JP4081474B2 - Cylindrical inner surface scanning image recording apparatus - Google Patents

Description

  The present invention relates to a cylindrical inner surface scanning type image recording apparatus that records an image by scanning a recording sheet held on a cylindrical inner surface with a plurality of light beams modulated according to image information.

  As a device for recording an image on a recording sheet using a laser beam, a planar scanning type image recording device that performs recording by irradiating a planar recording sheet conveyed in the sub-scanning direction in the main scanning direction, a rotating drum Cylindrical outer surface scanning type image recording apparatus for recording by irradiating the recording sheet adhered to the outer peripheral surface with the laser beam, and inner surface of the cylinder for performing recording by irradiating the recording sheet adhered to the inner surface of the cylinder with the laser beam There is a scanning image recording apparatus. In this case, in the cylindrical inner surface scanning type image recording apparatus, since the recording sheet is attached to the inner surface of the cylinder, there is no peeling of the recording sheet during recording, and the dimensional accuracy of the recorded image is high. Since it is excellent in high-speed scanning and economical efficiency, it has been frequently used.

  In the cylindrical inner surface scanning type image recording apparatus, for example, an optical scanner having a reflection surface set to about 45 ° with respect to the incident direction of the laser beam is disposed on the central axis of the cylinder, and the reflection surface is the center. The laser beam is scanned on the recording sheet by rotating about the axis.

  By the way, in the cylindrical inner surface scanning type image recording apparatus configured as described above, an attempt is made to improve the recording speed by performing scanning using a plurality of laser beams. In this case, if a plurality of laser beams are simply made incident on the optical scanner, the laser beams cannot be linearly scanned on the recording sheet, so that accurate image recording cannot be performed.

  That is, when the reflecting surface 4 of the optical scanner 2 is in the direction of FIG. 15A (the minor axis of the reflecting surface 4 coincides with the Y axis), the light is incident on the minor axis of the reflecting surface 4 in a state parallel to the Z axis. The laser beams # 1, # 2, and # 3 are reflected along the XY plane, and reach the recording sheet S in a state where the laser beams # 1, # 2, and # 3 travel on the same scanning line. To do. Further, when the reflecting surface 4 is rotated 90 ° from the state of FIG. 15A and becomes the direction of FIG. 15B, the laser beams # 1, # 2, and # 3 are reflected along the YZ plane, and each laser beam is reflected. The recording sheet S is reached in a state where the beams # 1, # 2, and # 3 are separated. Further, when the reflecting surface 4 is rotated 90 ° from the state of FIG. 15B and becomes the direction of FIG. 15C, the laser beams # 1, # 2, and # 3 are again reflected along the XY plane, The laser beams # 1, # 2, and # 3 reach the recording sheet S in a state of traveling on the same scanning line. In this case, since the positions of the incident laser beams # 1, # 2, and # 3 on the reflection surface 4 vary depending on the rotation angle of the optical scanner 2, they are incident on the recording sheet S at the center of the reflection surface 4. A curved scanning line is formed as shown in FIG. 16 except for the scanning line formed by the laser beam # 2.

  Therefore, in order to avoid the above-mentioned problems that occur when scanning using a plurality of laser beams, a hologram that rotates together with the optical scanner is disposed between the light source of the laser beam and the optical scanner, and the laser beam By adjusting the diffraction angle according to the incident position on the hologram, the incident position of the laser beam on the optical scanner is adjusted, and as a result, each scanning line on the recording sheet becomes a straight line. (Patent Document 1).

  Further, two laser beams of P-polarized light and S-polarized light are generated, and one of these laser beams is guided to a recording sheet via a rotating deflection beam splitter, and the other laser beam separated by the deflection beam splitter Is configured to be guided to the recording sheet via a reflecting plate rotating (Patent Document 2).

  In addition, when each of the two laser beams of P-polarized light and S-polarized light is modulated based on an image signal and then guided onto a recording sheet via a rotating hologon (hologram diffraction grating) deflector, The laser beam is controlled to be deflected by a piezo element with a mirror whose angle is controlled in accordance with the rotation angle of the hologon deflector, and the interval between two scanning lines is maintained (Patent Document 3).

  Also, there is an optical scanner that reflects the laser beam three times and guides it to the recording sheet, and is configured to eliminate the twist of the laser beam by rotating the optical scanner (Patent Documents 4 to 6). .

  In addition, there is a configuration in which a light emitting element array that outputs a plurality of light beams is rotatably disposed on a central axis of a cylinder and is rotated (Patent Document 7).

