JPH1124525A - Image recorder, image reader and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image recorder, an image reader and an image forming device where the image positions of a 1st side and a 2nd side are not deviated even when an error is found in the length of paper or the feeding speed of the paper. SOLUTION: The image recorder capable of recording an image on both sides of a recording member is provided with a measuring means 02 measuring the length of the recording member 01 when it is carried, and an image position control means 03 controlling the position of the image recorded on the member 01; and the length of the member 01 is measured in the case of forming the image on the 1st side of the member 01 and the image forming position of the 2nd side is controlled based on the measured result.

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 such as a printer capable of printing on both sides of a recording sheet, an image reading apparatus such as an image scanner capable of reading images on both sides of a document, and further, to both sides of a transfer sheet. The present invention relates to an image forming apparatus such as an electrophotographic copying machine capable of forming an image on a front side, and more particularly, to a method for correcting the image position on the front side and the back side during double-side reading or double-side printing.

[0002]

2. Description of the Related Art Conventionally, as an image recording apparatus such as a printer capable of printing on both sides of a recording sheet of this type, an image recorded on the back side of the recording sheet is rotated so that an image recorded on the front side of the recording sheet is rotated. There is a configuration in which the orientation of an image to be recorded on the back side of a sheet is matched (Japanese Patent Laid-Open No. 62-18 / 1987).
1155, JP-A-63-242665, JP-A-6-343125, etc.).

In such an image recording apparatus, for example, when a vertically written image is printed on both sides of a vertically fed sheet at the binding position on the left side, the image on the front side is printed as it is, and the image on the back side is rotated by 180 °. There is a printer that prints on the paper from the rear and aligns the image on the front and back of the paper.

However, in the above-described image recording apparatus, since there is a difference between the front side and the back side of the recording paper and the direction of the image to be printed, there is an error or variation in the paper length or paper feeding speed. 11-12
As shown in (1), there is a problem that the image position on the front and back sides of the recording paper is shifted.

Further, as an image reading apparatus such as an image scanner capable of reading images on both sides of the document, there is an image reading apparatus configured to rotate the read image in accordance with the orientation and the binding position of the image of the document (Japanese Patent Laid-Open Publication No. HEI 9-122572). 8-88861).

In such an image reading apparatus, for example, when reading a sheet which has been printed on both sides at the binding position left on a vertically fed sheet as a vertically fed document, the image on the front side of the document is read as it is, and the image on the back side of the document is read. Is rotated by 180 ° after reading, so that the orientation of the image is matched between the front surface and the back surface.

However, in the above-described image reading apparatus, since the original feeding direction and the direction of the printed image are different between the front side and the back side of the original, there is an error in the original length or the original feeding speed. In addition, there is a problem that an image position is shifted between an image obtained by reading the front surface of the document and an image obtained by reading the back surface of the document.

Further, as an image forming apparatus such as an electrophotographic copying machine capable of forming an image on both sides of the transfer sheet, an image to be copied on the back side of the transfer sheet is rotated and copied on the front side of the transfer sheet. There is a configuration in which the positional relationship between an image and an image copied on the back surface of a transfer sheet is matched (Japanese Patent Application Laid-Open Nos. 62-181155 and 63-24).
2665, JP-A-6-343125, etc.).

In such an image forming apparatus, for example, when an image on one side of a document is sequentially read and sequentially printed on both sides of a transfer sheet, the image is rotated by 180 ° when printing on the back side of the transfer sheet. Some are designed to print on paper from the rear (one-sided to two-sided copy).

Further, in such an image forming apparatus, there is also a system in which a double-sided document is sequentially read and sequentially printed on both sides of a transfer sheet (double-sided copying from both sides).

However, in the above-described image forming apparatus, in the case of one-sided to double-sided copying, since the paper feeding direction differs between the front and back sides of the paper and the direction of the image to be printed, an error occurs in the paper length or the paper feeding speed. If there is,
There is a problem that the image position on the front surface and the back surface is shifted.

In the above image forming apparatus, in the case of double-sided to double-sided copying, the original feeding direction and the direction of the printed image are different between the front side and the back side of the original. If there is an error in the feed rate,
The image position is shifted between the image read from the front side of the document and the image read from the back side, and the paper feed direction is different from the image to be printed on the front and back sides of the paper. Alternatively, there is a problem that the image position on the front surface and the back surface is shifted when an error occurs in the paper feeding speed.

Therefore, as a technique capable of solving such a problem, there is a technique disclosed in Japanese Patent Application Laid-Open No. 4-85064, for example. The double-sided printer according to Japanese Patent Application Laid-Open No. 4-85064 is a double-sided printer having a margin direction designation means for designating either a longitudinal edge or a lateral side edge of a sheet as a margin. When double-sided printing is performed with the longitudinal edge of the paper specified as a binding margin by the specifying means, the assumed paper size when creating print data in the memory and the size of the paper actually used for printing are determined. A size comparing means for comparing, and a printing position correcting means for correcting a printing position deviation between the front and back sides of the paper at the time of printing when the two sizes are determined to be different by the means are provided. is there.

[0014]

However, the prior art described above has the following problems. That is, in the case of the double-sided printer disclosed in Japanese Patent Application Laid-Open No. 4-85064, when double-sided printing is performed in a state where the side edge in the longitudinal direction of the paper is specified as a binding margin by the binding margin direction designating means, it is not possible to print on the memory. Size comparison means for comparing the assumed paper size when creating print data with the size of the paper actually used for printing; and, when the means determines that the two sizes are different, the surface of the paper at the time of printing And the print position correction means that corrects the print position deviation on the back side, so that the size of the paper actually used for printing is different from the assumed paper size when creating the print data in the memory. Although the printing position can be corrected to some extent by the printing position correction means, the printing If there is an error in the transport speed when transporting the paper for printing, or if there is an error in the paper size, and if there is an error in the transport speed when transporting the paper for printing, However, it is not possible to correct the printing position to an appropriate position only by the correction based on the image, and there is a problem that the printing position of the image on the front surface and the printing position of the image on the back surface are shifted.

