor of the present application has studied a mechanism for generating noise in a so-called galvano-type deflector, and has created a noise suppression technique based on the examination result. Hereinafter, “noise generation mechanism and suppression technology”, “embodiment of deflector”, and “image forming apparatus using the deflector” will be described in detail.

<Noise generation mechanism and suppression technology>
FIG. 1 is a diagram showing a basic configuration of a deflector. As shown in the figure, a conventionally known galvanometer mirror (deflector) 65 includes a movable member 652 having a deflection mirror surface 651 formed on the surface thereof, and a movable member 652 attached to the upper and lower ends of the movable member 652, respectively. And a torsion spring 653 that pivotally supports 652. These torsion springs 653 are extended in a drive axis direction Y substantially orthogonal to the main scanning direction X for scanning the light beam, and support the movable member 652 so as to vibrate around the drive axis AX. The deflector 65 is provided with a vibration driving unit 654 for generating a driving force for vibrating the movable member 652. When a mirror drive signal is input to the vibration drive unit 654, the movable member 652 resonates and vibrates at the same frequency as the frequency of the mirror drive signal, and a light source is generated by the deflecting mirror surface 651 formed on the surface of the movable member 652. Is deflected in the main scanning direction X.

  Here, the inertia torque T of the movable member 652 vibrating as described above will be examined. When the movable member 652 vibrates at the angular frequency ω, the displacement angle θ of the deflection mirror surface formed on the movable member 652 at time t, that is, the deflection angle θ from the stationary state (broken line in the figure) is as follows. It can be obtained by an expression.

なお、式１中の符号θ0は可動部材６５２の最大変位角、つまり振幅である。

The symbol θ 0 in Equation 1 is the maximum displacement angle of the movable member 652, that is, the amplitude.

  Further, the first-order differential of the displacement angle θ becomes the rotational speed of the movable member 652, and the rotational speed can be obtained by the following equation.

また、変位角θの２階微分が可動部材６５２の回転加速度となり、その回転加速度を次式で求めることができる。

Further, the second-order derivative of the displacement angle θ becomes the rotational acceleration of the movable member 652, and the rotational acceleration can be obtained by the following equation.

したがって、振動している可動部材６５２に発生する慣性トルクＴについては次式で求めることができる。

Therefore, the inertia torque T generated in the vibrating movable member 652 can be obtained by the following equation.

なお、式４中の符号Ｉは可動部材６５２の慣性モーメントを示している。

Note that the symbol I in Equation 4 indicates the moment of inertia of the movable member 652.

  As the movable member 652 vibrates in this manner, an inertia torque T is generated and applied to an external fixing member such as a frame or a case that supports the torsion spring 653, and the case of the external fixing member or the deflector 65 vibrates and generates noise. Was causing. Normally, since the deflector 65 is used by being incorporated in an optical scanning device or an image forming apparatus as will be described later, vibration from the deflector 65 is propagated to the apparatus housing and the like, and noise tends to increase due to a resonance phenomenon. is there.

  Thus, since the inertial force generated by the movable member 652 cannot be suppressed if the single movable member 652 is resonantly vibrated, the inventors of the present application have considered increasing the number of movable members to suppress noise. That is, when there are a plurality (n) of movable members 652 that vibrate on the same drive shaft AX, inertia torques T1, T2,... Tn generated by the movable members 6521, 6522,.

そして、慣性トルクの総和がゼロになるように偏向器６５を構成することによって、騒音の原因を取り除き、低騒音の偏向器６５が得られる。

Then, by configuring the deflector 65 so that the total sum of inertia torques becomes zero, the cause of noise is eliminated, and the deflector 65 with low noise is obtained.

このように慣性トルクの総和をゼロとするためには、可動部材の個数や各可動部材の形状に応じて振幅や位相を調整することができる。以下、本発明にかかる偏向器の実施形態について図面を参照しつつ詳述する。

Thus, in order to make the sum of inertia torques zero, the amplitude and phase can be adjusted according to the number of movable members and the shape of each movable member. Hereinafter, embodiments of a deflector according to the present invention will be described in detail with reference to the drawings.

<Embodiment of deflector>
FIG. 2 is a diagram showing a first embodiment of a deflector applicable to the image forming apparatus according to the present invention. In this deflector 65, as shown in FIGS. 2B and 2C, two movable members 6521 and 6522 are arranged in series apart from each other along the drive axis AX. Further, deflection mirror surfaces 6511 and 6512 are formed on the movable members 6521 and 6522, respectively, so that the light beam emitted from the light source can be reflected. Thus, in this embodiment, both the movable members 6521 and 6522 are reflection mirrors. Since the movable members 6521 and 6522 are made of the same material and have the same shape, the moments of inertia I1 and I2 of the movable members 6521 and 6522 have the same value. That means
I1 = I2 = I
It has become.

  The movable members 6521 and 6522 thus configured are connected to each other by a torsion spring 653 extending along the drive axis AX. Accordingly, the two movable members (reflection mirrors) 6521 and 6522 are pivotally supported by the three torsion springs 653 so as to freely vibrate around the drive axis AX. Although not shown in FIG. 2, a vibration driving unit 654 is provided to generate a driving force for vibrating the movable member 652, as in the deflector of FIG. This also applies to later embodiments. When a mirror drive signal is input to the vibration drive unit 654, the movable members 6521 and 6522 are resonantly vibrated at the same frequency as the frequency of the mirror drive signal, and are formed on the surfaces of the movable members 6521 and 6522. The light beams emitted from the light source are deflected in the main scanning direction X by the deflecting mirror surfaces 6511 and 6512.

  In this embodiment, by selecting the configuration of the torsion spring 653, the movable members 6521 and 6522 are adjusted so as to vibrate with the same amplitude and opposite phase as shown in FIG. Therefore, for example, when the displacement angle θ1 of the first deflection mirror surface 6511 formed on the movable member 6521 reaches the maximum value (−θ0) (time T1), the displacement of the second deflection mirror surface 6512 formed on the movable member 6522 The angle θ2 is the maximum value (+ θ0). Therefore, in this embodiment, the rotational acceleration of the movable members 6521 and 6522 has the following relationship.

したがって、可動部材６５２１、６５２２で発生する慣性トルクの総和Ｔは次式となる。

Accordingly, the sum T of inertia torques generated by the movable members 6521 and 6522 is expressed by the following equation.

このように、この実施形態では、慣性トルクの総和Ｔがゼロになり、この結果、偏向器６５から発生する騒音を効果的に抑制することができる。

Thus, in this embodiment, the total sum T of the inertia torque becomes zero, and as a result, noise generated from the deflector 65 can be effectively suppressed.

