JP2002211045A - Image recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image recorder which facilitates reusing used papers because a use form in which papers having front faces printed are reused to print to rear faces is generalized from a view point of saving resources, efficiently using papers, etc. SOLUTION: The image recorder 1 capable of double-sided printing is provided with a means 60 for detecting whether the paper face is already printed or not, and prints to the unprinted face and discharges the paper without printing to the other face if the other face is already printed.

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, and more particularly to an image recording apparatus capable of performing double-sided printing.

[0002]

2. Description of the Related Art Some image recording apparatuses (or image forming apparatuses) such as printers, copiers, facsimile machines, plotters and the like are capable of printing (recording) on both sides of a sheet. When such an image recording apparatus capable of double-sided printing is used, it is naturally assumed that blank paper (not printed) is used on both sides.

[0003]

However, from the viewpoints of resource saving and effective use of paper, a usage form of reusing paper printed on the front side and printing on the back side has been generalized. However, it is not always the case that blank paper is used on both sides.

Therefore, like a conventional image recording apparatus,
Naturally, when recording is performed on the premise that blank paper is used on both sides, printing is performed again on the already printed surface, and reprinting has been forced. Further, when reusing printed paper, when setting paper to be reused in a paper feed cassette or a paper feed tray, it is necessary to consider on which side the image recording apparatus prints. The setting of the paper to be reused was troublesome, and sometimes it was printed on the same side.

[0005] The present invention has been made in view of the above points, and an object of the present invention is to provide an image recording apparatus that facilitates reuse of used paper.

[0006]

In order to solve the above-mentioned problems, an image recording apparatus according to the present invention is a means for detecting whether or not a sheet surface is a printed surface in an image recording apparatus capable of double-sided printing. It is provided with. In this specification, “paper” means an image on which an image is recorded, and is not limited to paper.

Here, it is preferable that printing is performed on a non-printed surface according to the detection result of whether or not the paper surface is a printed surface. In this case, it is preferable to print a printed mark on the printed surface in accordance with the detection result of whether or not the surface of the paper is the printed surface.

Further, while printing one side of the sheet, it is detected whether or not the other side has been printed. If the other side has been printed, the sheet is discharged without printing on the other side, and the other side is not printed. Sometimes it is preferable to print on the other side.

Also, while printing one side of the sheet, it is detected whether or not the other side has been printed. If the other side has been printed, a printed mark is printed and discharged on the other side, and the other side is printed. If not, it is preferable to print on the other side.

Further, the means for detecting whether or not the surface of the paper is a printed surface comprises a black reflector, a white reflector, a light emitting means for emitting light, and a light receiving means for receiving reflected light. It is preferable to have a density detecting means. In this case, it is preferable to include a unit that also detects the type of paper based on the detection result of the density detecting unit.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective view showing an example of an ink jet recording apparatus which is an image recording apparatus according to the present invention, FIG. 2 is a side view showing a mechanism of the recording apparatus, and FIG. It is a schematic explanatory view provided.

This ink jet recording apparatus comprises a carriage movable in the main scanning direction inside the recording apparatus main body 1, a recording head including an ink jet head mounted on the carriage, an ink cartridge for supplying ink to the recording head, and the like. A paper feed cassette (or a paper feed tray) 4 serving as a paper feed unit capable of stacking a large number of sheets of paper 3 is inserted into and removed from the lower part of the apparatus main body 1 from below. A manual feed tray 5 can be freely mounted on the front side to take in paper fed from the paper feed cassette 4 or paper 3 set in the manual feed tray 5, and a printing mechanism. After a required image is recorded by the unit 2, the sheet is discharged to a sheet discharge tray 29 mounted on the rear side. An operation panel 8 is provided on the front.

