JPH10181082A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an image of good finish quality by preventing the generation of density irregularity by an exposure interval. SOLUTION: When a dot 282F is formed at the (n+1)-th time so as to be adjacent to a dot 282B in such a case that five dot rows are formed in a main scanning direction Z at the n-th time and (n+1)-th time in a sub-scanning direction L, the brightness of the LED chip forming the dot 282B is raised corresponding to an exposure interval. As a result, even if a photosensitive material 106 having characteristics becoming density lowered corresponding to an exposure time interval is used, the overlap peripheral edge part 284 between dots 282A, 282B exposed at the same time and the overlap peripheral edge part 284 between dots 282B, 282F exposed after the exposure interval become the same in density and the generation of density irregularity can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. 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]

2. Description of the Related Art At present, an image forming apparatus modulates a spot-like 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. In some cases, an image is formed on a recording medium by performing main scanning and sub-scanning. Also,
In this image forming apparatus, the density of the dots to be formed is changed by changing the intensity of the spot light in accordance with the digital image data at the time of scanning exposure, so that the density of the dot corresponding to the digital image data is changed on the recording medium. There are some which form dots.

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.

In such an image forming apparatus, a plurality of LEDs are arranged along the sub-scanning direction, and the plurality of LEs are arranged.
A device in which D is simultaneously main-scanned has been proposed. 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.

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 amount of exposure, the dot image formed on the photosensitive material can be seen smoothly using the color, and the finished quality can be further improved.

[0006]

However, when forming an image, the main scanning is repeated a plurality of times, so that adjacent dots along the main scanning direction are exposed almost simultaneously, but along the sub-scanning direction. Adjacent dots are not necessarily exposed at the same time. 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 simultaneously, 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.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described circumstances, and has as its object to provide an image forming apparatus capable of forming an image having good finish quality by preventing the occurrence of density unevenness due to an exposure interval. .

[0008]

According to the first aspect of the present invention, an exposure light source for emitting spot light, and a photosensitive material and the exposure light source are relatively moved in a main scanning direction and a sub-scanning direction. Scanning means and sub-scanning means, in synchronization with the scanning movement by the main scanning means and the sub-scanning means, the spot light emitted from the exposure light source is modulated based on digital image data, at predetermined time intervals Exposure control means for exposing the photosensitive material by repeating main scanning,
Light amount adjusting means for adjusting the light amount of the exposure light source so that the light amount corresponds to the predetermined time interval.

According to the present invention, when exposure is continuously performed in the sub-scanning direction while starting main scanning at a predetermined time interval, the exposure is performed based on the determined time interval between main scanning exposures, ie, the exposure interval. The light amount of the exposure light source is adjusted.
For this reason, a dot adjacent to a certain dot is an adjacent dot on one column of a main scanning line formed by exposure at substantially the same time as a dot of a different column 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 a predetermined 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.

According to a second aspect of the present invention, there is provided an exposure light source for emitting a spot light, and a main scanning means and a sub-scanning means for relatively moving a photosensitive material and the exposure light source in a main scanning direction and a sub-scanning direction. And, in synchronization with the scanning movement by the main scanning unit and the sub-scanning unit, modulate a spot light emitted from the exposure light source based on digital image data, and the photosensitive material along a main scanning direction and a sub-scanning direction. Exposure control means for exposing, an interval detection means for detecting a time interval from the start of the previous main scan to the start of the next main scan, and the interval detection means for performing the next main scan Light amount adjusting means for adjusting the light amount of the exposure light source based on the detected time interval.

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 the spot is irradiated with the light amount corresponding to the detected exposure interval. Since the exposure is performed, even if the length of the exposure interval is changed, it is possible to form a dot 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 is prevented.
An image having a good finish quality can be formed.

According to a third aspect of the present invention, the exposure light source comprises:
A plurality of light-emitting elements each emitting a spot light are formed at predetermined intervals along the sub-scanning direction, and when the light-emitting elements perform main scanning at the same time, the light amount adjusting means is arranged in the sub-scanning direction. It is characterized in that the light quantity of the light emitting element at the end is adjusted.

According to the present invention, the 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. Can be formed at the same time to efficiently form an image, and the amount of light is adjusted for the light emitting elements at the end portions, thereby preventing the occurrence of streak-like density unevenness. As a result, it is possible to efficiently form an image having a high finishing quality.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION

(Overall Configuration “Appearance”) FIGS. 1 to 3 show an image forming apparatus 100 according to the present embodiment.

