JP2005047653A - Light beam scanning device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light beam scanning device in which sub-scanning carrying of a film is stabled irrespective of service environment or frequency in use and two-dimensional scanning by a light beam can be stably performed, and an image forming device capable of restraining irregularity in image writing to improve a finished image. <P>SOLUTION: In the light beam scanning device, a pair of first rollers 170 in an upstream side and a pair of second rollers 180 in a downstream side nipping and carrying a sheet-like body 145 are arranged at an interval shorter than the carrying length of the sheet-like body. The sheet-like body is sub-scanned and carried by the pair of the first rollers and the pair of the second rollers, and a light beam deflected in a direction substantially orthogonal to a sub-scanning direction is irradiated between the pair of the first rollers and the pair of the second rollers for main scanning to two-dimensionally scan the sheet-like body. The light beam scanning device is provided with a rotary solenoid 50 adjusting nip pressure of at least one of the pair of the first rollers and the pair of the second rollers, a detection means 50c detecting the fluctuation of the rotary solenoid, and control means 148 controlling the adjusting means based on the fluctuation of the adjusting means detected by the detection means to adjust the nip pressure. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a light beam scanning apparatus and an image forming apparatus that convey a sheet-like scanned object in a sub-scanning manner by a first roller pair and a second roller pair.
[0002]
[Prior art]
In a medical imager, it is necessary to stably transport a film at a constant speed in the sub-scanning direction in order to make image writing to the film by the sub-scanning optical system constant. For this stable conveyance, it is generally known to mechanically control the nip pressure of the nip roller arranged at the front and back of the writing position by the laser beam at each stage of the writing process. As a method for controlling the nip pressure, a solenoid using a coil that converts an electric signal into motive power is generally used. However, such a solenoid generates heat depending on the use environment, use frequency, and control sequence, and the torque changes. It is generally known.
[0003]
On the other hand, in recent years, with the downsizing of imagers, the conveyance curvature before and after the sub-scanning section has changed abruptly, and the load fluctuation and the conveyance resistance due to the elasticity of the film have increased. It has become necessary.
[0004]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION In view of the above-described problems of the prior art, the present invention provides a light beam scanning apparatus that can stably carry out two-dimensional scanning with a light beam because the sub-scanning conveyance of the film is stable regardless of the use environment and the use frequency. With the goal. It is another object of the present invention to provide an image forming apparatus that can suppress uneven image writing and improve the finished image quality.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, an optical beam scanning apparatus according to the present invention includes an upstream first roller pair and a downstream second roller pair that sandwich and convey a sheet-like object to be scanned. The scanning body is arranged at an interval shorter than the conveying length of the scanning body, and the scanned body is sub-scanned and conveyed by the first roller pair and the second roller pair, and the first roller pair and the second roller pair In the light beam scanning apparatus that scans the object to be scanned two-dimensionally by irradiating a light beam deflected in a direction substantially orthogonal to the sub-scanning direction between the pair of rollers to perform main scanning, An adjusting means for adjusting a nip pressure of at least one of the roller pair and the second roller pair; a detecting means for detecting a change in the adjusting means; and the adjustment based on the change in the adjusting means detected by the detecting means. Means to control the nip Characterized in that it comprises a control means for adjusting the.
[0006]
According to this light beam scanning apparatus, when the fluctuation of the adjusting means for adjusting the nip pressure of the roller pair is detected, the nip pressure by the adjusting means is controlled based on the fluctuation. The sheet can be transported stably, and the sub-scan transport of the sheet-like object to be scanned is stable irrespective of the use environment and use frequency, and the two-dimensional scanning with the light beam can be performed stably.
[0007]
In the light beam scanning apparatus, the adjusting means may be a solenoid using a coil. In this case, since the detecting means detects the temperature of the coil or the temperature change of the coil and the temperature of the fluctuating portion and controls the solenoid based on the detected temperature, the coil generates heat during operation and the output of the solenoid The nip pressure can be adjusted appropriately by the solenoid even if the pressure drops. Further, the control means can adjust the nip pressure by gradually changing the rotation angle of the rotary solenoid by PWM control.
[0008]
In another light beam scanning apparatus according to the present invention, an upstream first roller pair and a downstream second roller pair which sandwich and convey a sheet-like object to be scanned are transported from the conveyance length of the object to be scanned. Are arranged at short intervals, and the scanned object is sub-scanned and conveyed by the first roller pair and the second roller pair, and between the first roller pair and the second roller pair. In the light beam scanning apparatus that scans the scanned object two-dimensionally by irradiating a light beam deflected in a direction substantially orthogonal to the sub-scanning direction and performing main scanning, the first roller pair and / or the Adjusting means for adjusting the nip pressure of the second roller pair, and the adjusting means for switching the nip pressure of the first roller pair and / or the second roller pair from the first value to the second value. Control means for controlling, the control means comprises a front Characterized in that occupy different transition state to said second value from said first value based on the number of pages fed scanning subjects.
[0009]
According to this light beam scanning apparatus, when the nip pressure of the first roller pair and / or the second roller pair is controlled by switching from the first value to the second value by the adjusting means, the scanning object is scanned. By controlling the transition state from the first value to the second value to be different based on the number of transported sheets, the sheet-like scanned object is used regardless of the use environment or usage frequency in which the number of transported sheets increases. Thus, the sub-scanning conveyance is stable, and the two-dimensional scanning with the light beam can be performed stably.
[0010]
In this case, the adjustment means includes a rotary solenoid, and the control means gradually changes the rotation angle of the rotary solenoid by PWM control, whereby the transition states can be made different.
[0011]
Still another light beam scanning apparatus according to the present invention includes a first roller pair on the upstream side and a second roller pair on the downstream side that sandwich and convey a sheet-like object to be scanned. Are arranged at a shorter interval than the first roller pair, and the first roller pair and the second roller pair convey the scanned object in a sub-scanning manner, and between the first roller pair and the second roller pair. In the light beam scanning apparatus that scans the scanned object two-dimensionally by irradiating a light beam deflected in a direction substantially perpendicular to the sub-scanning direction and performing main scanning, the first roller pair and / or Adjusting means having an electrical component that operates by energization and generates heat to adjust the nip pressure of the second roller pair, detection means for detecting the temperature of the electrical component, and the first roller pair and / or The nip pressure of the second roller pair is the first Control means for controlling the adjusting means so as to switch from a value to a second value, the control means changing the first value from the first value to the second value based on a detected temperature of the detecting means. It is characterized by making the transition state different.
