JPH10193673A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent fluctuation in the density of an image formed on a recording medium due to lowering of brightness of a semiconductor light emitting element by setting a timing for starting exposure based on an exposure interval required for single main scanning exposure depending on an image data and then repeating the main scanning exposure. SOLUTION: A controller 202 is provided with a field memory 244 for storing an image data of 10 scanning lines being exposed by single main scanning. At the time of image exposure, a corrected image data stored in a frame memory 240 is read out by an amount corresponding to single main scanning at a time and stored in the field memory 244. After delivering the stored image data at a specified timing to a light source section 204, the field memory 244 reads out a new image data for single main scanning from the frame memory 240 and stores the new image data. A controller 202 repeats main scanning exposure at a set exposure interval.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus that forms an image by exposing a recording medium such as a photosensitive material based on digital image data.

[0002]

2. Description of the Related Art In an image forming apparatus, a spot-shaped light beam (hereinafter referred to as "spot light") is emitted from a semiconductor light emitting element such as a semiconductor laser or a light emitting diode (LED) to a recording medium such as a photosensitive material or a photosensitive drum. There is an image forming apparatus that forms an image on a recording medium by performing main scanning and sub-scanning while performing modulation based on image data. Further, in the image forming apparatus, by changing the intensity of the spot light emitted from the light source based on the digital image data, the density of the dots to be formed is changed, and a dot image having a density corresponding to the digital image data is formed on a recording medium. Some are made to form.

In an image forming apparatus that exposes a recording medium such as a photosensitive material using LEDs as semiconductor light emitting elements, a large number of LEDs are closely arranged in a sub-scanning direction.
It has been proposed to expose a recording medium simultaneously with these LEDs. In such an image forming apparatus, by arranging a large number of LEDs closely in the sub-scanning direction, a region having a predetermined width along the sub-scanning direction of the recording medium is exposed in one main scan to thereby form a large number of main scans. Scan lines can be formed at the same time, and by repeating this main scan at a predetermined exposure interval, a high-quality image in which the interval between scan lines along the main scan direction is narrowed can be efficiently formed in a short time. it can.

[0004]

SUMMARY OF THE INVENTION However, LEDs
In this case, the luminance changes according to a change in the ambient temperature. If such LEDs are closely arranged to emit light simultaneously in a short exposure interval, at least the amount of heat generated in each of the LEDs will increase and the luminance will change. by this,
There is a problem that a relatively large density difference occurs between an area exposed at the start of exposure and an area exposed at the end of exposure, which impairs the finish of a formed image.

[0005] The present invention has been made in view of the above facts, and when forming an image by exposing a recording medium such as a photosensitive material with a large number of semiconductor light emitting elements arranged in the sub scanning direction. It is an object of the present invention to propose an image forming apparatus capable of forming an image having a high finish quality by preventing a density difference from occurring due to a change in luminance of a light emitting element.

[0006]

The invention according to claim 1 is
An image forming apparatus that forms an image by exposing a recording medium based on digital image data, wherein a plurality of semiconductor light emitting elements each capable of exposing the recording medium based on the digital image data are arranged along a sub-scanning direction. An exposure light source arranged in close proximity to the recording medium; main scanning means for performing main scanning exposure by the light emitting element by relatively moving the exposure light source in the main scanning direction with respect to the recording medium; Sub-scanning means for relatively moving in the sub-scanning direction with respect to the medium; calculating means for integrating the amount of power for the semiconductor light emitting element to emit light for each main scan based on the image data; Interval setting means for setting an exposure interval for each of the semiconductor light emitting elements based on a calculation result, and individual setting based on the set exposure interval. Light emission control means for controlling light emission of the conductor light emitting element, main scan control means for controlling main scan means based on the set exposure interval and according to operation of the light emission control means, and operation of the main scan control means And a sub-scanning control means for operating the sub-scanning means in synchronization with the sub-scanning means.

According to the present invention, recording is performed by causing the semiconductor light emitting element to emit light in accordance with image data while relatively moving the exposure light source and the recording medium in the main scanning direction and the sub scanning direction by the main scanning means and the sub scanning means. An image is formed by exposing the medium.

At this time, the amount of power required for each semiconductor light emitting element to emit light in accordance with image data is calculated for each main scanning exposure. An exposure interval is set based on the calculation result, and the main scanning exposure is repeated at the set exposure interval.

From the amount of power of the nuclear semiconductor light emitting element calculated for each main scan, a decrease in the luminance of the semiconductor light emitting element every time the main scanning exposure is completed can be estimated. Can be set as the exposure interval. Note that this exposure interval may be set using the calculated value for the semiconductor light emitting element having the highest integrated calculated value of the electric energy.