  Further, a transparent medium layer is provided on the reflecting surface of the rotating optical scanner, a plurality of laser beams having different wavelengths are incident on the transparent medium layer, and the laser beams are separated using a difference in refractive index to be recorded on the recording sheet. (Patent Documents 8 and 9).

Japanese Patent Publication No. 4-73829 Japanese Patent Laid-Open No. 5-27188 US Pat. No. 5,097,351 JP-A-5-27190 Japanese Patent Laid-Open No. 5-289018 JP-A-5-308488 JP-A-5-63920 JP-A-4-348311 Japanese Patent Laid-Open No. 6-95016

  However, in these prior arts, since there are many members that must be rotated together with the optical scanner, there is a problem that the accuracy is lowered and the configuration is complicated. Further, even if the configuration is relatively simple, for example, in Patent Documents 8 and 9, wavelength management is extremely difficult, and therefore the width of the scanning line on the recording sheet cannot be accurately adjusted. There is.

  Further, in Patent Document 3, it is possible to make the interval between two scanning lines constant, but there is a specific description of adjusting the scanning position of the two scanning lines in the main scanning direction. Therefore, high-precision image recording cannot be performed.

  Further, in Patent Documents 2 and 3, since only two laser beams can be controlled, a significant increase in speed cannot be desired.

  The present invention solves such problems, and without increasing the number of rotating components, a cylindrical inner surface capable of guiding a plurality of light beams onto a recording sheet with high accuracy and realizing high-speed recording without increasing the number of rotating components. An object of the present invention is to provide a scanning image recording apparatus.

In order to achieve the above object, the present invention provides a cylindrical inner surface scanning type image recording in which a recording sheet held on the inner surface of a cylinder is main-scanned with a plurality of light beams modulated according to image information to record an image. In the device
A light beam output means for outputting the plurality of light beams;
Scanning means having a reflecting surface with the central axis of the cylinder as a rotation axis, reflecting the plurality of light beams by the rotating reflecting surface, and performing main scanning on the recording sheet;
Deflection that causes the light beam to be deflected by a desired deflection amount two-dimensionally in a plane orthogonal to the rotation axis of the scanning means, and causes a desired displacement in the main scanning direction and the sub-scanning direction on the recording sheet. A variable amount of light deflecting means;
Control means for controlling the displacement position of the light beam on the recording sheet by the light deflecting means in synchronization with rotation of the reflecting surface;
It is characterized by providing.

  In the present invention, the light deflection means is controlled based on a control signal from the control means, and a plurality of light beams output from the light beam output means and incident on the scanning means are within a plane orthogonal to the rotation axis of the scanning means. By deflecting a desired deflection amount two-dimensionally, the curvature of the scanning lines of the plurality of light beams reflected by the scanning means is corrected and adjusted to a desired recording interval in the sub-scanning direction on the recording sheet. Lead. In this case, it is possible to record an image with high accuracy by keeping the scanning line interval constant at an arbitrary interval and the same length.

  In the present invention, since the movable part for making the interval between the scanning lines constant is only the scanning means, the mechanical adjustment is not required and the accuracy can be easily improved. In addition, the entire apparatus can be configured compactly. Further, since the scanning line on the recording sheet can easily adjust the scanning start position and the scanning end position by electrical control, high-precision image recording can be realized.

  In the present invention, the interval and length of the scanning lines can be adjusted simultaneously by deflecting the light beam two-dimensionally in a plane orthogonal to the rotation axis of the scanning means.

  Furthermore, it is possible to easily expand from the conventional type in which one light beam is deflected by an optical scanner to record an image to the type using a plurality of light beams of the present invention. In addition, since it is easy to increase the number of light beams, particularly three or more, it is possible to set the rotation speed of the scanning means to be low and improve the reliability of recording accuracy by scanning.

  FIG. 1 and FIGS. 2A and 2B are diagrams for explaining the principle of the first embodiment of the present invention.

When the reflecting surface 4 of the optical scanner 2 is in the direction shown in FIG. 1 (the minor axis of the reflecting surface 4 coincides with the Y axis), the laser beam L0 incident on the center of the reflecting surface 4 along the Z axis is the X axis. Is reflected along. Therefore, when the laser beam L0 is deviated by + θ _{X in the} X-axis direction with respect to the optical scanner 2, the reflected laser beam L0 is −Δz in the Z direction within a predetermined plane orthogonal to the X-axis. Displace only. Further, when the laser beam L0 is deviated by −θ _{X in the} X axis direction with respect to the optical scanner 2, the reflected laser beam L0 is + Δz in the Z direction within a predetermined plane orthogonal to the X axis. Displace.