Such a problem occurs not only in a double-sided printer but also in an image reading apparatus that reads images on both sides of a document and an image forming apparatus that forms images on both sides of a transfer sheet.

In view of the above, the present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to solve the problem of the first surface even when there is an error in the paper length or paper feeding speed. To provide an image recording apparatus, an image reading apparatus, and an image forming apparatus in which the image position on the second surface does not shift.

[0017]

That is, according to the first aspect of the present invention, there is provided an image recording apparatus capable of recording an image on both sides of a recording member as shown in FIG.
And a position control unit 03 for controlling the position of an image to be recorded on the recording member 01. When forming an image on the first surface of the recording member 01, First, the length of the recording member 01 is measured, and the image forming position on the second surface is controlled based on the measurement result.

According to a second aspect of the present invention, there is provided an image reading apparatus capable of reading images on both sides of a document.
Measuring means for measuring the length of the original when the original is transported, and reading position control means for controlling the reading position of the image of the original; and measuring the length of the original when reading the image on the first side of the original. The reading image position on the second surface is controlled based on the measurement result.

According to a third aspect of the present invention, there is provided an image forming apparatus capable of recording an image of a document on both sides of a transfer member, wherein the first measuring means measures a length of the document when the document is being transported; A second measuring unit for measuring a length of the member during conveyance, and an image position controlling unit for controlling a position of an image formed on the transfer member, wherein the length of the document is measured at the time of reading, and the transfer is performed. The length of the transfer member is measured when an image is formed on the first surface of the member, and the image forming position on the second surface of the transfer member is controlled based on the measurement results.

[0020]

According to a first aspect of the present invention, there is provided a recording apparatus comprising: a measuring unit for measuring a length of a recording member during conveyance; and an image position controlling unit for controlling a position of an image to be recorded on the recording member. Since the length of the recording member is measured when an image is formed on the first surface of the member, and the image forming position of the second surface is controlled based on the measurement result, the first surface of the recording member is controlled. The length of the recording member is measured by a measuring unit when an image is formed on the recording medium, and the image forming position on the second surface is controlled based on the measurement result. Even if there is an error, no shift occurs between the image positions of the first surface and the second surface.

According to a second aspect of the present invention, there is provided a measuring device for measuring a length of a document during conveyance, and a reading position control device for controlling a reading position of an image on the document. Since the length of the original is measured at the time of reading the image on the first side, and the position of the read image on the second side is controlled based on the measurement result, the measurement is performed at the time of reading the image of the first side of the original. The length of the original is measured by the means, and the reading position of the image on the back side is controlled based on the measurement result, so that even if there is an error in the length of the original or the feeding speed of the original, the first side and the It is possible to read the image of the document without causing a shift in the image positions of the two surfaces.

Further, according to the invention described in claim 3, the first measuring means for measuring the length of the original at the time of conveyance,
A second measuring unit that measures the length of the transfer member during conveyance, and an image position control unit that controls a position of an image that is formed on the transfer member. Since the length of the transfer member is measured when an image is formed on the front surface of the transfer member, and the image forming position on the back surface of the transfer member is controlled based on the measurement results, the image on the first surface of the document is When reading the original, the first measuring unit measures the length of the original, and the transfer member transporting length is measured by the second measuring unit,
By controlling the image forming position on the second surface of the transfer member by the image position control means based on these measurement results, there is no error in the length of the document or the feed of the document, or the length or feed speed of the transfer member. In this case, the image position of the first surface and the image position of the second surface do not shift, and the image of the document can be formed on both surfaces of the transfer member.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in the drawings.

FIG. 2 is a schematic configuration diagram showing an image recording apparatus using laser xerography according to one embodiment of the present invention.

In FIG. 2, reference numeral 1 denotes a casing of the image recording apparatus.
An image processing device 2 that performs predetermined image processing as needed on image information read by an image reading device (not shown) that reads an image of a document or an image signal sent from a personal computer or the like; ROS (Raster Output Sc) that performs image exposure based on image information on which predetermined image processing has been performed by
An image writing unit 3 including an ann.) is disposed, and the image writing unit 3 performs image writing with a laser beam LB according to image information.

The image writing means 3 emits a laser beam LB from a semiconductor laser (not shown) according to gradation data, and deflects and scans the laser beam LB emitted from the semiconductor laser by a rotary polygon mirror.
The scanning exposure is performed on the photosensitive drum 4 via the reflection mirror.

As the photosensitive drum 4 on which the laser beam LB is scanned and exposed by the image writing means 3, for example, a photosensitive body using an organic photoconductive substance is used.
The photosensitive drum 4 is rotated at a predetermined speed in a direction indicated by an arrow by a driving unit (not shown). After the surface of the photosensitive drum 4 is charged to a predetermined potential by a charging roll (not shown) in advance, an electrostatic latent image is formed by scanning and exposing the laser beam LB in accordance with image information. The electrostatic latent image formed on the photoconductor drum 4 is developed by a developing roll of a developing device (not shown) to become a toner image.

The toner image formed on the photosensitive drum 4 is transferred onto the recording paper 6 by charging of a transfer roll 5 arranged so as to be in contact with the photosensitive drum 4, and the toner image is formed. The transferred recording paper 6 is discharged by a separation charger composed of a needle-like electrode (not shown) and is discharged from the photosensitive drum 4 to be separated therefrom. An AC voltage obtained by superimposing an AC voltage or a DC voltage is applied to the separation charger including the needle electrodes. As shown in FIG. 2, the recording paper 6 is fed by a feed roll 8 from a paper tray 7 arranged at a lower part in the housing 1 of the image forming apparatus. The fed recording sheet 6 is conveyed to a registration roller 10 via a sheet conveyance path 9 and then temporarily stopped by the registration roller 10 to synchronize with the image on the photoconductor drum 4. It is transported to the surface of the drum 4. Reference numeral 11 denotes a paper detection sensor that detects the leading edge and the trailing edge of the recording paper 6.

