JPH08314150A - Image processor - Google Patents

Abstract

PURPOSE: To provide an image recorder in which a mechanical plotting timing control mechanism is not provided and image distortion is lessened. CONSTITUTION: Thirty two exposing elements B0 to B31 are divided into four groups respectively having eight exposing elements and the plotting timing is hastened as the groups becomes different in a sub-scanning direction. Thus, the figure distortion of a recorded image can be reduced without requiring the mechanical plotting timing control mechanism, and adjustment for changing a plotting beam diameter, and duplicating magnification of the recorded image, etc., can be facilitated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus for recording an image in scanning line order, and more particularly to a technique for correcting image distortion when recording images in parallel by a plurality of drawing beams. .

[0002]

2. Description of the Related Art An image recording apparatus for recording a duplicate image on a surface of a sensitive material or the like in a scanning line sequence by a drawing beam is well known, and its embodiment will be described below taking a drum type scanner as an example.

FIG. 11 is a development view of a photosensitive material film wound around a drum surface of a drum type scanner. First, an image is formed on the photosensitive material film in scanning line units by a single exposure beam (single beam). Consider the case where it is recorded. At this time, since the scanning line formed by the drawing beam actually has a width, the drum is rotated once, that is, in FIG.
Then, the scanning position is displaced in the sub-scanning direction by the width D of the scanning line between S1 and E1 of the first scanning. Therefore, the second scan is started from the position S2, which is displaced from the start position of the first scan by D in the sub-scanning direction. Therefore, each scanning line is inclined by a certain angle θ with respect to the outer peripheral direction of the drum 2 as shown by the solid line in FIG. 11, and the recorded image has distortion.

Therefore, as a method which has been widely used to prevent this distortion, there is a method disclosed in Japanese Patent Laid-Open No. 59-63876. This method is intended for the case of a single beam, and as shown in FIG. 12, the drawing is started earlier for each scanning line like a dotted line MS having an angle of θ with the sub-scanning direction. That is, the drawing start point after the second scanning line is S
2 to M2, S3 to M3 ... And the drawing end points are changed from E1 to N1, E2 to N2. This prevents distortion of the recorded image by making the angle between the main scanning direction and the sub scanning direction at the time of drawing a right angle.

Further, there are known some techniques used in the case where this method is used to draw in parallel with a plurality of drawing beams (hereinafter referred to as "multi-beam").

In the method of Japanese Patent Laid-Open No. 59-80061 as a first example, the multi-beam head is set so as to form an angle of θ in FIG. Go in the direction of arrow 12 AA. Then, the scanning at that time is performed simultaneously for the number of drawing beam elements. According to this method, there is no need to control the drawing start timing.

Further, as a second example, JP-A-58-111.
In the method of 566, the multi-beam head is set so as to make an angle of θ with respect to the rotation axis of the drum as in the previous example, but the sub-scan at the time of drawing is indicated by the arrow AB in FIG. 12, that is, the rotation axis of the drum. Go parallel to. Then, scanning is simultaneously performed by the number of drawing beam elements. In this method, the drawing start timing is
That is, each drawing beam is advanced every time it is scanned.

[0008]

By the way, in the above-mentioned conventional method, since the multi-beam head is inclined with respect to the rotation axis of the drum, the beam diameter is changed and the number of elements of the multi-beam head is changed. In the above-mentioned two examples, the tilt angle of the multi-beam head has to be mechanically adjusted when changing the size or the size, but it is quite difficult to prevent an error in this mechanical adjustment.

Further, in the above-described first example, when the tilt angle of the multi-beam head is changed, the sub-scanning direction (FIG.
The arrow AA direction in 2) must also be changed, but this requires delicate adjustment and requires skill of the operator.

Because of such a problem, it is desirable to perform distortion compensation without adjusting the mechanical angle of the multi-beam head. Therefore, it is conceivable to provide a delay circuit for each element belonging to the multi-beam head to perform timing compensation, but if the same number of delay circuits as the number of elements are provided, the circuit configuration becomes extremely complicated. Occurs.

[0011]

SUMMARY OF THE INVENTION The present invention is intended to overcome the above-mentioned problems in the prior art, has no mechanical drawing timing control mechanism, has a relatively simple circuit configuration, and has no image distortion. It is an object of the present invention to provide an image recording device with less power consumption.