[0010] By repeating the main scanning exposure at this exposure interval, it is possible to suppress a decrease in the luminance of the semiconductor light emitting element, and to surely prevent a decrease in the finished quality due to a density change due to the decrease in the luminance of the semiconductor light emitting element. Can be.

According to a second aspect of the present invention, the semiconductor light-emitting elements that are simultaneously turned on in accordance with the image data are divided into at least two sets, and the electric energy is integrated and calculated for each of the divided sets. Features.

According to the present invention, the semiconductor light emitting element of the exposure light source is divided into two sets so that they are not turned on at the same time.
Image exposure is performed. That is, all the semiconductor light emitting elements are turned on at the same time, and the main scanning of the area that can be exposed by one main scanning exposure is divided into two main exposures. Thereby, it is possible to reduce the number of semiconductor light emitting elements that are turned on at the same time, and by simultaneously lighting a large number of semiconductor light emitting elements, it is possible to prevent the luminance of each semiconductor light emitting element from being greatly reduced,
Exposure intervals can be shortened.

According to a third aspect of the present invention, there is provided an image forming apparatus which forms an image by exposing a recording medium based on digital image data, each of which is capable of exposing the recording medium based on the digital image data. An exposure light source in which a plurality of semiconductor light emitting elements are arranged close to each other along a sub-scanning direction, and a main scanning exposure is performed by the light emitting element by moving the exposure light source relative to the recording medium in a main scanning direction. Main scanning means, sub-scanning means for relatively moving the exposure light source in the sub-scanning direction with respect to the recording medium, and at least two sets of semiconductor light emitting elements of the exposure light source which are simultaneously turned on according to the digital image data. Light emission control means for dividing and emitting light at different timings, main scanning control means for controlling the light emission control means and the main scanning means in synchronization with each other, In synchronism with the operation of the serial main scanning control unit, characterized in that it comprises a sub-scanning control device for activating the sub-scanning means.

According to the present invention, the semiconductor light emitting device is divided into at least two sets in a predetermined combination, and the semiconductor light emitting device emits light for each of the divided sets to expose the recording medium.

For example, by selecting at least one of the individual semiconductor light emitting elements so that at least one of the semiconductor light emitting elements along the sub-scanning direction does not emit light at the same time, it is possible to suppress a decrease in luminance due to a rise in temperature. By performing main scanning by repeating the light emission of the semiconductor light emitting elements at a predetermined timing, a plurality of semiconductor light emitting elements arranged along the sub-scanning direction are simultaneously turned on and the luminance of the semiconductor light emitting elements is reduced as compared with repeating the main scanning exposure. It is possible to prevent a decrease in the brightness of the semiconductor light-emitting element, thereby preventing a change in the density of the formed image and a loss of the finished quality.

When an area that can be exposed by one main scanning exposure is exposed by two main scanning exposures, the exposure light source is alternately exposed by two divided semiconductor light emitting elements when the exposure light source is moved in the same direction. Also, when the exposure light source is reciprocated in the main scanning direction, exposure is performed by causing one set of semiconductor light emitting elements to emit light on the outward path, and causing the other set of semiconductor light emitting elements to emit light on the return path. Exposure may be performed.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION

(Overall Configuration “Appearance”) FIGS. 1 to 3 show a schematic configuration of an image recording apparatus 100 applied to the present embodiment. The image recording apparatus 100 is an apparatus that reads image data, exposes a photosensitive material 106 according to the image data, and then transfers an image formed on the photosensitive material 106 by exposure to an image receiving paper 108 and outputs the image. is there.

In the image recording apparatus 100, an upper portion of the front surface (left side in FIG. 3) of a 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 an image corresponding to the read image data is displayed on the monitor unit 114.

The input unit 116 has a plurality of operation keys 1.
18 and an input data confirmation display unit 120. The input data confirmation display unit 120 displays data necessary for image recording such as recording number input, size setting, color balance adjustment, negative / positive selection, and the like. The input can be performed by operating the operation keys 118 while confirming the display.

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 of FIG. 4 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. C on this tray 130
By mounting the D-ROM (optical disk) 102, the CD-ROM 102 can be loaded inside the apparatus.

On the other hand, the FD deck section 126 is provided with a slit-shaped FD insertion throttle 132, and the FD 104
By inserting the, the drive system inside the device operates,
The structure is such that the FD 104 is drawn in. FD
When the FD 104 is to be taken out, the FD 104 is operated by pressing the operation button 134 so that the FD
It is extruded from 2.

The optical disk deck 124 and F
Each of the D deck sections 126 has an access lamp 13
6, 138 are provided, and the access lamps 136, 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 142 (FIG. 2).
reference).