  Accordingly, the laser beams # 1 and # 3 incident on the optical scanner 2 are placed in the minus and plus directions of the X axis in a state where they are separated from the laser beam # 2 by a predetermined amount in the Y axis direction. By deviating a certain amount, the reflected laser beams # 1 and # 3 can be displaced in the Z-axis direction. Accordingly, the reflected laser beams # 1, # 2, and # 3 are substantially rotated around the X axis from the arrangement on the XY plane shown in FIG. 15A, and as shown in FIG. It can be set apart. Similarly, when the reflecting surface 4 of the optical scanner 2 is in the direction of FIG. 2B, the laser beam # 1 is deviated by a predetermined amount in the positive direction of the X axis, and the laser beam # 3 is shifted in the negative direction of the X axis. By deflecting by a predetermined amount, the reflected laser beams # 1, # 2, and # 3 are substantially rotated around the X axis from the arrangement on the XY plane shown in FIG. 15C, and as shown in FIG. 2B, It can be set at a certain distance in the Y-axis direction.

  In this way, the laser beams # 1, # 2, and # 3 on the recording sheet S are adjusted in a one-dimensional manner within the XZ plane by the incident directions of the laser beams # 1 and # 3 with respect to the reflecting surface 4. The scanning interval can be made constant regardless of the scanning position. Therefore, as shown in FIG. 3, the scanning lines recorded on the recording sheet S by the laser beams # 1, # 2, and # 3 can be formed as straight lines that are parallel over the entire scanning area.

Here, in the above description, as shown in FIG. 4A, the spots S of the laser beams # 1, # 2, and # 3 incident on the reflection surface 4 of the optical scanner 2 are conjugate with the recording sheet S. When projected upward, the trajectories of the laser beams # 1 and # 3 on the surface S ′ accompanying the rotation of the optical scanner 2 are as shown in FIG. 4B, where the angular velocity of the optical scanner 2 is ω.
X = −a · cos ωt... Locus of laser beam # 1 X = a · cos ωt... Single vibration represented by the locus of laser beam # 3. Therefore, by deflecting the laser beams # 1 and # 3 and guiding them to the optical scanner 2 according to the above equations, a plurality of scanning lines having a constant interval can be formed as shown in FIG. it can.

  FIG. 5 shows a cylindrical inner surface scanning type image recording apparatus of the first embodiment. This apparatus includes a laser beam generator 6 that generates a laser beam L, a beam splitter 8 that splits the laser beam L into three laser beams # 1, # 2, and # 3, and a laser beam # 1 as shown in FIG. And an acoustooptic device 10x that modulates according to image information without deflecting the laser beam # 2, and a laser beam # 3. Acoustooptic element 14x that deflects in the X-axis direction and modulates according to image information, mirrors 16, 18, and 20 that reflect laser beams # 1, # 2, and # 3, and laser beams # 1 and # 2 and a condensing lens 22 for condensing the light beam # 3 and an optical scanner 2 having a rotating reflecting surface 4 and reflecting the laser beams # 1, # 2, and # 3 onto the recording sheet S. Prepare. The recording sheet S is held on the cylindrical inner surface of the drum 24, and the optical scanner 2 is disposed on the central axis of the drum 24.

  FIG. 6 shows a circuit for controlling the acousto-optic elements 10x, 12 and 14x shown in FIG.

  This circuit generates a control clock signal based on a signal from an encoder (not shown) provided in the optical scanner 2 and generates a cosine wave voltage signal (X = −a · cosωt) according to the control clock signal. A cosine wave signal generation circuit 28a that generates a cosine wave voltage signal (X = a · cosωt) according to the control clock signal, and a constant voltage signal that generates a constant voltage signal according to the control clock signal. A generating circuit 30; voltage controlled oscillators 32a, 32b, and 32c that generate frequency modulation signals from the cosine wave voltage signal or the constant voltage signal; and modulators 34a and 34b that modulate the frequency modulation signals according to a binary image signal. , 34c and the modulated frequency modulation signals are supplied to the acoustooptic devices 10x, 12 and 14x, respectively. Amplifiers 36a, 36b, and 36c and a binary image signal generation circuit 38 that generates a desired binary image signal in accordance with a control clock signal from the control circuit 26 are provided.

  Here, as shown in FIG. 3, the scanning lines formed on the recording sheet S by the laser beams # 1, # 2, and # 3 deflected by the acousto-optic elements 10x, 12, and 14x are in the main scanning direction ( It has different scanning lengths in the direction of arrow X). Therefore, in order to correct the different scanning lengths and accurately record an image, the control circuit 26 includes a control clock signal generation circuit 40 shown in FIG.