As described above, the recording paper 6 on which the toner image has been transferred from the photosensitive drum 4 is discharged by the separation charger composed of the needle-shaped electrodes, and is separated from the surface of the photosensitive drum 4 as described above. Then, the toner image is conveyed to a fixing device 13 via a paper conveyance path 12, and the toner image is fixed on the recording paper 6 by heat and pressure by the fixing device 13. The image is discharged onto the discharge tray 15 by the reversing roll 14, and the image recording process ends. Reference numeral 16 denotes a paper detection sensor that detects the leading edge and the trailing edge of the recording paper 6.

After the toner image transfer step is completed, the surface of the photosensitive drum 4 is cleaned of residual toner and paper dust by a cleaning device having a cleaner blade and a brush (not shown) to remove the next image. It is prepared for the recording process.

When images are recorded on both sides of the recording sheet, the recording sheet 6 having the image recorded on one side is not discharged onto the discharge tray 15 as it is, but the trailing end of the recording sheet 6 is The sheet reversing roll 14 is rotated in the reverse direction while the sheet is held between the recording sheets 6 on which an image is recorded on one side.
Is transported again to the transfer position of the photosensitive drum 4 in a state where the front and back are reversed by the double-sided module 17 attached to the side surface of the image recording apparatus housing 1. The double-sided module 17 includes a plurality of paper transport rolls 19, 20, 21 arranged along a paper transport path 18, and registers the recording paper 6 on which an image is recorded on one side in a state where the recording paper 6 is turned upside down. It is configured to be conveyed to the registration roll 10 via a paper conveyance roll 22 arranged on the upstream side of the roll 10. Reference numeral 23 denotes a paper detection sensor that detects the leading edge and the trailing edge of the recording paper 6.

The image writing means 3 has an ASIC (Application Specification) provided with a register for controlling the position and length of an image to be written.
icIntegrated Circuit).

FIG. 4 is a diagram showing the relationship between the register of the ASIC and the position and length of the image to be written.

In FIG. 4, SOS (Start Of)
Scan) indicates a writing start reference position at which an image is written on the photosensitive drum 4.
The detection of S is performed by detecting the laser beam LB emitted from the image writing unit 3 by the sensor 25 provided at the SOS position. Also, LSUP
(Line Sync Up Point), LSDP
(Line Sync Down Point) indicates a rising position and a falling position of a line sync (LSYNC) signal in the sub-scanning direction, respectively. Furthermore, ALSUP (Another Line Sync)
Up Point), ALSDP (Another)
Line Sync Down Point is an actual image writing area in consideration of the side offset in the sub-scanning direction, and a PSSP (Page Sync Start).
Point) and PSEP (Page Sync End)
Point) is a page sync (PSYN) in the main scanning direction.
C) Rising and falling edges of the signal, APSSP (An
other Page Sync Start Point
t) and APSEP (Another Page Syn)
c EndPoint) indicates an actual image writing area in consideration of the offset at the front and rear ends in the main scanning direction. The registers for determining APSSP, APSEP, and the like are set according to the sheet size at the start of sheet feeding, and are capable of counting the number of lines actually written after writing is started.

FIG. 3 is a block diagram showing the control means of the image recording apparatus constructed as described above.

In FIG. 3, reference numeral 31 denotes a CPU for controlling the operation of the image recording apparatus; 32, a ROM (Read Only Memory); 33, a RAM (Random Access Memory);
Is an image rotating means for rotating image information, 35 is an image writing means 29, a control of the feed roll 8, the registration roll 10, and recognition of input values such as signals from the sensors 11, 16, and 23 and a time measuring means 36. This is an I / O port for control. The image rotation means 34 and the I / O port 35 are controlled by the CPU 31.
The image rotation means 34 includes a memory for storing images and an ASIC for controlling reading of the stored images.
It is composed of

In the above configuration, the image recording apparatus according to the present embodiment has the following structure in which the paper is conveyed for printing or reading despite the error in the paper size. Even if there is an error in the speed or the size of the paper, and if there is an error in the transport speed when transporting the paper for printing or reading, it is possible to prevent the misalignment of the image position between the front and back sides. To prevent it.

Next, a specific operation will be described with reference to the flowcharts shown in FIGS.

First, in the image recording apparatus, when the image recording operation is started, as shown in FIG. 5, the feeding of the recording paper 6 is started (step 11), and the recording paper fed from the paper tray 7 by the feed roll 8 is shown in FIG. Paper 6
Turns on the paper detection sensor 11 (step 1).
2). Then, the CPU 31 starts measuring time by the time measuring means 36 after the recording paper 6 has turned on the paper detection sensor 11, and determines whether or not a predetermined time has elapsed (step 13). Registration roll 10
Stops the conveyance of the sheet after the time to reach (Step 1)
4). After temporarily stopping the sheet conveyance, the CPU 31 waits for the preparation of an image to be written on the surface of the photosensitive drum 4 (step 15). The image written on the surface of the photosensitive drum 4 is an image read by an image reading device (not shown), an image developed by a host computer, an image received by facsimile, or the like.

