JPH0774935A - Digital copying machine - Google Patents

Abstract

PURPOSE:To switch the density of picture elements based upon adequate judgement by referring to records copied on the same recording paper and having respectively different picture element density at the time of selecting a sample copying mode, and selectively switching a copy productivity priority mode and a high picture quality priority mode. CONSTITUTION:A read picture is written in a line memory 4 through a writing unit 5, read out from the memory 4 again and recorded through an LED 8. When an MPU 4 selects one of respective oscillators 10a and 10b, 14a and 14b and 18a and 18b, recording having respectively different picture element density corresponding to the copy productivity priority mode or the high picture quality priority mode is executed under the control of the unit 5, a polygon mirror motor drive 13 and a main motor drive 17. When a sample copy mode selecting means is operated, pictures corresponding to respectively different modes are recorded on the same recording paper through the MPU 4 and the priority mode can be accurately switched based upon the adequate judgement referring to the records.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital copying machine.

[0002]

2. Description of the Related Art In copying, in order to obtain a copy more faithful to the original, it is better that the writing pixel density is high. Further, in order to further improve the productivity of copying, it is preferable that the copying speed (imaging linear velocity) is high. However, the pixel density and the image forming linear velocity are contradictory characteristics, and if the other conditions are constant, increasing the pixel density lowers the image forming linear velocity and lowers the copy productivity. On the contrary, if the image forming linear velocity is increased to increase the productivity of copying, the pixel density must be reduced. For this reason, in the past, the writing pixel density during image formation was fixed (one type), and one of the characteristics was sacrificed or set to have an intermediate characteristic. The current situation is not to satisfy the.

Such matters will be qualitatively described based on various specifications of a digital copying machine equipped with a laser writing system which is most popular.

First, the scanning frequency f _v [Hz] is given by f _v = (DPI / 25.4) × V, where DPI is the pixel density and V [mm / s] is the linear velocity of the photosensitive member. The rotation number R _m [rpm] of the polygon mirror is R _m = f _v × (60 / n) = (DPI × V × 60) / (25.4 × n) where n is the number of mirror surfaces. Pixel frequency f _H [MHz] is f _H = (f _v × L / ER) × (DPI / 25.4) × 10 ⁶ = (DPI) where L is the effective writing width and ER is the effective scanning period ratio. per 25.4) becomes ^{2 × (L × V / ER} ) × 10 ~ 6. Note that the effective scanning period ratio ER is the effective half angle of view θ
Then, ER = n × θ / 360 ° = n × θ / 3.6 [%].

Under such specifications, the pixel frequency f _H has an upper limit in terms of the responsiveness of the circuit elements forming the circuit. That is, when the pixel frequency f _H is constant, the relationship between the pixel density DPI and the photosensitive member linear velocity V is DPI ² × V = K, where K is the coefficient.

Since the linear velocity V of the photoconductor is one of the factors that determine the copy productivity, increasing the pixel density DPI lowers the copy productivity. The density DPI must be lowered. Further, the number of revolutions of the polygon mirror cannot be increased indefinitely in consideration of the life of the bearing of the polygon motor and the power consumption.

[0007]

However, when considering the mode of actually making a copy, the required pixel density differs depending on the type of original, and in the case of copying a photographic original, generally, when copying a text original. It is considered that the pixel density may be coarser than the above. That is, it is considered that a photographic document generally has a small change in density per unit area (low spatial frequency) and requires a low pixel density. However, in the case of a text original, the density change per unit area is large (the spatial frequency is high), and a high pixel density is required to obtain a copy faithful to the original.

Further, there are various demands of individual users.
That is, there are a case where the copy productivity is emphasized rather than the image quality, and a case where the image quality is emphasized regardless of the copy productivity.

Considering such a situation, the conventional method in which the writing pixel density during image formation is fixed to one is insufficient.

Further, the point that the speed of the image forming process is switched is shown in, for example, Japanese Unexamined Patent Publication No. 5-8439, but it is difficult to grasp the completion of copying, and the selection and designation of an appropriate image forming process speed. Has become difficult.

[0011]

According to a first aspect of the present invention, there is provided copy productivity priority mode selecting means and high image quality priority mode selecting means, and the pixel density is switched according to the selected priority mode to perform the recording process. The copy processing means for performing the sample processing and the sample copy processing means for performing the recording processing with a plurality of different pixel densities on the same recording paper when the sample copy mode is selected are provided.