An image receiving paper 108 on which an image is recorded in the image recording apparatus 100 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 recording apparatus 100 has a configuration in which 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 and 150 are individually detachable.
As shown in FIG. 4, a supply reel 152 and a take-up reel 154 on which the roll-shaped photosensitive material 106 is wound are provided inside the apparatus along the axial direction of the reels 8 and 150. Can be taken out or loaded with the cover members 148 and 150 removed. (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 is formed with a notch 158 in which a part of the peripheral surface is cut in a tangential direction. Usually, the notch 158 is formed with the uppermost image receiving paper 108 in the tray 144 and the notch 158. They are opposed 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 from the tray 144. The pulled-out image receiving paper 108 is sandwiched between the first roller pair 160, and is completely pulled out from the tray 144 by the driving force of the first roller pair 160.

On the downstream side of the first roller pair 160, a second roller
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) The photosensitive material 106 is supplied to the supply reel 15.
It is loaded into the device in the form of a long roll wound in two layers. Photosensitive material 10 wound on supply reel 152
6 is loaded at a predetermined position by removing the cover member 150 (rear side of the apparatus) and inserting the supply reel 152 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.

The exposure section 1 is located between the fourth roller pair 168 and the reservoir section 170 in the conveying path of the photosensitive material 106.
76 are provided. Further, a water application section 178 is provided between the reservoir section 170 and the guide plate 172. The details of the exposure section 176 and the water application section 178 will be described later.
After the image is exposed at 76, the emulsion surface (exposed surface) is superimposed on the image receiving paper 108 by the third roller pair 166 in a state where water is applied to the emulsion surface. (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. The image receiving paper 108 and the photosensitive material 106 are wound around a heat roller 74 in a state of being superposed on each other, and are heated and subjected to a thermal development transfer process. The image recorded on the photosensitive material 106 is transferred to the image receiving paper 108 by the thermal development transfer process.

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 1/3 is peeled off from the photosensitive material 106. The structure is such that the image receiving paper 108 is guided toward the discharge tray 140.

On the other hand, the photosensitive material 106 is a heat roller 1
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 forming an image. 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 mainly includes 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 an image signal (CD-R
A signal based on image data read from the OM 102 or the FD 104), and the light source unit 2
The light source unit 204 in 00 is turned on.
The light source unit 200 includes a main scanning unit 206 described later.
, The photosensitive material 106 can be moved in the width direction (main scanning direction), and the main scanning is performed when the photosensitive material 106 stops driving the exposure unit 176 stepwise.

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 a configuration without the aperture 216 is also possible.

At the center of the exposure casing 214 downstream of the aperture 216, a telecentric lens 212 is provided.
Is provided, and has a function of condensing light from the light source unit 204 and forming an image on the photosensitive material 106. 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. The lens has a characteristic that the magnification does not change even when the height of the image plane changes. The difference due to the mounting state can be absorbed.

The focus is constantly adjusted by an auto focus mechanism (not shown). Alternatively, adjustment may not be required by using a lens system having a deep focal depth.

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.

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, in a state where the photosensitive material 106 has moved 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, the light source unit 204 can rotate the stepping motor 226 in the reverse direction,
Return to the original position. When a predetermined area on the photosensitive material 106 is exposed by the movement of the light source unit 204, the next movement (movement in the sub-scanning direction) of the photosensitive material 106 is started simultaneously with the return operation of the light source unit 204. It has become so.

The photosensitive material 1 on the light output side of the light source unit 204
A photodiode 228 is disposed on the surface facing the optical disk 06, and outputs a signal corresponding to the light amount of the light source from the light source unit 204. This photodiode 228
Is connected to a light quantity correction unit 230, and the signal is input to the light quantity 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. The image signal sent to the light source unit 204 is corrected based on the correction value, and each LED chip 208 is turned on with an appropriate light amount.

As shown in FIG. 4, the light source 204
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 B-LE LED chip
D-chip 208B, LED chip that emits G color is G-
The LED chip 208G and the R-LED chip 208R are referred to as R-LED chips 208R).
0, the photosensitive material 106 is attached along the width direction (main scanning direction) of the photosensitive material 106 according to the same arrangement rule.
The R-LED chip 208R has a wavelength of 65 for each color.
0 ± 20 nm, G-LED chip 208G has 530 ± 3
0 nm, B-LED chip 208B is 470 ± 20 nm
It has been.

At the right end of the substrate 210 in plan view, 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.
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. Are arranged.

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. Therefore, heat generation due to lighting of the LED chip 208 can be suppressed, and a change (decrease) in luminance of the LED chip 208 due to a temperature rise 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 pitch L between rows in each column is 520 μm, and the step size D in a staggered manner 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.