The printing mechanism 2 holds a carriage 13 slidably in a main scanning direction (a direction perpendicular to the paper of FIG. 2) by a main guide rod 11 and a sub guide rod 12 which are laterally mounted on left and right side plates (not shown). On the lower surface side of the carriage 13, a recording head 14 composed of an ink jet head having nozzles for discharging ink droplets of yellow (Y), cyan (C), magenta (M), and black (Bk) is ejected. The ink tank (ink cartridge) 15 for supplying each color ink to the recording head 14 is exchangeably mounted on the upper side of the carriage 13.

As shown in FIG. 1, the carriage 13 is mounted on a timing belt 20 stretched between a driving pulley (drive pulley) 18 rotated by a main scanning motor 17 and a driven pulley (idler pulley) 19. The carriage 13 is moved in the main scanning direction by connecting and controlling the driving of the main scanning motor 17.

As the recording head 14, a plurality of heads for ejecting ink droplets of each color may be arranged in the main scanning direction, or a single head having a nozzle for ejecting ink droplets of each color. The used one may be used. In addition, the recording head 14 is configured to discharge ink droplets by pressurizing ink by displacing the diaphragm with an electromechanical transducer such as a piezoelectric element to change the volume of the liquid chamber, and disposed in the liquid chamber. A bubble that is generated by film boiling caused by the heated heating element and pressurizes the ink in the liquid chamber to discharge ink droplets. Using a diaphragm that forms the wall of the liquid chamber and electrodes facing the electrode, an electrostatic force between them is used. A device that displaces the diaphragm to eject ink droplets can be used.

On the other hand, the paper 3 is electrostatically attracted between the transport roller 21 and the transport driven roller 22 in order to transport the paper 3 in the sub-scanning direction with respect to the printing position (synonymous with the print position) by the recording head 14. The conveyor belt 23 for conveying the sheet is stretched and disposed. As shown in FIG. 1, a sub-scanning motor 24 is provided, and the rotation of the sub-scanning motor 24 is transmitted to the transport roller 21 via a gear train (not shown).
The transport roller 21 is rotated in the sub-scanning direction.

An image receiving member 26 is provided at a position facing the recording head 14 with the transport belt 23 interposed therebetween. Further, a tip roller 27 for defining a feed angle of the paper 3 is pressed against the transport roller 21 via a transport belt 23 and disposed.

On the other hand, in order to feed the paper 3 from the paper feed cassette 4 onto the conveyor belt 23, a paper feed roller 31 and a friction pad 32 which separate and feed the paper 3 one by one;
A guide member 34 is provided for guiding the fed sheet 3 to the intermediate roller 33 disposed in contact with the transport roller 21.

In order to feed the paper 3 from the manual tray 5 to the transport belt 23, a pickup roller 35 for picking up the paper 3 from the manual tray 5, a feed roller 36 for feeding the paper 3, and a feed roller 37 , Paper 3
And a guide member 38 that guides the roller to the intermediate roller 33.

A guide member 41 for guiding the paper 3 in order to discharge the printed paper 3 to the paper output tray 6.
And a paper discharge roller 42 for feeding the paper 3 to the paper discharge tray 6
And a paper discharge driven roller 43.

Further, the paper 3 which has passed the printing position by the recording head 4 in order to once discharge the printed paper 3 out of the apparatus main body 1 and feed it to the conveyor belt 23 again to perform double-sided printing. A guide member 45 for guiding the sheet 3 obliquely downward between the sheet discharge tray 6 and the sheet supply cassette 4 is provided, and near the entrance between the guide member 45 and the guide member 41 on the sheet discharge side, the sheet 3 is A first branch claw 46 for branching the discharge path is swingably provided.

In the vicinity of the end of the guide member 45,
The paper 3 is discharged toward the upper surface of the paper feed cassette 4 outside the apparatus main body 1 (this position is a position where the paper waits for re-feeding, that is, a double-sided printing paper standby position). A switchback roller 47 and a switchback follower roller 48 for feeding the cartridge 3 into the apparatus main body 1 again are provided. The switchback roller 47 is rotated forward when the paper 3 having been printed on one side is conveyed in the discharge direction, reversely rotated when the paper 3 is re-fed, and discharged in the discharge direction of the paper 3 when the paper 3 is discharged. It is stopped at a predetermined timing to hold the rear end.