When the CPU 31 detects that the image is ready, it starts the driving of the registration roll 10 and the writing by the image writing means 3 in synchronization (steps 16 to 18). The synchronization between the driving of the registration roll 10 and the writing by the image writing unit 3 is based on the distance between the registration roll 10 and the transfer roll 5, the writing position on the photosensitive drum 4, and the distance between the transfer roll 5. I have. In this embodiment, since the distance between the registration roll 10 and the transfer roll 5 is larger, after driving the registration roll 10 (step 16), the time measuring means 36
As a result, it is determined whether or not a certain time has elapsed (step 17), and after the certain time has elapsed, writing by the image writing means 3 is started (step 18). And resist roll 1
By driving 0, the recording paper 6 is conveyed by the registration roll 10 and reaches the transfer section (step 19). On the other hand, the image written on the photosensitive drum 4 by the image writing means 3 moves to the transfer section by the rotation of the photosensitive drum 4 (Step 19).

Since the driving of the registration roll 10 and the start of writing an image are synchronized as described above, the leading edge of the recording paper 6 and the leading edge of the image coincide, and the image is sequentially transferred to the recording paper 6. (Step 20). When the trailing end of the conveyed recording paper 6 passes through the paper detection sensor 11 and turns off the paper detection sensor 11 (step 21),
Time measurement is started by the time measuring means 36, and as shown in FIG. 6, it is determined whether or not a certain time has elapsed (step 22), and after a certain time, the writing by the image writing means 3 is finished (step 23). ), The rear end of the recording paper 6 is made to coincide with the end of image writing.

Then, the number of write lines L in the sub-scanning direction counted when the image writing is completed is stored in the memory in the ASIC provided in the image writing means 3 (step 24). The transported recording paper 6 turns on the paper detection sensor 16 (step 25) and reaches the paper reversing roll 14 (step 26). The paper reversing roll 14 is driven so as to convey the recording paper 6 in the direction of the discharge tray 15. When the transported recording paper 6 turns off the paper detection sensor 16 (step 27), time measurement is started by the time measuring means 36, and it is determined whether or not a certain time has elapsed (step 28). Reverse the paper reversing roll 14 (Step 2
8) Convey the recording paper 6 in the direction of the duplex module 17. The recording paper 6 is transported along a paper transport path 18,
The paper detection sensor 23 is turned on (step 29). When the paper detection sensor 23 is turned on, the conveyance of the recording paper 6 is stopped.

When the conveyance of the recording paper 6 is temporarily stopped, it waits for the preparation of the image to be written on the back surface (step 3).
0). The image on the back side written by the image writing means 3 is an image read by an image reading device, an image developed by a host computer, an image received by facsimile, or the like. When the image is ready, the image rotation means 3
The image information of the back side is stored in the image memory in the step 4 (step 31).

The direction in which the back side image information is stored in the image memory in the image rotating means 34 is as shown in FIG. When the storage of the back side image information is completed, the conveyance of the recording paper 6 is started as shown in FIG. 7 (step 32).
The recording paper 6 turns on the paper detection sensor 11 (step 33). Then, the CPU 31 sets the time measuring unit 36
Measurement is started, and it is determined whether or not a predetermined time has elapsed, and the recording paper 6 turns on the paper detection sensor 11.
Then, after the time for the leading edge of the sheet to reach the registration roll 10 has elapsed, the conveyance of the recording sheet 6 is stopped (step 34). When the conveyance of the recording paper 6 is temporarily stopped, a writing start point when the accumulated image is written on the back surface of the recording paper 6 is obtained.

FIG. 10 shows the direction of writing the image stored in the page memory and the writing start point.

FIG. 10 shows an example of writing at 180 ° rotation. When the image is not rotated at 180 °, the image is not accumulated, and the image sent from the host computer or the like may be written in the same manner as the front surface. Whether or not to rotate is determined in advance based on the binding position of double-sided printing or the like. The writing start point in the sub-scanning direction can be moved.When moving in the image direction, white is added to the image from the middle of the image, and when moving in the outward direction of the image, white is added to the image. To write.

The writing start point in the sub-scanning direction is determined by the accumulation length T in the sub-scanning direction at the time of accumulation and the number L of writing lines in the sub-scanning direction for front side printing. The CPU 31 calculates L =
It is determined whether or not T and L> T (step 35),
When L> T, writing is started from a position shifted to the outside of the image by LT lines (step 36).
When L <T, writing is started from a position shifted in the image direction by TL lines (step 37). When L = T, writing is started from the accumulation end point (step 38).

More specifically, when L> T, that is, when L> T,
If the number of lines L in the sub-scanning direction for the front side printing is larger than the accumulation length T in the sub-scanning direction when the recording is performed, the length of the recording paper 6 becomes a predetermined length as shown in FIG. M, or the transport speed of the recording paper 6 is slower than a predetermined speed. If an image is recorded on the rear surface of the recording paper 6 as it is at a predetermined distance M from the rear end, the image is recorded. As shown in FIG. 11, an image is recorded on the back surface of the recording paper 6 with a deviation from a predetermined position below. Therefore, when L> T, by starting writing from a position shifted to the outside of the image by LT lines, the image on the front surface and the image on the back surface of the recording paper 6 can be accurately aligned. .

When L <T, that is, when the accumulation length T in the sub-scanning direction when the accumulation is performed is larger than the number L of writing lines in the sub-scanning direction for front side printing, FIG. As described above, the length of the recording paper 6 is shorter than the predetermined length M, or the conveying speed of the recording paper 6 is faster than the predetermined speed. When recording is performed at a predetermined distance M from the recording paper 6, an image is recorded on the back surface of the recording paper 6 shifted upward from a predetermined position, as shown in FIG. Therefore, when L <T, by starting writing from a position shifted in the image direction by TL lines, it is possible to accurately align the images on the front surface and the back surface of the recording paper 6.