[0012]
According to this light beam scanning apparatus, when the nip pressure of the first roller pair and / or the second roller pair is controlled by switching from the first value to the second value by the adjusting means, the adjustment by the detecting means is performed. By controlling the transition state from the first value to the second value based on the detected temperature of the electrical component of the means, the sheet-shaped cover is used regardless of the usage environment and usage frequency where the electrical component generates heat. Sub-scan conveyance of the scanning body is stable, and two-dimensional scanning with a light beam can be performed stably.
[0013]
In this case, the adjustment means includes a rotary solenoid, the electrical component is a coil of the rotary solenoid, and the control means gradually changes the rotation angle of the rotary solenoid by PWM control, so that the transition state is different. It can be tightened.
[0014]
In each of the light beam scanning devices described above, when adjusting the nip pressure of the roller pair, or when switching from the first value to the second value, the rear end portion of the scanned object during the sub-scan transport is the upstream When the nip pressure of the first roller pair is switched from strong to weak when passing through the first roller pair on the side, the rear end portion of the scanned object during the sub-scan transport is the first roller on the upstream side The impact when passing through the pair can be reduced.
[0015]
In each of the light beam scanning devices described above, the second roller pair includes a driving roller and a driven roller having a large diameter portion and a small diameter portion, and the large diameter portion of the driven roller and the driving roller include By being configured to form a nip gap that is narrower than the thickness of the sheet-like scanned object, the impact when the sheet-like scanned object enters the nip gap of the second roller pair is mitigated. It is possible and preferable. In this case, the gap in the second roller pair is formed by the small diameter portion of the driven roller and the driving roller.
[0016]
An image forming apparatus according to the present invention includes any one of the above-described light beam scanning devices, and the scanning target is a heat-developable photosensitive film, and the heat-developable photosensitive member is two-dimensionally scanned by the light beam scanning device. A latent image corresponding to an image signal is formed on a film.
[0017]
According to this image forming apparatus, the sub-scan conveyance of the film is stable regardless of the use environment and the use frequency in the light beam scanning apparatus, and the two-dimensional scanning by the light beam can be stably performed, so that the image writing is stable. In addition, uneven image writing can be suppressed and the finished image quality can be improved.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0019]
<Light beam scanning device>
[0020]
FIG. 1 is a side view schematically showing two pairs of conveying rollers of the light beam scanning apparatus according to the present embodiment. FIG. 2 is a perspective view of a principal part showing a specific configuration example of the nip pressure adjusting mechanism of the light beam scanning apparatus of FIG. FIG. 3 is a side view of an essential part of the nip pressure adjusting mechanism of FIG. 4 is a perspective view (a) showing a driven roller of the second conveying roller pair shown in FIG. 2, a partially enlarged view (b), and a schematic front view when the driven roller is combined with a drive roller (c). It is.
[0021]
As shown in FIG. 1, the light beam scanning apparatus according to the present embodiment includes two pairs of conveyance rollers 170 and 180, and the conveyance roller pairs 170 and 180 are used for conveying a sheet-like body 145 such as a film to be conveyed. Arranged at intervals shorter than the length in the conveyance direction H, the sheet-like body 145 is conveyed in the conveyance direction H while being sandwiched. Light is irradiated by irradiating a light beam deflected in the direction perpendicular to the paper surface from the exposure unit (for example, see FIG. 6) onto the sheet-like body 145 that is being transported in the sub-scanning state between the transport roller pairs 170 and 180. Two-dimensional scanning exposure by a beam can be performed.
[0022]
The light beam scanning apparatus of FIG. 1 further includes a reflection type optical sensor 149 arranged on the upstream side of the first conveyance roller pair 170, and the conveyance roller pairs 170, 180 based on detection signals from the optical sensor 149. A control unit 148 including a central processing unit (CPU) that controls the nip pressure to be switched. The optical sensor 149 detects the leading end 146 of the sheet-like body 145 that has been transported in the transport direction H from the upstream side of the transport roller pair 170, and generates a detection signal. That is, light is emitted from the light emitting portion of the optical sensor 149 to the sheet-like body 145 side as indicated by the broken line in the figure, and the reflected light is incident on the light receiving portion of the optical sensor 149, thereby detecting the tip portion 146. The control unit 148 controls the rotary solenoid 50 so as to switch the nip pressure at a timing based on the detection signal from the optical sensor 149.
[0023]
The rotary solenoid 50 includes a coil and includes a temperature sensor 50c that detects the temperature in the vicinity of the coil. The control unit 148 rotates the rotary shaft of the rotary solenoid 50 based on a temperature detection signal from the temperature sensor 50c. The corner is controlled.
[0024]
The first conveying roller pair 170 on the upstream side in the conveying direction H includes a driving roller 171 that is rotated by a motor (not shown) in a rotation direction R ′ in FIG. 1 and a driven roller 172 that is driven to rotate. The second conveyance roller pair 180 on the downstream side in the conveyance direction H includes a drive roller 181 that is rotated by a motor (not shown) in the rotation direction R in the drawing, and a driven roller 182 that is driven to rotate.
[0025]
In the second conveying roller pair 180, the driven roller 182 has a large diameter part 182a and a small diameter part 182b, and the driving roller 181 and the large diameter part 182a abut against each other. A nip gap 183 is formed between the drive roller 181 and the small diameter part 182b. The nip gap 183 is provided in each of the large diameter part 182a and the small diameter part 182b so as to maintain an interval smaller than the thickness of the sheet-like body 145. The diameter is fixed. The leading end 146 of the sheet-like body 145 conveyed from the first conveying roller pair 170 enters the nip gap 183 of the second conveying roller pair 180.