  That is, the control clock signal generation circuit 40 is in accordance with a PLL circuit 42 that generates a phase synchronization signal from a rotation position signal P from an encoder (not shown) provided in the optical scanner 2 and a main scanning start signal LSYNC from the encoder. The basic clock signal generation circuit 44 that generates the basic clock signal B from the phase synchronization signal, the counter 46 that counts the basic clock signal, and the laser beams # 1, # 2, The basic clock from the basic clock signal generation circuit 44 according to the lookup table 48 for outputting a delay amount setting signal for setting the delay amount of the control clock signals CL1, CL2, CL3 for controlling # 3 and the delay amount setting signal The signal is delayed by a predetermined amount, and the control clock signals CL1, CL2, CL3 are Comprising forces a delay circuit 50a, 50b, and 50c. The control clock signals CL1, CL2, CL3 are supplied to the binary image signal generation circuit 38 shown in FIG.

  The cylindrical inner surface scanning type image recording apparatus of the first embodiment is basically configured as described above, and the operation thereof will be described next.

  The laser beam L output from the laser beam generator 6 is divided into three laser beams # 1, # 2, and # 3 by the beam splitter 8. The divided laser beam # 1 is deflected in the X-axis direction by the acousto-optic device 10x (see FIGS. 2A and 2B), and on / off controlled according to image information. Next, after being reflected and deflected by the mirror 16, the light is introduced into the optical scanner 2 through the condenser lens 22. The optical scanner 2 reflects and deflects the laser beam # 1 by the reflecting surface 4 that rotates about the Z axis and guides it to the recording sheet S. Similarly, the laser beam # 3 is guided to the recording sheet S via the acoustooptic device 14x, the mirror 20, the condenser lens 22, and the optical scanner 2. On the other hand, since the laser beam # 2 is introduced into the rotation center of the optical scanner 2, it is turned on / off according to the image information by the acoustooptic device 12 without being deflected, and then the mirror 18, The light is guided to the recording sheet S through the lens 22 and the optical scanner 2. On the recording sheet S, as shown in FIG. 3, an image is formed by three scanning lines having a constant interval.

  Next, control of laser beams # 1, # 2, and # 3 will be described in detail with reference to FIG.

  First, based on a rotation position signal P and a main scanning start signal LSYNC from an encoder (not shown) provided in the optical scanner 2, the control circuit 26 supplies a control clock signal to the cosine wave signal generation circuits 28a and 28b. The cosine wave signal generation circuits 28a and 28b supply cosine wave voltage signals (X = −a · cos ωt, X = a · cos ωt) whose phases are different by 180 ° to the voltage controlled oscillators 32a and 32c. The voltage controlled oscillators 32a and 32c convert the cosine wave voltage signal into a frequency modulation signal, and the converted frequency modulation signal is controlled to be turned on / off by the binary image signal in the modulators 34a and 34c. The signals are supplied to the acousto-optic elements 10x and 14x via the amplifiers 36a and 36c. In this case, the acoustooptic devices 10x and 14x deflect the laser beams # 1 and # 3 in the X-axis direction shown in FIGS. 2A and 2B based on the frequency modulation signal.

  Further, the control circuit 26 supplies a control clock signal to the constant voltage signal generation circuit 30, and supplies the generated constant voltage signal to the voltage control oscillator 32b. The voltage controlled oscillator 32b converts the constant voltage signal into a frequency modulation signal. Next, the frequency modulation signal is on / off controlled by the binary image signal in the modulator 34b, and then supplied to the acoustooptic device 12 via the amplifier 36b. In this case, the acoustooptic device 12 performs only on / off control without deflecting the laser beam # 2.

  As a result, the laser beam # 1 guided to the reflecting surface 4 of the optical scanner 2 makes a single oscillation in the X-axis direction as shown in FIG. 4B in synchronization with the rotation operation of the optical scanner 2. . Similarly, the laser beam # 3 makes a single oscillation as shown in FIG. 4B in a state where the phase of the laser beam # 1 is shifted by 180 °. Note that the laser beam # 2 is guided on the recording sheet S by performing only on / off control by a binary image signal without causing simple vibration. Then, as shown in FIG. 3, laser beams # 1, # 2, and # 3 whose intervals are controlled to be constant are guided to the recording sheet S, and an image is recorded. In this case, the interval can be easily adjusted by the amplification factor set by the amplifiers 36a, 36b, and 36c.