FIG. 3 is a diagram showing a second embodiment of a deflector applicable to the image forming apparatus according to the present invention. The second embodiment is greatly different from the first embodiment in that it has three movable members 6521 to 6523 and a phase relationship between the movable members 6521 to 6523 is different. That is, in the deflector 65 according to the second embodiment, as shown in FIG. 5A, the three movable members 6521 to 6523 are spaced apart from each other in series along the drive axis AX. Further, deflection mirror surfaces 6511 to 6513 are formed on the movable members 6521 to 6523, respectively, so that the light beam emitted from the light source can be reflected. These movable members 6521 to 6523 are reflection mirrors made of the same material and having the same shape. For this reason, the moments of inertia I1 to I3 of the movable members 6521 to 6523 have the same value. That means
I1 = I2 = I3 = I
It has become.

  In addition, the movable members 6521 to 6523 configured as described above are connected to each other by a torsion spring 653 extending along the drive axis AX so as to freely vibrate around the drive axis AX. When a mirror drive signal is input to the vibration drive unit 654 (FIG. 1), the movable members 6521 to 6523 resonate at the same frequency as the mirror drive signal due to the drive force generated by the vibration drive unit 654. The light beam that is vibrated and emitted from the light source is deflected in the main scanning direction X by the deflecting mirror surfaces 6511 to 6513 formed on the surfaces of the movable members 6521 to 6523.

  In this embodiment, in order to suppress noise, by selecting the configuration of the torsion spring 653, the first to third deflection mirror surfaces respectively formed on the movable members 6521 to 6523 as shown in FIG. 6511 (M1) to 6513 (M3) are adjusted so as to vibrate with the same amplitude and with rotational phases shifted from each other by 120 °. For this reason, the angular relationship between the deflecting mirror surfaces 6511 (M1) to 6513 (M3) changes as shown in the lowermost stage of FIG. Accordingly, the sum T of inertia torques generated by the movable members 6521 to 6523 is expressed by the following equation.

このように、この実施形態においても、慣性トルクの総和Ｔがゼロになり、この結果、偏向器６５から発生する騒音を効果的に抑制することができる。

Thus, also in this embodiment, the total sum T of inertia torque becomes zero, and as a result, noise generated from the deflector 65 can be effectively suppressed.

FIG. 4 is a diagram showing a third embodiment of a deflector applicable to the image forming apparatus according to the present invention. The third embodiment is greatly different from the second embodiment in that the shape relationship and phase relationship of the three movable members 6521 to 6523 are different. That is, in the deflector 65 according to the third embodiment, as shown in FIG. 6A, the heights H1 to H3 of the movable members 6521 to 6523 in the drive shaft direction Y have the following relationship. Yes. In other words,
H2 = 2 ・ H1 = 2 ・ H3
It has become. For this reason, the moments of inertia I1 to I3 of the movable members 6521 to 6523 also have the same relationship as the height relationship. That means
I2 = 2 ・ I1 = 2 ・ I3 = 2 ・ I
It has become.

  Further, in this embodiment, in order to suppress noise, the configuration of the torsion spring 653 is selected so that the following two conditions are satisfied as shown in FIG. The first condition is that first to third deflection mirror surfaces 6511 (M1) to 6513 (M3) formed on the movable members 6521 to 6523, respectively, vibrate with the same amplitude. The second condition is that the first and third deflection mirror surfaces 6511 (M1) and 6513 (M3) vibrate in the same phase, while the second deflection mirror surface 6512 (M2) is the first and third deflections. It vibrates in the opposite phase to the mirror surfaces 6511 (M1) and 6513 (M3). For this reason, the angular relationship between the deflecting mirror surfaces 6511 (M1) to 6513 (M3) changes as shown in the lowermost stage of FIG. Accordingly, the sum T of inertia torques generated by the movable members 6521 to 6523 is expressed by the following equation.

このように、この実施形態においても、慣性トルクの総和Ｔがゼロになり、この結果、偏向器６５から発生する騒音を効果的に抑制することができる。

Thus, also in this embodiment, the total sum T of inertia torque becomes zero, and as a result, noise generated from the deflector 65 can be effectively suppressed.

FIG. 5 is a diagram showing a fourth embodiment of a deflector applicable to the image forming apparatus according to the present invention. The fourth embodiment is greatly different from the second embodiment in that the shape relationship and the phase relationship of the three movable members 6521 to 6523 are different. That is, in the deflector 65 according to the fourth embodiment, as shown in FIG. 5A, the heights H1 to H3 of the movable members 6521 to 6523 in the drive shaft direction Y have the following relationship. Yes. In other words,
H2 = 4 ・ H1 = 4 ・ H3
It has become. For this reason, the moments of inertia I1 to I3 of the movable members 6521 to 6523 also have the same relationship as the height relationship. That means
I2 = 4 ・ I1 = 4 ・ I3 = 4 ・ I
It has become.

  Further, in this embodiment, in order to suppress noise, the configuration of the torsion spring 653 is selected so that the following two conditions are satisfied as shown in FIG. The first condition is that the first and third deflection mirror surfaces 6511 (M 1) and 6513 (M 3) formed on the movable members 6521 and 6523 vibrate with the same amplitude θ 0, while the first and third deflection mirror surfaces 6511 (M 3) are formed on the movable member 6522. The two-deflecting mirror surface 6512 (M2) vibrates with a half amplitude (θ0 / 2). The second condition is that the first and third deflection mirror surfaces 6511 (M1) and 6513 (M3) vibrate in the same phase, while the second deflection mirror surface 6512 (M2) is the first and third deflections. It vibrates in the opposite phase to the mirror surfaces 6511 (M1) and 6513 (M3). For this reason, the angular relationship between the deflecting mirror surfaces 6511 (M1) to 6513 (M3) changes as shown in the lowermost stage of FIG. Accordingly, the sum T of inertia torques generated by the movable members 6521 to 6523 is expressed by the following equation.

このように、この実施形態においても、慣性トルクの総和Ｔがゼロになり、この結果、偏向器６５から発生する騒音を効果的に抑制することができる。

Thus, also in this embodiment, the total sum T of inertia torque becomes zero, and as a result, noise generated from the deflector 65 can be effectively suppressed.

FIG. 6 is a diagram showing a fifth embodiment of a deflector applicable to the image forming apparatus according to the present invention. FIG. 7 is a diagram showing the operation of the deflector of FIG. The fifth embodiment is greatly different from the first embodiment in that it has four movable members 6521 to 6524 and a phase relationship between the movable members 6521 to 6524 is different. That is, in the deflector 65 according to the fifth embodiment, as shown in FIG. 6, the four movable members 6521 to 6524 are arranged in series apart from each other along the drive axis AX. In addition, deflection mirror surfaces 6511 to 6514 are formed on the movable members 6521 to 6524, respectively, so that the light beam emitted from the light source can be reflected. Thus, the movable members 6521 to 6524 are all made of the same material and are reflection mirrors having the same shape. For this reason, the moments of inertia I1 to I4 of the movable members 6521 to 6524 have the same value. That means
I1 = I2 = I3 = I4 = I
It has become.