[0026]
4A and 4B show specific examples of the driven roller 182 of the second conveying roller pair 180. The driven roller 182 has large diameter portions 182a at both ends, and the large diameter portions 182a and 182a The small-diameter portion 182b is intermittently formed between the two. The large-diameter portion 182a and the small-diameter portion 182b are made of a metal material such as stainless steel, and are manufactured by an integrated cutting process, or the large-diameter portion 182a and the small-diameter portion 182b are individually cut, and then It may be assembled and manufactured. The drive roller 181 is a metal roller such as stainless steel.
[0027]
When the driven roller 182 is combined with the drive roller 181 as shown in FIG. 4C, the large-diameter portion 182a and the drive roller 181 come into contact with each other at both ends, and the hatching in the figure is between the small-diameter portion 182b and the drive roller 181. A nip gap 183 is formed as shown in FIG.
[0028]
In the second conveying roller pair 180, the nip pressure when the sheet-like body 145 is conveyed with the nip gap 183 between the driving roller 181 and the small diameter portion 182b of the driven roller 182 being adjusted is switched to two stages. Next, a nip pressure adjusting mechanism for this nip pressure will be described.
[0029]
As shown in FIGS. 2 and 3, the light beam scanning apparatus includes a nip pressure adjusting mechanism for adjusting the nip pressure of the first and second transport roller pairs 170 and 180, and the nip pressure adjusting mechanism is a second nip pressure adjusting mechanism. A rotary solenoid 50 as an adjusting means for switching the nip pressure of the pair of conveying rollers 180, and a shaft that is moved by the rotary solenoid 50 in the horizontal direction k in FIG. 2 (lateral direction in FIG. 2) and in the opposite horizontal direction k ′. 51, the spring 52 connected to the shaft 51 to absorb the impact at the time of switching by the rotary solenoid 50, and the direction in which the conveying roller pair 170, 180 extends (the direction substantially orthogonal to the horizontal directions k and k ′). And a plate member 54 connected to the shaft 51.
[0030]
The nip pressure adjusting mechanism of the light beam scanning device further includes a shaft 57 extending in the same direction as the conveying roller pair 170 and 180 and connected to the plate member 54, and a spring 55 connected to the shaft 57 at an end portion 55a on the plate member 54 side. The first lever member 56 that rotates about the fulcrum shaft 60 so as to switch the nip pressure of the first conveying roller pair 170 by the expansion and contraction of the spring 55 due to the movement of the shaft 57, and the second conveying roller pair 180. A second lever member 58 that rotates about the fulcrum shaft 61 so as to switch the nip pressure of the shaft, and an end portion 59a that is connected to the shaft 57 and expands and contracts by the movement of the shaft 57 to rotate the second lever member 58. And a spring 59 to be provided. The shaft 57 passes through the holes of the first and second lever members 56 and 58 and does not contact the holes. Further, the shaft 51, the plate member 54, and the shaft 57 form one rigid body and move integrally.
[0031]
The first lever member 56 is connected to the driven roller 172 of the first conveying roller pair 170, and when the spring 55 is compressed by the movement of the shaft 57 in the arrow direction m in FIG. 3 is rotated about the fulcrum 60 in the rotation direction s of FIG. 3, and the driven roller 172 is rotated so as to increase the nip pressure with respect to the drive roller 171. Also, the direction 57 of the shaft 57 in FIG. When the spring 55 is extended by the movement in the arrow direction m ′ opposite to the rotation direction, it rotates in the rotation direction s ′ opposite to the rotation direction s in FIG. 3 around the fulcrum 60 to drive the driven roller 172. The roller 171 is rotated so as to weaken the nip pressure.
[0032]
The second lever member 58 is connected to the driven roller 182 of the second conveyance roller pair 180, and when the spring 59 is extended by the movement of the shaft 57 in the arrow direction m in FIG. 3, the end portion 59b of the spring 59 is extended. 3 is rotated about the fulcrum 61 in the rotation direction t in FIG. 3, and the driven roller 182 is rotated with respect to the drive roller 181 so as to weaken the nip pressure, and the shaft 57 is moved in the arrow direction m ′. When the spring 59 is compressed by this, it rotates about the fulcrum 61 in the rotation direction t ′ of FIG. 3 and rotates the driven roller 182 with respect to the drive roller 181 so as to increase the nip pressure.
[0033]
The first and second lever members 56 and 58 incorporate springs for pushing up the driven rollers 172 and 182 after the nip described above.
[0034]
Further, the control unit 148 in FIG. 1 controls the rotary solenoid 50 by pulse width modulation. That is, the control unit 148 can change the rotation angle of the rotary shaft of the rotary solenoid by changing the duty ratio of ON / OFF, and the first roller by gradually changing the rotation angle by changing the duty ratio gradually. Each nip pressure of the pair 170 and the second roller pair 180 can be gradually changed and switched.
[0035]
As described above, the switching of the nip pressure accompanied by the release of the first roller pair 170 and the switching of the nip pressure of the second roller pair 180 can be performed at the same time, and a simple drive mechanism can be realized by one rotary solenoid. It can be executed with. In addition, a rotary solenoid may be provided for each of the first roller pair 170 and the second roller pair 180, and each rotary solenoid may be individually controlled.
[0036]
Next, the output of the rotary solenoid decreases with continuous use. A countermeasure against this output decrease will be described with reference to FIG. FIG. 8 is a diagram showing the time change of the rotation angle of the rotary solenoid when the output of the rotary solenoid of FIGS. 2 and 3 is normal (solid line a) and when the output is lowered (broken line b).
[0037]
In the rotary solenoid, the rotor connected to the output shaft (rotating shaft) rotates when the coil as an electrical component is energized, causing a repulsive force between the rotor and the permanent magnet, stops at the rotational position, and energizes the coil. Although the rotating shaft rotates by stopping and returning to the original position and stopping, the torque (output) decreases due to the heat generation of the coil due to continuous use.
[0038]
As shown in FIG. 8, when the rotary solenoid 50 of FIGS. 2 and 3 changes in rotation angle due to the relationship of the solid line a before the fluctuation due to the heat generation of the coil, the fluctuation due to the heat generation of the coil occurs. The rotation angle changes according to the relationship of the broken line b. Thus, if the control is the same due to the heat generated by the rotary solenoid itself as it is used, the initial rotation angle is gradually not obtained as shown by the broken line b in FIG. 8, resulting in poor conveyance and poor nip pressure switching. Unevenness of conveyance appears.