According to the second aspect of the invention, the copy processing means is provided which has the character mode selection means and the photograph mode selection means and which switches the pixel density according to the selected mode to perform the recording processing.

According to another aspect of the present invention, there are provided a copy processing means having a character mode selection means and a photograph mode selection means for performing a recording process by switching the pixel density according to the selected mode, and a sample copy mode selection means. Therefore, when the sample copy mode is selected, the sample copy processing means for performing the recording processing on the same recording paper with a plurality of different pixel densities is provided.

According to the invention of claim 4, claim 1 or 3
Regarding the described invention, the sample copy processing means has a plurality of kinds of pixel density area recording patterns as selectable.

Further, in the invention according to claim 5, with respect to the invention according to claim 1, 3 or 4, the image forming linear velocity in the sample copy mode is set to correspond to the maximum pixel density, and the pixel density region with a low pixel density is set. The sample copy processing means for writing the same pixel in the main scanning direction and the sub scanning direction at the same time is recorded.

On the other hand, according to the present invention, the pixel density switching means and the density determination for reading the original image before the image forming step and determining the pixel density at the time of image formation by the pixel density switching means based on the image data thereof. Means and copy processing means for performing a recording operation at the determined pixel density are provided.

According to the present invention, the pixel density switching means, the automatic document feeding means, the reading means provided in the original feeding path of the automatic document feeding means for reading the original image, and the reading means. The density determining means determines the pixel density at the time of image formation by the pixel density switching means based on the image data read by, and the copy processing means performs the recording operation at the determined pixel density.

[0018]

According to the first aspect of the present invention, when the user wants to give priority to copy productivity, the copy productivity priority mode is selected to switch the pixel density to a lower one, thereby increasing the imaging linear velocity. You can copy in the state,
Also, if you want to give priority to image quality, you can select a high image quality priority mode to switch to a higher pixel density and perform copying in a state where the imaging linear velocity becomes slower. Copy processing can be performed.
In particular, in addition to such pixel density switching, a sample copy mode selection means and a sample copy processing means are provided, and recording processing can be performed at a plurality of different pixel densities on the same recording paper to provide samples. The difference in image quality due to the difference can be practically determined, and the mode can be properly selected.

Particularly, according to the second aspect of the invention, the character mode selecting means and the photo mode selecting means are provided, and the pixel density is switched according to each mode selection. By selecting
You can obtain a copy that is faithful to the original by switching the pixel density to the higher one, and in the case of a photo-based original, select the photo mode to switch the pixel density to the lower one and copy with high copy productivity. The action can be performed. As a result, it is possible to perform a copy process with an optimum pixel density according to the type of document.

In addition, in the invention described in claim 3,
As in the case of the first aspect of the invention, the sample copy mode selecting means and the sample copy processing means are provided, and the recording processing can be performed on the same recording paper at a plurality of different pixel densities to provide the sample. The difference in image quality due to the difference can be practically determined, and the mode can be properly selected in the case of a document having characters and photographs.

According to the fourth aspect of the invention, when a sample is created in the sample copy mode, a plurality of types of pixel density area recording patterns are selectable, so that an appropriate sample can be obtained according to the user's preference. Can
It can be used for more appropriate mode selection.

According to a fifth aspect of the present invention, the image forming linear velocity during the sample copy mode execution process is set to correspond to the maximum pixel density, and when recording in a pixel density region having a low pixel density, the same pixel is used in the main and sub scanning directions. Since it is dealt with by overlapping writing, it is not necessary to switch the image forming linear velocity for recording different pixel densities, and it is possible to obtain a sample without image disturbance at the boundary portion.

According to the sixth aspect of the invention, since the actual document image is read by the density determining means before the original image forming step and the pixel density corresponding to the image is determined to perform the recording operation, the recording operation is performed according to the document image. Copying can be performed with an optimum pixel density, and proper processing can be performed.

