JP3604847B2 - Image forming device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus that exposes a photosensitive material based on digital image data and forms an image corresponding to the digital image data.
[0002]
[Prior art]
At present, an image forming apparatus includes a main scan and a sub-light while modulating a spot-shaped light beam (hereinafter, referred to as “spot light”) emitted from a semiconductor laser, a light emitting diode (LED), or the like based on digital image data. Some form an image on a recording medium by scanning. Further, in this image forming apparatus, at the time of scanning exposure, by changing the intensity of the spot light according to the digital image data, the density of the dots to be formed is changed, and the density of the dots to be formed is changed according to the digital image data on the recording medium. There is one that forms dots of density.
[0003]
In such an image forming apparatus, one image is formed by repeatedly performing main scanning at predetermined time intervals. That is, the main scanning is repeated at a predetermined exposure interval. Here, a time interval from the start of the previous main scan to the start of the next main scan is referred to as an exposure interval.
[0004]
Further, as such an image forming apparatus, there has been proposed an image forming apparatus in which a plurality of LEDs are arranged in a sub-scanning direction, and the plurality of LEDs are simultaneously subjected to main scanning. This makes it possible to form a plurality of continuous dot lines in the main scanning direction (hereinafter, referred to as “main scanning lines”) at a time. As a result, the number of main scans can be reduced, and even when a high-quality image with a larger number of main scan lines is formed by narrowing the interval between main scan lines, such a high-quality image can be formed in a short time. It can be formed efficiently.
[0005]
By the way, when a dot image is formed on a recording medium such as a photosensitive material, the periphery of the area irradiated with the spot light is also exposed to a considerable extent. Since the peripheral portion develops color in accordance with the exposure amount, the dot image formed on the photosensitive material can be seen smoothly by using the color, and the finish quality can be further improved.
[0006]
[Problems to be solved by the invention]
However, when forming an image, the main scanning is repeated a plurality of times, so that dots adjacent in the main scanning direction are exposed almost simultaneously, but dots adjacent in the sub-scanning direction are not necessarily exposed simultaneously. For this reason, even if the exposure amount is the same, a density difference may occur between the main scanning lines. In particular, when a plurality of main scanning lines are formed at the same time, some of the dots adjacent in the sub-scanning direction are exposed at the same time. There is a problem that the finished quality of the resulting image is impaired.
[0007]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and has as its object to provide an image forming apparatus capable of forming an image having a high finish quality by preventing the occurrence of density unevenness due to an exposure interval.
[0008]
[Means for Solving the Problems]
The invention described in claim 1 is an exposure light source that emits a spot light, The photosensitive material has a characteristic that the density decreases when the time interval of exposure is extended, or has the characteristic that the density increases when the time interval of exposure is extended A main scanning unit and a sub-scanning unit that relatively move the photosensitive material and the exposure light source in the main scanning direction and the sub-scanning direction, and the exposure is performed in synchronization with the scanning movement by the main scanning unit and the sub-scanning unit. Exposure control means for modulating a spot light emitted from a light source based on digital image data and repeating the main scanning at a predetermined time interval to expose the photosensitive material, and a light amount corresponding to the predetermined time interval Light amount adjusting means for adjusting the amount of light of the exposure light source so that
[0009]
According to the present invention, when exposure is performed continuously in the sub-scanning direction while starting main scanning at a predetermined time interval, the time interval between the fixed main scanning exposures, that is, the exposure light source is determined based on the exposure interval. The light intensity is adjusted. For this reason, a dot adjacent to a certain dot is an adjacent dot on one row of main scanning lines formed by exposure at substantially the same time, and a dot of a different row formed by exposure at a predetermined exposure interval. Exposure is performed with different amounts of light when the dots are adjacent to each other on the scanning line, and the density of the area between the adjacent dots can be made the same. Therefore, it is possible to make the density of the portion exposed by the exposure light source emitted at substantially the same time and the density of the portion exposed at the fixed exposure interval substantially the same, thereby preventing the occurrence of streak-like density unevenness. Thus, an image having a good finish quality can be formed.
[0010]
The invention according to claim 2 is an exposure light source that emits spot light, The photosensitive material has a characteristic that the density decreases when the time interval of exposure is extended, or has the characteristic that the density increases when the time interval of exposure is extended A main scanning unit and a sub-scanning unit that relatively move the photosensitive material and the exposure light source in the main scanning direction and the sub-scanning direction, and the exposure is performed in synchronization with the scanning movement by the main scanning unit and the sub-scanning unit. Exposure control means for modulating a spot light emitted from a light source based on digital image data and exposing the photosensitive material along a main scanning direction and a sub-scanning direction; and a main scanning after starting a previous main scanning. Interval detection means for detecting a time interval until the start, and light amount adjustment means for adjusting the light amount of the exposure light source based on the time interval detected by the interval detection means when performing the next main scan, It is characterized by having.
[0011]
According to the present invention, the time interval from the start of the main scan to the start of the next main scan, that is, the length of the exposure interval is detected, and spot exposure is performed with a light amount corresponding to the detected exposure interval. Even if the length of the exposure interval is changed, dots can be formed by exposing with a light emitting element having a light amount corresponding to the changed exposure interval. As a result, even when adjacent dots are exposed at different exposure intervals, substantially the same density can be obtained, and the occurrence of streak-like density unevenness can be prevented to form an image having a high finish quality. Can be.