  In addition, the movable members 6521 to 6524 configured as described above are connected to each other by a torsion spring 653 extending along the drive axis AX and can freely vibrate around the drive axis AX. When a mirror drive signal is input to the vibration drive unit 654 (FIG. 1), the movable members 6521 to 6524 resonate at the same frequency as the mirror drive signal due to the drive force generated by the vibration drive unit 654. The light beam emitted from the light source is deflected in the main scanning direction X by the deflecting mirror surfaces 6511 to 6514 formed on the surfaces of the movable members 6521 to 6524.

  In this embodiment, in order to suppress noise, the configuration of the torsion spring 653 is selected so that the following two conditions are satisfied. The first condition is that the first to fourth deflection mirror surfaces 6511 (M1) to 6514 (M4) formed on the movable members 6521 to 6524 respectively vibrate with the same amplitude. The second condition is that the first and fourth deflection mirror surfaces 6511 (M1) and 6514 (M4) vibrate in the same phase, while the second and third deflection mirror surfaces 6512 (M2) and 6513 (M3). ) Vibrate in the opposite phase to the first and fourth deflection mirror surfaces 6511 (M1) and 6514 (M4). Therefore, the angular relationship between the deflecting mirror surfaces 6511 (M1) to 6514 (M4) changes as shown in the lowermost stage of FIG. Therefore, the sum T of inertia torques generated by the movable members 6521 to 6524 is expressed by the following equation.

このように、この実施形態においても、慣性トルクの総和Ｔがゼロになり、この結果、偏向器６５から発生する騒音を効果的に抑制することができる。

Thus, also in this embodiment, the total sum T of inertia torque becomes zero, and as a result, noise generated from the deflector 65 can be effectively suppressed.

  In the first to fifth embodiments, the deflection mirror surfaces are formed for all the movable members. However, the deflection mirror surfaces may be formed only for some of the movable members. . In this case, the movable member having the deflection mirror surface functions as a reflection mirror that reflects the light beam, while the remaining movable members function for noise prevention. An example of such a deflector is shown in FIG.

  FIG. 8 is a diagram showing a sixth embodiment of a deflector applicable to the image forming apparatus according to the present invention. The sixth embodiment differs greatly from the first embodiment in that the movable member 6522 has no deflection mirror surface, and the surface of the movable member 6522 is a surface NM that does not deflect the light beam. . Of course, when a mirror surface is formed on the surface of the movable member 6522, but the light beam from the light source is not incident on the mirror surface, the mirror surface can be substantially regarded as the surface NM. Other configurations and operations are exactly the same as those in the first embodiment. When the deflector 65 configured as described above is used, only the deflection mirror surface 6511 is irradiated with the light beam, and the light beam is scanned.

  In the above embodiment, the deflection mirror surface is formed only on the surface of the movable member, but the deflection mirror surface may be formed on both surfaces. In particular, a deflector having deflection mirror surfaces on both sides is suitable for a tandem type image forming apparatus as will be described later.

<Image Forming Apparatus Using Deflector>
The deflector configured as described above can be applied to various image forming apparatuses. Hereinafter, embodiments of the image forming apparatus according to the present invention using the deflector will be described in detail with reference to the drawings.

<< First Image Forming Apparatus >>
FIG. 9 is a view showing an image forming apparatus using the sixth embodiment of the deflector. FIG. 10 is a block diagram showing an electrical configuration of the image forming apparatus of FIG. This image forming apparatus (hereinafter referred to as “first image forming apparatus”) is a so-called four-cycle color printer. That is, in this image forming apparatus, when an image forming command is given from an external device such as a host computer to the main controller 11 having a CPU, a memory and the like in response to a user's image forming request, an image corresponding to the image forming command is displayed. Signals, control signals, and the like are given from the main controller 11 to the engine controller 10 and the engine unit EG. Then, the CPU of the engine controller 10 controls each part of the engine unit EG to form an image corresponding to the image formation command on the sheet S such as copy paper, transfer paper, paper, and OHP transparent sheet.

  In the engine unit EG, the photosensitive member 2 is rotatably provided in the arrow direction (sub-scanning direction) in FIG. Further, a charging unit 3, a rotary developing unit 4, and a cleaning unit (not shown) are arranged around the photoconductor 2 along the rotation direction. A predetermined charging bias is applied to the charging unit 3 from the engine controller 10. By applying this bias, the outer peripheral surface of the photoreceptor 2 is uniformly charged to a predetermined surface potential. Further, the photosensitive member 2, the charging unit 3, and the cleaning unit integrally constitute a photosensitive member cartridge, and the photosensitive member cartridge is integrally detachable from the apparatus main body 5.

  Then, the light beam L is irradiated from the exposure unit 6 toward the outer peripheral surface of the photosensitive member 2 charged by the charging unit 3. As a result, an electrostatic latent image corresponding to the image data included in the image formation command is formed on the photoreceptor 2. Thus, the exposure unit 6 corresponds to the optical scanning device according to the present invention, and the configuration and operation thereof will be described in detail later.

  The electrostatic latent image thus formed is developed with toner by the developing unit 4. That is, in this embodiment, the developing unit 4 is configured as a support frame 40 that is rotatably provided around the axis, and a cartridge that is detachable with respect to the support frame 40, and for yellow that contains toner of each color. A developing unit 4Y, a magenta developing unit 4M, a cyan developing unit 4C, and a black developing unit 4K are provided. Then, based on a control command from a developing device controller (not shown) of the engine controller 10, the developing unit 4 is driven to rotate, and these developing devices 4Y, 4C, 4M, and 4K are selectively connected to the photoreceptor 2. When positioned at a predetermined development position that abuts or opposes with a predetermined gap, toner is applied to the surface of the photoreceptor 2 from a developing roller 44 that is provided in the developing unit and carries toner of a selected color. Give. As a result, the electrostatic latent image on the photoreceptor 2 is visualized with the selected toner color.

  The toner image developed by the developing unit 4 as described above is primarily transferred onto the intermediate transfer belt 71 of the transfer unit 7 in the primary transfer region TR1. The transfer unit 7 includes an intermediate transfer belt 71 that is stretched over a plurality of rollers 72, 73, and the like, and a drive unit (not shown) that rotates the intermediate transfer belt 71 in a predetermined rotation direction by rotationally driving the roller 73. It has. A transfer belt cleaner (not shown) is disposed in the vicinity of the roller 72.