  Here, when the laser beams # 1, # 2, and # 3 are controlled to be deflected only in the X-axis direction, the scanning start position and the scanning end position are different as shown in FIG. If the lengths of the images are different and the difference is large, the image distortion may be visually recognized. However, such a problem can be solved by adjusting the output timing of the binary image signal by the control clock signals CL1, CL2, and CL3 generated by the control clock signal generation circuit 40 shown in FIG.

  That is, the phase of the rotational position signal P from the encoder (not shown) of the optical scanner 2 is controlled by the PLL circuit 42 to generate a phase synchronization signal. This phase synchronization signal is supplied to the basic clock signal generation circuit 44, and the basic clock signal B shown in FIG. 8 is generated at the timing of the main scanning start signal LSYNC supplied from the encoder. The basic clock signal B is counted by a counter 46 and supplied to delay circuits 50a, 50b, and 50c described later. The count value of the basic clock signal B counted by the counter 46 is supplied to the lookup table 48. The look-up table 48 sends a preset delay amount setting signal to each delay circuit 50a according to the count value, that is, according to the scanning position of the laser beams # 1, # 2, and # 3 with respect to the recording sheet S. 50b and 50c. Each of the delay circuits 50a, 50b, 50c delays the basic clock signal B from the basic clock signal generation circuit 44 by a predetermined amount based on the delay amount setting signal, and outputs binary image signals as control clock signals CL1, CL2, CL3. This is supplied to the generation circuit 38.

  In this case, the control clock signal CL1 is a signal for controlling the output timing of the binary image signal recorded on the recording sheet S by the laser beam # 1, and as shown in FIG. Based on the delay amount setting signal, the delay circuit 50a delays the image recording start time of the binary image signal by Td1 from the basic clock signal B, and sets the recording end time to the main scanning end timing of the basic clock signal B ( Set according to the m-th clock signal). The interval between the pulses of the control clock signal CL1 is set to be as equal as possible by the delay amount setting signal from the lookup table 48.

  The control clock signal CL2 is a signal for controlling the output timing of the binary image signal recorded on the recording sheet S by the laser beam # 2, and the amount of delay from the lookup table 48 as shown in FIG. Based on the setting signal, the delay circuit 50b delays the recording start time of the image by the binary image signal by Td2 from the basic clock signal B, and sets the recording end time to the main scanning end timing of the basic clock signal B (mth The clock signal is set to be delayed by Td2 from the clock signal. The interval between the pulses of the control clock signal CL2 is set so as to be as even as possible by the delay amount setting signal from the lookup table 48.

  Further, the control clock signal CL3 is a signal for controlling the output timing of the binary image signal recorded on the recording sheet S by the laser beam # 3, and the delay amount from the lookup table 48 as shown in FIG. Based on the setting signal, the delay circuit 50c sets the image recording start time of the binary image signal to be the same as the main scanning start time of the basic clock signal B, and sets the recording end time to the end of the main scanning of the basic clock signal B. Setting is delayed by Td3 from the timing (m-th clock signal). The interval between the pulses of the control clock signal CL3 is set so as to be as even as possible by the delay amount setting signal from the lookup table 48.

  In this case, if the delay positions between the adjacent scanning lines overlap, a beat is generated between the adjacent scanning lines and there is a possibility of unevenness on the image. It is desirable to set so as to be random between scanning lines.

  The control clock signals CL1, CL2, and CL3 set as described above are supplied to the binary image signal generation circuit 38, and the binary image signal is supplied to the modulators 34a, 34b, and 34c at each timing shown in FIG. Output. In this case, the laser beams # 1, # 2, and # 3 modulated based on the binary image signal record an image on the recording sheet S in the same recording range as the laser beam # 3 (see FIG. 3). It will be. Therefore, it is possible to form a highly accurate image with the same recording range of the image in the main scanning direction and without distortion.

  In the first embodiment described above, the difference in scanning line length due to the laser beams # 1, # 2, and # 3 on the recording sheet S is overcome by adjusting the respective recording timings. By using the second embodiment shown in FIG. 2, the interval and length of the scanning lines can be made constant. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  9A to 9C and FIGS. 10A and 10B are diagrams for explaining the principle of the second embodiment of the present invention.

First, when the reflecting surface 4 of the optical scanner 2 is in the direction of FIG. 9A (the minor axis of the reflecting surface 4 coincides with the Y axis), the laser beam L0 incident on the center of the reflecting surface 4 along the Z axis is emitted. When the incident direction is deviated by −θ _{X in the} X axis direction with respect to the scanner 2, the reflected laser beam L0 is displaced by + Δz in the Z direction within a predetermined plane orthogonal to the X axis. Further, as shown in FIG. 9B, when the laser beam L0 is deviated by + θ _{Y in the} Y-axis direction with respect to the optical scanner 2, the reflected laser beam L0 is within a predetermined plane orthogonal to the X-axis. , It is displaced by + Δy in the Y direction. Therefore, as shown in FIG. 9C, the reflected laser beam L0 can be displaced two-dimensionally on the recording sheet S by deflecting the laser beam L0 by θ _XY in the X and Y axis directions.