Further, when L = T, that is, when the accumulation length T in the sub-scanning direction at the time of accumulation is equal to the number L of writing lines in the sub-scanning direction for front side printing, as shown in FIG. The length of the recording sheet 6 is equal to the predetermined length M, and the transport speed of the recording sheet 6 is equal to the predetermined speed. If the images are recorded separately, the images on the front surface and the back surface of the recording paper 6 can be accurately aligned as shown in FIG.

When the writing start point on the back side is determined in this way, the registration roll 10 is driven to drive the recording paper 6.
Is started (step 39), and as shown in FIG.
Writing is started in the same manner as in front side printing (step 40). Since the driving of the registration roll 10 and the start of writing are synchronized, the leading edge of the recording sheet 6 and the leading edge of the image coincide (step 41), and the image is sequentially transferred to the recording sheet 6 (step 42). When the recording sheet 6 that has been conveyed turns off the paper detection sensor 11, the image writing is terminated after a certain period of time, and the end of the image writing coincides with the end of the image writing (step 43). Conveyed recording paper 6
Turns on the sheet detection sensor 16 and sets the sheet reversing roll 1
4 is reached (step 44). Paper reversing roll 14
Is driven so as to convey the recording paper 6 in the direction of the discharge tray 15, and discharges the recording paper 6 onto the discharge tray 15 (step 45).

In the above embodiment, the number of sub-scanning lines is used to measure the length of the recording paper 6, but the time when the recording paper 6 passes over the paper detection sensor 11 is measured. Alternatively, the timing of image writing and registration roll drive may be changed to correct the image position. Further, in the case of the main scanning direction, a sensor for measuring the length in the main scanning direction may be provided on the paper transport path, and the length of the paper may be measured to perform the same as in the embodiment.

In this way, it is possible to provide an image recording apparatus in which there is no deviation between the image position on the front surface and the image position on the back surface of the recording sheet 6 even when there is an error in the sheet length or the sheet feeding speed.

Embodiment 2 FIG. 14 is a schematic configuration diagram showing an image reading apparatus according to Embodiment 2 of the present invention.

The image reading apparatus has an automatic document feeder 40 as shown in FIG. The automatic document feeder 40 has a document tray 42 on which a plurality of documents 41 to be copied are set with the copy surface facing upward, and the plurality of documents 41 set on the document tray 42.
Is the uppermost original 41 by the original feed roll 43.
Are sequentially picked up and sent to the original transport rolls 45 and 46 along the original transport path 44. A document detection sensor 47 for detecting the leading edge and the trailing edge of the document 41 is disposed between the document transport rolls 45 and 46. Then, the original 41 is separated one by one by the original feed roll 43 as described above, and is sent to the image reading unit 48 by the plural original transport rolls 45 and 46 provided along the original transport path 44. Is conveyed.
The document 41 conveyed to the image reading unit 48 is placed on a document conveying roll 49 disposed downstream of the image reading unit 48.
While being conveyed at a constant speed, the image is read by an image reading element such as a CCD via a scanning optical system of the image reading apparatus stopped at a reading position (not shown).
Although not shown, the scanning optical system includes an illumination lamp for illuminating the original 41, a full-rate mirror for reflecting a light image of the original illuminated by the illumination lamp, and a light image from the full-rate mirror to be folded. It comprises two reflecting half-rate mirrors, and an imaging lens that forms an optical image of a document reflected by these half-rate mirrors on an image reading element in a reduced state.

When reading the image of the document 41 moving at a constant speed on the image reading section 48 by the image reading device, the image of the document 41 is read with the scanning optical system (not shown) stopped. It has become. When reading the image of the document 41 placed on the platen glass 50 by the image reading device, an illumination lamp (not shown) and a full-rate mirror and a half-rate mirror move along the lower surface of the document 41 along the lower surface of the document 41. The image on the document 41 is read by scanning at a speed ratio of 1/2.

Thereafter, the document 41 read by the image reading section 48 is discharged onto a document discharge tray 52 by a document reversing roll 51. Reference numeral 53 denotes a document detection sensor that detects the leading edge and the trailing edge of the document 41.

When the two-sided reading of the original is performed by the image reading apparatus, the original 41 on which one side of the image has been read is transferred by the original reversing roll 51 to the original discharge tray 5.
The document reversing roll 51 is temporarily stopped while the rear end of the document 41 is being nipped by the document reversing roll 51 without being directly discharged onto the sheet 2. Next, by reversing the document reversing roll 51, the document 41 is transported again to the document transport path 44 via a transport path switching member (not shown) in a state where the document 41 is turned upside down. And read by the image reading element via the scanning optical system. Thereafter, the document 41 from which the images on the front and back sides have been read is discharged onto a document discharge tray by the document reversing roll 51.

As described above, the document 41 is fixed and placed on the image reading section of the image reading apparatus, so that the platen glass 50 for reading the image of the document 41 and the document are fixed. And an image reading section 48 for reading an image of the document while automatically transporting the document at the speed. In addition, above the image reading device,
As described above, the automatic document feeder 40 having a function as a document pressing member is provided so as to be freely opened and closed.
The automatic document feeder 40 is provided with a platen cover 54 for pressing the document 41 at a position corresponding to an upper portion of the platen glass 50.

The image reading section of the image reading apparatus counts the number of read lines,
The length of the document 41 at the time of conveyance is detected.

FIG. 15 is a block diagram showing the control means of the image reading apparatus constructed as described above.

In FIG. 15, reference numeral 61 denotes a CPU for controlling the operation of the image reading apparatus; 62, a ROM (read only memory); 63, a RAM (random access memory);
4 is an image reading means 66, a document feed roll 43,
Control of the document reversing roll 51 and the sensor 47,
Recognition of input value such as signal from 53 and time measuring means 67
An I / O port 65 for controlling the image reading means and an image rotating means 65 for rotating the read image. The image rotating means 65 and the I / O port 64 are connected to the CPU 6.
1 is controlled. Further, the image rotating means 65 includes a memory for storing the read image and an ASIC for controlling reading of the stored image.