According to the invention of claim 7, claim 6 is provided.
Although the same as the described invention, since the original image is read by the reading means provided in the original conveying path using the automatic original conveying means to determine the pixel density, it is possible to perform processing without wasting time. Become.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. The present embodiment corresponds to the invention described in claims 1, 4 and 5. This embodiment is applied to a digital copying machine using a laser beam writing system in the printer section, and its control system configuration is shown in the block diagram of FIG. First, a reading unit 2 having a one-dimensional line sensor for reading an original image, for example, a CCD 1 is provided.
The image data read by the CD 1 is configured to be temporarily stored in the line memory 5 via the writing unit 4 after undergoing necessary processing in the image processing unit 3.
The image data stored in the line memory 5 is MPU.
(Microprocessor unit) 6 is read by the writing unit 4 in synchronization with the writing timing and sent to the LD driver 7, and a semiconductor laser (LD) 8 serving as a writing light source is modulated and emitted according to image data,
Optical writing is performed on a photoconductor (not shown). Reference numeral 9 is a synchronization detection sensor for controlling the synchronization timing.

Here, the writing unit 4 is provided with oscillators 10a and 10b having different oscillation frequencies via a selection switch 11 so that the oscillator 10a or 10b can be selected according to the writing pixel density. Is configured.

A motor for driving a polygon motor 12 for rotationally driving a polygon mirror (not shown) for deflecting and scanning (main scanning) the writing beam emitted from the semiconductor laser 8 toward the photosensitive member. The driver 13 is provided so as to be connected to the MPU 4. The motor driver 13 is of a PLL type, and oscillators 14a and 14b having different oscillation frequencies, which are basic clocks for controlling the rotation speed according to the writing pixel density, are provided via a selection switch 15 so as to be freely rotated. Used for number control.

Further, a main motor 16 for rotationally driving the photoconductor and the like is provided, and is connected to the MPU 4 via a motor driver 17. The motor driver 17 also has an oscillator 18 having a different oscillation frequency which serves as a basic clock for controlling the rotation speed of the photoconductor or the like according to the writing pixel density.
a and 18b are provided so as to be selectable via a selection switch 19 and are used for rotation speed control.

The MPU 4 also functions as a copy processing means, a sample copy processing means or a density determining means as will be described later, and the reading unit 2, the image processing unit 3 and the writing unit 5 in the copying machine main body 20. , Drivers 13, 17, 21 (21 is for the scanner motor 22 for the reading unit 2) and other control commands, and the document processing apparatus 2 such as an ADF.
3. It also handles control commands for the sorter unit 24 and the like. Also,
The selection switches 11, 15 and 19 function as pixel density switching means.

Although not particularly shown, various keys are provided on the operation panel of the copying machine main body, a copy productivity priority mode selection key, a high image quality priority mode selection key (these keys may be alternative), and a sample. Selection means such as a copy output mode selection key and a pattern selection key are also provided.

With such a configuration, the copy operation control in this embodiment will be described with reference to the flowchart shown in FIG. First, it is checked whether the sample copy output mode selection key is pressed. If it is not pressed, it is recognized as the normal copy mode, and the processing according to the selection of the copy productivity priority mode selection key or the high image quality priority mode selection key is performed. That is, if the copy productivity priority mode is selected, the pixel density is set to 200 dpi.
If the image quality priority mode is selected by the copy processing means performing the operation processing to be performed, the pixel density is doubled to 40.
An operation process for setting 0 dpi is executed by the processing means.
That is, when the copy productivity priority mode is selected, the pixel density is roughened to 200 dpi, but the image forming linear velocity on the photoconductor becomes fast, and the copy process with high productivity is performed, and the high copy rate is achieved. When the image quality priority mode is selected, the pixel density is increased to 400 dpi, so the copy productivity is reduced, but a high image quality copy can be obtained, and processing according to the user's request becomes possible. .

On the other hand, if the sample copy output mode is selected, a sample copy is created and output prior to the processing of the normal copy mode. Here, in the sample copy, when an original image is copy-recorded on a recording paper as a sample, the copy processing is performed so as to have areas having different pixel densities on the same recording paper. Corresponding to the invention of Item 4, plural types,
Here, two kinds of pixel density area recording patterns are prepared so as to be selectable, and a sample copy is created with a pattern according to key selection. First, if the pattern 1 is selected, the sample copy processing means causes the pixel density to be 200
For the operation processing in dpi, half the size of the recording paper (L / L
2) After performing, by performing the operation process for switching the pixel density to 400 dpi for the remaining half size of the recording paper,
A sample copy 25a is created. That is, pattern 1
The resulting product of the sample copy 25a according to the above is as shown in FIG. On the other hand, if the pattern 2 is selected, the sample copy processing means causes the pixel density to be 200.
The operation processing in dpi is performed for a size of 1/4 of the recording paper (L /
4) After the operation, the operation processing in which the pixel density is switched to 400 dpi is also performed for the size of 1/4 (L / 4), and then
The operation processing with a pixel density of 200 dpi is performed again on the recording paper 1 /
After performing 4 sizes (L / 4), the pixel density is set to 400d.
The sample copy 25b is created by performing the operation processing switched to pi for the remaining 1/4 size. That is, the result of the sample copy 25b according to the pattern 2 is as shown in FIG. 3 (b).