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.

With the light source unit 204 having the above-described structure, ten main scanning lines can be simultaneously formed on the photosensitive material 106 by one main scanning for each color. For this reason, for example, the photosensitive material 10 after ten main scanning lines are formed.
The step movement in the sub-scanning direction 6 is performed at a pitch of 10 times the main scanning line width recorded on the photosensitive material 106,
It is controlled to repeat the stop. (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 is moved 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.

By the way, the controller 202
The microcomputer includes a microcomputer in which U, ROM, RAM, and input / output ports are connected by a bus, and various drivers and sensors (all not shown) connected to the microcomputer via the input / output ports.

FIG. 6 is a functional block diagram of a main part of the controller 202 applied to the present embodiment.

The controller 202 includes the photosensitive material 1
A frame memory 240 for storing image data for one image (one frame) for exposing 06 is provided. Image data input to the controller 202 is stored in the frame memory 240. This frame memory 2
The image data stored in 40 is corrected by the correction unit 242 based on the correction value input from the light amount correction unit 230 described above.

The controller 202 is provided with a field memory 244 for storing image data of 10 main scanning lines exposed in one main scanning. The image data (corrected image data) stored in the frame memory 240 is read from the frame memory 240 by one main scan at the time of image exposure, and is read from the field memory 2.
44. When the stored image data is output to the light source unit 204 at a predetermined timing, the field memory 240 reads new image data for one main scan from the frame memory 240 and stores it.

On the other hand, the controller 202 is provided with an exposure control section 246. The exposure controller 246 causes the LED chip 208 to emit light based on the image data output from the field memory 244, and
Light source unit 2 having the function of an exposure control unit for exposing 06
04, a main scanning drive unit 248 that drives a stepping motor 226, and a sub-scanning stepping motor 2
A sub-scanning drive unit 252 for driving the driving unit 50 is connected.

As shown in FIG. 3, the stepping motor 250 connected to the sub-scanning drive section 252 is provided opposite to the exposure section 176 and is pinched by a fourth roller pair 168 constituting sub-scanning means. It is for driving the roller pair 192 (the stepping motor 250 is not shown in FIG. 3). This stepping motor 250 is provided with the light source unit 20.
4 drives the fourth roller pair 168 and the nipping roller pair 192 in synchronization with the exposure of the photosensitive material 106 by
06 is conveyed stepwise to perform sub-scanning of the photosensitive material 106.

As shown in FIG. 6, the controller 202 is provided with a power calculation unit 254 and an interval setting unit 256. The power calculation unit 254 integrates the amount of power for each LED chip 208 to emit light according to the image data in one main scan from the image data stored in the field memory 244. Power calculator 254
Is output to the interval setting unit 256.

In the interval setting section 256, each LED
An exposure interval necessary for causing the chip 208 to emit light with appropriate luminance according to the image data is set, and the set exposure interval is output to the exposure control unit 246.

The exposure control section 246 controls the light source section 204, the main scanning drive section 248 and the sub-scanning drive section 252 based on the exposure interval set by the interval setting section 256.
Is controlled to scan and expose the photosensitive material 106.

That is, the LED chip 208 used as a semiconductor light emitting element generates a small amount of heat, but generates a considerable amount of heat. For this reason, as shown by a curve a in FIG. 7, the brightness gradually decreases when the light is continuously turned on. Further, when the ten LED chips 208 are arranged close to each other, when these LED chips 208 are continuously turned on, the decrease in the brightness of each LED chip 208 increases as shown by the curve b. . For this reason, for example, when an area of A4 size is scanned and exposed by the light source unit 200 in which ten LED chips 208 are arranged close to each other, depending on the image, the image is recorded between the exposure start position and the exposure end position. In some cases, a difference of about 20% occurs in the density of the image.

It is known that the amount of heat generated by a semiconductor light emitting element such as the LED chip 208 is also proportional to the power consumption. In this embodiment, the occurrence of a density difference due to a decrease in the luminance of the LED chip 208 is prevented. To do so, the power calculation unit 254 integrates the amount of power that is the power consumption of each LED chip 208 for each main scan. The power amount may be integrated, for example, by calculating the average luminance for each main scanning line, and calculating the power from the LED chip 208 to emit light at the calculated luminance and the scanning time Ts.

The interval setting unit 256 determines, from the calculated integrated value of the electric energy of each LED chip 208, the time until the decrease in luminance due to a rise in temperature is restored when one main scan is completed. Set as Ti. Thus, when the time set as the exposure interval Ti elapses, the main scanning exposure can be started in a state where the luminance does not decrease due to the temperature rise.