In the above configuration, the image reading apparatus according to this embodiment reads the image of the front and back sides of the original even if there is an error in the original length or the original feeding speed as follows. The position is prevented from being shifted.

Next, a specific operation will be described with reference to flowcharts shown in FIGS.

First, when the image reading operation is started in the image reading apparatus, as shown in FIG. 16, the feeding of the document 41 is started (step 51), and the document 41 is conveyed one by one by the document feed roll 43. You. The document 41 fed by the document feed roll 43 is
The document detection sensor 47 is turned on (step 51). After the document detection sensor 47 is turned ON for the document 41, the time measurement is started by the time measuring means 67, and it is determined whether or not a predetermined time has elapsed (step 52). After the arrival time has elapsed, image reading is started and counting of the number of read lines is started (step 52). Document 4 transported
When 1 sets the document detection sensor 047 to 0FF (step 53), the image reading is terminated after a predetermined period of time (step 54), and the rear end of the document 41 coincides with the end of the image reading.

Then, the number M of read lines in the sub-scanning direction counted when the image reading is completed is stored in a memory provided in the image reading means (step 5).
5). The conveyed document 41 turns on the document detection sensor 53 and reaches the document reversing roll 51 (step 5).
6). The document reversing roll 51 transfers the document 41 to the discharge tray 5.
It is driven to transport in two directions. When the conveyed document 41 turns off the document detection sensor 53 (step 57), the document conveying roll 51 is reversed after a predetermined time, and
The document 41 is transported in the direction of the document transport roll 45 (step 58). When the document 41 turns on the document detection sensor 47 (step 59), image reading is started after the time when the leading end of the document 41 reaches the image reading unit 48, and accumulation of the image in the memory of the image rotating means 65 is started. (Step 60). When the conveyed document 41 turns off the document detection sensor 47 (step 61), the image accumulation is terminated after a certain period of time, and the end of the document is coincident with the end of image reading (step 62). Document 4 transported
1 turns on the document detection sensor 53, reaches the document reversing roll 51, and is discharged to the discharge tray 52 (step 63).

FIG. 19 shows the direction in which the read image is stored and the storage start point. FIG. 20 shows an example in which data is read out after being rotated by 180 degrees. Whether to rotate by 180 degrees is determined in advance based on the binding position of a double-sided document. The read start point in the sub-scanning direction can be moved. When the image is moved in the image direction, white is added to the image from the middle of the image when the image is moved outward, and the image is read by adding white. The reading start point in the sub-scanning direction is the image size S at the time of reading.
(Usually a standard size) and the number M of reading lines in the sub-scanning direction when accumulated. M−S when M> S
Reading is started from the position shifted in the image direction by the amount of the line. When M = S, reading is started from the accumulation start point. FIG. 20 shows an example where S> M.

In this embodiment, the number of sub-scanning lines is used to measure the length of the document 41, but the time when the document passes over the document detection sensor may be measured.
Further, in the case of the main scanning direction, a sensor for measuring the length in the main scanning direction may be provided on the document conveying path to measure the length of the document and perform the same operation as in the embodiment.

In this way, it is possible to provide an image reading apparatus in which there is no deviation between the image position on the front surface and the image position on the back surface even when there is an error in the length of the document or the document feeding speed.

Embodiment 3-1 FIG. 21 is a schematic configuration diagram showing an electrophotographic copying machine as an image forming apparatus according to Embodiment 3 of the present invention.

In FIG. 21, reference numeral 71 denotes a housing of an electrophotographic copying machine. At the upper end of the electrophotographic copying machine, an image reading device 73 for reading an image of a document 72 is arranged. The upper portion of the image reading device 73 has a function as a document pressing member that presses a document 72 placed on a first platen glass, which will be described later, and a function of moving the document 72 on the second platen glass at a constant speed. The automatic document feeder 74, which also has an automatic document feed function for conveying,
It is arranged to be freely openable and closable with respect to the copier housing 71.

As shown in FIG. 22, the automatic document feeder 74 has a document set tray 75 for setting a plurality of documents 72 to be copied with the copy side up. The plurality of originals 72 set on the uppermost original 7 are moved by a nudger roll 75a.
2 and are sent to a feed roll 76 and a retard roll 77. A document feed sensor 9 for detecting the feed state of the document 72 is provided at the rear end of the feed roll 76 and the retard roll 77.
8 are arranged. Then, the document 72 is separated one by one by the feed roll 76 and the retard roll 77, and the transport path 78 formed in a substantially arc shape.
Is transported to a reading position on the second platen glass 80 by a plurality of takeaway rolls 79 provided on the way. While the document 72 conveyed to the reading position on the second platen glass 80 is conveyed at a constant speed by a document conveyance roll 81 arranged above the second platen glass 80, FIG. Are read by an image reading element 83 such as a CCD via a scanning optical system 82 of the image reading apparatus stopped at the position shown in FIG. The scanning optical system 82 includes an illumination lamp 84 for illuminating the original 72, a full-rate mirror 85 for reflecting an optical image of the original 72 illuminated by the illumination lamp 84, and a light image from the full-rate mirror 85 to be turned back. The two half-rate mirrors 86 and 87 that reflect light, and an image-forming lens 88 that forms an optical image of the document 72 reflected by the half-rate mirrors 86 and 87 on the image reading element 83 in a reduced state. It is configured.

When reading the image of the original 72 moving at a constant speed on the second platen glass 80 by the image reading device 73, as shown in FIG. The image of the original 72 is read with the scanning optical system 82 stopped so as to come to a reading position immediately below the glass 80. When the image reading device 73 reads the image of the original 72 placed on the first platen glass 89, the illumination lamp 80, the full-rate mirror 85, and the half-rate mirrors 86 and 87 The original 72 is scanned by scanning along the lower surface of the document at a speed ratio of 1: 1/2.
Is read.