[0012]

In order to achieve the above object, the first apparatus of the present invention is formed by a plurality of exposure elements on the image recording medium while continuously conveying the image recording medium. In an image recording apparatus for recording a duplicate image on an image recording medium in a scanning line sequential manner using a plurality of exposure beams, a plurality of exposure elements adjacent to each other in the array of the plurality of exposure elements are set as one group, Of the exposure elements are conceptually divided into a plurality of groups, and timing control means for shifting the timing of the image signal given to each of the exposure elements in group units according to the spatial distance between the groups is provided. .

A second apparatus of the present invention is characterized in that, in the first apparatus, the difference in the number of exposure elements belonging to each group between groups is minimized.

[0014]

According to the invention of claim 1, when there are N (N is an integer of 4 or more) exposure elements,
They are divided into k (k is an integer of 2 or more) groups, and each group is adjacent to each other in Nk (Nk is 2).
The above exposure elements are integers. However, N1 + N2 + ... + Nk = N.

Further, according to the present invention, the timing of the image signal applied to each of the exposure elements is shifted in group units according to the size of the spatial distance between the groups.

Therefore, for example, in the case of a cylindrical scanning type recording apparatus, when the size of the exposure beam (beam spot diameter) on the image recording medium is d, the maximum distortion amount of the image without any tilt compensation is a ・ Nd (a is a constant)
However, in the present invention, a · (max [N1, N2, ..., Nk] · d) is obtained. However, the symbol max [] indicates the maximum value of the argument.

By the definition of the above number Nj (j = 1, 2, ..., K), max [N1, N2, ..., Nk] <N, so a. (Max [N1, N2, ..., Nk ] ・ D) <a ・
(Nd), which means that the distortion due to the inclination is reduced. In the present invention, since the timing is adjusted in units of groups, tilt compensation within the groups is not performed, but image distortion is certainly reduced as compared with the case where no compensation is performed.

Further, in the present invention, since the timing adjustment is performed in units of groups, unlike the case where the timing control means is provided for each of all the exposure elements, the timing control may be performed in units of groups, so the circuit configurations are also compared. Will be easier.

On the other hand, in the second aspect of the invention, "to minimize the difference between the number of exposure elements belonging to each group among the groups" means, for example, that there are 32 exposure elements and they are divided into 4 groups. When dividing conceptually into, this corresponds to dividing them into four equal parts so that 32/4 = 8 exposure elements belong to each group. By doing so, the difference in the number of writing beams belonging to each group is minimized (that is, zero).

By satisfying such a condition, not only the number of exposure elements belonging to each group becomes equal, but also the difference in the number of exposure elements belonging to each group is minimized. For example, in the above example, 32 exposure elements (1
0,10,10,2) is divided into 10
A tilt of 10 scanning lines remains in the group of exposure elements, and the tilt of the image in the group of 10 exposure elements differs from the tilt of the image in the group of 2 exposure elements. Will be things. On the other hand, if the division is performed as (8,8,8,8) as described above, only the inclination of eight scanning lines remains in the group, and the inclination in the group is changed in all groups. The same is true and image distortion is minimized.

In other words, it is preferable to divide the groups into equal parts so that the number of exposure elements belonging to each group is the same. By doing so, the inclinations remaining in the group vary and the inclinations are minimized, and the effect of reducing the distortion of the duplicate image is enhanced.

Of course, there are cases where the number of exposure elements and the number of divisions cannot be equally divided mathematically as described above, but in this case the following may be done. That is, for example, when it is necessary to conceptually divide 32 exposure elements into three groups, (12, 12, 8); (11, 11, 10); (12,
There are various division methods such as 11, 9, etc., but the one in which the maximum difference between the numbers of exposure elements is the minimum, that is, (11, 11, 10): maximum difference = 11-10 = 1 is adopted. Good. By the way, (12,12,8): maximum difference = 12-8 = 4; (12,11,9): maximum difference = 12-9 = 3.

In this way, the variation in the distortion of the duplicated image is reduced even when the equal division cannot be performed. However, it is preferable to select the division number that allows the equal division as in the above example.