For example, as shown by a curve c in FIG.
During a scanning time Ts during which the D chip 208 emits light,
By providing an exposure interval Ti (Ti ₁ , Ti ₂ ,...) And returning the main scan, the LED chip 208
Exposure can be performed in a range where the luminance of the image does not fall below a predetermined range (for example, 95% or less). In the curve c, L
The light emitting state of the CD chip 208 is indicated by a solid line, and the non-light emitting state is indicated by a two-dot chain line.

Further, when a large number of LED chips 208 which are continuously arranged in close proximity to each other are simultaneously turned on, the amount of heat generated by each other greatly affects the brightness, and the time until the brightness is restored is large. The exposure interval Ti to be set also increases. For this reason, as shown in FIG. 5, in this embodiment, each LED chip 208
, The LED chip 208 is divided into two blocks A, B, C, D, and E so that one of the LED chips adjacent to each other is turned off.
It lights up every other block at the same time. In other words, one main scanning area is exposed twice in blocks A, C, and E and blocks B and D.
Therefore, the exposure interval Ti is determined by the blocks A, C,
E and each of the blocks B and D are set.

That is, as shown in FIG.
First, the arrow W of the exposure unit 200 ₁Move along direction
LED chips 208 for blocks A, C, and E
The main scanning exposure is performed by emitting light, and then the light source unit 20
0 to arrow W_TwoTo the main scanning start position
Thereafter, as shown in FIG.
To perform main scanning exposure.

When the two main scanning exposures in the main scanning exposure area at the same position are completed, the light source unit 20
0 is returned to the main scanning start position, and the photosensitive material 106 is step-transported to perform sub-scanning.

Thereafter, as shown in FIG. 8 (C), main scanning exposure to new main scanning exposure areas by blocks A, C and E and blocks B and D is performed in order. At this time, the start of the main scanning exposure by the blocks A, C, and E and the start of the main scanning exposure by the blocks B and D are determined by the previous blocks A,
This is performed after the time set as the exposure interval has elapsed from the end of the main scanning by C and E (corresponding to FIG. 8A) and from the end of the main scanning exposure by the previous blocks B and D.

8A to 8C, the arrow W indicates the main scanning direction, the arrow L indicates the sub-scanning direction,
The dots exposed by each LED chip 208 are indicated by circles. Further, in FIG. 5, the substrate 210 provided with the LED chips 208 is viewed from the photosensitive material 106 side, whereas in FIGS. 8A to 8C, the exposed surface of the photosensitive material 106 is It is a schematic diagram viewed from above.

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

The tray 144 is loaded in the tray loading port 146, and the supply reel 152 in which the photosensitive material 106 has been wound and the empty take-up reel 154 are loaded in predetermined positions, respectively, and the loading is completed. When the print start key of the operation display unit 112 is operated, image data is sent to the controller 202.

When the image data is input, the controller 202 generates an image signal based on the image data and drives the supply reel 152 so that the photosensitive material 106
Starts transporting.

When the photosensitive material 106 reaches a predetermined position of the exposure unit 176, the photosensitive material 106 stops temporarily, and an image data signal is output from the controller 202 to the light source unit 204. This image signal is output every ten lines, and the light source unit 204 is guided by the guide shaft 218 by the driving of the stepping motor 226 and moves along the width direction of the photosensitive material 106 (main scanning). Before the output of the image signal is started, the light source unit 20 is operated by the photodiode 228.
4 to detect the light amount of each color, and the light amount correction unit 230
In, 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 scan is completed, the photosensitive material 10
6 moves 1 step (10 line pitch) and stops,
A second main scan is performed. By repeating this, an image for one frame is recorded on the photosensitive material 106 based on the image data. The photosensitive material 106 on which 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.

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 recorded) 106 is transported to the water application unit 178. In the water application section 178, water is uniformly applied by the application piece 188 while the photosensitive material 106 is transported at a constant speed.
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.

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 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 172, and the image receiving paper 108 is guided by the guide plate 164. It is conveyed to the 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. According to the present embodiment, image recording can be performed with a compact structure, and the optical disc deck 124 and the FD
Image data can be quickly taken in. Further, since the image to be recorded can be confirmed by the monitor unit 114, the adjustment of the density and the color balance is easy.

Since the discharge tray 140 is of a retractable type, the tray 144 containing the image receiving paper 108 can be stored when not in use.
By removing the outer shape, the outer shape has less irregularities, and the working space can be effectively used.

Further, in the apparatus of the present embodiment, the water application section 178 and the exposure section 176 are fixed in the transport direction of the photosensitive material 106, and the relative movement with respect to the photosensitive material 106 is
Since all the operations are performed by moving the photosensitive material 106, the moving mechanism is simplified.