Further, on the upstream side of the switchback roller 47 and the switchback driven roller 48 in the sheet discharging direction,
A second branching claw 49 for switching the transport path of the sheet 3 between a discharge path to the outside of the apparatus main body 1 and a path for re-feeding the sheet 3 into the apparatus main body 1 is provided swingably. In order to feed the paper 3 fed into the apparatus main body 1 by the reverse rotation of the paper to the transport belt 23, a guide member 51 for guiding the paper 3, a double-sided relay roller 52 for transporting the paper 3 and a double-sided relay roller driven roller 53 and transport roller 2
1 and a transport roller driven roller 54 that feeds the sheet 3 to the intermediate roller 33 following the first roller 1.

Further, the feeding roller 31
In the middle of the paper transport path leading to No. 1, printing for detecting whether or not the surface is a printed surface by detecting the density of each surface of the paper 3 fed respectively across the paper transport path. Completed detection sensor 60 is disposed. As shown in FIG. 3, the printed detection sensor 60 includes a plurality of reflective photosensors 60a in a direction (main scanning direction) orthogonal to the sub-scanning direction.
Are arranged side by side. The photo sensor 60a is 1
One line can be scanned, and n lines can be scanned n lines.

The printed detection sensor 60 utilizes the characteristics that the reflectance is poor when the density of the surface of the paper 3 is high (not white paper), and the light reception amount of the photosensor 60a is small.
Since a signal corresponding to the density of the surface of the sheet 3 is output, the output of the photosensor 60 is compared with a reference level to determine whether or not the sheet is blank and to detect whether or not printing has been completed. For example, in a photographic image and a graphic image, a high-density state and a low-density state repeatedly occur in a long cycle, while a character image has a low-density state and sometimes a high-density state occurs in a pulse shape. Basically, it is determined that printing has been completed if there is at least one high density state.

As the printed detection sensor 60, for example, a sensor as shown in FIGS. 4 and 5 can be used. This sensor 60 has two density sensors 61 and 62 which are density detecting means. These density sensors 61 and 62 are provided on the paper transport path side of the holding member 64.
A light-emitting element 65 for emitting light to the conveyed paper;
A black reflector 66 having a black color, a light receiving element 67 for receiving light reflected from the paper, a white reflector 68 having a white color, and a light emitting element 65 for emitting light to the paper are sequentially arranged in series. It was done.

These density sensors 61 and 62 are disposed on both sides of the paper transport path, and are provided so as to be able to advance and retreat with respect to the paper transport path by a drive source such as a solenoid (not shown). Further, the density sensor 61 detects the side printed first in double-sided printing or the side printed in single-sided printing, and the density sensor 62 detects the side printed later in double-sided printing or the side not printed in single-sided printing. Is located on the side that detects It should be noted that a color sensor or the like that detects the color of the paper surface can be used instead of the density sensor that detects the density of the paper surface.

In the printed detection sensor 60 shown in FIGS. 4 and 5, the density sensor 61 is separated from the paper 3 and the density sensor 62 is moved to a position where it comes into contact with the paper 3 as shown in FIG. The detection signal from the light receiving element 67 when the light emitting element 65 emits light is fetched, and then the light emitting element 69
By taking in the detection signal from the light receiving element 67 when the light is emitted, the paper 3 when the back is the black reflection plate 66 is obtained.
A detection signal corresponding to light reflected from one surface of the sheet 3 and a detection signal corresponding to light reflected from one surface of the paper 3 when the back is the white reflection plate 68 are obtained. The density of one side of the paper 3 can be detected. Here, the density when the back is the black reflector 66 is referred to as “back black density”, and the density when the back is the white reflector 68 is referred to as “back white density”. The density obtained based on is referred to as “table density”.