  When transferring a color image to a sheet, each color toner image formed on the photoreceptor 2 is superimposed on the intermediate transfer belt 71 to form a color image and taken out from the cassette 8 one by one. The color image is secondarily transferred onto the sheet conveyed along the conveyance path F to the secondary transfer region TR2.

  At this time, in order to correctly transfer the image on the intermediate transfer belt 71 to a predetermined position on the sheet, the timing of feeding the sheet to the secondary transfer region TR2 is managed. Specifically, a gate roller 81 is provided on the transport path F on the front side of the secondary transfer region TR2, and the gate roller 81 rotates in accordance with the timing of the circumferential movement of the intermediate transfer belt 71. Are sent to the secondary transfer region TR2 at a predetermined timing.

  Further, the sheet on which the color image is formed in this way is conveyed to the discharge tray portion 51 provided on the upper surface portion of the apparatus main body 5 via the fixing unit 9 and the discharge roller 82. When images are formed on both sides of the sheet, the sheet on which the image is formed on one side as described above is switched back by the discharge roller 82. As a result, the sheet is conveyed along the reverse conveyance path FR. Then, it is put again on the transport path F before the gate roller 81. At this time, the image is transferred to the surface of the sheet that is in contact with the intermediate transfer belt 71 and transfers the image in the secondary transfer region TR2. The surface is the opposite of the surface. In this way, images can be formed on both sides of the sheet.

  FIG. 11 is a main scanning sectional view showing the structure of an exposure unit equipped in the image forming apparatus of FIG. FIG. 12 is a sub-scan sectional view of the exposure unit. FIG. 13 is a diagram showing an exposure unit and an exposure control unit for controlling the exposure unit of the image forming apparatus of FIG. FIG. 14 is a view showing a deflector as one component of the exposure unit. Hereinafter, the configuration and operation of the exposure unit 6 will be described in detail with reference to these drawings.

  As shown in FIG. 11, the exposure unit 6 has an exposure housing 61. A single laser light source 62 is fixed to the exposure housing 61, and a light beam can be emitted from the laser light source 62. The laser light source 62 is ON / OFF controlled based on the image signal Sv from the main controller 11, and a light beam modulated in accordance with the image signal Sv is emitted forward from the laser light source 62. That is, in this image forming apparatus, the video clock generator 111 is provided in the main controller 11 and outputs a video clock signal VC having a reference frequency, for example, 68 MHz. Then, the image output unit 112 creates an image signal Sv corresponding to the image data included in the image formation command given to the main controller 11 with the video clock signal VC as a reference. The image signal Sv is output to the laser light source 62 of the exposure unit 6, the light beam is modulated according to the image signal Sv, and the modulated light beam is emitted forward from the laser light source 62.

  Further, in the exposure housing 61, a collimator lens 631, a cylindrical lens 632, a mirror 64, and a deflector 65 are used to scan and expose the light beam from the laser light source 62 onto the surface (not shown) of the photoreceptor 2. A scanning lens 66 and a mirror 67 are provided. That is, the light beam from the laser light source 62 is shaped into collimated light of an appropriate size by the collimator lens 631 and then incident on the cylindrical lens 632 having power only in the sub-scanning direction Y. Then, by adjusting the cylindrical lens 632, the collimated light is imaged in the vicinity of the deflection mirror surface 651 of the deflector 65 in the sub-scanning direction Y. Thus, in this embodiment, the collimator lens 631 and the cylindrical lens 632 function as the beam shaping system 63 that focuses the light beam from the laser light source 62 in the sub-scanning direction Y. Further, the beam shaping system 63 makes the focused light beam Li obliquely incident on the deflection mirror surface 6511 (M1) as shown in FIG. In other words, in this image forming apparatus, a mirror 64 is provided between the beam shaping system 63 and the deflecting mirror surface 6511 of the deflector 65 to constitute a so-called oblique incident structure. More specifically, the focused light beam Li is incident on the deflection mirror surface 6511 so as to form an acute angle γ with respect to the reference surface SS orthogonal to the drive axis AX of the deflection mirror surface 651 of the deflector 65.

  The deflector 65 is formed by using a micromachining technique in which a micromachine is integrally formed on a semiconductor substrate by applying a semiconductor manufacturing technique. The deflector 65 is a first deflector applicable to the image forming apparatus according to the present invention. It has the same configuration as the sixth embodiment. That is, the movable members 6521 and 6522 and the torsion spring 653 are integrally formed and are fixed to the external fixing member 655 of the deflector 65. Then, a mirror drive signal for driving the movable members 6521 and 6522 to the vibration drive unit 654 is applied from the mirror drive unit 121 of the exposure control unit 12. As a result, as shown in FIG. 8, the movable members 6521 and 6522 resonate and vibrate at the same frequency as that of the mirror drive signal, and the light beam Li is generated by the deflecting mirror surface 6511 (M1) formed on the surface of the movable member 6521. Is deflected in the main scanning direction X.

  This scanning light beam forms an image on the photosensitive member 2 via the scanning lens 66 and the folding mirror 67, and a light beam spot is formed on the photosensitive member surface 21. In this embodiment, the scanning lens 66 is composed of a single lens, but the lens configuration is not limited to this, and may be composed of a plurality of lenses as in a third embodiment to be described later. . Note that reference numeral OA in FIG. 11 indicates the optical axis of the scanning lens 66.

  Further, the light beam thus scanned in the main scanning direction X is guided to the light detection sensor 60 by the folding mirror 69. In addition, a signal Hsync output by the sensor 60 detecting and outputting a light beam is given to the writing timing adjusting unit 102 of the engine controller 10. The write timing adjusting unit 102 is supplied with a clock signal for timing from the count clock generating unit 103 of the engine controller 10, and based on this clock signal for timing, the write timing adjusting unit 102 has elapsed from the detection signal Hsync. Time is measured, and video request (write request) signals Vreq are sequentially output to the image output unit 112 at an appropriate timing. Upon receiving the video request signal Vreq, the image output unit 112 outputs the image signal Sv with reference to the video clock signal VC. In this way, the writing timing adjusting unit 102 adjusts the output timing of the video request signal Vreq, thereby adjusting the latent image writing position in the main scanning direction X. In this embodiment, the frequency of the clock signal for timing is set to a value larger than that of the video clock signal VC, for example, four times the frequency of the video clock signal VC. As a result, the video request signal Vreq can be controlled with high resolution, and the writing start position of the latent image can be accurately controlled.