[0024]

【Example】

[0025]

[1. Mechanical Schematic Structure and Device Arrangement FIG. 1 is a block diagram of the main part of an image recording apparatus in an embodiment of the present invention. The outline of the processing of the image recording apparatus of this embodiment will be described below with reference to FIG.

The rotation of the main scanning motor 3 causes the drum 2 around which the photosensitive material film F is wound to rotate. An image is exposed on the photosensitive material film F by spiral scanning by a plurality of exposure beams emitted by the multi-beam head 5 while the drum 2 is rotating. At that time, the main scanning is performed by the rotation of the drum 2. Further, the sub-scanning motor 6 rotates the sub-scanning axis 8 and the feed screw engraved on the sub-scanning axis causes the multi-beam head 5 to move in the sub-scanning direction (drum 2).
Parallel to the axis of rotation).

Further, in the image recording apparatus of this embodiment, although details of the multi-beam head 5 are not shown in the figure, it has 32 exposure elements and a zoom lens for changing the magnification, and at the same time 32 lines are provided. Exposure beam can be irradiated. Further, the multi-beam head 5 is installed parallel to the rotation axis of the drum 2. And with this device 3
The two exposure elements are conceptually divided into four groups of eight, and the image distortion is suppressed by accelerating the timing of drawing start and the subsequent image signal supply as the groups differ in the sub-scanning direction. . The control unit 1 controls the timing of the drawing start.

The main scanning position of the drum 2 is measured by the main scanning encoder 4 as the main scanning encoder signal SS, and the sub-scanning position of the multi-beam head 5 is measured by the sub-scanning encoder 7 as the sub-scanning encoder signal FS.
It is sent to the control unit 1. Then, the control unit 1 sends a control signal for starting drawing of each group of exposure elements to the multi-beam head 5 based on these signals.

[0029]

[2. Drawing start timing control of the embodiment: The drawing start timing control of the image recording apparatus of this embodiment will be described below.

FIG. 2 is a development view of the scanning surface by the image recording apparatus of this embodiment. As described above, in the apparatus of this embodiment, when the exposure pixel size is approximated by a square area of one side P, the multi-beam exposure optical system is configured to collectively expose 32 pieces in the sub-scanning direction. These three
An example of a linear array of two exposure beams B0 ... B31 is shown in FIG.
0 (a).

As shown in FIG. 2, since 32 scans are performed per scan, the beam at the left end of the 32 scans must be scanned 32P apart in the sub-scanning direction at the time of the next scan. I won't. Therefore, the outer peripheral direction AD of the drum 2 and the scanning line form an angle θ (hereinafter referred to as “scanning angle θ”). As is apparent from FIG. 2, when the outer peripheral length of the drum 2 is L, tan θ = 32P / L (1) From this equation (1), it can be understood that the scanning angle θ changes when the exposure pixel size is changed (that is, P is changed) by changing the exposure beam diameter or the copy magnification of the recorded image.

In order to eliminate the image distortion due to the presence of this scanning angle, the recording start point is set to A0 as shown in FIG. 3, and M pixels from A0 in the sub-scanning direction, that is, M · P.
Exposure is started from the point AM for the distant exposure beam. Therefore, in the apparatus of this embodiment, the upper end reference line UL is set as shown in FIG. 3, and control is performed based on the distance LM from that position to the point AM.

From FIG. 3, the distance LM from the upper end reference line UL of AM is LM = L0-M.P.tan.theta. (2). In this equation, θ is given by equation (1).

Next, PS = P / 16 is introduced as a scale for expressing the length when performing such correction. This PS is for more precise control. Further, using this PS, NM = [LM / PS] (3) is defined. However, [] is a Gauss symbol (rounded down to the nearest decimal place). NM represents LM in units of the scale PS.

Therefore, in the following, these LM and NM
The control of the exposure beam of the apparatus of this embodiment will be described using FIG. As a method of controlling the timing of starting the exposure, it is conceivable to provide a timing circuit for all the exposure elements, but there is a problem that a considerably large control unit 1 is required and the control circuit becomes complicated. There is. Therefore, in the apparatus of this embodiment, 32 exposure beams are divided into 4 groups every 8 beams, exposure is started at the same timing within the same group, and exposure is started at different timing for each group. 8 exposure beams of 32
The reason for dividing the book into units is that if too many beams are used at the same timing, the distortion of the recorded image becomes noticeable, and conversely if too many beams are used, the control becomes complicated as described above. .