Similarly, the density sensor 61 comes into contact with the paper 3, the density sensor 62 moves to a position away from the paper 3, and the density sensor 62 also moves from the one surface of the paper 3 when the back is the black reflector 66. A detection signal corresponding to the reflected light of
Since a detection signal corresponding to the reflected light from one surface of the paper 3 when the back is the white reflection plate 68 is obtained, the back black density and the back white density of the other surface of the paper 3 are determined based on these detection signals. Is obtained. Note that the density obtained based on the detection signal of the density sensor 62 is referred to as “back density”.

Therefore, it is possible to detect whether or not each surface of the paper 3 has been printed based on the back black density and the back white density of the density sensors 61, 62, and to detect the detection signals from the density sensors 61, 62. The back black density (density when using a black reflector) and the back white density (density when using a white reflector) on each side of the obtained various types of paper depend on the type of paper, for example, plain paper, single-side coated paper, glossy paper, etc. Since they are different, the type of the sheet surface can also be detected.

Next, an outline of a control section of the ink jet recording apparatus will be described with reference to FIG. The control unit includes a microcomputer (hereinafter, referred to as a “CPU”) 70 that controls the entire recording apparatus, a ROM 71 that stores necessary fixed information, a RAM 72 that is used as a working memory, and the like. An image memo 73 for storing the processed data, a parallel input / output (PIO) port 74, an input buffer 75, and a gate array (G
A) or a parallel input / output (PIO) port 76, a head drive circuit 77, drivers 78, 79, 80, etc.

Here, image information to be printed (recording and printing are also used synonymously) from the printer driver 101 of the host 100 via a cable or a network, and whether the printing mode of each side is a dedicated paper mode or a plain paper mode. , Information for specifying double-sided printing, and the like are transferred to the PIO port 74, and required information is transmitted to the host 100 via the PIO port 74.

Various kinds of designation or selection information, such as information for designating a print mode from the operation panel 8 shown in FIG. 1 (for example, a default value is a plain paper mode and a designation is made only when a special paper mode is designated), Each detection signal from the above-described printed detection sensor 60 (one surface is referred to as “front sensor 91” and the other surface is referred to as “back sensor 92”).
Input of signals from various sensors such as a home position sensor for detecting the home position (reference position) of the carriage 13 and transmission of information such as display information to the operation panel 8 are also performed through the PIO port 74.

The head drive circuit 77 operates based on various data and signals supplied through the PIO port 76 to actuator means (electromechanical conversion such as a piezoelectric element) corresponding to each nozzle of the recording head (inkjet head) 14. A driving waveform corresponding to image information is applied to an element, an electrothermal conversion element such as a heating resistor, a diaphragm, or a counter electrode. In addition, as a driving waveform, a rectangular pulse, a triangular waveform, and other shapes such as a sin (sine) waveform can be used.

Further, the driver 78 includes the PIO port 7
The main scanning motor 17 is controlled to drive the carriage 13 in the main scanning direction in accordance with the driving data given through the control unit 6, and the sub-scanning motor 25 is driven to control the conveyance rollers 21.
Is rotated in the paper transport direction (sub-scanning direction). The driver 79 includes a motor 81 for rotating the switchback roller 47 and a solenoid 8 for swinging the first branch claw 46.
The driving of the solenoid 83 for swinging the second and second branch claws 49 is controlled.

Next, a first example of the printing operation of the ink jet recording apparatus thus configured will be described with reference to FIGS.
This will be described with reference to FIG. First, referring to FIG. 7, the paper feed roller 31 is driven to rotate to feed the paper 3 from the paper feed cassette 4. The paper 3 is sent to the transport belt 23 of the transport roller 21, is electrostatically attracted to the transport belt 23, and is transported in the sub-scanning direction. At this time, each detection signal from the front surface sensor 91 and the back surface sensor 92 is taken in, and a process of determining (detecting) whether the front surface and the back surface of the fed paper 3 have been printed or not.