Therefore, according to this embodiment, in parallel with the optional selection of the copy productivity priority mode / high image quality priority mode, a mode in which a sample copy in which the pixel densities of these modes are mixed on the same recording paper can be output can be output. Since it is also prepared, if you are wondering which priority mode to select, you can accurately judge whether a rough pixel density (200 dpi) is sufficient by looking at the sample copy, The optimization of mode selection can be improved. In particular, even in the sample copy output mode itself, a plurality of patterns are prepared so that it is possible to select a document image portion where the difference in image quality due to the difference in pixel density is compared, and a more appropriate mode selection can be made. It will be possible.

By the way, when making a sample copy by such a sample copy processing means, the pixel density is switched during recording on the same recording paper. However, the number of revolutions of the polygon motor 12 and the photoconductor are changed corresponding to the switching of the pixel density. When the number of rotations of the (main motor 16) is changed, it takes time to change the number of rotations, so that the writing output is disturbed in the pixel density switching region. Therefore, in this embodiment, the sample copy 2 with such pixel density switching is performed.
No. 5 is created, the rotational speed of the polygon motor 12 and the rotational speed of the photoconductor (main motor 16) are not changed at all, and the image forming linear velocity is set to the maximum pixel density (here, 400).
The same pixel output is overlapped and written in the main scanning direction and the sub-scanning direction at the time of recording in an area having a low pixel density (here, the pixel density is 1/2, 200 dpi,
It is controlled so as to be substantially achievable by performing (writing) (corresponding to the invention of claim 5). Therefore, the image is not disturbed in the pixel density switching region. FIG. 4 shows such control, that is, 400 dpi.
The control for achieving a pixel density of 200 dpi at a corresponding linear velocity is exaggerated and is schematically shown. In the figure, ◯ indicates 400.
An individual pixel corresponding to dpi is shown. Therefore, 4
In the pixel density area of 00 dpi, the recording operation is performed in units of individual ◯ in both the main and sub scanning directions. On the other hand, in a pixel density region with a half pixel density of 200 dpi, two circles in the main and sub-scanning directions are used as a unit, that is, the same pixel output (the same number in the circle indicates the same pixel output) twice. A recording operation is performed by writing.

Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those shown in the above-mentioned embodiments are designated by the same reference numerals (the same applies to the following embodiments).
This embodiment corresponds to the invention described in claims 2, 3, 4 and 5. In the copying machine of this embodiment, on the operation panel thereof, a character mode selection key, a photo mode selection key (instead of the copy productivity priority mode selection key and the high image quality priority copy mode selection key of the above embodiment) These keys may be alternative).

With such a configuration, the copy operation control in this embodiment will be described with reference to the flow chart shown in FIG. First, it is checked whether the sample copy output mode selection key is pressed. If it is not pressed, it is recognized as the normal copy mode, and the processing corresponding to the selection of the character mode selection key or the photo mode selection key is performed. That is, if the character mode is not selected (in the photograph mode), the character pixel density is set to 200 dpi.
When the character mode is selected, the operation processing for changing the pixel density to 400 dpi is doubled so that the processing suitable for the character image is executed by the processing means. That is, when the photographic mode is selected, the pixel density is roughened to 200 dpi, but the image forming linear speed with respect to the photoconductor becomes high, and the copying process with high productivity is performed, and the character mode is selected. If so, the pixel density is increased to 400 dpi, so that the copy productivity is reduced, but a high-quality copy is obtained, and the processing according to the type of the original image becomes possible.

On the other hand, if the sample copy output mode is selected, a sample copy is created and output prior to the above normal copy mode processing. This processing is performed in the same manner as in the case of the above-described embodiment described with reference to FIGS.