Now, as shown in FIG. 10A, 32 exposure elements B0 ... B31 are arranged in groups of 8 adjacent to each other.
Timing is controlled by dividing each group into groups G1, G2, G3, G4, and the left end of each group becomes exposure elements B0, B8, B16, B24. Of these, the state of S0 for the exposure element B0 is shown in FIG.
It was shown to. The amount of movement of each left-end exposure element in the sub-scanning direction during R rotations of spiral scanning from point A0 can be expressed as follows. That is, for B0: S0 = 32R · P For B8: S8 = 32R · P + 8P For B16: S16 = 32R · P + 16P For B24: S24 = 32R · P + 24P.

Further, in the main scanning direction, by substituting these values into R and P in the expression (2), the distance LRi from the upper end reference line UL to each left end exposure element is obtained, and these are further calculated as LR in the expression (3). Substituting for P for the exposure element B0
The upper end reference line UL with S as a scale and the distance NRi to the exposure start point are obtained. However, i = 0, 8, 16, and 24 are shown.

As an example, i = 0, that is, LR0 and NR0 for the exposure element B0 are obtained. That is, LR0 = L0−S0 · tan θ NR0 = [LR0 / PS] (4) The relationship between these quantities appears in FIG. In this way, NRi (R = 1, 2 ... And i = 0, 8,
16 and 24) are calculated in advance by a computer or the like and stored in respective addresses R (= 1, 2 ...) Of the NR0 memory 13 to NR24 memory 16 shown in FIG. In this way, NR0 to NR24 can be easily obtained by reading this memory at the address R.

In the apparatus of this embodiment, the exposure element 4
The exposure start of one group is the time during which the drum 2 rotates in the main scanning direction by NRi obtained by the expression (4) after the multi-beam head 5 passes over the upper reference line UL (hereinafter referred to as “delay time”). After each), each group starts exposure. FIG. 5 shows this state. The parallelogram in the figure corresponds to the exposed pixel, and the hatched portion is the exposed image. As can be seen from FIG. 5, by shifting the exposure start timing of each group of the exposure heads, the angle of the apex angle α of the exposed image becomes a right angle, so that the distortion of the image is suppressed. Considering only within each group, it is tilted from the ideal tilt DIR, but this is only within a section of about 1/4 as compared with the case where no tilt compensation is performed,
In practice, this alone is a sufficient improvement.

Further, in order to make the apex angle α right angle, the apparatus of this embodiment obtains NR0 to NR24 as different drawing start positions of each group of exposure elements and stores them in the memory. Therefore, even if the scanning angle θ changes by changing the exposure beam diameter or the copy magnification of the recorded image according to the equation (1), NR0 stored in the memory
It is only necessary to change ˜NR24, and it is not necessary to adjust the angle of the multi-beam head 5 itself or its sub-scanning direction with respect to the rotation axis of the drum 2.

FIG. 6 is a block diagram showing the internal structure of the control unit 1. Specific exposure timing control by the processing unit 1 will be described below with reference to FIG. The main scanning encoder signal SS sent from the main scanning encoder 4 and the sub scanning encoder signal FS sent from the sub scanning encoder 7 are input to the clock generator 10. Then, the clock generator 10 generates three types of pulse signals TP, TSV and TSH based on those signals.

FIG. 7 is a timing chart of those pulse signals. As for the signal TSV, the exposure beam is the upper reference line UL
It is a pulse signal generated when passing through. Also signal T
SH is a pulse signal when the multi-beam head 6 passes the left end of the recording area by sub-scan feed. Also the signal TP
Is a pulse signal generated each time the exposure beam moves in the main scanning direction by PS (= (P / 16)), both of which are the main scanning encoder signal SS and the sub-scanning encoder signal FS.
It is created based on.

In FIG. 7, the binary counter 11 is cleared by the pulse signal TSV and counted up by the pulse signal TP. Therefore, the output of the binary counter 11 indicates the movement distance of the exposure beam from the upper reference line UL by P
S is expressed as a scale.