  The detection signal Hsync of the scanning light beam from the light detection sensor 60 is also transmitted to the measurement unit 123 of the exposure control unit 12, and the measurement unit 123 calculates drive information related to the scanning time of the light beam and the drive cycle. The The actual measurement information calculated by the measuring unit 123 is transmitted to the mirror driving unit 121, and the mirror driving unit 121 adjusts the mirror driving signal as necessary.

  As described above, in the first image forming apparatus shown in FIG. 9, since the image is formed by scanning the light beam using the deflector 65 according to the sixth embodiment, noise generated from the deflector 65 is reduced. Therefore, the noise of the image forming apparatus can be reduced.

<< Second Image Forming Apparatus >>
By the way, in the first image forming apparatus configured as described above, since the deflection mirror surface 6511 is resonantly oscillated, the light beam from the laser light source 62 is scanned on the photoreceptor surface 21 in both the forward path and the backward path. The resolution can be increased by executing the double-sided scanning mode.

  However, the scanning trajectory of the spot on the photosensitive member surface 21 in the double-sided scanning mode is as indicated by the alternate long and short dash line in FIG. Accordingly, in the double-sided scanning mode, when a latent image is formed by scanning a spot on the photosensitive member surface 21, the scanning pitch in the sub-scanning direction Y is not constant, so that the degree of spot overlap in the sub-scanning direction Y varies. Will occur. That is, when the scanning pitch in the sub-scanning direction Y is narrow, the overlap of spots in the sub-scanning direction Y becomes large, whereas when the scanning pitch in the sub-scanning direction Y is wide, the overlap of spots in the sub-scanning direction Y is large. Get smaller. Therefore, in the double-sided scanning mode, color shading may occur corresponding to the non-uniformity of the scanning pitch in the sub-scanning direction Y.

  Therefore, in order to increase the resolution without causing uneven density, it is desirable to configure the image forming apparatus using the deflector according to the first embodiment. Hereinafter, this image forming apparatus (hereinafter referred to as “second image forming apparatus”) will be described with reference to the drawings. The second image forming apparatus is largely different from the first image forming apparatus in the configuration and operation of the exposure unit (optical scanning device), and other configurations are the same as those in the apparatus in FIG. Therefore, in the following description, it demonstrates centering around difference, the same code | symbol is attached | subjected about the same structure and description is abbreviate | omitted.

  FIG. 16 is a main scanning sectional view showing a configuration of an exposure unit provided in the second image forming apparatus. FIG. 17 is a sub-scan sectional view of the exposure unit. FIG. 18 is a view showing an exposure unit and an exposure control unit for controlling the exposure unit. FIG. 19 is a view showing a deflector as one component of the exposure unit.

  The exposure unit (optical scanning device) in the second image forming apparatus is greatly different from that of the first image forming apparatus in that the deflector 65 (FIG. 2) according to the first embodiment is employed and the light The upper scanning system 6U and the lower scanning system 6D are provided as scanning systems for scanning the beam. Each of these scanning systems 6U and 6D has the same configuration as the scanning system shown in FIGS. 11 and 12, and is vertically arranged with the optical axis OA of the scanning lens 66 interposed therebetween. That is, as shown in FIGS. 17 and 19, in the second image forming apparatus, the deflector 65 according to the first embodiment is used as a deflector, and corresponds to the deflection mirror surface 6511 of the deflector 65. While an upper scanning system 6U is provided, a lower scanning system 6D is provided corresponding to the deflection mirror surface 6512.

  In the upper scanning system 6U, as shown in FIGS. 16 and 17, a laser light source 62U is provided corresponding to the deflection mirror surface 6511 (651U). The light beam emitted from the laser light source 62U is shaped into a focused light beam Li by a beam shaping system 63D constituted by a collimator lens 631U and a cylindrical lens 632U, and further, a deflecting mirror surface of the deflector 65 via a mirror 64U. 6511 (651U). In this deflector 65, the movable members 6521 and 6522 resonate and vibrate at the same frequency as that of the mirror drive signal, and the light beam Li of the laser light source 62U is formed by the deflection mirror surface 6511 (651U) formed on the surface of the movable member 6521. Is deflected in the main scanning direction X. Then, the scanning light beam forms an image on the photosensitive member 2 through the scanning lens 66 and the folding mirror 67, and a light beam spot is formed on the photosensitive member surface 21. Thus, the laser light source 62U corresponds to the “first light source”.

  On the other hand, the lower scanning system 6D is configured similarly to the upper scanning system 6U. That is, the laser light source 62D is provided as a “second light source” corresponding to the deflection mirror surface 6512 (651D). The light beam emitted from the laser light source 62D is shaped into a focused light beam Li by the beam shaping system 63D, and is incident on the deflecting mirror surface 6512 (651D) of the deflector 65 via the mirror 64D. The light beam Li of the laser light source 62D is deflected in the main scanning direction X by the deflection mirror surface 6512 (651D) formed on the surface of the movable member 6522. This scanning light beam forms an image on the photosensitive member 2 via the scanning lens 66 and the folding mirror 67, and a light beam spot is formed on the photosensitive member surface 21.

  As described above, the second image forming apparatus includes the two scanning systems 6U and 6D, and the deflecting mirror surfaces 6511 (651U) and 6512 (651D) vibrate in mutually opposite phases. At the location, the light beam scans in the forward direction by one scanning system, and at the same time, the light beam scans in the backward direction by the other scanning system. Therefore, as shown in FIG. 20, the forward writing (1) is performed in the effective image area by emitting the modulated light beam from the laser light source 62U while the optical beam is forward scanned by the upper scanning system 6U. During this period, the laser light source 62D of the lower scanning system 6D is turned off (return scan (1)). When the latent image formation for one line is completed and the displacement directions of the movable members 6521 and 6522 are switched, the laser light source 62D is reversely scanned while the light beam is being scanned forward by the lower scanning system 6D. Outgoing writing (2) can be performed within the effective image area by emitting a modulated light beam from the laser beam 62 during this period, and during this time, the laser light source 62U of the upper scanning system 6U is turned off (return scanning (2)). In this way, each time a light beam is scanned in the forward direction to form a line latent image (outward writing), the light beam emission source is alternately switched between the laser light sources 62U and 62D to form a latent image in the double-sided scanning mode. The same resolution can be obtained as when. In addition, since the forward writing is always performed, the scanning pitch in the sub-scanning direction Y is constant, and density unevenness can be prevented. As a result, according to the second image forming apparatus, an image with high resolution and good image quality can be formed with low noise.

  In the second image forming apparatus, a single light beam is emitted from each of the light sources 62U and 62D, but a configuration in which a plurality of light beams are emitted may be employed. For example, in an image forming apparatus that emits two modulated light beams from each of the light sources 62U and 62D, forward writing is performed in units of two as shown in FIG. As described above, the point where the light source emits a plurality of light beams can be employed in the first image forming apparatus and the image forming apparatus described later.