[0039]
That is, as shown in FIGS. 2 and 3, when the rotary shaft 53 rotates in the rotation direction r of FIG. 2 by the operation of the rotary solenoid 50, the rotation angle of FIG. 8 becomes large (rotation angle d). While the nip pressure of the first conveying roller pair 170 becomes a strong value (first value), when the rotary shaft 53 rotates in the rotational direction r ′ of FIG. The state changes to a small rotation angle (rotation angle e), and the nip pressure of the first conveying roller pair 170 changes to a weak value (second value). During the transition, if the rotation angle of the rotary solenoid 50 changes with the relationship of the solid line a in FIG. 8, the first nip pressure of the first conveying roller pair 170 is a strong first value (to the rotation angle d in FIG. 8). The sheet-like body 145 is stably conveyed even if it is switched from the corresponding) to the weak second value (corresponding to the rotation angle e in FIG. 8), whereas the coil of the rotary solenoid 50 is continuously used by continuous use. When heat is generated, in the case of the same control, the rotation angle of the rotary solenoid 50 changes due to the relationship of the broken line b in FIG. 8, and when the nip pressure is switched from strong to weak as indicated by the broken line b, the rotation angle is particularly abrupt. In the changing range b1, the balance between the torque of the rotary solenoid 50 and the spring pressure of the springs 55 and 59 in FIGS. 2 and 3 is disturbed, and uneven conveyance due to switching occurs in the sheet-like body 145.
[0040]
Therefore, when the temperature sensor 50c detects that the coil inside the rotary solenoid 50 generates heat and the temperature in the vicinity of the coil rises during continuous use, the control unit 148 in FIG. 1 detects the rotary solenoid based on the temperature detection signal. In the pulse width (PWM) modulation for 50, the ON / OFF duty ratio of energization is controlled so as to change the rotation angle (increase the ON pulse ratio) in relation to the solid line a in FIG. The nip roller can be controlled, and the switching conveyance unevenness due to the switching failure when the nip pressure of the first conveyance roller pair 170 is switched from strong to weak can be suppressed, and the sheet-like body 145 can be conveyed stably. it can. In addition, since the impact when the rear end portion 146 of the sheet-like body 145 passes through the first conveying roller pair 170 on the upstream side can be effectively mitigated, it is possible to suppress uneven conveyance due to poor conveyance.
[0041]
Next, the reason why a rotation angle switching stop range in which the change is temporarily stopped while the rotation angle is decreasing in the solid line a in FIG. 8 will be described with reference to FIG. FIG. 9 is a diagram showing changes in the rotation angle of the rotary solenoid for explaining the reason why the rotation angle switching stop range of FIG. 8 is provided.
[0042]
Although the rotation angle of the rotary solenoid 50 may be changed so as to decrease almost linearly in the transition region due to the relation of the thick line f in FIG. 9, it is accumulated in the springs 55 and 59 in FIGS. 2 may be released at a stroke due to variations in the power of the rotary solenoid, the spring pressure, etc., causing vibrations in each part of the nip pressure adjusting mechanism in FIGS. This may cause uneven conveyance of the sheet-like body 145. For this reason, the occurrence of such vibration is prevented in advance by providing a rotation angle switching stop range a1 that temporarily stops the change while the rotation angle is decreasing as shown in FIG.
[0043]
Further, as described above, if the coil of the rotary solenoid 50 generates heat due to continuous use and the torque of the rotating shaft 53 decreases, and the spring pressure of the springs 55, 59, etc. becomes larger than that torque, As shown by the thin line g, when the rotary shaft 53 tries to move to the small rotation angle e corresponding to the weak nip pressure at once, vibration is generated, and similarly, the sheet-like body 145 is conveyed within the range h in FIG. Although unevenness may occur, the occurrence of such vibration can be prevented beforehand by controlling the duty ratio of ON / OFF of energization to the rotary solenoid 50 as described above.
[0044]
Next, the operation of the light beam scanning apparatus shown in FIGS. 1 to 3 will be described. First, when the sheet-like body 145 is conveyed in the conveyance direction H of FIG. 1, the front end 146 is detected by the optical sensor 149 of FIG. 1, while the sheet-like body 145 is moved from the front end 146 to the first conveyance roller pair 170. storm in.
[0045]
Next, the control unit 148 controls the rotary solenoid 50 shown in FIGS. 2 and 3, and the rotary solenoid 50 of the rotary solenoid 50 changes the rotation angle of the rotary shaft 53 so that the rotary member 50a is turned in the rotation direction shown in FIG. When rotated to r, the linearly moving member 50b coupled to the shaft 51 moves linearly, the shaft 51 moves in the arrow direction k of FIGS. 2 and 3, and the shaft 57 is illustrated via the plate member 54. 3 moves in the direction m. The movement of the shaft 57 in the direction m compresses the spring 55 and presses the first lever member 56 in the direction m to rotate the driven roller 172 in the rotation direction s in FIG. The nip pressure of the driven roller 172 to the driving roller 171 at 170 is increased. Thereby, the sheet-like body 145 can be stably conveyed by the first conveyance roller pair 170.
[0046]
Further, when the spring 59 extends in the direction m and the second lever member 58 is pulled in the direction m by the movement of the shaft 57 in the direction m, the driven roller 182 is rotated in the rotation direction t in FIG. The nip pressure with respect to the driving roller 181 of the driven roller 182 in the second conveying roller pair 180 is weakened. Thereby, it is possible to suppress the occurrence of a leading edge entry failure when the sheet-like body 145 comes out of the first conveying roller pair 170 and enters the second conveying roller pair 180 from the leading edge 146.
[0047]
Next, after the sheet-like body 145 has entered the second conveying roller pair 180, the rotary solenoid of the rotary solenoid 50 causes the rotary member 50a to move in the rotational direction r ′ of FIG. 2 under the control of the control unit 148 of FIG. When rotated, the linearly moving member 50b moves the shaft 51 in the arrow direction k ′ in FIGS. 2 and 3, and the shaft 57 moves in the direction m ′ opposite to the direction m via the plate member 54. Due to the movement of the shaft 57 in the direction m ′, the spring 55 expands and the first lever member 56 rotates the driven roller 172 in the rotation direction s ′ of FIG. Decrease the nip pressure and release the crimp. As a result, it is possible to suppress the occurrence of a disconnection failure when the sheet-like body 145 comes out of the first conveying roller pair 170.