By the way, the controller 202 of the image recording apparatus 100 sets an exposure interval for performing the main scanning exposure based on the input image data, and repeats the main scanning exposure at the set exposure interval. .

Here, an example will be described with reference to the flowchart shown in FIG. In the following description,
An exposure interval Ti set between the LED chips 208 of the blocks A, C, and E is set as an exposure interval Ta, and a dew interval Ti set between the LED chips 208 of the blocks B and D is set as an exposure interval Tb.

This flowchart starts when image data is selected and execution of processing is instructed. In the first step 300, initialization is performed. In this initial configuration,
The photosensitive material 106 is arranged at a predetermined position facing the light source unit 200, and an exposure interval, a timer for measuring the exposure interval, a counter for counting the number of exposures, and the like are reset. At the time of initial setting, the main scanning unit 206 causes the light source unit 200 to operate.
Is moved and the light amount of the LED chips 208 of each color is measured, and the light amount correction unit 230 sets a correction value for correcting the color balance, the color tone, and the like.

When the initial setting is completed, the process proceeds to step 302 where image data for one image is read and stored in the frame memory 240. At the same time, the frame memory 24
The image data stored in 0 is corrected, and the number N of main scanning exposures is set (step 204).

Thereafter, in step 206, the count value n of the counter for counting the number of exposures is incremented. Thus, at the start of the first main scan, the count value n of the counter is set to “1”.

Next, in step 208, the image data for one main scan is read into the field memory 244. Based on the image data read by the field memory 244, the power required for each main scan by each LED chip 208 is determined. The amounts are integrated (step 210).

In the next step 212, the exposure intervals of the blocks A to E are calculated based on the calculation result, and the maximum value of the exposure intervals of the blocks A, C and E and the maximum value of the exposure intervals of the blocks B and D are calculated. value, respectively exposure interval Ta _n, is set to Tb _n.

[0097] In this way exposure interval to one main scanning Ta _n, the Tb _n is set, the routine proceeds to step 314, previous blocks A, C, the exposure interval Ta _n-1 of E is measured Check whether the timer that is running has timed out. When the first main scan is performed, since the timer for measuring the exposure interval Ta has not been started, an affirmative determination is made in step 314, and the flow advances to step 316 to turn on the LED chips 208 of the blocks A, C, and E. The main scanning exposure that is turned on according to the image data is performed. As a result, as shown in FIG.
Block A moves to the main scanning direction (arrow W ₁ direction),
The C and D LED chips 208 make the photosensitive material 106
Is exposed.

In the flowchart shown in FIG. 9, when the main scanning exposure by the blocks A, C, and D is completed, the process proceeds to step 318 to reset / start the timer for measuring the exposure intervals of the blocks A, C, and D. This together with the exposure unit 200 is returned to the main scanning start position (movement in the arrow W ₂ direction in FIG. 8 (A)).

In the next step 320, blocks B and D
Timer for measuring the exposure interval Tb _n of to confirm whether or not the time is up. When the first main scan is performed, since this timer is not operated, the determination is affirmative, and the process proceeds to step 322 to perform the main scan exposure by the LED chips 208 of the blocks B and D. As a result, FIG.
As shown in (B), the exposure unit 200 moves
The region moved in _two directions and exposed by the blocks A, C, and D is exposed by the LED chips 208 of the blocks B and D.

Thereafter, in the flowchart shown in FIG. 9, the LED chips 2 of the blocks B and D are determined in step 324.
08 timer for measuring the exposure interval Tb _n of to reset / start.

In this manner, one main scanning exposure,
Check when the reset / start the exposure interval Ta _n, a timer for measuring the Tb _n, in step 326, whether the scanning exposure in accordance with image data of one image from the count value n of the counter (one frame) has been completed If the scanning has not been completed (No in Step 326), the process proceeds to Step 328 to perform a sub-scan for stepwise transporting the photosensitive material 106 by a predetermined amount.
Then, the process proceeds to step S6 to start the main scanning exposure according to the image data for the next one field.

Note that this flowchart corresponds to step 3
When it is confirmed in step 26 that the scanning exposure for one image has been completed (Yes in step 326), the process proceeds to step 330, in which the timer for measuring the exposure intervals Ta and Tb is stopped, and the exposed photosensitive material is terminated. 106 is sent to the next step from the position facing the exposure unit 200, and the processing is terminated.

By executing steps 306 to 312, the count value n of the counter is incremented, and based on the image data newly read into the field memory 244 and used for the next main scanning exposure, the blocks A, Exposure interval Ta of C and F and blocks B and C
_n and Tb _n are set. After the second time, steps 306 to 312 may be performed in parallel with the main scanning exposure by the exposure unit 200.