  Therefore, the laser beam # 1 is deviated by a predetermined amount in the negative direction of the X axis and the positive direction of the Y axis, and the laser beam # 3 is deviated by a predetermined amount in the positive direction of the X axis and the negative direction of the Y axis. The reflected laser beams # 1, # 2, and # 3 can be corrected from the arrangement on the XY plane shown in FIG. 15A to the arrangement along the Z-axis direction on the XZ plane shown in FIG. 10A. Similarly, when the reflecting surface 4 of the optical scanner 2 is in the direction of FIG. 10B, the laser beam # 1 is deviated by a predetermined amount in the positive direction of the X axis and the positive direction of the Y axis, and the laser beam # 3 is Arrangement of the reflected laser beams # 1, # 2, and # 3 along the Z-axis direction on the XY plane shown in FIG. 15C by deviating by a predetermined amount in the negative direction of the X-axis and the negative direction of the Y-axis To the arrangement on the XZ plane shown in FIG. 10B.

  In this way, by adjusting the incident directions of the laser beams # 1 and # 3 with respect to the reflecting surface 4 two-dimensionally, the spots of the laser beams # 1, # 2, and # 3 on the recording sheet S are always Z-axis. Can be arranged in a direction. Accordingly, as shown in FIG. 11, the scanning lines recorded on the recording sheet S by the laser beams # 1, # 2, and # 3 can be formed as parallel straight lines over the entire scanning area. The scanning line length can be the same.

で表される円となる。従って、前記の各式に従ってレーザビーム＃１および＃３を偏向して光走査器２に導くようにすることで、図１１に示すように、一定間隔からなる複数の走査線を形成することができる。 Here, in the above description, as shown in FIG. 12A, the spots of the laser beams # 1, # 2, and # 3 incident on the reflection surface 4 of the optical scanner 2 are surfaces S ′ that are conjugate with the recording sheet S. When projected upward, the trajectories of the laser beams # 1 and # 3 on the surface S ′ accompanying the rotation of the optical scanner 2 are as shown in FIG. 12B, where the angular velocity of the optical scanner 2 is ω,

It becomes a circle represented by. Therefore, by deflecting the laser beams # 1 and # 3 and guiding them to the optical scanner 2 in accordance with the above equations, as shown in FIG. 11, a plurality of scanning lines having a constant interval can be formed. it can.

  FIG. 13 shows a cylindrical inner surface scanning type image recording apparatus of the second embodiment. This apparatus deflects the laser beam # 1 in the X-axis direction of the optical scanner 2 shown in FIGS. 9A to 9C, deflects the laser beam # 1 in the Y-axis direction, and responds to image information. The acoustooptic element 10y that modulates the laser beam # 2 according to the image information without deflecting the laser beam # 2, the acoustooptic element 14x that deflects the laser beam # 3 in the X-axis direction, and the laser beam. The third embodiment includes an acoustooptic device 14y that deflects # 3 in the Y-axis direction and modulates it according to image information, and the other configuration is the same as that of the first embodiment shown in FIG.

  FIG. 14 shows a circuit for controlling the acousto-optic elements 10x and 10y shown in FIG. This circuit generates a control clock signal based on a signal from an encoder (not shown) provided in the optical scanner 2 and generates a cosine wave voltage signal (X = −a · cos ωt) according to the control clock signal. A cosine wave signal generation circuit 28a for generating a sine wave voltage signal (Y = −a · sin ωt) according to the control clock signal, and a voltage for generating a frequency modulation signal from the cosine wave voltage signal. A control oscillator 32a, a voltage control oscillator 32d for generating a frequency modulation signal from the sine wave voltage signal, an amplifier 36a for amplifying the frequency modulation signal from the voltage control oscillator 32a and supplying it to the acoustooptic device 10x, and a control circuit A binary image signal generation circuit 38 for generating a desired binary image signal in accordance with a control clock signal from A modulator 34d for modulating the frequency modulation signal from the control oscillator 32a with the binary image signal, and an amplifier 36d for amplifying the frequency modulation signal on / off-modulated by the modulator 34d and supplying the frequency modulation signal to the acoustooptic device 10y. Is provided.