<< Third Image Forming Apparatus >>
The first and second image forming apparatuses are so-called four-cycle color printers, but the application target of the present invention is not limited to this, and a so-called tandem color image forming apparatus or a single-color image is formed. The above deflector can be applied to a monochrome image forming apparatus. Hereinafter, a tandem color image forming apparatus according to the present invention will be described with reference to the drawings.

  FIG. 23 is a diagram showing an image forming apparatus using the fifth embodiment of the deflector. This image forming apparatus (hereinafter referred to as “third image forming apparatus”) is a so-called tandem color printer, and yellow (Y), magenta (M), cyan (C), and black (K) as latent image carriers. The four color photoconductors 2Y, 2M, 2C, and 2K are arranged in the apparatus main body 5 side by side. The apparatus forms a full-color image by superimposing the toner images on the photoreceptors 2Y, 2M, 2C, and 2K, or forms a monochrome image using only the black (K) toner image. That is, in this image forming apparatus, when an image forming command is given from an external device such as a host computer to the main controller 11 having a CPU, a memory and the like in response to a user's image forming request, an image corresponding to the image forming command is displayed. Signals, control signals, and the like are given from the main controller 11 to the engine controller 10 and the engine unit EG. Then, the CPU of the engine controller 10 controls each part of the engine unit EG to form an image corresponding to the image formation command on the sheet S such as copy paper, transfer paper, paper, and OHP transparent sheet.

  In the engine unit EG, a charging unit, a developing unit, and a cleaning unit are provided for each of the four photoconductors 2Y, 2M, 2C, and 2K. Since the structure of the charging unit, the developing unit, and the cleaning unit is the same for all color components, the structure related to yellow will be described here, and the other color components will be denoted by the same reference numerals and description thereof will be omitted. .

  The photoreceptor 2Y is rotatably provided in the direction of the arrow in FIG. A charging unit 3Y, a developing unit 4Y, and a cleaning unit (not shown) are arranged around the photoreceptor 2Y along the rotation direction. The charging unit 3Y is composed of, for example, a scorotron charger, and uniformly charges the outer peripheral surface of the photoreceptor 2Y to a predetermined surface potential by applying a charging bias from a charging control unit (not shown) of the engine controller 10. Then, a scanning light beam Ly is emitted from the exposure unit 6 toward the outer peripheral surface of the photoreceptor 2Y charged by the charging unit 3Y. As a result, an electrostatic latent image corresponding to yellow image data included in the image formation command is formed on the photoreceptor 2Y. The exposure unit 6 is not dedicated to yellow but is provided in common for each color component, and operates according to a control command from an exposure control unit described later. The configurations and operations of the exposure unit 6 and the exposure control unit will be described in detail later.

  The electrostatic latent image formed in this way is developed with toner by the developing unit 4Y. The developing unit 4Y contains yellow toner. When a developing bias is applied from the developing device controller 104 to the developing roller 41Y, the toner carried on the developing roller 41Y partially adheres to each surface portion of the photoreceptor 2Y according to the surface potential. As a result, the electrostatic latent image on the photoreceptor 2Y is visualized as a yellow toner image. As the developing bias applied to the developing roller 41Y, a DC voltage or a voltage obtained by superimposing an AC voltage on the DC voltage can be used. In particular, the photosensitive member 2Y and the developing roller 41Y are spaced apart from each other. In a non-contact development type image forming apparatus that develops toner by flying toner with a voltage waveform in which an alternating voltage such as a sine wave, a triangular wave, or a rectangular wave is superimposed on a direct current voltage in order to efficiently fly the toner It is preferable that

  The yellow toner image developed by the developing unit 4Y is primarily transferred onto the intermediate transfer belt 71 of the transfer unit 7 in the primary transfer region TRy1. The color components other than yellow are also configured in exactly the same way as yellow, and a magenta toner image, a cyan toner image, and a black toner image are formed on the photoreceptors 2M, 2C, and 2K, respectively, and a primary transfer region. Primary transfer is performed on the intermediate transfer belt 71 by TRm1, TRc1, and TRk1, respectively.

  The transfer unit 7 includes an intermediate transfer belt 71 stretched between two rollers 72 and 73, and a belt driving unit (not shown) that rotates the intermediate transfer belt 71 in a predetermined rotation direction R2 by driving the roller 72 to rotate. ). Further, a secondary transfer roller 74 is provided at a position facing the roller 73 with the intermediate transfer belt 71 interposed therebetween, and is configured to be able to contact and separate with respect to the surface of the belt 71 by an electromagnetic clutch (not shown). Yes. When transferring a color image to the sheet S, the primary transfer timing is controlled to superimpose the toner images to form a color image on the intermediate transfer belt 71, and the color image is taken out from the cassette 8 and transferred to the intermediate transfer belt 71. The color image is secondarily transferred onto the sheet S conveyed to the secondary transfer region TR2 between the belt 71 and the secondary transfer roller 74. On the other hand, when a monochrome image is transferred to the sheet S, only the black toner image is formed on the photoreceptor 2K, and the monochrome image is secondarily transferred onto the sheet S conveyed to the secondary transfer region TR2. In addition, the sheet S that has received the secondary transfer of the image in this way is conveyed toward the discharge tray portion provided on the upper surface portion of the apparatus main body via the fixing unit 9.

  The surface potential of each of the photoreceptors 2Y, 2M, 2C, and 2K after the toner image is primarily transferred to the intermediate transfer belt 71 is reset by a neutralizing unit (not shown), and the toner remaining on the surface is cleaned. Then, the next charging is performed by the charging units 3Y, 3M, 3C, and 3K. A transfer belt cleaner 75 is disposed in the vicinity of the roller 72. Among these, the cleaner 75 can be moved toward and away from the roller 72 by an electromagnetic clutch (not shown). Then, the blade of the cleaner 75 abuts on the surface of the intermediate transfer belt 71 that is stretched over the roller 72 while moving to the roller 72 side, and the toner that remains on the outer peripheral surface of the intermediate transfer belt 71 after the secondary transfer. Remove.

  FIG. 24 is a sub-scan sectional view showing the structure of an exposure unit equipped in the image forming apparatus of FIG. FIG. 25 is a sub-scan sectional view in which the optical configuration of the exposure unit is developed. FIG. 26 is a view showing an exposure unit of the image forming apparatus of FIG. 23 and an exposure control unit for controlling the exposure unit. FIG. 27 is a view showing a deflector as one component of the exposure unit. Hereinafter, the configuration and operation of the exposure unit (optical scanning device) will be described in detail with reference to these drawings.