[0012]
According to a third aspect of the present invention, the exposure light source is formed by arranging a plurality of light emitting elements each emitting a spot light at a predetermined interval in the sub-scanning direction, and the main scanning is performed simultaneously by the respective light emitting elements. In some cases, the light amount adjusting means adjusts the light amount of the light emitting element at the end in the sub-scanning direction.
[0013]
According to the present invention, since the light amount is adjusted for the light emitting element at the end of the plurality of light emitting elements arranged along the sub-scanning direction, a plurality of main scanning lines are simultaneously formed by the plurality of light emitting elements. As a result, an image can be formed efficiently, and the amount of light for the light emitting element at the end is adjusted, so that the occurrence of stripe-like density unevenness can be prevented. As a result, an image having a good finish quality can be efficiently formed.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
(Overall configuration "Appearance")
1 to 3 show an image forming apparatus 100 according to the present embodiment.
[0015]
The image forming apparatus 100 reads image data recorded on an optical disc 102 or an FD 104 (see FIG. 3), exposes the photosensitive material 106, and transfers an image recorded on the photosensitive material 106 to an image receiving paper 108. It is a device that outputs.
[0016]
The upper part of the front surface (left side in FIG. 3) of the box-shaped casing 110 is an inclined surface, and an operation display unit 112 is provided.
[0017]
As shown in FIG. 2, the operation display section 112 is classified into a monitor section 114 located on the right side and an input section 116 located on the left side, and the monitor section 114 is configured to display the read image.
[0018]
The input unit 116 includes a plurality of operation keys 118 and an input data confirmation display unit 120, and is necessary for image formation, such as inputting the number of records, setting the size, adjusting the color balance, and selecting negative / positive. You can enter data.
[0019]
Below the operation display unit 112, a deck unit 122 is provided. The deck section 122 includes an optical disk deck section 124 located on the right side of FIG. 3 and an FD deck section 126 located on the left side.
[0020]
The tray 130 can be opened and closed by pressing the open / close button 128 on the optical disk deck 124. By placing the optical disc 102 on the tray 130, the optical disc 102 can be loaded inside the apparatus.
[0021]
On the other hand, the FD deck section 126 has a structure in which an FD insertion throttle 132 is provided, and when the FD 104 is inserted, a drive system inside the apparatus operates to draw in the FD 104. When the FD 104 is taken out, the FD 104 can be pulled out by pressing the operation button 134.
[0022]
The optical disk deck section 124 and the FD deck section 126 are provided with access lamps 136 and 138, respectively. These access lamps 136 and 138 are turned on during access in the apparatus.
[0023]
A discharge tray 140 is provided further below the deck section 122. The discharge tray 140 is usually housed in the apparatus, and can be pulled out by putting a finger on the grip 142 (see FIG. 1).
[0024]
The image receiving paper 108 on which the image is recorded is discharged onto the discharge tray 140.
[0025]
The image receiving paper 108 is stored in a layer on a tray 144 in advance, and the tray 144 is to be loaded into a tray loading port 146 provided on the upper surface of the casing 110. The image receiving paper 108 is taken out one by one from the tray 144 loaded in the tray loading port 146, the image is transferred, and then guided to the discharge tray 140.
[0026]
Two circular cover members 148 and 150 are attached to the right side surface (the front side in FIG. 1) of the casing 110. The cover members 148 and 150 are individually detachable, and the photosensitive material 106 in the form of a roll is wound inside the apparatus along the axial direction of the cover members 148 and 150 as shown in FIG. A supply reel 152 and a take-up reel 154 are provided, and these reels can be taken out or loaded with the cover members 148 and 150 removed.
(Receiver paper transport system)
As shown in FIG. 3, the tray 144 loaded in the tray loading port 146 has an upper end portion facing the half-moon roller 156.
[0027]
The semicircular roller 156 has a part of its peripheral surface cut in a tangential direction. Normally, the notch 158 faces the uppermost image receiving paper 108 in the tray 144 at a predetermined interval. Here, when the half-moon roller 156 rotates, the uppermost layer of the image receiving paper 108 comes into contact with the peripheral surface of the half-moon roller 156, and the half-moon roller 156 makes one rotation, so that the image receiving paper 108 is slightly pulled out. The pulled-out image receiving paper 108 is nipped by a first roller pair 160, and is completely pulled out of the tray 144 by the driving force of the first roller pair 160.
[0028]
On the downstream side of the first roller pair 160, a second roller pair 162, a guide plate 164, and a third roller pair 166 are arranged in this order, and the image receiving paper 108 is sandwiched by the first roller pair 160. After that, it is nipped by the second roller pair 162 and guided by the guide plate 164, and is nipped by the third roller pair 166.
[0029]
The third roller pair 166 also performs superposition with the photosensitive material 106. That is, the third roller pair 166 is also used as a conveyance path for the photosensitive material 106.
(Photosensitive material transport system)
Next, a photosensitive material transport system corresponding to the scanning means of the present invention will be described.
[0030]
The photosensitive material 106 is loaded in the apparatus in a long form wound around a supply reel 152 in a layered manner. The supply reel 152 can be loaded at a predetermined position by removing the cover member 150 (on the rear side of the apparatus) and inserting the cover member 150 in the axial direction.