Thereafter, the flow shifts to step 314. First, the elapsed time from the end of the exposure by the LED chips 208 of the previous blocks A, C and E is set in accordance with the previous image data. Interval Tan _n-1
Is determined, and the previous exposure interval Ta
After confirming that _n-1 has been reached, the process proceeds to step 316.

In step 320, the elapsed time from the end of the exposure by the LED chips 208 of the previous blocks B and D is set to the exposure interval Tb set according to the image data of the previous main scanning exposure. _It is determined whether or not _n-1 has been reached, and after confirming that the previous exposure interval Tb _n-1 has been reached, the flow proceeds to step 322.

As described above, when performing exposure by causing the LED chip 208 to emit light, the exposure interval Tan _n− set based on the amount of power when the LED chip 208 is caused to emit light in accordance with the image data at the previous exposure. ₁ , Tb _n-1 is checked. This exposure interval Ta
_{Since n-1} and Tb _n-1 are set as a time for recovering the decrease in luminance caused by causing the LED chip 208 to emit light, a new main scanning exposure is performed after the exposure intervals Ta and Tb elapse. LE when starting
It is possible to reliably prevent the luminance of the D chip 208 from being reduced due to the influence of the previous main scanning exposure.

Accordingly, the main scanning exposure of the LED chip 208 is repeated while maintaining a substantially constant luminance,
When the photosensitive material 106 is exposed in accordance with the image data to form an image for one image, the finished quality such as density unevenness due to the reduced brightness of the LED chip 208 does not occur.

When performing the main scanning exposure, the LCD chips 208 arranged along the sub-scanning direction are divided into two blocks A to E, and one LCD chip 208 is formed.
LCD chips 2 adjacent to both sides in the sub-scanning direction
Since only one of the LCD chips 08 emits light at the same time, the temperature rise due to light emission can be suppressed as compared with the case where the LCD chips 208 on both sides are simultaneously turned on. This makes it possible to shorten the exposure interval.

In the present embodiment described above, the required exposure interval Ti is at least twice as long as the reciprocating time for one main scan of the exposure unit 200. The chip 208 is divided into blocks.
It is not limited to the present embodiment. For example, 10 LEs
3 or 4 LEDs in the center for D chip 208
Chip 208 and 4 or 3 LED chips 2 on both sides
08 may not be turned on at the same time. As a result, a large number of LED chips 208 are turned on at the same time, so that it is possible to prevent a significant decrease in luminance due to a temperature rise caused by heating by the mutual heat.

As described above, if the exposure interval can be suppressed within the time required for one reciprocating movement of the light source unit 200 along the main scanning direction by preventing the temperature rise, the exposure interval can be set without setting the exposure interval. Exposure according to image data for one field may be performed by two reciprocations along the main scanning direction.
That is, step 3 of the flowchart shown in FIG.
10 to 314, 318, 320, and 324 may be omitted.

The LED chips 208 which are simultaneously turned on
Exposure interval is the main scanning time T
s is reduced to about two times (2Ts), one of the LED chips 20 of the block divided on the outward path of the reciprocating movement of the exposure unit 200 along the main scanning direction.
8 is turned on and the other LED of the block divided on the return path
The exposure may be performed by turning on the chip 208.

That is, in the flowchart shown in FIG. 9 described above, when the first exposure is completed in step 316, the exposure unit 200 is returned to the main scanning start position until the second exposure is started in step 322. However, step 316 may be executed when the light source unit 200 moves forward in the main scanning direction, and step 322 may be executed when the exposure unit 200 moves backward.

[0113] That is, as shown in FIG. 10 (A), when the exposure unit 200 is moved in the arrow W ₁ direction, when performing divided one block A, C, the exposure by the LED chip 208 of the E is wherein the is the same as the power sale flowchart shown in FIG. 9, as shown in FIG. 10 (B), when the exposure unit 200 returns (moves in the arrow W ₂ direction), divided the other block B, D
Exposure is performed by the LED chip 208.

Thereafter, as shown in FIG. 10C, each time the set exposure interval elapses, the outward movement of the exposure unit 200 in the main scanning direction (arrow W _1).
Direction), block A while repeating backward movement (arrow W ₂ direction), C, E and the block B, and the LED of D
Exposure by the chip 208 may be repeated.

On the other hand, also in this case, if the exposure interval can be made shorter than the main scanning time Ts (forward movement time or backward movement time) by the combination of the LED chips 208 that are simultaneously turned on, the exposure interval is not set. Exposure can be alternately repeated in accordance with the reciprocation of the exposure unit 200.