The image forming apparatus 100 includes an optical disc 1
This device reads image data recorded on the FD 02 or the 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 for output.

The upper portion of the front surface (left side in FIG. 3) of the box-shaped casing 110 has an inclined surface, and an operation display unit 112 is provided.

As shown in FIG. 2, the operation display unit 112
Are classified into a monitor unit 114 located on the right side and an input unit 116 located on the left side, and the monitor unit 114 is configured to project the read image.

The input unit 116 has a plurality of operation keys 1.
18 and an input data confirmation display unit 120, so that it is possible to input data necessary for image formation, such as input of the number of recording sheets, size setting, color balance adjustment, negative / positive selection, and the like. I have.

Below the operation display section 112, a deck section 1 is provided.
22 are provided. The deck section 122 includes an optical disk deck section 124 located on the right side in FIG. 3 and an FD deck section 126 located on the left side.

The optical disk deck 124 can open and close the tray 130 by pressing an open / close button 128. By mounting the optical disk 102 on the tray 130, the optical disk 102
Can be loaded inside the device.

On the other hand, the FD deck section 126 is provided with an FD insertion throttle 132, and when the FD 104 is inserted, the drive system inside the apparatus operates to draw in the FD 104. When the FD 104 is taken out, the operation button 134 is pressed to
D104 can be pulled out.

The optical disk deck 124 and the FD
Access lamps 136,
138 are provided, and the access lamps 136 and 138 are turned on during access in the apparatus.

A discharge tray 140 is provided below the deck 122. This discharge tray 140
Is usually housed in the device, and can be pulled out by putting a finger on the grip portion 142 (FIG. 1).
reference).

The image receiving paper 108 on which the image is recorded is discharged onto the discharge tray 140.

The image receiving paper 108 is stored in a layer on a tray 144 in advance.
0 is provided in the tray loading port 146 provided on the upper surface of the tray. 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.

Two circular cover members 148 and 150 are mounted on the right side surface (the front side in FIG. 1) of the casing 110. The cover members 148, 150
The cover members 148 and 148 are individually detachable.
As shown in FIG. 3, a supply reel 152 and a take-up reel 154 for winding the photosensitive material 106 in a roll form are arranged inside the apparatus along the axial direction of 150. It can be taken out or loaded with the members 148 and 150 detached. (Receiver paper transport system) As shown in FIG.
The upper surface of the tip end of the tray 144 loaded in 46 is opposed to the half-moon roller 156.

The semicircular roller 156 has a part of its peripheral surface cut in a tangential direction. Usually, the notch 158 faces the uppermost image receiving paper 108 in the tray 144 at a predetermined interval. I have. Here, when the half moon roller 156 rotates, the uppermost image receiving paper 108 and the half moon roller 156 are rotated.
When the semicircular roller 156 makes one rotation, the image receiving paper 108 is slightly pulled out. The pulled-out image receiving paper 108 is nipped by the first roller pair 160,
The driving force of the first roller pair 160 causes the tray 1
44 to be completely drawn out.

Downstream of the first roller pair 160 is a second roller pair.
Roller pair 162, guide plate 164, third roller pair 1
66 are arranged in order, and the image receiving paper 108 is nipped by the first roller pair 160, is nipped by the second roller pair 162, is guided by the guide plate 164, and is received by the third roller pair 166. Be pinched.

The third roller pair 166 also overlaps the photosensitive material 106. That is, the third roller pair 166 is also used as a transport 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.

The photosensitive material 106 is loaded into 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.

With the photosensitive material 106 loaded at a predetermined position, the outermost layer is pulled out and loaded along a predetermined transport path as an initial setting. In the loading procedure, the outermost layer is pulled out from the supply reel 152, and the fourth roller pair 1 near the loading position of the supply reel 152
68, via the reservoir 170 and the guide plate 172, between the third roller pair 166, around the heat roller 174, and around the take-up reel 154. In this case, a leader tape of a length necessary for loading may be provided at the leading end of the photosensitive material 106 wound around the supply reel 152.