[0031]
With the photosensitive material 106 loaded in a predetermined position, the outermost layer is pulled out and loaded along a predetermined conveyance path as initial setting. The loading procedure is as follows. The outermost layer is pulled out from the supply reel 152 and is held between the fourth roller pair 168 near the loading position of the supply reel 152, and the third roller pair is inserted via the reservoir 170 and the guide plate 172. After being pinched by 166, it is wound around heat roller 174 and wound around take-up reel 154. In this case, a leader tape of a length necessary for loading may be provided at the end of the photosensitive material 106 wound around the supply reel 152.
[0032]
An exposure section 176 is provided between the fourth roller pair 168 and the reservoir section 170 in the conveying path of the photosensitive material 106. Further, a water application section 178 is provided between the reservoir section 170 and the guide plate 172. The details of the exposure unit 176 and the water application unit 178 will be described later. However, after the image is exposed on the photosensitive material 106 by the exposure unit 176, the water is applied to the emulsion surface (exposed surface). The roller pair 166 is superposed on the image receiving paper 108.
(Heat roller)
The heat roller 174 is a thermal development transfer unit of the present apparatus, and includes a cylindrical roller main body 180 and a heater 182 provided along an axis inside the roller main body 180. The surface of the roller main body 180 is heated by the operation, and has a role of applying heat to the members (the photosensitive material 106 and the image receiving paper 108) wound around the roller main body 180. By this heating, a heat development transfer process is performed, and the image recorded on the photosensitive material 106 is transferred to the image receiving paper 108.
[0033]
A peeling roller 184 and a peeling claw 186 are provided near the lower right of the heat roller 174, and the image receiving paper 108 wound around the heat roller 174 by about ３ is peeled off from the photosensitive material 106, and is moved toward the discharge tray 140. It has a structure for guiding the image receiving paper 108.
[0034]
On the other hand, the photosensitive material 106 is wound about a half by the heat roller 174, turned 180 °, and guided to a position where the winding reel 154 is loaded.
(Water application section)
As shown in FIG. 3, the water application section 178 has a function of applying water as a solvent for image formation to the photosensitive material 106 or the image receiving paper 108, bringing the overlapping surfaces of the two into close contact, and performing thermal development. And a long coating piece 188 along the width direction of the photosensitive material 106 and a tank 190 for storing water.
[0035]
The application piece 188 is a highly absorbent member such as a felt or a sponge and has an appropriate hardness, so that the photosensitive material 106 comes into contact with a predetermined pressure during transportation. The water in the tank 190 always transfers an appropriate amount to the coating piece 188 by utilizing the capillary phenomenon. When the photosensitive material 106 and the coating piece 188 come into contact with each other, the water is exposed by the coating piece 188. Water is applied to the surface (emulsion surface) of the material 106.
[0036]
Further, since the application piece 188 is in contact with the photosensitive material 106 at an appropriate pressure, the water is uniformly applied.
[0037]
The water in the tank 190 is replenished by removing the entire water application section 178. However, it is also possible to supply water from outside the apparatus by providing a pipe.
[0038]
In the present embodiment, water is used as the image forming solvent. However, the water is not limited to pure water but includes water in a widely used sense. Further, a mixed solvent of water and a low boiling point solvent such as methanol, DMF, acetone, diisobutyl ketone and the like may be used. Further, a solution containing an image formation accelerator, an antifoggant, a development terminator, a hydrophilic heat solvent and the like may be used.
(Exposure section)
FIG. 4 shows an exposure unit 176 according to the present embodiment.
[0039]
The exposure unit 176 is connected to the controller 202 with the light source unit 200 provided above the conveyance path of the photosensitive material 106 as a main component. Digital image data is stored in the controller 202 (image data read from the optical disk 102 or the FD 104), and the light source unit 204 in the light source unit 200 is turned on according to the digital image data. .
[0040]
The light source unit 200 can be moved in the width direction (main scanning direction) of the photosensitive material 106 by driving a main scanning unit 206 corresponding to a scanning unit of the present invention, which will be described later. Main scanning is performed at the time of stopping during step driving.
[0041]
The light source unit 200 of the exposure unit 176 is covered by a box-shaped exposure casing 214, and a light source unit 204 is disposed on the upper end surface of the exposure casing 214. The light emitting surface of the light source unit 204 is located inside the exposure casing 214. Is pointed. An aperture 216 is provided on the light emitting surface side of the light source unit 204 to limit the spread of light from the plurality of LED chips 208. Note that the aperture 216 may not be provided.
[0042]
A telecentric lens 212 is disposed on a support portion 215 at the center of the exposure casing 214 downstream of the aperture 216, and collects predetermined light from the light source portion 204 so as to be appropriately focused on the photosensitive material 106. As described above. The resolution of the light to be imaged is about 250 to 400 dpi.
[0043]
Here, the telecentric lens 212 is composed of a plurality of lenses and a diaphragm, and has a characteristic that the magnification does not change even if the height of the image plane changes. Differences due to time and the mounting state of the exposure casing 214 can be absorbed.
[0044]
The overall focus is always adjusted by an unillustrated autofocus mechanism. Alternatively, it is also possible to make adjustment unnecessary by using a lens system having a large depth of focus.