Then, it is determined whether or not the printing is double-sided printing. If it is not double-sided printing, the process proceeds to a single-sided printing process shown in FIG. It is checked whether both sides of the sheet 3 are blank (non-printed side) based on the result of the determination.

At this time, if the front and back surfaces of the sheet 3 are both blank, normal double-sided printing processing is performed because double-sided printing on the sheet 3 is possible. In this normal double-sided printing process, as shown in FIG. 8, the first branching pawl 46 is switched to the double-sided printing side, the second branching pawl 49 is switched to the discharge side,
7 is rotated forward (rotated in a direction to discharge the sheet 3 out of the apparatus). Then, the carriage 13 moves on one surface of the sheet 3 electrostatically attracted to the transport belt 23 and transported in the sub-scanning direction.
By driving the actuator means of the recording head 14 in accordance with the recording image while moving in the main scanning direction, a required image is printed on one surface (front surface) of the paper 3.

The paper 3 on which printing by the recording head 14 has been completed is guided by the guide member 45 because the first branching pawl 46 has been switched to the double-sided printing side. And is conveyed by the switchback roller 47 and the switchback driven roller 48 and discharged out of the apparatus main body 1. At this time, when the rear end of the sheet 3 is positioned between the switchback roller 47 and the switchback driven roller 48, the switchback roller 47 is stopped, and
So that the rear end is held.

Next, after switching the first branching pawl 46 to the paper discharge side and switching the second branching pawl 49 to the paper re-feeding side, the switchback roller 47 is reversed and the intermediate roller 51 is driven, whereby the switch is switched. The guide belt 51 guides the sheet 3, the end of which is sandwiched between the back roller 47 and the switchback driven roller 48, while the conveyance belt 2 is moved by the intermediate roller 51.
3 and refeed the paper (upside down).

While the paper 3 thus re-fed is conveyed by the conveyance belt 23, a required image is printed on the back surface (other surface) by the recording head 14, and the recording head 14
The paper 3 having been printed by the printer 3 is guided by the guide member 41 on the paper discharge side via the first branching pawl 46, conveyed between the paper discharge roller 42 and the paper discharge roller 43, and discharged to the paper discharge tray 6. You.

As described above, by reversing the sheet by the switchback method and re-feeding the paper for the double-sided printing, the configuration for performing the double-sided printing is simplified, and the ink drying time is secured. In addition, other processing can be performed.
It is also possible to discharge the paper once to the paper discharge tray 6 and make the paper discharge roller 42 function as a switchback roller.

Returning to FIG. 7, if the front and back surfaces of the paper 3 are not blank in both-side printing, it is checked whether or not the surface of the paper 3 is blank. After printing the required recording image on the front side, the sheet is discharged as it is. If the front side of the paper 3 is not blank, it is checked whether or not the back side of the paper 3 is blank. Similarly, once the sheet 3 is discharged, the sheet 3 is turned over, and the sheet 3 is fed again.
After a required recording image is printed on the back surface of the sheet 3, the sheet is discharged.

As described above, when printing can be performed on only one side of the sheet 3 even in the case of double-sided printing, it is preferable that message information to that effect be transferred to the host. It is also possible to selectively determine whether to perform printing on only one side.

Furthermore, if the back surface of the sheet 3 is not blank,
That is, if both the front and back surfaces of the paper 3 have been printed,
The sheet 3 is discharged as it is. At this time, it is possible to immediately return to the process of feeding a new sheet 3 or, as described above, transfer the message information to that effect to the host 100 and wait for a response from the host side, and then wait for a response from the host. It is also possible to selectively determine whether or not to feed paper.