Thereafter, the original 72 read at the reading position on the second platen glass 80 is transferred to a tri-roll 90 where the original transport roll 81 and the three rolls are pressed against each other.
The conveyance path is switched by the conveyance path switching member 91 via the document feed tray 8, so that the discharge rollers 92 provide the document discharge tray 8 provided below the document set tray 75.
3 is discharged.

The automatic document feeder 74 also controls the document 7
In the case of performing double-sided copying of No. 2, the original 72 on which an image on one side has been read is not directly discharged onto the original discharge tray 93 by the discharge roll 92, and the transport path switching member 9 is used.
By switching the transport path by 1, the original 72 on which one side of the image has been read is temporarily stored in the original temporary storage section 95 below the original discharge tray 93 by the transport roll 94, and the rear end of the original 72 is held between the transport rolls 94. During this operation, the transport roll 94 is temporarily stopped. Next, by reversing the transport roll 94, the original 72 is transported again to the transport path 78 via the transport path switching member 91 in a state where the original 72 is turned upside down, and the back side of the original 72 is placed on the second platen glass 80. To the reading position, and the scanning optical system 8
2 is read by the image reading device 73. Then, the original 72 from which the images on the front and back sides have been read is
The conveyance path is switched by the conveyance path switching member 91 via the document conveyance roll 81 and the tri-roll 90, so that the document set tray 9 is conveyed by the conveyance roll 94.
The document is temporarily stored in a lower original temporary storage unit 95. The original 72 stored in the original temporary storage section 95 is
By rotating the transport roll 94 in the reverse direction while the trailing end is held between the transport rolls 94, the original 72 is turned upside down and the output tray 8 is turned through the U-turn path 96.
The document 72 is discharged onto the document 3 with the surface of the document 72 facing down.

As described above, by mounting the original 72 on the upper end of the electrophotographic copying machine housing 71 in a fixed state, the first area having a large area for reading the image of the original 72 is obtained. A platen glass 89 and a second platen glass 80 having a small area for reading an image of the original 72 while automatically transporting the original 72 at a constant speed.
And are arranged. Also, the electrophotographic copying machine housing 7
As described above, an automatic document feeder 74 also having a function as a document pressing member is disposed above and below the document feeder 1 so as to be openable and closable.
At the position corresponding to the upper part of the platen glass 89 of the
A document pressing member 97 made of an elastic member for pressing the document 2 is provided.

In the above-described electrophotographic copying apparatus, as shown in FIG. 21, the image information of the document 72 is read by the image reading device 73 and the automatic document feeder 74 configured as described above. The image information of the document 72 read by the image reading device 73 is stored in a temporary storage device (not shown), subjected to predetermined image processing as needed, and ROS (Rast
The image exposure is performed on the photosensitive drum 100 by an er Output Scanner (99) to form an electrostatic latent image. The electrostatic latent image formed on the photosensitive drum 100 is developed by a developing device 101 to be a toner image, and this toner image is transferred onto a transfer sheet 103 by a transfer charger 102. The transfer paper 103 is fed with paper of a predetermined size from a plurality of paper trays 104 to 107 housed in a lower part of the electrophotographic copying machine housing 71 and detected by feed sensors 108 to 111. Thereafter, the plurality of transport rolls 112 are once transported to a registration roll 113 in front of the photoconductor drum 100, and synchronized with a toner image formed on the photoconductor drum 100 by the registration roll 113,
The photosensitive drum 100 is conveyed to the surface.

The transfer paper 103 onto which the toner image has been transferred from the photosensitive drum 100 is separated from the photosensitive drum 100 by a separation charger 114, and then the transfer belt 11
5 to the fixing device 116, where the fixing device 11
6, the toner image is fixed on the transfer paper 103 by heat and pressure, and the discharge tray 117 disposed outside the apparatus.
And the image copying process is completed.

After the toner image transfer process is completed, the surface of the photosensitive drum is cleaned of residual toner, paper dust, and the like by the cleaning device 118 to prepare for the next transfer process.

When performing double-sided copying with the above-described electrophotographic copying machine, transfer paper 103 having an image copied on one side is used.
Is transported once to the sheet reversing path 119 by switching the transport path without directly discharging the sheet to the discharge tray 117, and the transfer sheet 103 is turned upside down via the transport path 120 in a state where the transfer paper 103 is turned upside down. By transferring the image again on the back surface of the transfer sheet 103 by transporting the transfer sheet 103 to the image forming unit again, the transfer sheet 103 is discharged onto a discharge tray 117.

FIG. 23 is a block diagram showing control means of the electrophotographic copying machine according to the third embodiment of the present invention.

In FIG. 23, reference numeral 131 denotes a CPU for controlling the operation of the electrophotographic copying machine; 132, a ROM (read only memory); 133, a RAM (random access memory); 134, an image reading device 73;
4. I / O for controlling the document feed roll 76, the registration roll, recognizing input values such as signals from the sensors 108 to 111, and controlling the time measuring means 135.
Ports 135 represent image rotating means for rotating the read image. Image rotation means 136
The I / O port 134 and the like are controlled by the CPU 131. The image rotation means 135 is composed of a memory for storing the read image and an ASIC for controlling reading of the stored image.

In the above-described electrophotographic copying machine, when an image is copied from the original 72 having an image formed on one side to both sides of the transfer sheet 103, as described in the second embodiment, Since the image of the original 72 is sequentially read and the original is not inverted by the reversing unit, only the front surface of the original 72 is read and discharged as it is. Copying of the image of the document 72 is performed as in the first embodiment.