[0045]
The light source unit 204 is supported by a pair of parallel guide shafts 218 that constitute a part of the main scanning unit 206. The guide shaft 218 is disposed along the width direction of the photosensitive material 106 (the direction of the arrow W in FIG. 4), and the light source unit 204 is guided by the guide shaft 218 to move in the width direction of the photosensitive material 106. It is possible to move.
[0046]
A part of the endless timing belt 220 is fixed to the exposure casing 214 of the light source unit 204. Both ends of the timing belt 220 are wound around sprockets 222 located near both ends of the guide shaft 218, respectively. The rotation shaft of one sprocket 222 is connected to the rotation shaft of a stepping motor 226 via a transmission 224, and the reciprocating rotation of the stepping motor 226 causes the light source unit 204 to reciprocate along the guide shaft 218. You.
[0047]
As shown in FIG. 6, the stepping motor 226 is connected to the controller 202 via a driver 227. A counter 225 is attached to the stepping motor 226, and the counter 225 is connected to a driver 227. The counter 225 outputs a pulse signal corresponding to the driving amount of the stepping motor 226 to the driver 227. The driver 227 adjusts the driving amount of the stepping motor 226 based on the input pulse signal.
[0048]
The drive of the stepping motor 226 is controlled by the controller 202, and is synchronized with the step drive of the photosensitive material 106. That is, with the photosensitive material 105 moving one step and stopping, the stepping motor 226 starts rotating, and the light source unit 204 moves on the photosensitive material 106 along the width direction of the photosensitive material 106. After confirming the predetermined pulse, the light source unit 204 returns to the original position by rotating the stepping motor 226 in the reverse direction. The next movement of the photosensitive material 106 is started simultaneously with the return operation of the light source unit 204.
[0049]
As shown in FIG. 4, a photodiode 228 is provided on the light output side of the light source unit 204 and on the surface facing the photosensitive material 106 so that a signal corresponding to the light amount of the light source from the light source unit 204 is output. Has become. The photodiode 228 is connected to the light amount correction unit 230, and the signal is input to the light amount correction unit 230.
[0050]
The light quantity correction unit 230 has a role of comparing the detected light quantities from the LED chips 208 of the respective colors, adjusting the density and the color balance, and outputting a correction value to the controller 202. Further, the light amount correction unit 230 outputs an end detection signal indicating that the light source unit 204 has reached the end of the guide shaft 218 to the controller 202 based on a signal from the photodiode 228.
[0051]
As shown in FIG. 5, the light source unit 204 is configured by assembling LED chips 208, and each of the LED chips 208 (hereinafter, referred to as B (blue), G (green), and R (red), respectively. In the case of individually describing each color, an LED chip that emits B color is a B-LED chip 208B, an LED chip that emits G color is a G-LED chip 208G, and an LED chip that emits R color is an R-LED. Chips 208R) are mounted on the substrate 210 along the width direction (main scanning direction) of the photosensitive material 106 according to the same arrangement rule. The respective exposure wavelengths are 650 ± 20 nm for the R-LED chip 208R, 530 ± 30 nm for the G-LED chip 208G, and 470 ± 20 nm for the B-LED chip 208B. That is, in the plan view of the substrate 210, at the right end, ten B-LED chips 208B are arranged in two rows and in a staggered manner, and at the left end, ten R-LED chips 208R are arranged in two rows. In the center, ten G-LED chips 208G are arranged in two rows and in a staggered manner in the center, and a total of six rows of LED chips are arranged.
[0052]
A predetermined wiring is formed on the substrate 210 by an etching process or the like, and is covered with a metal so as not to short-circuit between the wirings, and has a heat radiation function. For this reason, heat generation due to lighting of the LED chip 210 can be suppressed, and fluctuations in the light emission amount can be suppressed.
[0053]
The dimensions of each part of the light source unit 204 applied in the present embodiment will be described below.
First, the horizontal (X) × vertical (Y) dimensions of the substrate 210 are 5 × 5 mm (maximum), and the outer dimensions (x × y) of the LED chip 208 are about 360 × 360 μm. The pitch P between columns of the same color is 600 μm, the row pitch L of each column is 520 μm, and the step size D in a staggered shape is 260 μm. The gap G between the colors is determined by the telecentric lens 212 and cannot be unambiguously determined, but it is preferable that the gap G between R and G and between G and B be the same.
[0054]
The hatched portion of the LED chip 208 shown in FIG. 5 is a region where light is actually emitted, and as shown by a chain line in FIG.
[0055]
With the light source unit 204 having the above structure, ten main scanning lines can be recorded on the photosensitive material 106 by one main scanning for each color. For this reason, the step movement of the photosensitive material 106 is controlled so that driving and stopping are repeated at a pitch 10 times the main scanning line width recorded on the photosensitive material 106.
(Reservoir section)
The reservoir section 170 is disposed between the exposure section 174 and the water application section 178 as described above, and includes two pairs of nipping rollers 192 and 194 and one dancer roller 196. The photosensitive material 106 is stretched over two pairs of sandwiching rollers 192 and 194, and a substantially U-shaped slack is provided in the photosensitive material 106 between them. The dancer roller 196 moves up and down in response to the slack, and holds the photosensitive material 106 at the slack portion.