Since the binary counter 12 is cleared by the pulse signal TSH and counted up by the pulse signal TSV, this output expresses the number of main scans since the multi-beam head 5 began to face the image recording area. .
Therefore, as described above, the output of the binary counter 12 becomes the address of the NR0 memory 13 to NR24 memory 16 storing the distance NRi from the upper end reference line UL to the exposure start point.

FIG. 8 is a timing chart of the output signals of the S terminal of the subtractor 17, the second power of 3 terminal, the second power of 4 and the image signal from the image memory 22 to the latch circuit 23. .

The processing for the groups of exposure elements B0 to B7 will be described below as an example with reference to FIG.

By subtracting the output NR0 of the NR0 memory from the output of the binary counter 11 in the subtractor 17, the exposure element in which the moment when the sine signal S of the subtractor output is inverted from negative to positive is corrected. At the timing of starting exposure of the groups B0 to B7, after that, the image signals of the image memory 22 are read out in synchronization with each other as described below, and image exposure is performed.

The binary number represented by the output signal of the terminal of the subtracter 17 which is equal to or higher than the second power of 4 is incremented by one every 16 pulse signals TP, that is, every 16PS, so that the exposure pixel of the exposure beam is exposed. The distance from the exposure start point is expressed using one side P (= 16 PS) of the above as a scale. This is input to the image memory 22 as an address of the image memory. Then, the image signal for one pixel stored at that address is input to the latch circuit 23 and latched.

After the sine signal S is inverted from negative to positive, the control signal generator 21 generates the image memory read control signal GS every time the output signal from the terminal of the power of 2 of the subtractor 17 falls. To be done. The signal is input to the latch circuit 23, and the image signal stored in the image memory 22 is read out in synchronization with the change in the address of the image memory 22 described above. The image signal output from the latch circuit 23 is sent to the exposure elements B0 to B7 to modulate each exposure beam and recorded on the photosensitive material film F.

The same processing as the above processing is performed by the image controller 30.
In parallel with steps 60 to 60, images with less distortion are recorded on the photosensitive material film F.

[0051]

[3. Modified Example In the image recording apparatus of this embodiment, the case where 32 exposure elements are arranged in a line in the sub-scanning direction has been described, but the arrangement of the exposure elements may be changed to each group as shown in FIG. 9 for various reasons. In some cases, such arrangement is performed diagonally, and for such an arrangement, in addition to the timing control performed in the above-described embodiment, timing control corresponding to the position in the main scanning direction of each element is performed for the horizontal single-row arrangement. I'll do it.

Further, the present invention can be applied to a multi-beam having a staggered arrangement as shown in FIG. In this case, for example, 16 beams B0 ... B15 are conceptually divided into a first group G11 + G12 consisting of eight beams on the left side and a second group G21 + G22 consisting of eight beams on the left side, The timing of the image signal given to one group is delayed from the timing of the image signal given to the second group.

In the case of the waveform arrangement of FIG. 9 and the staggered arrangement of FIG. 10, in addition to the timing adjusting means for tilt compensation,
A circuit configuration for compensating for the timing deviation due to the non-linear arrangement is required, but the circuit configuration is simple compared to the case where different timing adjustments are made for all exposure beams. For example, in the case of the staggered arrangement in FIG. 11, since the drawing beams are arranged in two rows, there is one kind of timing adjustment for staggered compensation and one kind of timing adjustment for inclination compensation, so there are a total of two. There are only types. On the other hand, if an attempt is made to adjust the timing for tilt compensation for all exposure beams, a large number of timing adjustments are required.

Further, in the case of FIG. 9, since the waveform array is periodic, the timing adjustment for compensating for this waveform array is performed by adjusting the number of beams included in one wave, that is, seven timing adjustments. There are only four types (three types if the delay is omitted for the earliest image signal output) for tilt compensation between groups (one by one wave type), and when performing individual timing adjustment for all beams. 8
× 4 = 32 types (31 types that output the image signal earliest even if delay is omitted) are required. As described above, the application of the present invention can prevent the circuit configuration from becoming complicated regardless of the variation in the arrangement of the beams.

Further, the exposure start timing intended by the present invention can be controlled by performing appropriate timing control for the array of issuing elements other than that shown in FIG.