As described above, when the single-sided original 72 is sequentially read and printed on both sides of the transfer sheet 103, even if there is an error in the length of the transfer sheet 103 or the sheet feeding speed, the image position on the sheet front side and the sheet back side is shifted. It is possible to provide a copying machine that does not cause a shift.

Embodiment 3-2 In the case of double-sided to double-sided, both sides of the document 72 are read as in the second embodiment without correcting the reading position of the back of the document 72. At this time, the number M of read lines in the sub-scanning direction on the front surface of the document 72 is stored. Next, an image is formed on the surface of the transfer sheet 103 as in the first embodiment, and the number L of write lines in the sub-scanning direction is stored. In the first embodiment, the writing start point on the back surface of the sheet is obtained by comparing the number T of accumulation lines in the sub-scanning direction and the number L of reading lines in the sub-scanning direction. The write start point on the back surface of the transfer paper 103 is obtained by comparing the number L of write lines in the sub-scanning direction. L
When> M, writing starts from a position shifted in the image direction by LM lines. When L = M, writing is started from the accumulation end point. Otherwise, image formation on the back surface of the transfer sheet 103 is performed as in the first embodiment.

In this way, when reading a two-sided original sequentially and copying it on both sides of the paper, if there is an error in the original length or original feed speed, or if there is an error in the paper length or original feed speed. Therefore, it is possible to provide a copying machine in which the image position on the front surface of the paper and the image position on the back surface of the paper do not shift.

[0087]

As described above, according to the first aspect of the present invention, the image on the first side is printed as it is, and the image on the second side is rotated by 180 ° and printed on the paper from the rear of the image. It is possible to provide an image forming apparatus in which the image position on the first surface and the image position on the second surface do not shift even when there is an error in the length of the sheet or the sheet feeding speed.

According to the second aspect of the present invention, the first side of the original is read as it is, and the second side of the original is rotated by 180 ° after being read, so that the image is rotated between the first and second sides. An image reading apparatus that does not cause a shift in the image position between an image obtained by reading the first surface and an image obtained by reading the second surface of the document even when there is an error in the document length or the document feed speed when the orientation is adjusted. Can be provided.

Further, according to the third aspect of the present invention, when a single-sided original is sequentially printed on both sides of a reading sheet, the image on the first side is printed as it is, and the image on the second side is 180 °.
Provided is an image forming apparatus in which, even when there is an error in the paper length or the paper feed speed when printing on the paper from the rear portion of the image by rotating the image, there is no deviation between the image positions of the first and second paper surfaces. It is possible to do.

Further, the invention described in claim 3 is:
When two-sided originals are sequentially read and printed on both sides of the paper, if there is an error in the original length or original feed speed, or even if there is an error in the paper length or original feed speed, the first side of the paper It is possible to provide an image forming apparatus in which the image position on the second surface of the sheet does not shift.

[Brief description of the drawings]

FIG. 1 is a conceptual explanatory view of an image recording apparatus according to the present invention.

FIG. 2 is a schematic configuration diagram showing an image recording apparatus using laser xerography according to one embodiment of the present invention.

FIG. 3 is a block diagram showing control means of an image recording apparatus using laser xerography according to one embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a control state of image recording.

FIG. 5 is a flowchart showing an image recording operation.

FIG. 6 is a flowchart showing an image recording operation.

FIG. 7 is a flowchart showing an image recording operation.

FIG. 8 is a flowchart showing an image recording operation.

FIG. 9 is an explanatory diagram showing a method of storing image information.

FIG. 10 is an explanatory diagram showing a method of writing image information.

FIG. 11 is an explanatory diagram showing a method of writing image information.

FIG. 12 is an explanatory diagram showing a method of writing image information.

FIG. 13 is an explanatory diagram showing a method of writing image information. is there.

FIG. 14 is a schematic configuration diagram showing an image reading apparatus according to Embodiment 2 of the present invention.

FIG. 15 is a block diagram showing control means of the image reading apparatus according to Embodiment 2 of the present invention.

FIG. 16 is a flowchart showing an image reading operation.

FIG. 17 is a flowchart showing an image reading operation.

FIG. 18 is a flowchart showing an image reading operation.

FIG. 19 is an explanatory diagram showing a method of storing image information.

FIG. 20 is an explanatory diagram illustrating a method of reading image information.

FIG. 21 is a schematic configuration diagram showing an image forming apparatus according to Embodiment 3 of the present invention.

FIG. 22 is a configuration diagram showing an automatic document feeder used in the image forming apparatus.

FIG. 23 is a block diagram showing control means of the image forming apparatus according to Embodiment 3 of the present invention.

[Explanation of symbols]

01 recording member, 02 measuring means, 03 image position control means.

Claims (3)

[Claims] 1. An image recording apparatus capable of recording an image on both sides of a recording member, a measuring means for measuring a length of the recording member when the recording member is conveyed, and an image position control for controlling a position of the image recorded on the recording member. And a first member of the recording member.
An image recording apparatus comprising: measuring a length of a recording member when forming an image on a surface; and controlling an image forming position on the second surface based on the measurement result. 2. An image reading apparatus capable of reading images on both sides of a document, comprising: measuring means for measuring a length of the document when the document is being transported; and reading position control means for controlling a reading position of the image on the document. And an image reading device that measures the length of the original when reading the image on the first side of the original and controls the read image position on the second side based on the measurement result. 3. An image forming apparatus capable of recording an image of a document on both sides of a transfer member, a first measuring means for measuring a length of the transfer member during transport, and measuring a length of the transfer member during transport. A second measurement unit, and an image position control unit that controls a position of an image formed on the transfer member,
Measure the length of the original when reading, and measure the length of the transfer member when forming an image on the first surface of the transfer member,
An image forming apparatus for controlling an image forming position on a second surface of a transfer member based on the measurement results.