[0056]
In the exposure unit 176, the photosensitive material 106 moves stepwise, but in the water application unit 178, it is necessary to convey the photosensitive material 106 at a constant speed for uniform application of water. Therefore, a difference in the conveying speed of the photosensitive material 106 occurs between the exposure unit 176 and the water application unit 178. In order to absorb this speed difference, the dancer roller 196 moves up and down to adjust the amount of slack in the photosensitive material 106 so that the step movement and the constant speed movement of the photosensitive material 106 can be performed simultaneously.
[0057]
By the way, as shown in FIG. 6, the controller 202 is provided with an exposure control unit 400, and an image signal is input to the exposure control unit 400. Further, a light amount correction unit 230 is connected to the exposure control unit 400, and a correction value is input from the light amount correction unit 230. In the exposure control unit 400, the digital image signal sent to the light source unit 204 is corrected based on the input correction value, whereby each LED chip 208 can be turned on with an appropriate amount of light.
[0058]
The main scanning control unit 410 and the sub-scanning control unit 412 provided in the controller 202 are connected to the exposure control unit 40. The main scanning control section 410 is connected via a driver 227 to a stepping motor 226 for moving the main scanning unit 206. An end detection signal is input to the main scanning control unit 410 from the light amount correction unit 230 via the exposure control unit 400. The main scanning control unit 410 outputs an edge detection signal to the driver 227. The counter 225 is connected to the exposure control unit 400 via a timer 406 provided in the controller 202, and inputs the operation time of the stepping motor 226 to the exposure control unit 400.
[0059]
Thus, when the main scanning is started by an instruction from the main scanning control unit 410, the stepping motor 226 is driven while the counter 225 counts the driving amount of the stepping motor 226 by the pulse signal, and the end detection signal is output. When input to the scanning control unit 410, the stepping motor 226 rotates in the reverse direction to perform the return operation of the light source unit 204. The return operation of the light source unit 204 is performed by moving until the same number of pulses as the number of pulses counted until the edge detection signal is input is detected. Once the driving amount of the stepping motor 226 for performing the main scanning based on the edge detection signal is detected, the main scanning is repeated by repeatedly performing the forward rotation and the reverse rotation of the same driving amount. The exposure control unit 400 measures, via a timer 406, an exposure interval when main scanning is performed.
[0060]
A sub-scanning control unit 412 is connected to the exposure control unit 400, and a motor 416 is connected to the sub-scanning control unit 412 via a driver 414. The motor 416 is connected to the fourth pair of rollers 168 of the photosensitive material transport system and the pair of holding rollers 192 of the reservoir (see FIG. 3). The sub-scanning control unit 412 controls the driving of the fourth roller pair 168 and the sandwiching roller pair 192 to move the photosensitive material 106 step by step, and controls the sub-scanning in synchronization with the main scanning by the main scanning control unit 410. ing.
[0061]
The exposure controller 400 is connected to an LED light amount controller 404 for adjusting the light amount of the LED chip 208. The LED light amount adjustment unit 404 receives the digital image data from the exposure control unit 400 and the exposure interval detected via the timer 406, and is subjected to a light amount adjustment process according to a light amount adjustment process described later. The light amount data of the LED chip 208 is adjusted according to the exposure interval.
[0062]
The LED light amount adjustment unit 404 is connected to the LED light emission control unit 408. The LED light emission control unit 408 controls the light emission of each LED chip 208 based on the exposure image balance adjustment processing and the digital image data on which the light amount adjustment processing has been performed on the target LED chip 208.
[0063]
Next, regarding the light amount adjustment processing performed in the LED light amount adjustment unit 404, five dots arranged linearly by the R-LED chip 208R, the G-LED chip 208G, and the B-LED chip 208B, each of which is arranged in two rows. The case where is formed will be described as an example.
[0064]
As shown in FIG. 7A, five dots 282 are formed on the photosensitive material 106 by being exposed at one time. This is continuously exposed along the main scanning direction (arrow Z direction), thereby forming five main scanning lines composed of a large number of dots 282 on the photosensitive material 106. At this time, the continuous exposure in the main scanning direction can be performed at a high speed because the image data has already been read at the start of the main scanning. Is Such five main scanning lines are repeatedly formed a predetermined number of times in the sub-scanning direction (the direction of the arrow L) (FIG. 7 shows a case where they are formed by the n-th and (n + 1) -th exposures). To form
[0065]
A peripheral portion 284 is formed at the peripheral edge of the dot 282. The peripheral portion 284 is a low-density portion where the light beam of the LED chip 208 forming the dot 282 is slightly exposed, and mainly has a density equal to or less than half the density of the dot 282. When the dots 282 are formed closely and continuously at a predetermined distance, the peripheral portions 284 of the adjacent dots 282 overlap.
[0066]
Here, the photosensitive material 106 has a characteristic that the image density is reduced according to the time interval of exposure. For this reason, when the LED chip 208 emits light to expose the photosensitive material 106 to form two continuous dots 282, the peripheral portion 284 of these dots 282 is exposed twice by the LED chip 208 and fixed. It becomes the density of. This density varies with the time interval between two exposures.
[0067]
Therefore, the overlapping peripheral portion 284 between the dots 282A, 282B, and 282D formed by being exposed by the LED chip 208 emitting light at the same time or almost simultaneously, and between the dots 282B, 282C, and 282E. The overlapping peripheral portion 284 has substantially the same density.