Further, in the image recording apparatus of this embodiment, the number of image elements is 32 and each of them is divided into 4 groups, but the total number of image elements and the division of groups may be other numbers. In any case, it is preferable to minimize the difference between the groups in the number of writing beams belonging to each group.

Further, the present invention is not limited to a cylindrical scanning type image recording device, but may be a plane scanning type image recording device.
Since the sub-scanning is continuously performed, it can be generally used for an apparatus in which the scanning line is not perpendicular to the sub-scanning direction as it is.

Furthermore, the invention is not limited to image recording by a light beam, but can be applied to an electron beam image recording device, an ink jet printer and the like.

[0059]

As described above, according to the first aspect of the invention, the plurality of exposure elements are divided into at least two or more groups, and the drawing timing is shifted according to the size of each group. Therefore, it is possible to reduce the distortion of the recorded image without requiring a mechanical drawing timing control mechanism.

Further, since there is no mechanical mechanism for timing control, it is easy to adjust the exposure beam diameter and the reproduction magnification of the recorded image. In particular, since it is not necessary to control the timing of every exposure element for each element, the circuit configuration becomes simple.

Further, according to the second aspect of the present invention, the conceptual division of the plurality of exposure elements minimizes the difference between the groups in the number of exposure elements belonging to each group. The difference is small, and the effect of image distortion compensation is particularly large.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part in an image recording apparatus according to an embodiment.

FIG. 2 is a development view of a scanning surface in the image recording apparatus of the embodiment.

FIG. 3 is an explanatory diagram of a recording area in the image recording apparatus of the embodiment.

FIG. 4 is an explanatory diagram of an exposure start position in the image recording apparatus of the embodiment.

FIG. 5 is an explanatory diagram of an exposure start point of each group of exposure elements in the image recording apparatus of the embodiment.

FIG. 6 is a block diagram showing an internal configuration of a control unit 1 in the image recording apparatus of the embodiment.

FIG. 7 is a timing chart of each pulse signal in the image recording apparatus of the embodiment.

FIG. 8 is a timing chart of various output signals of the subtractor 17 and the reading of the image signal from the image memory in the image recording apparatus of the embodiment.

FIG. 9 is an explanatory diagram of a wavy array of exposure heads in a modified example.

FIG. 10 is an explanatory diagram of a linear array of exposure heads in an example and a staggered array of exposure heads in a conventional example.

FIG. 11 is an explanatory diagram of distortion of a recorded image by a conventional image recording apparatus.

FIG. 12 is an explanatory diagram of an exposure head and its sub-scanning inclination in an image recording apparatus of a conventional example.

[Explanation of symbols]

1 control unit 2 drum 3 main scanning motor 4 main scanning encoder 5 multi-beam head 6 sub-scanning motor 7 sub-scanning encoder 8 sub-scanning axis θ angle between scan line and drum P length of one side of exposure pixel A0 left edge recording start Point AM Recording start point M pixels away from the left end in the sub-scanning direction L0 Distance from the upper end reference line to the left end start point LM Distance from the upper end reference line to AM NR0 Upper end of B0 after R rotation from the start of exposure Distance from the reference line to the exposure start point in units of P / 16 S A0 and the distance between AM in the sub-scanning direction B0 to B36 Exposure element TP Pulse signal generated every time P / 16 of main scanning advances TSV exposure Pulse signal generated when the beam passes the upper reference line UL TSH Pulse signal when the exposure beam passes the left edge of the recording area

Claims (2)

[Claims] 1. A duplicate image is recorded on an image recording medium in a scanning line sequential manner by using a plurality of exposure beams generated by a plurality of exposure elements on the image recording medium while continuously conveying the image recording medium. In the image recording apparatus, a plurality of exposure elements adjacent to each other in the arrangement of the plurality of exposure elements are set as one group, and the plurality of exposure elements are conceptually divided into a plurality of groups, and each of the exposure elements is An image recording apparatus comprising: a timing control unit that shifts the timing of an image signal given to the group for each group according to the size of the spatial distance between the groups. 2. The image recording apparatus according to claim 1, wherein the difference in the number of exposure elements belonging to each group between groups is minimized.