  The exposure unit 6 has an exposure housing 61. Four laser light sources 62Y, 62M, 62C, and 62K are fixed to the exposure casing 61 corresponding to the four color photoconductors (latent image carriers) 2Y, 2M, 2C, and 2K, respectively. Light beams can be emitted from 62Y, 62M, 62C, and 62K. Each of the laser light sources 62Y, 62M, 62C, and 62K is ON / OFF controlled based on the image signal Sv from the main controller 11, and a light beam modulated in accordance with the image signal Sv is emitted.

  In addition, a scanning system is configured inside the exposure housing 61 for scanning exposure of the modulated light beam emitted from the laser light source on the surface of the photosensitive member for each color. Here, a scanning system related to magenta among the four colors will be described with reference to FIG. 25, but the other toner colors are the same as magenta. In this magenta scanning system, as shown in FIG. 25, a beam shaping system 63M is used to scan and expose the light beam emitted from the magenta light source 62M onto the surface 21M of the magenta photoreceptor 2M. A deflector 65, a first scanning lens 661M, a folding mirror group 67, and a second scanning lens 662M according to the embodiment are provided. That is, the light beam from the magenta laser light source 62M is shaped into the focused light Li and incident on the deflecting mirror surface 6512 (M2) of the deflector 65, as in the first image forming apparatus.

  In the third image forming apparatus, as shown in FIG. 27, the deflector 65 of the fifth embodiment is used, and four movable members 6521 to 6524 are provided. The light beam from the magenta light source 62M is incident on the deflecting mirror surface 6512 (M2) provided on the movable member 6521, and is reflected by the deflecting mirror surface 6512 toward the magenta photoconductor 2M to be scanned in the main scanning direction X. To be biased. The other toner colors Y, C, and K are configured in the same manner as the magenta color. That is, the light beams emitted from the laser light sources 62Y, 62C, and 62K are incident on the deflecting mirror surfaces 6511 (M1), 6513 (M3), and 6514 (M4), respectively. The light beams are reflected by the deflecting mirror surfaces 6511 (M1), 6513 (M3), and 6514 (M4) toward the photoreceptors 2Y, 2C, and 2K and deflected in the main scanning direction X, respectively. Thus, in the third image forming apparatus, the laser light sources 62Y, 62M, 62C, and 62K are provided corresponding to the four color photoconductors (latent image carriers) 2Y, 2M, 2C, and 2K, respectively. Each color light beam is reflected toward the photoconductor corresponding to the light beam and deflected in the main scanning direction X.

  The scanning light beam Lm thus scanned by the deflecting mirror surface 6512 (M2) of the deflector 65 is applied to the surface 21M of the photoreceptor 2M selected via the first scanning lens 661M, the folding mirror group 67, and the second scanning lens 662M. Irradiation forms a line-like latent image. The other color components are exactly the same as magenta.

  In this way, the latent images formed by the photoreceptors 2Y, 2M, 2C, and 2K are developed by the developing units 4Y, 4M, 4C, and 4K, respectively, to form toner images of four colors. A color image is formed by superimposing these four color toner images on the intermediate transfer belt 71.

  As described above, in the image forming apparatus shown in FIG. 23, since the image is formed by scanning the light beam using the deflector 65 according to the fifth embodiment, noise generated from the deflector 65 is suppressed. Therefore, the noise of the image forming apparatus can be reduced.

  In the third image forming apparatus, the four movable members 6521 to 6524 are vibrated around the drive axis AX, and light beams are scanned by the deflection mirror surfaces 6511 to 6514 formed on the surfaces of the movable members 6521 to 6524. However, for example, as shown in FIG. 28, a deflector 65 having two movable members 6521 and 6522 may be used. In this embodiment, a deflection mirror surface is formed on each of the movable members 6521 and 6522 on the front and back surfaces. The light beam from the yellow laser light source 62Y is scanned by the deflection mirror surface formed on the back surface of the movable member 6522. The scanning light beam Ly is imaged on the surface of the photoreceptor 2Y via the first scanning lens 661B, the folding mirror 67, and the second scanning lens 662Y. The light beam from the magenta laser light source 62M is deflected by a deflecting mirror surface formed on the back surface of the movable member 6521. This scanning light beam Lm forms an image on the surface of the photoreceptor 2M via the first scanning lens 661B, the folding mirror 67, and the second scanning lens 662M. The light beam from the cyan laser light source 62C is deflected by a deflecting mirror surface formed on the surface of the movable member 6521. This scanning light beam Lc is imaged on the surface of the photoreceptor 2C via the first scanning lens 661F, the folding mirror 67, and the second scanning lens 662C. Further, the light beam from the black laser light source 62K is deflected by a deflecting mirror surface formed on the surface of the movable member 6522. This scanning light beam Lk forms an image on the surface of the photoreceptor 2K through the first scanning lens 661F, the folding mirror 67, and the second scanning lens 662K.

<Others>
The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, in the above-described image forming apparatus, the deflectors according to the first, fifth, and sixth embodiments are used, but other deflectors can be used. That is, an appropriate deflector is used according to the configuration of the image forming apparatus from among various deflectors configured to have a plurality of movable members and the sum of inertia torques generated by the movable members to be zero. be able to.

The figure which shows the basic composition of a deflector. 1 is a diagram showing a first embodiment of a deflector applicable to an image forming apparatus according to the present invention. FIG. 6 is a diagram showing a second embodiment of a deflector applicable to the image forming apparatus according to the present invention. FIG. 10 is a diagram showing a third embodiment of a deflector applicable to the image forming apparatus according to the invention. FIG. 10 is a diagram illustrating a fourth embodiment of a deflector applicable to the image forming apparatus according to the invention. FIG. 10 is a diagram showing a fifth embodiment of a deflector applicable to the image forming apparatus according to the invention. The figure which shows operation | movement of the deflector of FIG. FIG. 10 is a diagram illustrating a sixth embodiment of a deflector applicable to the image forming apparatus according to the invention. 1 is a diagram showing an embodiment of an image forming apparatus according to the present invention. FIG. 10 is a block diagram showing an electrical configuration of the image forming apparatus in FIG. 9. FIG. 10 is a main scanning sectional view showing a configuration of an exposure unit provided in the image forming apparatus of FIG. 9. FIG. 10 is a sub-scan sectional view of an exposure unit provided in the image forming apparatus of FIG. 9. The figure which shows the exposure control unit for controlling the exposure unit and exposure unit of the image forming apparatus of FIG. FIG. 10 is a diagram showing a deflector used in the image forming apparatus of FIG. 9. The figure which shows the scanning locus | trajectory in double-sided scanning mode. FIG. 6 is a main scanning sectional view showing a configuration of an exposure unit provided in the second image forming apparatus. FIG. 6 is a sub-scanning sectional view of an exposure unit provided in the second image forming apparatus. The figure which shows the exposure control unit for controlling the exposure unit and exposure unit with which the 2nd image forming apparatus was equipped. The figure which shows the deflector used in the 2nd image forming apparatus. FIG. 10 is a view showing the operation of an exposure unit equipped in the second image forming apparatus. FIG. 10 is a view showing the operation of an exposure unit equipped in the second image forming apparatus. The figure which shows the latent image formation operation | movement by the modification of a 2nd image forming apparatus. FIG. 6 is a diagram showing another embodiment of the image forming apparatus according to the present invention. FIG. 10 is a sub-scanning sectional view showing a configuration of an exposure unit provided in the third image forming apparatus. FIG. 10 is a sub-scan sectional view in which an optical configuration of an exposure unit provided in the third image forming apparatus is developed. The figure which shows the exposure control unit for controlling the exposure unit and exposure unit of a 3rd image forming apparatus. The figure which shows the deflector used in the 3rd image forming apparatus. The figure which shows the modification of a 3rd image forming apparatus.