[0068]
On the other hand, when the n-th main scan is completed, the (n + 1) -th main scan is performed after the exposure interval has elapsed. That is, the dot 282 (for example, the dot 282F) formed by the (n + 1) th main scan is formed by exposing the dot 282 (for example, the dot 282B) formed by the nth main scan, and after an exposure interval. It is formed by exposure. For this reason, when the LED chip 208 emits light with the same light amount and performs exposure, the density of the overlapping peripheral portion 284 between these dots 282 decreases.
[0069]
Therefore, as shown in FIG. 7B, the light amount of the adjacent dot 282F exposed to the dot 282B after the exposure interval is increased more than the light amount of the dot 282B (changed from the solid line S to the broken line P). As a result, the amount of light in the overlapping peripheral portion 284 between the dots 282F and 282B also increases, and as a result, the main scanning line formed by exposure in the n-th main scan and the light exposure in the (n + 1) -th main scan The main scanning line along the sub-scanning direction L has substantially the same density as that between the main scanning lines formed by the exposure and the other main scanning lines formed by exposure in the n-th main scanning. Concentration fluctuations between the two can be reduced.
[0070]
Therefore, the light amount adjustment process adjusts the light amount of the LED chip 208 in accordance with the length of the exposure interval for the dots 282 formed adjacently in the sub-scanning direction L and exposed after a predetermined exposure interval. I do. As a result, the overlapping peripheral portions 284 between the adjacent dots 282 exposed at different exposure intervals have substantially the same density as the overlapping peripheral portions 284 between the dots 282 exposed at substantially the same time.
[0071]
The operation of the present embodiment will be described below.
First, the overall flow for image formation will be described.
[0072]
With the tray 144 loaded in the tray loading port 146, the supply reel 152 with the photosensitive material 106 wound thereon and the empty take-up reel 154 are loaded at predetermined positions, and the operation is performed in a state where the loading is completed. When a print start key on the display unit 112 is operated, the controller 202 reads image data from the optical disk 102 or the FD 104 and stores the image data.
[0073]
When the controller 202 stores the image data, the supply reel 152 is driven, and the conveyance of the photosensitive material 106 is started.
[0074]
When the photosensitive material 106 reaches a predetermined position of the exposure unit 176, the photosensitive material 106 stops temporarily, and an image signal is output from the controller 202 to the light source unit 204. This image signal is output every 10 lines, and the light source unit 204 performs exposure at predetermined close intervals while moving along the width direction of the photosensitive material 106 while being guided by the guide shaft 218 by driving of the stepping motor 226. , A main scanning line composed of a large number of dots 282 is formed.
[0075]
At this time, before the output of the digital image signal is started, the light amount of each color from the light source unit 204 is detected by the photodiode 228, and the correction value for adjusting the density, the color balance, and the like is adjusted in the light amount correction unit 230 by the controller. 202 to correct the image signal. This correction value is executed for each image.
[0076]
When one main scanning exposure is completed, the photosensitive material 106 moves one step (10 line pitch) and stops, and the second main scanning exposure is performed. By repeating this, an image for one frame is recorded on the photosensitive material 106.
[0077]
The photosensitive material 106 on which the recording has been completed is wound around the dancer roller 196 by driving only the pair of nipping rollers 192 on the upstream side of the reservoir 170 (the pair of nipping rollers 194 on the downstream side is stopped). , So as not to reach the water application section 178.
[0078]
When the photosensitive material 106 having a length corresponding to one image is accumulated in the reservoir 170, the pair of holding rollers 194 on the downstream side of the reservoir 170 starts driving. As a result, the photosensitive material (image formed) 106 is transported to the water application section 178. In the water application section 178, the photosensitive material 106 is conveyed at a constant speed, and water is uniformly applied by the application piece 188.
[0079]
Since water is constantly sent from the tank 190 to the coating piece 188 and the photosensitive material 106 is pressed with a predetermined pressure, an appropriate amount of water is applied to the photosensitive material 106.
[0080]
The photosensitive material 106 to which the water has been applied is guided by the guide plate 172 and conveyed to the third roller pair 166.
[0081]
On the other hand, when the half-moon roller 156 makes one rotation, the peripheral surface of the half-moon roller 156 comes into contact with the leading end of the image-receiving paper 108, and the uppermost layer of the image-receiving paper 108 is pulled out. 160 are sandwiched. By the driving of the first roller pair 160, the image receiving paper 108 is pulled out from the tray 144, and waits for the photosensitive material 106 to arrive while being held by the second roller pair 162.
[0082]
The driving of the first roller pair 160 and the second roller pair 162 is started in synchronization with the passage of the photosensitive material 106 through the guide plate, and the image receiving paper 108 is guided by the guide plate 164 and the third roller Conveyed to pair 166.
[0083]
In the third roller pair 166, the photosensitive material 106 and the image receiving paper 108 are sandwiched in a superposed state, and are sent to the heat roller 174. At this time, the two are brought into close contact with each other by the water applied to the photosensitive material 106.
[0084]
The superposed photosensitive material 106 and the image receiving paper 108 are wound around a heat roller 174, receive heat from a heater 182, and undergo a thermal development transfer process.