[0048]
Further, when the spring 59 is compressed in the direction m ′ by the movement of the shaft 57 in the direction m ′ and the second lever member 58 is pressed in the direction m ′, the driven roller 182 is rotated in the rotation direction t ′ in FIG. The nip pressure with respect to the driving roller 181 of the driven roller 182 in the second conveying roller pair 180 is increased. Thereby, the sheet-like body 145 can be stably conveyed by the second conveyance roller pair 180, and the conveyance performance of the sheet-like body 145 can be improved.
[0049]
In each of the above-described operations, the rotary shaft 53 of the rotary solenoid 50 does not rotate abruptly but gradually rotates with a small rotation angle change in the rotation direction r or r ′ as shown in FIG. Since it gradually moves to m or m ′, the nip pressures in the first conveying roller pair 170 and the second conveying roller pair 180 gradually change without suddenly changing. When the coil of the rotary solenoid 50 generates heat due to continuous use, the duty ratio of ON / OFF of energization to the rotary solenoid 50 is set as indicated by the solid line a in FIG. 8 based on the temperature detection signal of the temperature sensor 50c as described above. It controls so that a rotation angle changes in relation.
[0050]
When the shaft 51 is switched to move in the direction k or k ′ by the operation of the rotary solenoid 50, the spring 52 expands and contracts to absorb the shock at the time of switching, and the first and second transport roller pairs 170, The conveyance of the sheet-like body 145 at 180 is not affected.
[0051]
According to the light beam scanning apparatus of FIGS. 1 to 4, when the sheet-like body 145 comes out of the first conveying roller pair 170, the nip pressure is weakened and the pressure-bonding is released, so that the sheet-like body 145 becomes the first conveying roller. It is possible to alleviate the impact when exiting from the pair 170 and suppress the occurrence of failure. In addition, the nip gap 183 in the second conveying roller pair 180 is narrower than the thickness of the sheet-like body 145 and is set to a weak nip pressure when the sheet-like body 145 enters, so that the second conveying roller pair 180 can enter. In addition, the nip pressure is increased when the rear end of the sheet-like body 145 is transported at the latest, and switching to two stages satisfies both the suppression of the tip entry failure and the improvement of transportability. In addition, since only the nip pressure level is changed, there is no impact on the sheet-like body unlike the film-roller pressure bonding method.
[0052]
In addition, when the nip pressures are switched between the first transport roller pair 170 and the second transport roller pair 180, the nip pressures are gradually changed without suddenly changing, so that the nip pressures can be switched more smoothly. And the occurrence of vibration is suppressed, and the conveyance of the sheet-like body 145 is not affected.
[0053]
Further, even if the coil of the rotary solenoid 50 generates heat due to continuous use and the rotation angle of the rotary shaft 53 changes, the duty ratio of ON / OFF of energization to the rotary solenoid 50 is determined by the relationship of the solid line a in FIG. Therefore, even when the nip pressure of the first conveying roller pair 170 is switched from strong to weak, unevenness of switching conveyance can be suppressed, and the sheet-like body 145 can be conveyed stably.
[0054]
In addition, the above-described control of the duty ratio of ON / OFF of energization to the rotary solenoid 50 is performed by, for example, the optical sensor 149 of FIG. 1 using the tip of the sheet-like body 145 instead of the temperature detection signal from the temperature sensor 50c. The number of detection signals generated each time 146 is detected may be counted and stored by the control unit 148 as the number of conveyed sheets 145, and may be performed based on the number of conveyed sheets. That is, when the sheet-like body 145 is continuously used so that the number of conveyed sheets becomes equal to or greater than the predetermined number, the sheet-like body 145 can be stably conveyed by performing the same control as described above.
[0055]
As described above, even when the coil of the rotary solenoid 50 generates heat or continuously uses a large number of sheet-like bodies 145, high accuracy is obtained regardless of changes in the usage environment and usage frequency. The nip conveyance can be realized, the sub-scan conveyance of the sheet-like body 145 is stable, and the two-dimensional scanning by the light beam can be stably performed.
[0056]
<Image forming device>
[0057]
Next, an image forming apparatus including a light beam scanning unit for image formation to which the above-described light beam scanning apparatus of FIGS. 1 to 4 is applied as a sub-scanning mechanism will be described with reference to FIGS. .
[0058]
FIG. 5 is a front view showing a main part of the image forming apparatus according to the present embodiment. FIG. 6 is a diagram schematically showing a light beam scanning unit of the image forming apparatus of FIG. FIG. 7 is a perspective view specifically showing the sub-scanning mechanism of the light beam scanning unit of FIGS.
[0059]
As shown in FIG. 5, the image forming apparatus 100 includes a first and second loading units 11 and 12 for loading a package in which a predetermined number of sheets of a sheet-shaped photothermographic material are packaged, and one sheet of film. A supply unit 110 having a supply unit 90 that is transported and supplied for exposure / development one by one, and a film fed from the supply unit 110 is exposed while being sub-scanned two-dimensionally with a light beam to form a latent image. A light beam scanning unit 120, a developing unit 130 that thermally develops the film on which the latent image is formed, a densitometer 200 that measures the density of the developed film and obtains density information, and conveys the heated film while cooling it A cooling and conveying unit 150 for discharging the film, and a discharge tray unit 160 for discharging the film.
[0060]
A film is conveyed from the first and second loading sections 11 and 12 of the supply section 110 one by one by the supply section 90 and the pair of conveyance rollers 39, 41, and 141 in the arrow direction (1) in FIG. Yes.
[0061]
Next, the light beam scanning unit 120 of the image forming apparatus 100 will be described with reference to FIG. As shown in FIG. 6, the light beam scanning unit 120 rotates a laser beam L having a predetermined wavelength within a wavelength range of 780 to 860 nm, which is intensity-modulated based on the image signal S of the diagnostic image information input to the input unit 133, in a rotating multifaceted manner. The film 113 is deflected by the mirror 113 to perform main scanning on the film F, and the film F is converted into laser light L by a sub-scanning mechanism including the first and second transport roller pairs 170 and 180 shown in FIGS. On the other hand, it is sub-scanned by relative movement in a substantially horizontal direction, which is a direction substantially perpendicular to the main scanning direction, and a latent image is formed on the film F using the laser light L. In FIG. 6, the driven rollers of the first and second transport roller pairs 170 and 180 are not shown.