Therefore, according to this embodiment, the character mode /
There is also a mode that allows you to output a sample copy in which the pixel densities suitable for these modes are mixed on the same recording paper in parallel with the optional selection of photo modes, so if you are wondering which mode to select By looking at the sample copy, it is possible to accurately determine whether or not a coarse pixel density (200 dpi) is sufficient, and it is possible to improve the optimization of mode selection. In particular, even in the sample copy output mode itself, a plurality of patterns are prepared so that it is possible to select a document image portion where the difference in image quality due to the difference in pixel density is compared, and a more appropriate mode selection can be made. It will be possible.

A third embodiment of the present invention will be described with reference to FIG. The present embodiment corresponds to the invention described in claim 6. This embodiment also has a pixel density switching means for different pixel densities (400/200 dpi) as in the above-described embodiments, but the MPU 4 and the like are read by reading the original image to be copied before the image forming step. Then, the type of the image (character image / photo image) is recognized, the pixel density at the time of image formation is determined (density determining means), and the determined pixel density is set so that the recording operation is actually performed. It is a thing.

This embodiment also corresponds to the invention described in claim 7, and in order to read the original image to be copied prior to the image forming step, the automatic original conveying apparatus as shown in FIG. (ADF) 26 is used. This A
The DF 26 is placed on the contact glass 27 of the main body 20 of the copying machine, and an original set on the original table 28 with the original surface facing upward is turned by the separating / feeding unit 29 toward the contact glass 27. On the contact glass 27, the paper is taken over by the carrying belt 30, set at a predetermined position and subjected to the exposure scanning by the scanner, and after the exposure is completed, the carrying belt 30 is driven again and the paper is discharged through the turn paper discharging section 31. The sheet is discharged onto the original table 28 through the tray 32 or the recycling path 33. In such an ADF 26, a contact type original detection sensor that reads the image facing the original surface of the original facing the contact glass 27 at the original conveying path, specifically, at a position upstream of the contact glass 27 ( A reading means) 34 is provided.

Therefore, according to this embodiment, the document is the ADF.
While being conveyed and set on the contact glass 27 by 26, the image is read by the contact type original detection sensor 34, it is determined whether the original is mainly a character image or a photographic image, and the image is set on the contact glass 27. Since the original pixel density at the time of original image formation is determined, a copy with a pixel density suitable for the type of original can be obtained without the user performing mode setting by key operation or the like.
In particular, since the original image is read while the original is being conveyed and the type of the original image is determined, there is no need for wasteful time for temporary reading prior to the original image forming step. That is, in order to read the original image before the original image forming process,
The original may be pre-scanned by a scanner such as the CCD 1 that performs the original reading, but this requires a wasteful scanning time for only the temporary reading.

Next, a fourth embodiment of the present invention will be described with reference to FIGS. This embodiment also corresponds to the invention according to claim 6 as in the case of the above-mentioned embodiment, has a pixel density switching means for different pixel densities, and reads the original image to be copied by the MPU 4 or the like prior to the image forming step. The type of the image is recognized, the pixel density at the time of image formation is determined,
Although the recording operation is actually performed by setting the determined pixel density, as shown in FIG. 7, the scanner 3 used in the original image forming process for reading the original image is used.
5 is used. That is, the scanner 35 scans the original set on the contact glass 27 while slit-exposing it with the light source 36, and scans the reflected light from the original with the first, second, third mirrors 37, 38, 39, and the imaging lens. The image is read by CCD 1 via 40. Here, the light source 36 and the first mirror 37 scan and move the document surface as a first traveling body, and the second and third mirrors 38 and 3
The second traveling body 9 is set to move in the same direction as the first traveling body at a speed of 1/2.

Here, the first and
The two traveling bodies are located at the home position as shown by the phantom line in FIG. 7 in the standby state, but when the original image is read prior to the image forming process as described above, the temporary line as shown by the solid line in FIG. The image of the original that is moved and fixed to the reading position and conveyed on the contact glass 27 at this position is read by the CCD 1
The operation is controlled to be read by. In other words, even in the present embodiment, the scanner 35 for performing the original image reading is equivalent to the scanner 35 provided as a reading unit for the conveyance path of the document conveyed by the conveyance belt 30 (the invention according to claim 7). However, unlike the case of the above-described embodiment, it is not necessary to provide a dedicated contact-type document detection sensor 34 for temporary reading prior to image formation, and the cost can be reduced.