In the conveying path of the photosensitive material 106,
An exposure section 176 is provided between the fourth roller pair 168 and the reservoir section 170. In addition, the reservoir 170
A water application unit 178 is provided between the guide plate 172 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 third step is performed in a state where water is applied to the emulsion surface (exposed surface). Receiving paper 1 with roller pair 166 of
08 is superimposed. (Heat Roller) The heat roller 174 is a thermal development transfer section 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 body 180 is heated by the operation of the heater 182, and has a role of applying heat to the members (the photosensitive material 106 and the image receiving paper 108) wound around the roller body 180. By this heating, a thermal development transfer process is performed, and the image recorded on the photosensitive material 106 is transferred to the image receiving paper 108.

A peeling roller 184 and a peeling claw 186 are provided near the lower right of the heat roller 174. The image receiving paper 108 wound around the heat roller 174 by about 1/3 is peeled off from the photosensitive material 106, and a discharge tray is provided. The image receiving paper 108 is guided in a 140 direction.

On the other hand, the photosensitive material 106 is
The take-up reel 154 is wound by about 、, is turned by 180 °, and is guided to a position where the take-up reel 154 is loaded. (Water application unit) As shown in FIG.
Water as an image forming solvent is applied to the photosensitive material 106 or the image receiving paper 108, and the superposed surfaces of the two are brought into close contact with each other, and have a role of heat development. Application piece 188 and tank 190 for storing water
It is composed of

The coating piece 188 is made of a highly absorbent material such as felt or sponge and has an appropriate hardness.
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 side) of the material 106.

Further, since the coated piece 188 is in contact with the photosensitive material 106 at an appropriate pressure, the water is uniformly applied.

The water in the tank 190 is replenished by removing the entire water application section 178. However, water may always be supplied from outside the apparatus by providing a pipe.

In this embodiment, water is used as a solvent for image formation. However, the water is not limited to pure water, but includes water in a widely used sense. Further, it may be a mixed solvent of water and a low boiling point solvent such as methanol, DMF, acetone and diisobutyl ketone. Further, a solution containing an image formation accelerator, an antifoggant, a development terminator, a hydrophilic heat solvent and the like may be used. (Exposure Unit) FIG. 4 shows an exposure unit 176 according to the present embodiment.
It is shown.

The light exposure unit 176 is mainly composed of a light source unit 200 provided above the conveying path of the photosensitive material 106.
It is connected to the controller 202. Controller 2
02 stores digital image data (image data read from the optical disk 102 or the FD 104), and turns on the light source unit 204 in the light source unit 200 according to the digital image data.

The light source unit 200 is movable in the width direction (main scanning direction) of the photosensitive material 106 by driving a main scanning unit 206 corresponding to the scanning means of the present invention described later. Main scanning is performed when the unit 176 is stopped when step driving is performed.

The light source unit 200 of the exposure unit 176 is covered with a box-shaped exposure casing 214, and a light source unit 204 is disposed on an upper end surface of the exposure casing 214. 214
Pointed inward. On the light emitting surface side of the light source unit 204,
An aperture 216 is provided, and a plurality of LED chips 20 are provided.
8 limits the spread of light. Note that the aperture 216 may not be provided.

A telecentric lens 212 is provided on a support 215 at the center of the exposure casing 214 on the downstream side of the aperture 216, and condenses predetermined light from the light source 204 so that an appropriate light is applied on the photosensitive material 106. It has a function of forming an image so as to be focused. The resolution of the light to be imaged is about 250 to 400 dpi.

Here, the telecentric lens 212
Is a lens composed of a plurality of lenses and an aperture, each having a characteristic that the magnification does not change even if the height of the image plane changes. It is possible to absorb the difference due to the state of attachment of the.

The overall focus is always adjusted by an auto-focus mechanism (not shown). Alternatively, it is possible to make adjustment unnecessary by using a lens system having a large depth of focus.

The light source unit 204 includes a pair of parallel guide shafts 21 that constitute a part of the main scanning unit 206.
8 supported. 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 connected to the guide shaft 2.
The photosensitive material 106 is movable in the width direction of the photosensitive material 106 by being guided by the photosensitive material 18.

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. One sprocket 2
The rotation shaft of the stepping motor 226 is connected to the rotation shaft of the stepping motor 226 via a transmission 224.
It is reciprocated along the guide shaft 218.