[0062]
A more specific configuration of the light beam scanning unit 120 will be described below. In FIG. 6, when an image signal S that is a digital signal input from the outside is input via the input unit 133, the image signal S is converted into an analog signal by the D / A converter 122 and input to the modulation circuit 123. . The modulation circuit 123 controls the driver 124 of the laser light source unit 110a based on the analog signal to irradiate the laser light L modulated from the laser light source unit 110a.
[0063]
Next, after passing through the lens 112, the laser light L emitted from the laser light source unit 110a is converged only in the vertical direction by the cylindrical lens 115 and is rotated with respect to the rotating polygonal mirror 113 that rotates in the direction of arrow A in FIG. The incident light is incident as a line image perpendicular to the drive shaft. The rotary polygon mirror 113 reflects and deflects the laser light L in the main scanning direction, and the deflected laser light L passes through an fθ lens 114 including a cylindrical lens formed by combining four lenses, and then main-scans on the optical path. The surface to be scanned of the film F reflected by the mirror 116 extending in the direction and conveyed in the arrow Y direction by the first and second conveyance roller pairs 170 and 180 (sub-scanned) On 117, main scanning is repeated in the direction of the arrow X. As a result, the laser beam L scans the entire surface to be scanned 117 on the film F.
[0064]
The cylindrical lens of the fθ lens 114 converges the incident laser beam L on the scanning surface of the film F only in the sub-scanning direction, and the distance from the fθ lens 114 to the scanning surface of the film F Is equal to the focal length of the entire fθ lens 114. As described above, the light beam scanning unit 120 includes the cylindrical lens 115 and the fθ lens 114 including the cylindrical lens so that the laser light L is once converged on the rotary polygonal mirror 113 only in the sub-scanning direction. Therefore, even if surface rotation or axial blurring occurs in the rotary polygon mirror 113, the scanning position of the laser beam L does not shift in the sub-scanning direction on the surface to be scanned of the film F, and the scanning lines have an equal pitch. Can be formed. The rotary polygon mirror 113 has an advantage that it is superior in scanning stability compared to other optical polarizers such as a galvanometer mirror. As described above, a latent image based on the image signal S is formed on the film F.
[0065]
Next, the developing unit 130 of the image forming apparatus in FIG. 5 will be described. As shown in FIG. 5, the developing unit 130 holds the film F on the outer periphery, holds the film F between the heating drum 14 that can be heated and the heating drum 14 that is disposed to face the heating drum 14. A plurality of opposed rollers 16. The film is heated while being sandwiched between the heating drum 14 and the plurality of opposing rollers 16, and is conveyed by the rotation of the heating drum 14.
[0066]
A heater (not shown) provided inside the heating drum 14 is energized and controlled to maintain the film F at a temperature equal to or higher than a predetermined minimum heat development temperature (for example, around 110 ° C.) for a predetermined heat development time. Heat and heat develop. Thereby, the latent image formed on the film F by the light beam scanning unit 120 is formed as a visible image. Further, density adjustment can be performed by changing the developing temperature by changing the heater temperature by energization control. It is preferable that the periphery of the heating drum 14 is covered with a heat insulating material because the temperature of the heating drum 14 can be easily controlled.
[0067]
The densitometer 200 of FIG. 5 includes a light emitting unit 200a and a light receiving unit 200b, and the developed film is transported between the light emitting unit 200a and the light receiving unit 200b as described above and passes through the light emitting unit 200a. Is received by the light receiving unit 200b through the film, and the density is measured based on the degree of attenuation of the received light amount. Based on the measured density information, the laser light amount of the light beam scanning unit 120 is feedback-controlled so that the final density of the film is constant.
[0068]
The film conveyed in the arrow direction (1) in FIG. 5 is conveyed in the arrow direction (2) to form a latent image as described above, and then the developing unit 130 is moved in the arrow direction (3) by the conveyance roller pair 142. Then, the latent image is visualized by being heat-developed as described above, and is then transported by the transport roller pairs 144a and 144 while being cooled, the density is measured by the densitometer 200, and further transported. It is conveyed in the arrow direction (4) by the roller pair 144 and discharged to the discharge tray section 160.
[0069]
Next, the sub-scanning mechanism including the first and second transport roller pairs 170 and 180 shown in FIGS. 1 to 4 will be further described with reference to FIG.
[0070]
As shown in FIG. 7, the sub-scanning mechanism of the light beam scanning unit 120 includes the first and second transport roller pairs 170 and 180 of FIGS. 1 to 4, and the first and second transport roller pairs 170. , 180 is provided with a nip pressure adjusting mechanism as shown in FIGS.
[0071]
That is, as described with reference to FIGS. 1 to 4, the rotary solenoid of the rotary solenoid 50 is operated by the detection of the film leading end of the optical sensor 149 of FIG. 1 and the control of the control unit 148. That is, when the film F comes out of the first conveying roller pair 170, the nip pressure is weakened to release the pressure bonding. Further, the nip pressure of the second conveyance roller pair 180 is weakened before the film F enters the second conveyance roller pair 180, and the nip pressure is increased at the time of conveyance of the rear end portion of the film F at the latest. Yes. In this way, by switching the nip pressure in the second conveyance roller pair 180 in two stages, it is possible to satisfy both the suppression of the tip entry failure and the improvement of the conveyance performance, and only the nip pressure level change. The film is not impacted unlike the pressure bonding method between the film and the roller, so that the quality of the formed image can be improved.
[0072]
Further, when the coil inside the rotary solenoid 50 of FIGS. 2 and 3 generates heat due to continuous use of the image forming apparatus 100, the energization of the rotary solenoid 50 is turned on based on the temperature detection signal from the temperature sensor 50c of FIG. The duty ratio of / OFF is controlled as shown in FIG. Accordingly, even if the nip pressure of the first transport roller pair 170 is switched from strong to weak, the switching transport unevenness can be suppressed, and the film can be transported stably in the sub-scanning direction.