By the way, in the method of reading the original image and determining the pixel density prior to the original image forming operation as described above, when processing a plurality of originals by the ADF 26, the image is read for each original. It is preferable that the pixel density is switched and set for each document. According to this, the pixel density is appropriately set for each document, and it is possible to obtain a copy having a pixel density suitable for the image type for all documents.

When considering the original image, it is actually 1
In many cases, a character image and a photographic image are mixed in one manuscript, and it is essentially preferable to switch and record the pixel density even during the image forming process on the same recording paper. However, switching of the pixel density requires switching processing such as switching of the writing clock frequency, switching of the rotation speed of the polygon motor, and switching of the rotation speed of the photoconductor (main motor). Here, the writing clock frequency can be switched electrically immediately, but it takes time to switch the number of rotations of the polygon motor and the main motor. Therefore, if the same recording paper is changed in the middle of recording, image distortion will occur. It is not preferable because it may occur. Therefore,
Here, the switching of the recording density is changed by manuscript unit = recording paper unit. For example, after recording on a certain recording paper at a pixel density of 200 dpi, recording is performed on the next recording paper at a pixel density of 400 dpi, and the subsequent recording When recording is performed on paper with a pixel density of 200 dpi, control is performed so that the rotation speed of the polygon motor (or main motor) is switched between recording papers as shown in FIG. I chose As a result, a copy having no image defect can be obtained.

On the other hand, in the case of processing a plurality of originals, if the pixel density is changed over so as to obtain the optimum pixel for each original as described above, it takes time to change the number of rotations, etc. If you look at it, there is a concern that copy productivity will decrease. Therefore, for example, by utilizing the recycle type ADF 26, the contact type document detection sensor 34 or the CCD 1 and the storage means (not shown) in the scanner 35 as shown in FIG. 6 or 7, prior to the original image forming process. The images of the originals stacked on the original table 28 are continuously read, the optimum pixel density is determined for each original, and the pixel density data is stored in the storage means. That is, it becomes possible to classify a plurality of originals that should be handled with the same pixel density in advance, and by controlling the operation in the original image forming process based on the stored data, the originals with the same pixel density can be classified. The images can be made continuous.

However, prior to the image forming step, as long as the original image can be read and the pixel density suitable for the original image can be determined, the originals having the same pixel density as described above can be continuously read without using the storage means. It is possible to control the image formation. For example, in the case where two types of pixel densities, the first and second pixel densities, are assumed, the recycling type ADF 26 of FIG. 6 is borrowed for description. First, in the copying machine main body 20, the pixel density is set to be the first pixel density. Under such a situation, the originals on the original table 28 are sequentially conveyed one by one toward the contact glass 27, and the original image is read by the contact type original detection sensor 34 in the middle thereof, and the first original is detected. It is determined whether the pixel density is suitable or the second pixel density is suitable. The original document which is determined to have the first pixel density suitable is set on the contact glass 27, the CCD 1 performs the reading operation, and the image is formed with the first pixel density as it is. On the other hand, an image is not formed on a document which is determined to have the second pixel density suitable even when fed from the document table 28, and the contact glass 27 and the recycling path 33 are used.
After that, it is returned to the original table 28 as it is. By repeating such an operation, the image forming process is performed only on an original having a suitable first pixel density among a plurality of originals. That is, during this period, the pixel density switching process is not required. When the image formation with the first pixel density is completed in this way, the copying machine body 20 is switched and set to a mode in which the pixel density becomes the second pixel density. Also, ADF
In 26, the document is fed again, and the document image is read by the contact-type document detection sensor 34 in the middle thereof, and it is determined whether the first pixel density or the second pixel density is suitable. The original document that is determined to have the second pixel density suitable is set on the contact glass 27, the CCD 1 performs the reading operation, and the image is formed with the second pixel density as it is. On the other hand, an image is not formed on a document that is determined to have the first pixel density suitable even when fed from the document table 28, and the contact glass 27 and the recycling path 3 are used.
Then, it is returned to the original table 28 as it is after the step 3. By repeating such operations, the image forming process is performed only on the remaining originals having the second pixel density suitable for the plurality of originals.

As described above, by discriminating only those images which are formed with the same pixel density and continuously processing them, the pixel density can be changed over a minimum number of times as a whole, and copying can be performed. Productivity can be improved.