As shown in FIG. 6, the stepping motor 226 is connected to the controller 20 via a driver 227.
2 are connected. A counter 225 is attached to the stepping motor 226.
Are connected to the driver 227. 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.

The driving of the stepping motor 226 is controlled by the controller 202, and is synchronized with the step driving of the photosensitive material 106. That is, photosensitive material 1
In a state where 05 has moved by one step and stopped, 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, stepping motor 2
By reversely rotating 26, the light source unit 204 returns to the original position. The next movement of the photosensitive material 106 is started simultaneously with the return operation of the light source unit 204.

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, and outputs a signal corresponding to the light amount of the light source from the light source unit 204. It is supposed to. The photodiode 228 is connected to the light amount correction unit 230, and the signal is input to the light amount correction unit 230.

The light quantity correction unit 230 compares the detected light quantities from the LED chips 208 of the respective colors to determine the density,
It has a role of performing color balance adjustment and outputting a correction value to the controller 202. Also, the light amount correction unit 2
At 30, an end detection signal indicating that the light source 204 has reached the end of the guide shaft 218 is output to the controller 202 based on the signal from the photodiode 228.

As shown in FIG. 5, the light source unit 204 has an L
The ED chips 208 are collectively configured, and the LED chips 208 that emit colors of B (blue), G (green), and R (red), respectively (hereinafter, when individually described for each color, B LED chips that develop colors are BL
ED chip 208B, LED chip emitting G color
LED chip 208G, an R-LED chip 208R is referred to as an R-LED chip 208R).
On the reference numeral 10, the photosensitive material 106 is attached along the width direction (main scanning direction) of the photosensitive material 106 according to the same arrangement rule. Note that each exposure wavelength is 650 ± 20 nm for the R-LED chip 208R and 5 for the G-LED chip 208G.
30 ± 30 nm, 470 for B-LED chip 208B
± 20 nm. That is, at the right end of the substrate 210 in plan view, two rows of ten B-LED chips 208B are provided.
And arranged in a zigzag pattern, 10 R-LEDs on the left end
The chips 208R are arranged in two rows and in a staggered manner, and in the center, ten G-LED chips 208G are arranged in two rows and in a staggered manner. A total of six rows of LED chips are arranged. I have.

The substrate 210 is provided with predetermined wiring by etching or the like. The wiring is covered with metal so as to prevent 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 amount of emitted light can be suppressed.

The dimensions of each section of the light source section 204 applied in this embodiment will be described below. First, the horizontal (X) × vertical (Y) dimensions of the substrate 210 are 5 × 5 mm (maximum),
The outer dimensions (x × y) of the LED chip 208 are about 360 ×
360 μm. The pitch P between rows 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 form is 260 μm. Gap G between each color
Is determined by the telecentric lens 212 and cannot be unambiguously determined, but it is preferable that the gap dimensions G between R and G and between G and B are the same.

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. 5, the boundaries between the light emitting regions of the staggered adjacent columns coincide with each other. ing.

By the light source unit 204 having the above-described structure, ten main scanning lines can be recorded on the photosensitive material 106 by one main scanning for each color. Therefore, the photosensitive material 1
The step movement of 06 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. Have been. The photosensitive material 106 is stretched over two pairs of nipping 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 slack portion of the photosensitive material 106.

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. For this reason,
The photosensitive material 106 is disposed between the exposure unit 176 and the water application unit 178.
The difference in the conveying speeds is caused. To absorb this speed difference,
The dancer roller 196 moves up and down to adjust the slack amount of the photosensitive material 106 so that the photosensitive material 106 can be simultaneously moved stepwise and at a constant speed.

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 light source unit 20 is controlled based on the input correction value.
The digital image signal sent to the LED chip 4 is corrected, so that each LED chip 208 can be turned on with an appropriate amount of light.

The exposure controller 40 includes a controller 202
Main scanning control unit 410 and sub-scanning control unit 41 provided for
2 are connected. The main scanning control unit 410 is connected via a driver 227 to a stepping motor 226 for moving the main scanning unit 206. Further, 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.

Thus, when the main scanning is started by an instruction from the main scanning control unit 410, the counter 225 drives the stepping motor 226 while counting the driving amount of the stepping motor 226 by the pulse signal, and detects the end. When the signal is input to the main scanning control unit 410, the stepping motor 226 rotates in the reverse direction to rotate the light source unit 20.
4 is performed. 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. Exposure controller 400
In the embodiment, the exposure interval when the main scanning is performed is measured via the timer 406.