  In the circuit for controlling the acoustooptic elements 14x and 14y, in the circuit of FIG. 14, the cosine wave signal generation circuit 28a generates a cosine wave voltage signal (X = a · cosωt), and the sine wave signal generation circuit 28c sine. Except for generating a wave voltage signal (Y = a · sin ωt), the circuit is configured in the same manner as the circuit for controlling the acoustooptic device 10y.

  The cylindrical inner surface scanning type image recording apparatus of the second embodiment is basically configured as described above, and the operation thereof will be described next.

  The laser beam L output from the laser beam generator 6 is divided into three laser beams # 1, # 2, and # 3 by the beam splitter 8. The divided laser beam # 1 is deflected in the X-axis direction by the acousto-optic element 10x, and then deflected in the Y-axis direction by the acousto-optic element 10y (see FIGS. 10A and 10B), and according to the image information. ON / OFF controlled. Next, after being reflected and deflected by the mirror 16, the light is introduced into the optical scanner 2 through the condenser lens 22. The optical scanner 2 reflects and deflects the laser beam # 1 by the reflecting surface 4 that rotates about the Z axis and guides it to the recording sheet S. Similarly, the laser beam # 3 is guided to the recording sheet S via the acoustooptic element 14x, the acoustooptic element 14y, the mirror 20, the condenser lens 22, and the optical scanner 2. On the other hand, since the laser beam # 2 is introduced along the rotation axis of the optical scanner 2, the laser beam # 2 is turned on / off according to the image information only by the acoustooptic device 12, and then the mirror 18, the condensing lens 22, The light is guided to the recording sheet S through the optical scanner 2. On the recording sheet S, as shown in FIG. 11, three parallel scanning lines having a constant interval and a constant length are formed.

  Here, the control of the laser beam # 1 will be described in detail with reference to FIG.

  First, based on a position signal from an encoder (not shown) provided in the optical scanner 2, the control circuit 27 supplies a control clock signal to the cosine wave signal generation circuit 28a. The cosine wave voltage signal (X = −a · cos ωt) output from the cosine wave signal generation circuit 28a is converted into a frequency modulation signal by the voltage controlled oscillator 32a, and then supplied to the acoustooptic device 10x via the amplifier 36a. The In this case, the acoustooptic device 10x deflects the laser beam # 1 in the X-axis direction shown in FIGS. 10A and 10B based on the cosine wave voltage signal.

  The control circuit 27 supplies the control clock signal to the sine wave signal generation circuit 28c. The sine wave voltage signal (Y = −a · sin ωt) output from the sine wave signal generation circuit 28c is converted into a frequency modulation signal by the voltage controlled oscillator 32d, and then the binary image signal generation circuit 38 in the modulator 34d. ON / OFF control is performed by a binary image signal from. This on / off-controlled frequency modulation signal is supplied to the acoustooptic device 10y via the amplifier 36d. In this case, the acoustooptic device 10y deflects the laser beam # 1 modulated in the X-axis direction by the acoustooptic device 10x in the Y-axis direction shown in FIGS. 10A and 10B based on the sine wave voltage signal.

  As a result, the laser beam # 1 guided to the reflecting surface 4 of the optical scanner 2 is rotated by the rotation of the optical scanner 2 as shown in FIGS. 12A and 12B in synchronization with the rotation operation of the optical scanner 2. A substantially circular locus is drawn on the surface S ′ perpendicular to the axis. As will be described later, when a correction signal is added to correct distortion, aberration, etc. of the optical system, this circular locus is not a perfect circle but a slightly deformed circle. Similarly, the laser beam # 3 draws a substantially circular locus as shown in FIGS. 12A and 12B in a state where the phase of the laser beam # 1 is shifted by 180 °. Note that the laser beam # 2 is guided onto the recording sheet S only by on / off control by a binary image signal without moving the position on the surface S ′. Then, as shown in FIG. 11, laser beams # 1, # 2, and # 3 whose intervals are controlled to be constant are guided to the recording sheet S, and an image is recorded. In this case, the interval can be easily adjusted by the amplification factor set by the amplifiers 36a and 36c.