In this case, it is preferable to control the image forming order so that the time required for switching the pixel density is minimized. For example, description will be made assuming a case where three types of pixel densities of 200 dpi, 400 dpi, and 600 dpi are set to be switchable. In this case, the time required to change the motor rotation speed or the like corresponding to each pixel density is 200 dpi → 400 dpi 4 seconds 400 dpi → 600 dpi 5 seconds 200 dpi → 600 dpi 9 seconds 600 dpi → 400 dpi 10 seconds 400 dpi → 200 dpi 8 seconds 600 dpi → 200 dpi 18 seconds, 200 dpi → 400 dpi → 600 dpi
It can be seen that it is most efficient to switch the pixel density in the order of. That is, the total time required for switching is 9 seconds (= 4 seconds +
5 seconds). On the other hand, for example, 20
If the pixel density is switched in the order of 0 dpi → 600 dpi → 400 dpi, it takes 19 seconds (= 9 seconds + 10 seconds).

By the way, if the images having the same pixel density are continuously formed as a group as described above, the discharged recording papers are different from the original order and become unordered. Therefore, in the present embodiment, as shown in FIG. 9, a sorter unit 42 (in FIG. 2, in the case of FIG.
(Corresponding to the sorter unit 24) is devised. That is, in this sorter unit 42, for example, 200 d
intermediate stacker 43 for pixel density of pi and 400 dpi
And an intermediate stacker 44 for useful pixel density,
The copy product created at the time of image formation at dpi is once stacked on the intermediate stacker 43, then the copy product made at the time of image formation at 400 dpi is once stacked on the intermediate stacker 44, and after completion of all copying, these The sheet re-feeding units of the intermediate stackers 43 and 44 are selectively driven in correspondence with the order of originals, and the sheets are discharged to the final stacker (here, sorter bin) 45 according to the final order of originals. Therefore, even if the image forming method that minimizes the time required to switch the pixel density is adopted, the resultant products can be arranged in the order of the originals.

[0051]

According to the first aspect of the present invention, there is provided the copy productivity priority mode selecting means and the high image quality priority mode selecting means, and the pixel density is switched according to the selected priority mode to perform the recording processing. Means and sample copy processing means having a sample copy mode selection means and performing recording processing on the same recording paper at a plurality of different pixel densities when the sample copy mode is selected, the user prioritizes copy productivity. If you want to select the copy productivity priority mode, you can switch to a lower pixel density and copy in a state where the imaging linear velocity becomes faster,
Also, when it is desired to give priority to image quality, by selecting the high image quality priority mode, it is possible to switch to a higher pixel density and perform copying, and it is possible to perform copy processing according to the user's request. In particular, in addition to such a pixel density switching, a sample copy mode selection means and a sample copy processing means are provided so that recording processing can be performed on the same recording paper at a plurality of different pixel densities, so that a sample can be provided. The difference in image quality due to the difference in density can be practically and accurately determined, and the mode can be properly selected.

According to the second aspect of the invention, the copy processing means is provided which has the character mode selection means and the photograph mode selection means, and changes the pixel density according to the selected mode to perform the recording processing. In the case of a document mainly composed of characters, by selecting the character mode, the pixel density can be switched to a higher one to obtain a copy faithful to the document, and in the case of a document mainly composed of photographs, the photo mode should be selected. As a result, the pixel density can be switched to the lower one to perform the copy operation with high copy productivity, and eventually, the copy processing with the optimum pixel density can be performed according to the type of the original.

According to the third aspect of the present invention, the copy processing means having the character mode selection means and the photograph mode selection means for performing the recording processing by switching the pixel density according to the selected mode, and the sample copy mode selection means. In addition to the effect of the invention of claim 2, in addition to the effect of the invention of claim 2, the sample copy processing means for performing recording processing on the same recording paper at a plurality of different pixel densities is provided when the sample copy mode is selected. As in the case of the invention, the sample copy mode selection means and the sample copy processing means are provided, and it is possible to provide a sample by performing recording processing at a plurality of different pixel densities on the same recording paper. It is possible to make a practical judgment, and it is possible to properly select the mode in the case of a document having characters and photographs.

According to the invention described in claim 4, in the invention described in claim 1 or 3, the sample copy processing means having a plurality of kinds of pixel density area recording patterns is selectable, so that it is appropriate according to the user's preference. It is possible to obtain various samples and to provide more appropriate mode selection.