Explanation of symbols

  2, 2Y, 2M, 2C, 2K ... photosensitive member (latent image carrier), 4, 4Y, 4M, 4C, 4K ... developing unit (or developing unit), 6 ... exposure unit (optical scanning device), 62, 62U , 62D, 62Y, 62M, 62C, 62K ... laser light source, 65 ... deflector, 6511-6514 ... deflection mirror surface, 6521-6524 ... movable member, 653 ... torsion spring, 654 ... vibration drive, AX ... drive Axis, L, Li, Ly, Lm, Lc, Lk ..... Light beam, X ... Main scanning direction, Y ... Sub scanning direction

Claims (6)

In an image forming apparatus in which a light beam is scanned in the main scanning direction by an exposure unit to form a latent image on a latent image carrier, and the latent image is developed by a developing unit to form an image.
The exposure unit includes (a) a light source that emits a light beam, and (b) a deflector that deflects the light beam from the light source in the main scanning direction,
The deflector (b)
(B-1) a plurality of movable members arranged in series apart from each other along a predetermined drive shaft;
(B-2) a plurality of torsion springs provided along the drive shaft to support the shaft by connecting the plurality of movable members;
(B-3) a vibration drive unit that generates a driving force for vibrating the plurality of movable members around the drive shaft;
A deflection mirror surface is formed on one of the plurality of movable members, and the plurality of movable members are vibrated to deflect a light beam by the deflection mirror surface,
An image forming apparatus, wherein a phase and an amplitude of each movable member are set so that inertial torques generated in each movable member are mutually canceled when the plurality of movable members are vibrated.   The image forming apparatus according to claim 1, wherein the vibration driving unit drives the plurality of movable members at the same driving frequency.   The image forming apparatus according to claim 1, wherein the plurality of movable members have the same configuration. In an image forming apparatus that scans a light beam in the main scanning direction with an exposure unit to form a line latent image on a latent image carrier, and develops the latent image with a developing unit to form an image.
The exposure unit includes (a) first and second light sources that emit light beams, and (b) a deflector that deflects the light beams from the first and second light sources in the main scanning direction, Each time the light beam is scanned forward to form a line latent image, the light beam emission source is alternately switched between the first and second light sources,
The deflector (b)
(B-1) first and second movable members having the same configuration and arranged in series apart from each other along a predetermined drive shaft;
(B-2) a plurality of torsion springs provided along the drive shaft to support the first movable member and the second movable member;
(B-3) a vibration drive unit that generates a drive force for vibrating the first and second movable members around the drive shaft at the same drive frequency;
The first and second movable members receive the driving force from the vibration drive unit and vibrate with the same amplitude and in opposite phase, while the first deflection mirror surface formed on the first movable member causes the first An image forming apparatus characterized in that a light beam from a light source is deflected while a light beam from the second light source is deflected by a second deflection mirror surface formed on the second movable member. A light beam is scanned in the main scanning direction for each of N different colors (N ≧ 2) by the exposure unit to form a latent image on the latent image carrier, and the latent image is formed for each color by the N color developing unit. In an image forming apparatus for developing an image to form an image,
The exposure unit includes (a) N light sources that are provided corresponding to the N latent image carriers and emit light beams, and (b) light beams from the N light sources. A deflector that reflects each of the light beam toward the latent image carrier corresponding to the light beam and deflects the light beam in the main scanning direction;
The deflector (b)
(B-1) N movable members provided corresponding to each of the N light sources and arranged in series spaced apart from each other along a predetermined drive axis;
(B-2) a plurality of torsion springs that are provided along the drive shaft and support the N movable members by connecting them;
(B-3) a vibration drive unit that generates a drive force for vibrating the N movable members around the drive shaft at the same drive frequency;
While receiving the driving force from the vibration driving unit, the N movable members vibrate with the same amplitude, and each of the N movable members causes a light beam from a light source corresponding to the movable member to be emitted from the movable member. Deflection by the deflection mirror surface formed on the surface,
An image forming apparatus, wherein the phases of the movable members are set so that inertial torques generated by the movable members when the N movable members are vibrated cancel each other. Each of the first to fourth latent image carriers is scanned with a light beam in the main scanning direction by the exposure unit to form a latent image on the latent image carrier, and the first to fourth latent image carriers are formed by the four color developing units. In the image forming apparatus for developing the latent image formed on each of the four latent image carriers to form an image,
The exposure unit includes: (a) first to fourth light sources that are provided corresponding to the first to fourth latent image carriers, respectively, and emit light beams; and (b) the first to fourth light sources. A deflector that reflects each of the light beams from the laser beam toward the latent image carrier corresponding to the light beams and deflects the light beams in the main scanning direction.
The deflector (b)
(B-1) two movable members having the same configuration and arranged in series apart from each other along a predetermined drive shaft;
(B-2) a plurality of torsion springs provided along the drive shaft and supporting the two movable members by connecting them;
(B-3) a vibration drive unit that generates a drive force for vibrating the two movable members around the drive shaft at the same drive frequency;
The first movable mirror surface formed on one surface of the first movable member while the two movable members vibrate at the same amplitude and in opposite phase in response to the driving force from the vibration drive unit. While deflecting the light beam from one light source and simultaneously deflecting the light beam from the second light source by the second deflection mirror surface formed on the other surface, the third deflection formed on one surface of the second movable member. An image forming apparatus characterized in that a light beam from the third light source is deflected by a mirror surface and at the same time a light beam from the fourth light source is deflected by a fourth deflection mirror surface formed on the other surface.

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