[0073]
Further, as shown in FIG. 7, a conveyance guide member 190 formed in a curved surface with a predetermined radius is disposed on the downstream side of the second conveyance roller pair 180, and the film on which the latent image is formed is shown in FIG. As shown in FIG. 5, it is conveyed upward in the figure while changing the traveling direction to the curved surface direction V. The guide surface of the transport guide member 190 is provided with a plurality of ribs 191 formed so as to protrude from the surface and extend in the transport direction.
[0074]
The film transport for sub-scanning when forming a latent image in the image forming apparatus 100 of FIGS. 5 to 7 will be described. When the film is transported from the transport direction H of FIG. The nip pressure is switched from weak to strong before entering the film, and switched to weak before the film exits the first conveying roller pair 170. Then, the nip gap 183 of the second conveying roller pair 180 is made narrower than the thickness of the sheet-like body 145, and the nip pressure of the second conveying roller pair 180 is set before the film enters the second conveying roller pair 180. Since it is weakened, the impact at the time of rushing can be alleviated, and the occurrence of tip rush failure can be suppressed by suppressing the occurrence of tip rush failure. In addition, when the nip pressures are switched between the first transport roller pair 170 and the second transport roller pair 180, the nip pressures are gradually changed without suddenly changing, so that the nip pressures can be switched more smoothly. And the occurrence of vibrations is suppressed and the film transport is not affected. For this reason. This can contribute to improving the image quality formed on the film.
[0075]
Next, after the film F enters the second conveyance roller pair 180, the nip pressure of the second conveyance roller pair 180 is increased, so that the film conveyance performance is improved. As shown in FIG. 7, the film F is transported by the second pair of transport rollers 180, and the front end of the film F comes into contact with the curved guide member 190 disposed immediately downstream, and proceeds in the curved surface direction V of FIG. When the film F is conveyed while being changed in direction and guided upward in FIG. 5, the film F receives resistance from the guide member 190 at the front end and becomes difficult to convey, and as a result, the conveyance of the film in the sub-scanning direction is hindered. As described above, the nip pressure of the second conveying roller pair 180 is switched to a strong force to increase the conveying force, so that the resistance of the film from the guide member 190 is increased. The film can be conveyed in the curved surface direction V against the force, and the film can be stably conveyed in the sub-scanning direction to improve the image quality. Further, the plurality of ribs 191 provided on the guide member 190 is preferable because the resistance force to the film F being conveyed is reduced.
[0076]
When the image forming apparatus 100 is continuously used as described above, the coil inside the rotary solenoid 50 shown in FIGS. 2 and 3 generates heat, and the torque of the rotary solenoid 50 is reduced. As shown by the broken line b in FIG. Although the nip pressure of the first conveying roller pair 170 changes, the sub-scanning conveyance property of the film is lowered, and it is likely to appear as unevenness in the image of the film. The temperature sensor 50c in FIG. 1 detects that the temperature has risen, and based on the temperature detection signal, the ON / OFF duty ratio of energization to the rotary solenoid 50 is changed to the original relationship (the coil is connected to the solid line a in FIG. By controlling so that the rotation angle changes according to the relationship before heat generation), even if the nip pressure of the first conveying roller pair 170 is switched from strong to weak, switching conveyance unevenness is suppressed. It can, the film can be stably auxiliary scan transport to, since the two-dimensional scanning by the light beam can be stably performed, it is possible to suppress image unevenness of writing, can prevent image unevenness of the film. In this way, even if the use environment or use frequency changes due to continuous use of the apparatus, the finished image quality by the image forming apparatus 100 can be improved regardless of such changes.
[0077]
5 inevitably reduces the radius of curvature of the guide member 190 and increases the resistance to the film, but the film conveying force can be increased as described above. The range of the radius of curvature of the guide member 190 that can transport the film is expanded. In particular, the lower limit of the radius of curvature of the guide member 190 may be small, which can contribute to downsizing of the apparatus.
[0078]
As described above, the present invention has been described with reference to the embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made within the scope of the technical idea of the present invention. For example, the light beam scanning device and the light beam scanning device of the present invention may be applied to devices other than the image forming device. For example, an image in which a sheet-like member on which image information is recorded is irradiated with the light beam to read the image information. It can be applied to a reading device or the like.
[0079]
Further, the rotation angle of the rotary solenoid 50 indicated by the solid line a in FIG. 8 may be changed with time, for example, as indicated by the solid line h in FIG. 10, and the rotation angle is changed to the small rotation angle e after the rotation angle switching stop range a1. A range a2 that gradually decreases may be provided, or the entire rotation angle may be increased from a solid line h to a broken line i. Furthermore, as shown by a broken line j in FIG. 11, the rotation angle may be increased only in the intermediate region of the solid line h. Further, FIG. 10 and FIG. 11 may be combined to increase the entire broken line j in FIG. As described above, the rotation angle of the rotary solenoid 50 may be controlled by any one of the three patterns of FIGS. 10 and 11 and the combination of FIGS. Even when the rotary solenoid 50 is continuously used, the unevenness of conveyance can be similarly suppressed by controlling the rotation angle of the rotary solenoid 50 as shown in FIGS.
[0080]
Further, the torque reduction due to continuous use of the rotary solenoid 50 is measured, for example, by measuring an arbitrary portion that can be converted into the nip pressure of the conveying roller pair over time, detecting a deviation from a predetermined value, and correcting the deviation amount. In this manner, the rotation angle of the rotary solenoid 50 may be controlled. As such measurement means (detection means), for example, a displacement meter may be used when the amount of displacement of a two-dimensional member is viewed, an encoder if a rotating member, and a pressure sensor may be used when directly measuring pressure.
[0081]
In the present embodiment, the change in the rotation angle of the first conveyance roller pair 170 has been described. However, the rotation angle caused by the torque reduction due to the continuous use of the rotary solenoid 50 in the second conveyance roller pair 180 is described. Changes can be controlled in the same way.