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 a fourth roller pair 168 of the photosensitive material transport system.
And a pair of holding rollers 192 (see FIG. 3) in the reservoir section. The sub-scanning control unit 412 controls the driving of the fourth roller pair 168 and the nipping 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.

The exposure control section 400 includes the LED chip 20
The LED light amount adjusting unit 404 for adjusting the light amount of No. 8 is connected. The LED light amount adjustment unit 404 includes an exposure control unit 40
Digital image data is input from 0 and timer 4
06, the detected exposure interval is input,
In accordance with the light amount adjustment process described later, the light amount data of the LED chip 208 to be subjected to the light amount adjustment process is adjusted according to the exposure interval.

The LED light amount adjusting unit 404 is connected to the LED light emission control unit 408. LED light emission control unit 408
Now, the exposure balance adjustment processing and the target LE
The light emission of each LED chip 208 is controlled based on the digital image data on which the light amount adjustment processing has been performed on the D chip 208.

Next, regarding the light amount adjustment processing performed in the LED light amount adjustment unit 404, R-
An example in which five dots arranged linearly are formed by the LED chip 208R, the G-LED chip 208G, and the B-LED chip 208B will be described.

As shown in FIG. 7A, photosensitive material 1
On 06, five dots 282 are formed by exposing all at once. Along the main scanning direction (arrow Z direction)
By performing continuous exposure, five main scanning lines composed of a large number of dots 282 are formed on the photosensitive material 106. At this time, continuous exposure in the main scanning direction
Since the image data has already been read at the start of the main scan, continuous exposure processing at a high speed is possible.
It takes place almost simultaneously at very short time intervals. Such five main scanning lines are repeatedly formed a predetermined number of times in the sub-scanning direction (the direction of arrow L) (FIG. 7 shows the case where the main scanning lines are formed by the n-th and (n + 1) -th exposures). To form

At the periphery of the dot 282, a periphery 284 is formed. Peripheral portion 284 is an L that forms dot 282.
This is a low-density portion where the light beam of the ED chip 208 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.

Here, the photosensitive material 106 has a characteristic that the image density is reduced according to the time interval of exposure. Therefore, 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 becomes constant. It becomes the density of. This density varies with the time interval between two exposures.

For this reason, the dots 282A, 282B, and 282D formed by being exposed by the LED chip 208 emitting light simultaneously or almost simultaneously.
And overlapped edge 2 between dots 282B, 282C, and 282E.
84 is substantially the same concentration.

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 dots 282 (for example, dots 282B) formed in the n-th main scan, and then exposing after an exposure interval. For this reason,
When exposure is performed by causing the LED chip 208 to emit light with the same amount of light, overlapping peripheral portions 284 between these dots 282 are formed.
Concentration decreases.

Therefore, as shown in FIG. 7B, the light amount of the adjacent dot 282F exposed after the exposure interval to the dot 282B 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 at 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.

Therefore, the light amount adjustment processing is performed on the dots 282 formed adjacent to each other in the sub-scanning direction L and exposed after a predetermined exposure interval in accordance with the length of the exposure interval. Adjust the light intensity.
Thus, 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.

The operation of the present embodiment will be described below. First, the overall flow for image formation will be described.

The tray 144 is loaded in the tray loading port 146, and the supply reel 152 with the photosensitive material 106 wound thereon and the empty take-up reel 154 are loaded at predetermined positions, respectively, and the loading is completed. When the print start key of the operation display unit 112 is operated, the controller 202 causes the optical disk 102 or the FD 104 to operate.
And reads and stores the image data.

When the controller 202 stores the image data, the supply reel 152 is driven, and the conveyance of the photosensitive material 106 is started.

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,
4 performs exposure at predetermined close intervals while moving along the width direction of the photosensitive material 106 while being guided along the guide shaft 218 by the driving of the stepping motor 226 to form a main scanning line composed of a large number of dots 282. I do.

At this time, before starting the output of the digital image signal, the light source unit 2 is driven by the photodiode 228.
04, the light amount of each color is detected, and the light amount correction unit 23
At 0, a correction value for adjusting the density, color balance, and the like is supplied to the controller 202 to correct the image signal. This correction value is executed for each image.