By performing such processing, it is possible to appropriately perform printing on a blank sheet even when a sheet with a single-sided printed sheet is set, and to reuse a double-sided blank sheet or a single-sided printed sheet. Even in a case where sheets are mixed and set in the paper feed cassette 4, appropriate double-sided printing can be performed, and reuse of used paper becomes easy.

Next, the one-sided printing process will be described with reference to FIG. 9, which is basically the same as the case of the two-sided printing.
It is checked whether or not the surface of the paper 3 is blank. If the surface of the paper 3 is blank, a required recording image is printed on the surface of the paper 3 and then the paper 3 is discharged. If the front side of the paper 3 is not blank, it is checked whether or not the back side of the paper 3 is blank. Similarly, the sheet 3 is once discharged, the sheet 3 is reversed, and the sheet 3 is re-fed, a required recording image is printed on the back surface of the sheet 3, and the sheet 3 is discharged.

Further, if the back surface of the sheet 3 is not blank,
That is, if both the front and back surfaces of the paper 3 have been printed,
The sheet 3 is discharged as it is. At this time, it is possible to immediately return to the process of feeding a new sheet 3 or, as described above, transfer the message information to that effect to the host 100 and wait for a response from the host side, and then wait for a response from the host. It is also possible to selectively determine whether or not to feed paper.

As described above, by detecting whether or not the front and back surfaces of the paper 3 have been printed, and printing on the non-printed surface, no matter how the used paper is set, it can be printed on the blank paper surface. Printing can be performed, and even in a case where double-sided blank paper or single-sided printed recycled paper is mixed and set in the paper feed cassette 4, appropriate single-sided printing can be performed. Reuse becomes easier.

Next, a second example of the printing operation of the ink jet recording apparatus will be described with reference to FIGS. In the process of the second example, first, referring to FIG. 10, when the front and back sides of the sheet 3 fed in the duplex printing are not blank, it is checked whether the front side of the sheet 3 is blank. If the surface of the sheet 3 is blank, a required recording image is printed on the surface of the sheet 3 and then the sheet 3 is reversed and fed again.
The printed mark is printed on the back surface of the paper 3 and discharged. If the front side of the sheet 3 is not blank, it is checked whether the back side of the sheet 3 is blank. If the back side of the sheet 3 is blank, a printed mark is printed on the front side of the sheet 3 and then the sheet 3 is printed. The sheet 3 is reversed and re-fed, a required recording image is printed on the back side of the sheet 3, and the sheet 3 is discharged.

Similarly, referring to FIG. 11, if the front and back sides of the sheet 3 fed in the processing of the first example are not blank during single-sided printing, it is checked whether the front side of the sheet 3 is blank. If the front surface of the paper 3 is blank, a required recording image is printed on the front surface of the paper 3, then the paper 3 is reversed and fed again, and a printed mark is printed on the back surface of the paper 3 and discharged. Paper. If the front side of the sheet 3 is not blank, it is checked whether the back side of the sheet 3 is blank. If the back side of the sheet 3 is blank, a printed mark is printed on the front side of the sheet 3 and then the sheet 3 is printed. The sheet 3 is reversed and re-fed, a required recording image is printed on the back side of the sheet 3, and the sheet 3 is discharged.

Here, as the printed mark, for example, a hatched mark M1 as shown in FIG. 12 (a), an "x" mark M2 as shown in FIG. 12 (b), or FIG. 12 (c). Any mark may be used as long as it is a solid-filled mark M3 as shown, and indicates that at least the surface is not the one printed in the current printing. In addition, the printed mark may be a single black color, a monocolor, or a full color.

When the printed paper is reused as described above, the user can easily identify the currently printed surface by printing the printed mark on the already printed surface.