  In the second embodiment described above, the acoustooptic elements 10x and 10y are configured separately. However, the acoustooptic elements 10x and 10y are integrally configured, and the deflection and image information in the X-axis and Y-axis directions are formed by one acoustooptic element. It is also possible to configure so as to realize modulation according to the above. In each embodiment, an electro-optic element may be used instead of the acousto-optic element. Further, four or more laser beams can be generated by the beam splitter 8 to record an image. Further, by eliminating the beam splitter 8 and preparing the laser beam generator 6 for each of the laser beams # 1, # 2, and # 3, independently guiding them to the acoustooptic elements 10x, 12, and 14x, respectively. Further, it is possible to avoid heterodyne interference between the laser beams # 1, # 2, and # 3, and to record an image with higher accuracy. Further, if the deflection amounts of the laser beams # 1 and # 3 by the acoustooptic elements 10x, 10y, 14x, and 14y can be switched, a cylindrical inner surface scanning type image recording apparatus with variable image resolution can be obtained. . Further, by adding correction signals to the signals output from the cosine wave signal generation circuits 28a and 28b and the sine wave signal generation circuit 28c, the aberration of the condenser lens 22 and the distortion of the reflection surface 4 of the optical scanner 2 are obtained. The deflection of the rotation axis of the optical scanner 2, the distortion of the scanning line when the laser beams # 1, # 2, and # 3 are incident on the rotation axis of the optical scanner 2 at an angle or offset, etc. It is also possible to correct.

It is principle explanatory drawing of 1st Example of this invention. 2A and 2B are explanatory views of the principle of the first embodiment of the present invention. It is explanatory drawing of the scanning line on the recording sheet by 1st Example of this invention. 4A and 4B are explanatory diagrams of the locus of the light beam on the plane conjugate with the recording sheet in the first embodiment. 1 is a configuration diagram of a first embodiment of a cylindrical inner surface scanning image recording apparatus. FIG. 1 is a circuit configuration diagram of a first embodiment of a cylindrical inner surface scanning type image recording apparatus. FIG. FIG. 7 is a configuration diagram of a control clock signal generation circuit in the control circuit shown in FIG. 6. It is a timing chart of a control clock signal. 9A, 9B, and 9C are explanatory diagrams of the principle of the second embodiment of the present invention. 10A and 10B are explanatory diagrams of the principle of the second embodiment of the present invention. It is explanatory drawing of the scanning line on the recording sheet by 2nd Example of this invention. 12A and 12B are explanatory views of the locus of the light beam on the surface conjugate with the recording sheet in the second embodiment. It is a block diagram of 2nd Example of a cylindrical inner surface scanning type image recording apparatus. It is a circuit block diagram of 2nd Example of a cylindrical inner surface scanning type image recording apparatus. FIG. 15A, FIG. 15B, and FIG. 15C are explanatory diagrams when light beam deflection control is not performed. It is explanatory drawing of the scanning line formed when not performing deflection control of a light beam.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Optical scanner 6 ... Laser beam generator 8 ... Beam splitter 10x, 10y, 12, 14x, 14y ... Acoustooptic element 28a, 28b ... Cosine wave signal generation circuit 28c ... Sine wave signal generation circuit 40 ... Control clock signal generation circuit

Claims (6)

In a cylindrical inner surface scanning type image recording apparatus that performs main scanning on a recording sheet held on a cylindrical inner surface with a plurality of light beams modulated according to image information, and records an image,
A light beam output means for outputting the plurality of light beams;
Scanning means having a reflecting surface with the central axis of the cylinder as a rotation axis, reflecting the plurality of light beams by the rotating reflecting surface, and performing main scanning on the recording sheet;
Deflection that causes the light beam to be deflected by a desired deflection amount two-dimensionally in a plane orthogonal to the rotation axis of the scanning means, and causes a desired displacement in the main scanning direction and the sub-scanning direction on the recording sheet. A variable amount of light deflecting means;
Control means for controlling the displacement position of the light beam on the recording sheet by the light deflecting means in synchronization with rotation of the reflecting surface;
A cylindrical inner surface scanning type image recording apparatus. The apparatus of claim 1.
The light deflection means includes a first light deflection element that deflects the light beam in a first direction, and a second light deflection element that deflects the light beam in a second direction orthogonal to the first direction. A cylindrical inner surface scanning type image recording apparatus. The apparatus of claim 2.
The first light deflection element and the second light deflection element are integrally formed, and the light beam is deflected two-dimensionally in a plane perpendicular to the rotation axis of the scanning means. An internal scanning image recording apparatus. The apparatus of claim 1.
The cylindrical inner surface scanning type image recording apparatus, wherein the control means controls the rotation of the light beam around a rotation axis of the scanning means within a plane orthogonal to the rotation axis. The apparatus of claim 1.
The cylindrical inner surface scanning type image recording apparatus, wherein the light deflection means comprises an acousto-optic element. The apparatus of claim 1.
The cylindrical inner surface scanning type image recording apparatus, wherein the light deflecting means comprises an electro-optic element.

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