That is, the image recorded on the photosensitive material 106 is transferred to the image receiving paper 108 and visualized.
[0085]
The thermal development transfer is completed in a state of being wound around the heat roller 174 by about 1/3, and the image receiving paper 108 is peeled off from the photosensitive material 106 by the peeling roller 184 and the peeling claw 186, and is wound around the peeling roller 184. Is discharged onto the discharge tray 140.
[0086]
On the other hand, the photosensitive material 106 is wound around the heat roller 174 by about １ ／, then moves in the tangential direction, and is wound on the take-up reel 154.
[0087]
Accordingly, an image can be formed with a compact structure, and an image to be recorded can be confirmed by the monitor unit 114, so that the density and color balance can be easily adjusted.
[0088]
Next, the light amount adjustment processing by the controller 202 will be described.
FIG. 8 shows an example of the luminance correction processing of the LED chip 208 as the light amount adjustment processing.
[0089]
After resetting the number n of main scans and the correction amount Ct in step 300, the number n of main scan exposures is incremented in step 302, and the first main scan exposure process is started.
[0090]
Next, in step 304, digital image data for each LED chip 208 set for a main scanning line formed by one main scanning of one image is fetched, and luminance is set in step 306. Here, one image is composed of a predetermined number of main scanning lines, and since five main scanning lines can be simultaneously formed by each LED chip 208, digital image data can be formed by one main scanning. The data is acquired in units of a plurality of main scanning lines. The luminance is calculated from the exposure amount recorded as digital image data and a preset exposure time. Alternatively, the luminance may be recorded as digital image data.
[0091]
When the brightness is set, it is determined in step 308 whether or not the timer 406 has started. Since the timer 406 is started when the main scanning is started, the determination is negative in the case of the main scanning in the first row, and the process proceeds to step 316.
[0092]
In the case of the main scanning of the second and subsequent columns, the timer 406 has been started at the start of the main scanning of the first column, so the determination is affirmative, the process proceeds to step 310, and the timer 406 is stopped. Here, the time from the start of the main scanning in the front row to the start of the next main scanning, that is, the exposure interval is measured.
[0093]
When the timer 406 is stopped, in step 312, a correction value Ct according to the measured exposure interval is calculated, and in step 314, the luminance of the LED chip 208 on the upstream side in the sub-scanning direction is calculated using the correction value Ct. The correction is made, and the process proceeds to step 316.
[0094]
In step 316, exposure by the LED chip 208 at each set luminance is started. The exposure is performed by emitting light from the plurality of LED chips 208 at a time, and the light source unit 204 is moved along the main scanning direction, thereby forming, for example, five main scanning lines at the same time.
[0095]
When the exposure starts, in step 318, the timer 406 is reset / started. Thereby, the time measurement is started, and the time from the start of the exposure can be measured.
When the exposure is started and the timer 406 is started, it is determined in step 320 whether or not the n-th exposure is completed, and the determination is negative until the n-th exposure is completed. When the stepping motor 226 is driven until the edge detection signal is input or up to the set count value, the n-th exposure is completed, and thus the determination is affirmed, and the process proceeds to step 322.
[0096]
In step 322, the light source unit 204 is returned to the origin position. That is, the stepping motor 226 reversely rotates to the same number of pulses as the number of pulses detected by the movement to the end, and moves from the end toward the origin.
[0097]
When returning to the origin position, it is determined in step 324 whether or not all exposures have been completed. That is, since one image is formed by repeating a plurality of main scans a predetermined number of times, if all the exposures have not been completed, the determination is negative and the process proceeds to step 302 where the value of n is incremented. Then, the next main scanning is started.
[0098]
If all the exposures have been completed, the determination is affirmed and the process proceeds to step 326, where the timer 406 that continuously measures the time is stopped, and a series of processing ends.
[0099]
When a plurality of images are continuously formed on the photosensitive material 106, this process is repeated for each image.
[0100]
As a result, the brightness of the tip LED chip 208A is adjusted by the correction value Ct according to the length of the exposure interval, and exposure is performed, and the dot 282 is continuously formed with the dot 282 of the main scanning line by the previous main scanning exposure. It is formed. As a result, the overlapping peripheral portions 284 between the dots 282 are substantially the same between the main scanning lines formed by exposure at substantially the same time and between the main scan lines formed by exposure at intervals of the exposure interval. And the density fluctuation in the sub-scanning direction L between the main scanning lines can be reduced. For this reason, it is possible to form an image with good finishing quality without stripe-like density unevenness extending in the main scanning direction on the obtained dot image.
[0101]
Also, the exposure interval from the start of the main scanning to the start of the next main scanning is measured, and the light amount of the LED chip 208 is adjusted according to the measured exposure interval. Even if it takes time to capture image data and the exposure interval is longer than the other exposure intervals, the light amount can be adjusted accordingly.
[0102]
In the present embodiment, the exposure interval at which the main scanning is performed is measured, and the light amount of the LED chip 208 is adjusted in accordance with the measured exposure interval. The light amount can be adjusted for this fixed exposure interval. In this case, it is not necessary to measure the exposure interval every time the main scanning exposure is performed, so that the processing can be performed quickly.