Next, a first example of another different embodiment of the image recording apparatus according to the present invention will be described with reference to FIG. In this recording apparatus, a carriage 101 having a recording head 100 mounted thereon is driven by a drive roller 102 and an idler roller 10.
3, the carriage 101 is moved and scanned in the main scanning direction in the same manner as in the above-described embodiment. A printed detection sensor 106 similar to the printed detection sensor 60 that detects whether the lower surface of the paper 105 has been printed is attached to a portion of the timing belt 104 opposite to the side to which the carriage 101 is attached. .

With this configuration, the carriage 101
When an image is recorded on one side of the sheet 105 by the recording head 100 by performing main scanning, it is possible to detect and determine whether or not the other side of the sheet 105 has been printed based on the detection signal of the printed state detection sensor 106. it can. Since the printed detection sensor 106 can be scanned in the main scanning direction, the entire surface of the paper in the sub-scanning direction can be detected by one sensor, and the sensor configuration and determination processing can be simplified.

As described above, the configuration in which the main scanning of the carriage and the detection of whether or not the paper surface has been printed is performed in parallel is described in the first embodiment.
The configuration is not limited to the example, and configurations such as the second to fourth examples may be used as shown in FIGS.

That is, in the second example shown in FIG. 14, the paper 10 is provided separately from the timing belt 104 for the carriage.
5, a timing belt 114 stretched between the rollers 112 and 113 with the drive path of the drive roller 10 therebetween.
2 rotates the roller 11 via the timing belt 115.
2 so that the timing belt 104 and the timing belt 114 rotate in the same direction.

Then, the carriage 101 is attached to the lower portion of the timing belt 104, the printed detection sensor 106 is attached to the upper portion of the timing belt 114, and the lower surface of the paper 105 is printed while printing is performed on the upper surface of the paper 105. Whether or not it is detected.

In the third example shown in FIG. 15, a timing belt 114 is provided in the same manner as in the second example, but the lower part of the timing belt 104 and the lower part of the timing belt 114 are separated. The carriage 101 is attached to the lower part of the timing belt 104 so that the conveyance path of the paper 105 is
A printed detection sensor 106 is attached to the lower part of the paper 105 to detect whether or not the lower surface of the paper 105 has been printed while printing on the upper surface of the paper 105. Space becomes smaller.

Further, the fourth example shown in FIG.
A timing belt 114 is provided in the same manner as in the example, except that the transport path of the sheet 105 is located inside the timing belt 104, and the carriage 101 is attached to an upper portion of the timing belt 104.
The printed detection sensor 106 is attached to the upper part of the paper 105 to detect whether or not the lower surface of the paper 105 has been printed while printing on the upper surface of the paper 105. Vertical space is reduced.

Next, a printing operation in another embodiment will be described with reference to FIGS. First,
At the time of double-sided printing, as shown in FIG. 17, the paper 3 is fed, a desired image is printed on the front surface, the paper 3 is reversed, the paper is fed again, and the printed end is detected when the paper 3 is printed. Based on the detection result of the detection signal of the sensor 106, it is determined whether or not the back side of the sheet 3 has been printed. If the back side of the sheet 3 has not been printed, a required image is printed, and the back side of the sheet 3 has been printed. If so, print the printed mark and discharge the paper. In this case, the printed mark may be discharged without printing, as in the above-described embodiment.

Also, at the time of one-sided printing, as shown in FIG. 18, the paper 3 is fed, a required image is printed on the front side, and the detection signal of the printed detection sensor 106 at the time of printing on the front side of the paper 3 is output. It is determined whether or not the back side of the sheet 3 has been printed based on the result of the capture. If the back side of the sheet 3 has not been printed, the sheet 3 is discharged as it is. The sheet is inverted and re-fed, a printed mark is printed on the back side of the sheet 3, and the sheet 3 is discharged. Also in this case, the printed mark may be discharged without printing, as in the above-described embodiment.