[0082]
【The invention's effect】
According to the present invention, it is possible to provide a light beam scanning apparatus that can stably carry out two-dimensional scanning with a light beam because the sub-scanning conveyance of the sheet-like object to be scanned is stable regardless of the use environment and the use frequency. In addition, it is possible to provide an image forming apparatus capable of suppressing uneven image writing and improving the finished image quality.
[Brief description of the drawings]
FIG. 1 is a side view schematically showing two pairs of conveyance rollers of a light beam scanning apparatus according to the present embodiment.
2 is a perspective view of a principal part showing a specific configuration example of a nip pressure adjusting mechanism of the light beam scanning apparatus of FIG. 1. FIG.
3 is a side view of an essential part of the nip pressure adjusting mechanism of FIG. 2;
4 is a perspective view (a) showing a driven roller of the second conveying roller pair shown in FIG. 2, a partially enlarged view (b), and a schematic front view when the driven roller is combined with a driving roller (c). It is.
FIG. 5 is a front view showing a main part of the image forming apparatus according to the present embodiment.
6 is a diagram schematically showing a light beam scanning unit of the image forming apparatus of FIG. 5. FIG.
7 is a perspective view specifically showing a sub-scanning mechanism of the light beam scanning unit in FIGS. 5 and 6. FIG.
FIG. 8 is a diagram showing temporal changes in the rotation angle of the rotary solenoid when the output of the rotary solenoid of FIGS. 2 and 3 is normal (solid line a) and when the output is lowered (broken line b).
FIG. 9 is a diagram showing a change over time in the rotation angle of the rotary solenoid for explaining the reason for providing the rotation angle switching stop range in FIG. 8;
10 is a diagram showing a change over time in the rotation angle of a rotary solenoid for explaining a modification of FIG. 8; FIG.
FIG. 11 is a diagram showing a change over time in the rotation angle of a rotary solenoid for explaining another modification of FIG. 8;
[Explanation of symbols]
50 .. Rotary solenoid (adjustment means)
53 ... Rotary shaft of rotary solenoid
145 ... Sheet-like body (scanned body)
146 ... The tip of the sheet
148... Control unit (control means)
50c ... Temperature sensor (detection means)
170: First conveying roller pair
171 ... Driving roller
172 ... driven roller
180 ... second conveying roller pair
181 ... Driving roller
182 ... Follower roller
F ... Film

Claims (11)

An upstream first roller pair and a downstream second roller pair that sandwich and convey the sheet-like scanned object are arranged at an interval shorter than the conveying length of the scanned object, and the first The scanned object is sub-scanned and conveyed by the roller pair and the second roller pair, and is deflected in a direction substantially orthogonal to the sub-scanning direction between the first roller pair and the second roller pair. In a light beam scanning device that scans the object to be scanned two-dimensionally by irradiating the light beam and performing main scanning,
Adjusting means for adjusting the nip pressure of at least one of the first roller pair and the second roller pair;
Detecting means for detecting fluctuations in the adjusting means;
A light beam scanning apparatus comprising: a control unit configured to control the adjustment unit based on a change in the adjustment unit detected by the detection unit to adjust the nip pressure. The light beam scanning apparatus according to claim 1, wherein the adjusting unit is a solenoid using a coil. 3. The light beam scanning apparatus according to claim 2, wherein the detection unit detects a temperature of the coil or a temperature of a portion that fluctuates with a temperature change of the coil. 4. The light beam scanning apparatus according to claim 2, wherein the control means adjusts the nip pressure by gradually changing a rotation angle of the rotary solenoid by PWM control. An upstream first roller pair and a downstream second roller pair that sandwich and convey the sheet-like scanned object are arranged at an interval shorter than the conveying length of the scanned object, and the first The scanned object is sub-scanned and conveyed by the roller pair and the second roller pair, and is deflected in a direction substantially orthogonal to the sub-scanning direction between the first roller pair and the second roller pair. In a light beam scanning device that scans the object to be scanned two-dimensionally by irradiating the light beam and performing main scanning,
Adjusting means for adjusting the nip pressure of the first roller pair and / or the second roller pair;
Control means for controlling the adjusting means so as to switch the nip pressure of the first roller pair and / or the second roller pair from a first value to a second value;
The light beam scanning apparatus according to claim 1, wherein the control unit changes the transition state from the first value to the second value based on the number of transported objects to be scanned. 6. The light beam scanning according to claim 5, wherein the adjusting means includes a rotary solenoid, and the control means makes the transition state different by gradually changing the rotation angle of the rotary solenoid by PWM control. apparatus. An upstream first roller pair and a downstream second roller pair that sandwich and convey the sheet-like scanned object are arranged at an interval shorter than the conveying length of the scanned object, and the first The scanned object is sub-scanned and conveyed by the roller pair and the second roller pair, and is deflected in a direction substantially orthogonal to the sub-scanning direction between the first roller pair and the second roller pair. In a light beam scanning device that scans the object to be scanned two-dimensionally by irradiating the light beam and performing main scanning,
Adjusting means having an electrical component that operates by energization and generates heat to adjust the nip pressure of the first roller pair and / or the second roller pair;
Detecting means for detecting the temperature of the electrical component;
Control means for controlling the adjusting means so as to switch the nip pressure of the first roller pair and / or the second roller pair from a first value to a second value;
The light beam scanning apparatus according to claim 1, wherein the control unit changes a transition state from the first value to the second value based on a temperature detected by the detection unit. The adjusting means includes a rotary solenoid, the electrical component is a coil of the rotary solenoid, and the control means gradually changes the rotation angle of the rotary solenoid by PWM control to make the transition states different. 8. The light beam scanning apparatus according to claim 7, wherein The nip pressure of the first roller pair is switched from strong to weak when a rear end portion of the scanning target during the sub-scanning conveyance passes through the first roller pair on the upstream side. 9. The light beam scanning apparatus according to any one of 1 to 8. The second roller pair includes a driving roller and a driven roller having a large diameter portion and a small diameter portion. The light beam scanning apparatus according to claim 1, wherein the light beam scanning apparatus is configured to form a nip gap narrower than a thickness of the body. A light beam scanning device according to any one of claims 1 to 10,
The scanning object is a photothermographic film, and a latent image corresponding to an image signal is formed on the photothermographic film by two-dimensional scanning of a light beam by the light beam scanning device. .

Images