Further, according to the invention of claim 5, with respect to the invention of claim 1, 3 or 4, the image forming linear velocity in the sample copy mode is set to correspond to the maximum pixel density, and the pixel density with a low pixel density is set. Since the sample copy processing means for writing the same pixel in the main scanning direction and the sub-scanning direction in an overlapping manner is used at the time of recording the area, it is not necessary to switch the image forming linear velocity for recording the different pixel density, and the image at the boundary portion It is possible to obtain undisturbed samples.

On the other hand, according to the sixth aspect of the invention, the pixel density switching means and the density for determining the pixel density at the time of image formation by the pixel density switching means based on the image data of the document image read before the image forming step. A determining unit and a copy processing unit that performs a recording operation at the determined pixel density are provided, and the actual document image is read by the density determining unit before the original image forming process, and the pixel density corresponding to the image is determined to perform the recording operation. As a result, since it is possible to make a copy with an optimum pixel density according to the original image, it is possible to obtain coherence with an appropriate pixel density.

According to the seventh aspect of the invention, the pixel density switching means, the automatic document feeding means, the reading means provided in the original feeding path of the automatic document feeding means for reading the original image, and the reading means. Since the density determining means for determining the pixel density at the time of image formation by the pixel density switching means based on the image data read by the means and the copy processing means for performing the recording operation at the determined pixel density are provided,
Although the same as the invention described in claim 6, since the original image is read by the reading means provided in the original feeding path using the automatic original feeding means to determine the pixel density, the reading for determining the pixel density is performed. Therefore, the processing can be performed without wasting time.

[Brief description of drawings]

FIG. 1 is a flowchart showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a control system configuration.

FIG. 3 is an explanatory diagram showing an output example of sample copy.

FIG. 4 is a schematic diagram showing an example of dual-purpose writing for different pixel densities.

FIG. 5 is a flowchart showing a second embodiment of the present invention.

FIG. 6 is a schematic front view of an ADF showing a third embodiment of the present invention.

FIG. 7 is a schematic front view of the vicinity of an ADF showing a fourth embodiment of the present invention.

FIG. 8 is an explanatory diagram schematically showing a pixel density switching timing.

FIG. 9 is a schematic front view showing an improved example in consideration of ejecting copies.

[Explanation of symbols]

1 Reading Means 4 Copy Processing Means, Sample Copy Processing Means, Density Determining Means 11, 15, 19 Pixel Density Switching Means 26 Automatic Document Feeder 34 Reading Means

Claims (7)

[Claims] 1. A copy processing unit having a copy productivity priority mode selection unit and a high image quality priority mode selection unit for performing a recording process by switching pixel densities in accordance with the selected priority mode, and a sample copy mode selection unit. A digital copying machine having a sample copy processing means for carrying out recording processing on the same recording paper at a plurality of different pixel densities when the sample copy mode is selected. 2. A digital copying machine comprising a copy processing means which has a character mode selection means and a photo mode selection means, and performs a recording process by switching the pixel density according to the selected mode. 3. A copy processing unit having a character mode selection unit and a photo mode selection unit for performing a recording process by switching the pixel density according to the selected mode, and a sample copy mode having a sample copy mode selection unit. A digital copying machine, comprising sample copy processing means for performing recording processing on the same recording paper at a plurality of different pixel densities when selected. 4. The digital copying machine according to claim 1, wherein the sample copying processing means has a plurality of kinds of pixel density region recording patterns as selectable. 5. A sample copy process in which the image forming linear velocity in the sample copy mode is set to correspond to the maximum pixel density, and the same pixel is overwritten in the main scanning direction and the sub scanning direction when recording a pixel density region having a low pixel density. 5. The digital copying machine according to claim 1, 3 or 4, wherein the means is means. 6. A pixel density switching means, a density determining means for reading an original image before the image forming step and determining a pixel density at the time of image formation by the pixel density switching means based on the image data, and the determined pixel density. A digital copying machine, comprising: 7. A pixel density switching means, an automatic document feeding means, a reading means provided in a document feeding path of the automatic document feeding means for reading a document image, and an image data read by the reading means. A digital copying machine comprising: a density determining means for determining a pixel density at the time of image formation by the pixel density switching means, and a copy processing means for performing a recording operation at the determined pixel density.