The image recording apparatus 10 used in the above description
0 does not limit the configuration of the present invention. The present invention is directed to various types of arrangements in which a plurality of semiconductor light emitting elements such as LED chips are arranged to form an image according to image data while forming a plurality of main scanning lines on a photosensitive material by one main scanning exposure. The present invention can be applied to an image forming apparatus having a configuration.

[0117]

As described above, according to the present invention, the timing of the start of exposure is set based on the exposure interval required for each main scanning exposure according to the image data. By repeating the above, it is possible to prevent the luminance of the semiconductor light emitting element from decreasing and the density of the image formed on the recording medium from changing.

Further, according to the present invention, a plurality of semiconductor light emitting elements arranged continuously are divided into two sets and emitted at different timings, so that the exposure is repeated while simultaneously lighting a large number of semiconductor light emitting elements. Thus, by preventing the brightness of each semiconductor light emitting element from gradually decreasing, it is possible to prevent the finish quality from deteriorating due to a change in the density of an image formed on a recording medium. Is obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view of an image recording apparatus according to an embodiment.

FIG. 2 is a front view of the image recording apparatus according to the present embodiment.

FIG. 3 is a side sectional view showing an internal configuration of the image recording 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 illustrating a controller provided in the exposure unit.

FIG. 7 is a diagram schematically illustrating a change in luminance with respect to a light emission time of an LED.

FIGS. 8A to 8C are schematic diagrams respectively showing an exposure position on an LED chip and a photosensitive material of an exposure unit according to the present embodiment, and FIG. 8A is a first main scanning exposure; (B) shows the time of the second main scanning exposure, and (C) shows the time of the third main scanning exposure.

FIG. 9 is a flowchart according to the embodiment showing an application example of the present invention.

FIGS. 10A to 10C are schematic diagrams each showing an LED chip of an exposure unit and an exposure position on a photosensitive material according to another application example of the present invention, and FIG. At the time of main scanning exposure, (B) at the time of the second main scanning exposure, (C)
Indicates the third and subsequent main scanning exposures.

[Explanation of symbols]

Reference Signs List 100 image recording device (image forming device) 106 photosensitive material (recording medium) 108 image receiving paper 176 exposure unit 178 water application unit 200 light source unit 202 controller 204 light source unit (light emission control unit) 206 main scanning unit 208 LED chip (semiconductor light emitting element) 226 Stepping motor (main scanning unit) 246 Exposure control unit (light emission control unit, main scanning control unit, sub-scanning control unit) 248 Main scanning drive unit (main scanning control unit) 250 stepping motor (sub-scanning unit) 252 sub-scanning Driving unit (sub-scanning control unit) 254 Power calculation unit (calculation unit) 256 Interval setting unit (interval setting unit) A, B, C, D, E blocks

Claims (3)

[Claims] An image forming apparatus that forms an image by exposing a recording medium based on digital image data, wherein a plurality of semiconductor light emitting elements each capable of exposing the recording medium based on the digital image data are provided. An exposure light source arranged closely in the sub-scanning direction; main scanning means for performing main scanning exposure by the light emitting element by relatively moving the exposure light source relative to the recording medium in the main scanning direction; Sub-scanning means for relatively moving the exposure light source relative to the recording medium in the sub-scanning direction; calculating means for integrating and calculating the amount of power for the semiconductor light emitting element to emit light for each main scan based on the image data; An interval setting unit that sets an exposure interval for each of the semiconductor light emitting elements based on a calculation result of the calculation unit; and the set exposure interval. A light emission control unit that controls light emission of each semiconductor light emitting element based on the main scanning control unit that controls a main scanning unit based on the set exposure interval and according to an operation of the light emission control unit; And a sub-scanning control unit that operates the sub-scanning unit in synchronization with the operation of the scanning control unit. 2. The method according to claim 1, wherein the semiconductor light-emitting elements that are simultaneously turned on in accordance with the image data are divided into at least two sets, and the power amount is integrated for each of the divided sets. An image forming apparatus according to claim 1. 3. An image forming apparatus that forms an image by exposing a recording medium based on digital image data, wherein a plurality of semiconductor light emitting elements each capable of exposing the recording medium based on the digital image data are provided. An exposure light source arranged closely in the sub-scanning direction; main scanning means for performing main scanning exposure by the light emitting element by relatively moving the exposure light source relative to the recording medium in the main scanning direction; Sub-scanning means for relatively moving the exposure light source in the sub-scanning direction with respect to the recording medium; Emission control means for emitting light; main scanning control means for controlling the emission control means and main scanning means in synchronization with each other; and the main scanning control means And a sub-scanning control means for operating the sub-scanning means in synchronization with the operation of the image forming apparatus.