When one main scanning exposure is completed, the photosensitive material 106 moves by 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.

The photosensitive material 106 on which recording has been completed is
By driving only the pair of holding rollers 192 on the upstream side of the reservoir 170 (the pair of holding rollers 194 on the downstream side is stopped),
It is held in a slack state in the reservoir section 170 so as to be wound around the dancer roller 196, and does not reach the water application section 178.

When the length of the photosensitive material 106 for one image is accumulated in the reservoir 170, the pair of nipping 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 unit 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.

The coating piece 188 is constantly supplied with water from the tank 190, and is supplied with the photosensitive material 10 at a predetermined pressure.
6 is pressed, an appropriate amount of water is applied to the photosensitive material 106.

The photosensitive material 106 to which water has been applied is guided by a guide plate 172 and conveyed to a third roller pair 166.

On the other hand, the image receiving paper 108 is a half-moon roller 156.
Makes one rotation, the peripheral surface of the half-moon roller 156 and the leading end of the image receiving paper 108 come into contact with each other, and the uppermost layer of the image receiving paper 108
Is pulled out, and the first roller pair 160 is pinched. The driving of the first roller pair 160 causes the image receiving paper 108
Is pulled out of the tray 144 and the second roller pair 162
Wait for the photosensitive material 106 to arrive.

The first roller pair 160 and the second roller pair 1 are synchronized with the passage of the photosensitive material 106 through the guide plate.
The driving of the image receiving paper 108 is started.
4 and is conveyed to a third roller pair 166.

In the third roller pair 166, the photosensitive material 10
6 and the image receiving paper 108 are pinched in a superposed state, and sent out to the heat roller 174. At this time, the photosensitive material 10
Both are brought into close contact with each other by the water applied to 6.

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.

The heat development transfer is completed when the heat roller 174 is wound about 1/3, and the image receiving paper 108 is
The photosensitive material 1 is separated by the peeling roller 184 and the peeling claw 186.
, And is discharged onto a discharge tray 140 so as to be wound around a peeling roller 184.

On the other hand, the photosensitive material 106 is
After being wrapped about 1/2 by 74, it moves tangentially and is taken up by the take-up reel 154.

As a result, an image can be formed with a compact structure, and the image to be recorded can be confirmed by the monitor unit 114, so that the density and color balance can be easily adjusted.

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.

In step 300, the number of main scans n,
After resetting the correction amounts Ct, the number n of main scanning exposures is incremented in step 302, and the first main scanning exposure process is started.

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 in step 306, luminance is set. Here, one image is composed of a predetermined number of main scanning lines, and five main scanning lines can be simultaneously formed by each LED chip 208, so that digital image data can be formed by one main scanning. The data is acquired in units of a plurality of main scanning lines. The brightness is calculated from an exposure amount recorded as digital image data and a preset exposure time. Alternatively, the luminance may be recorded as digital image data.

When the luminance 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.

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. Therefore, the judgment is affirmative, the process proceeds to step 310, and the timer 406 is stopped. Here, the time from the start of the main scan in the front row to the start of the next main scan, that is, the exposure interval is measured.

When the timer 406 is stopped, in step 312, a correction value Ct corresponding 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 corrected using the correction value Ct, and the process proceeds to step 316.

In step 316, exposure by the LED chip 208 at each set luminance is started. In the exposure, the plurality of LED chips 208 emit light at a time, and the light source unit 2
04 is performed by moving along the main scanning direction, whereby, for example, five main scanning lines are simultaneously formed.

When exposure is started, 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, at step 320, n
It is determined whether or not the exposure at the end is completed, and the determination is negative until the exposure at the n-th is completed. When the stepping motor 226 is driven until the end detection signal is input or up to the set count value, the n-th exposure is completed, and the determination is affirmative, and the process proceeds to step 322.

In step 322, the light source unit 2 is moved to the origin position.
Return 04. That is, the stepping motor 226 has the same number of pulses as the number of pulses detected by the movement to the end.
Rotates backward and moves from the end toward the origin.

After 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 to return to n.
Is incremented, and the next main scanning is started.

When all the exposures have been completed, the determination is affirmed, and the process shifts to step 326 to stop the timer 406 for continuously measuring the time, thereby ending a series of processing.

A plurality of images are continuously formed on the photosensitive material 10.
6, the process is repeated for each image.