[0103]
In this case, since the correction value Ct can be set in advance, the light amount adjustment processing may be performed on any one of the LED chips 208 at the end in the sub-scanning direction. The light amount adjustment processing can also be performed on the LED chips 208 together. That is, for example, the amount of light can be adjusted by changing the luminance of the LED chip 208 that forms the dots 282 (dots 282B in FIG. 7A) disposed on the rear end side of the photosensitive material 106 in the transport direction.
[0104]
In this case, since the correction value Ct can be set in advance, in the light amount adjustment processing shown in FIG. 8, after the digital image data is captured, the luminance of the target LED chip 208 is set in advance when setting the luminance. The exposure process can be started by correcting the corrected correction value and omitting steps 308 to 314.
[0105]
In the present embodiment, the photosensitive material 106 has a characteristic that the density decreases when the time interval of the exposure is extended, but the characteristic that the density increases when the time interval of the exposure is extended. May be used. In this case, by lowering the luminance of the LED chip 208 so that the amount of light decreases as the time interval is extended, the same operation as described above can be performed, and an image without density unevenness can be efficiently formed.
[0106]
【The invention's effect】
According to the image forming apparatus of the present invention, when performing continuous exposure while starting main scanning at a predetermined time interval, the light amount of the exposure light source is adjusted based on the time interval. The density of the portion exposed by the exposure light source and the portion exposed at a predetermined time interval can be made substantially the same, and the occurrence of density unevenness can be prevented.
[0107]
Further, the time interval from the start of the main scan to the start of the next main scan is detected, and spot exposure is performed with a light amount corresponding to the detected time interval, thereby changing the time interval at which the main scan is started. However, the exposure can be performed with the light amount corresponding to the changed time interval, and the occurrence of density unevenness can be prevented.
[0108]
Further, in the case where light amount adjustment is performed on the light emitting element at the end of the plurality of light emitting elements arranged along the sub-scanning direction, a plurality of main scanning lines are formed in one main scan, and the density difference is adjusted. Thus, it is possible to efficiently form an image having a good finish quality by preventing the occurrence of the image.
[Brief description of the drawings]
FIG. 1 is a perspective view of an image forming apparatus according to an embodiment.
FIG. 2 is a front view of the image forming apparatus according to the embodiment.
FIG. 3 is a side sectional view showing an internal configuration of the image forming apparatus according to the embodiment.
FIG. 4 is a front view illustrating a schematic configuration of an exposure unit.
FIG. 5 is a plan view showing a light source unit of the exposure unit.
FIG. 6 is a functional block diagram of a controller.
FIG. 7A is a plan view of a photosensitive material on which an exposure spot is formed by two successive main scans, and FIG. 7B is a diagram showing the light amount of dots formed by the nth main scan and the (n + 1) th dot; 6 is a graph showing light amounts of dots formed by main scanning.
FIG. 8 is a flowchart illustrating an example of an adjustment process according to an exposure interval time.
[Explanation of symbols]
100 Image forming apparatus
106 photosensitive material
176 Exposure unit
178 water application section
200 light source unit
202 Controller
204 light source unit (exposure light source)
206 main scanning unit
208 LED chip (light emitting element)
226 Stepping motor (main scanning means)
282 dots
284 rim
400 Exposure control unit (exposure control means, interval detection means)
404 LED light quantity adjustment unit (light quantity adjustment means)
408 LED emission control unit
410 Main scanning control unit
412 Sub-scanning control unit
416 motor (sub-scanning means)

Claims (3)

An exposure light source that emits a spot light;
A photosensitive material having a characteristic that the density is reduced when the time interval of exposure is extended or a photosensitive material having a characteristic that the density is increased when the time interval of exposure is extended, and the exposure light source are moved in the main scanning direction and the auxiliary light source. A main scanning unit and a sub-scanning unit that relatively perform scanning movement in the scanning direction;
In synchronization with the scanning movement by the main scanning unit and the sub-scanning unit, the spot light emitted from the exposure light source is modulated based on digital image data, and the main scanning is repeated at predetermined time intervals to repeat the photosensitive material. Exposure control means for exposing
Light amount adjusting means for adjusting the light amount of the exposure light source so as to be a light amount corresponding to the predetermined time interval,
An image forming apparatus comprising: An exposure light source that emits a spot light;
A photosensitive material having a characteristic that the density is reduced when the time interval of exposure is extended or a photosensitive material having a characteristic that the density is increased when the time interval of exposure is extended, and the exposure light source are moved in the main scanning direction and the auxiliary light source. A main scanning unit and a sub-scanning unit that relatively perform scanning movement in the scanning direction;
In synchronization with the scanning movement by the main scanning unit and the sub-scanning unit, the spot light emitted from the exposure light source is modulated based on digital image data, and the photosensitive material is exposed along the main scanning direction and the sub-scanning direction. Exposure control means,
Interval detecting means for detecting a time interval from the start of the previous main scan to the start of the next main scan,
Light amount adjusting means for adjusting the light amount of the exposure light source based on the time interval detected by the interval detecting means when performing the next main scanning,
An image forming apparatus comprising: The exposure light source is formed by arranging a plurality of light emitting elements each emitting a spot light at predetermined intervals along the sub-scanning direction, and when performing main scanning simultaneously by each light emitting element, the light amount adjusting means is 3. The image forming apparatus according to claim 1, wherein a light amount of a light emitting element at an end in a sub-scanning direction is adjusted.

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