As a result, the brightness of the leading LED chip 208A is adjusted by the correction value Ct in accordance with the length of the exposure interval, and exposure is performed. A dot 282 is formed. As a result, between main scanning lines formed by exposure at substantially the same time and main scanning lines formed by exposure with an interval corresponding to the exposure interval,
The overlapping peripheral portions 284 between the dots 282 have substantially the same density, 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 a high-quality image having no stripe-like density unevenness extending in the main scanning direction on the obtained dot image.

Also, the exposure interval from the start of the main scan to the start of the next main scan 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 digital image data to be used and the exposure interval is longer than the other exposure intervals, the light amount can be adjusted correspondingly.

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 according to the measured exposure interval. Scanning may be performed to adjust the amount of light 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.

In this case, since the correction value Ct can be set in advance, any one of the LED chips 208 at the end in the sub-scanning direction may be subjected to light amount adjustment processing.
Further, the light amount adjustment processing can be performed on both of the LED chips 208 at both ends in the sub-scanning direction. 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 (the dots 282B in FIG. 7A) arranged on the rear end side of the photosensitive material 106 in the transport direction.

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 brightness of the target LED chip 208 is set when the brightness is set. Is corrected by a preset correction value, and the exposure processing can be started by omitting steps 308 to 314.

In the present embodiment, the photosensitive material 106 has a characteristic that the density is reduced when the time interval between exposures is extended. However, when the time interval between exposures is extended, the density is reduced. A photosensitive material having higher characteristics 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]

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. Therefore, it is possible to make the density of the part exposed by the exposure light source that emits light almost at the same time as the density of the part exposed at a predetermined time interval substantially the same, thereby preventing the occurrence of density unevenness. it can.

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 to thereby start the main scan. Can be exposed with a light amount corresponding to the time interval after the change, and it is possible to prevent the occurrence of density unevenness.

Further, when adjusting the light quantity to the light emitting element at the end of the plurality of light emitting elements arranged in the sub-scanning direction, a plurality of main scanning lines are formed by one main scanning. At the same time, it is possible to prevent the occurrence of the density difference and efficiently form an image having a good finish quality.

[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 present 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.
9 is a graph showing the light amount of dots formed by the first main scan and the light amount of dots formed by the (n + 1) th main scan.

FIG. 8 is a flowchart illustrating an example of an adjustment process according to an exposure interval time.

[Explanation of symbols]

REFERENCE SIGNS LIST 100 image forming apparatus 106 photosensitive material 176 exposure unit 178 water application unit 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 unit) 282 dot 284 peripheral part 400 Exposure control unit (exposure control unit, interval detection unit) 404 LED light amount adjustment unit (light amount adjustment unit) 408 LED light emission control unit 410 main scanning control unit 412 sub-scanning control unit 416 motor (sub-scanning unit)

Claims (3)

[Claims] An exposure light source that emits a spot light; a main scanning unit and a sub-scanning unit that relatively move the photosensitive material and the exposure light source in a main scanning direction and a sub-scanning direction; Exposure control means for synchronizing with the scanning movement by the sub-scanning means, modulating spot light emitted from the exposure light source based on digital image data, and exposing the photosensitive material by repeating main scanning at predetermined time intervals. An image forming apparatus comprising: a light amount adjusting unit that adjusts a light amount of the exposure light source so as to have a light amount corresponding to the predetermined time interval. An exposure light source for emitting spot light; main scanning means and sub-scanning means for relatively moving the photosensitive material and the exposure light source in a main scanning direction and a sub-scanning direction; In synchronization with the scanning movement by the sub-scanning means, the spot light emitted from the exposure light source is modulated based on digital image data, exposure control means for exposing the photosensitive material along the main scanning direction and the sub-scanning direction, Interval detection means for detecting a time interval from the start of the previous main scan to the start of the next main scan, and based on the time interval detected by the interval detection means when performing the next main scan. An image forming apparatus comprising: a light amount adjusting unit configured to adjust a light amount of the exposure light source. 3. The exposure light source is formed by arranging a plurality of light emitting elements each emitting a spot light at a predetermined interval in a sub-scanning direction, and performing main scanning by each light emitting element simultaneously. The image forming apparatus according to claim 1, wherein the light amount adjusting unit adjusts a light amount of a light emitting element at an end in a sub-scanning direction.