Next, a printing completion detection process using the density detection sensor shown in FIGS. 4 and 5 will be described with reference to FIGS. 19 and 20. Here, the density sensors 61 and 6
The back black density and the back white density on each side of the one-side coated paper and the plain paper obtained by the detection signal from No. 2 are as shown in FIG. 19, for example. In the drawing, the area of the back black density (density area) is indicated by a solid line, and the area of the back white density (density area) is indicated by a broken line.

In the example shown in the drawing, the surface of the coated layer of the single-side coated paper on which the coated layer is formed is defined as the front surface, and the surface on which the coated layer is not formed is defined as the rear surface. Both densities are higher than the back black density and the back white density on the back surface. Also, in the case of single-side coated paper, the difference between the back black density and the back white density (“B−W”) is smaller than the difference between the back black density and the back white density of the plain paper. By doing so, it is possible to distinguish between coated paper and plain paper. Furthermore, when one surface is a printed surface, the density increases, so that it is possible to determine whether or not the surface has been printed.

Therefore, for example, as shown in FIG. 20, the control unit compares the front density obtained from the density sensor 61 with the back density obtained from the detection sensor 62, and determines whether (B−W) is large. And (B−W) is large, the paper 3
Is plain paper, and if (B-W) is not large, the paper 3 is determined to be coated paper.

Then, the back black density and the back white density of the table density obtained from the density sensor 61 are compared with the reference density, and if the back black density and the back white density are higher than the reference value, the surface of the sheet 3 is printed. If the back black density and the back white density are within the reference value, it is determined that the surface of the sheet 3 is a blank sheet. As described above, the determination accuracy is further improved by determining whether or not printing has been performed based on the back black density and the back white density.

In the above embodiment, the present invention is applied to an ink jet recording apparatus. However, the present invention is not limited to the ink jet recording apparatus but is applied to other image recording apparatuses (including an image forming apparatus). You can also.

[0068]

As described above, according to the image recording apparatus of the present invention, the image recording apparatus capable of printing on both sides is provided with the means for detecting whether or not the paper surface is the printed surface. In addition, it is possible to detect and print a surface that has not been printed, and to easily reuse used paper.

Here, by printing on the non-printed surface according to the detection result of whether or not the paper surface is the printed surface,
Reuse of used paper is facilitated. In this case, the printed mark is printed on the printed surface in accordance with the detection result of whether or not the surface of the paper is the printed surface, thereby making it easy to identify the printed surface when printing on reusable paper. .

Further, while printing one side of the sheet, it is detected whether or not the other side has been printed. If the other side has been printed, the sheet is discharged without printing on the other side, and the other side has not been printed. Sometimes printing on the other side facilitates reuse of used paper and simplifies the configuration for detecting whether or not printing has been completed.

It is also detected whether or not the other side has been printed during printing on one side of the sheet. If the other side has been printed, a printed mark is printed on the other side and discharged, and the other side has been printed. If not, printing on the other side facilitates the reuse of used paper, makes it easier to identify the printing side when printing on reused paper, and detects whether or not printing has been performed. The configuration is simplified.

Further, the means for detecting whether or not the surface of the paper is a printed surface includes a black reflector, a white reflector, a light emitting means for emitting light, and a light receiving means for receiving reflected light. The presence of the density detecting means enables detection with higher accuracy. In this case, by providing a unit that also detects the type of paper based on the detection result of the density detection unit, it is possible to detect whether or not printing has been performed with higher accuracy according to the type of paper.

[Brief description of the drawings]

FIG. 1 is a perspective explanatory view of an ink jet recording apparatus which is an image recording apparatus according to the present invention.

FIG. 2 is an explanatory side view of a mechanism of the recording apparatus.

FIG. 3 is an explanatory diagram illustrating a density sensor in the recording apparatus.

FIG. 4 is an explanatory diagram illustrating another example of the density sensor.

FIG. 5 is an explanatory diagram for explaining the operation of the density sensor of FIG. 4;

FIG. 6 is a block diagram showing an outline of a control unit of the recording apparatus.

FIG. 7 is a flowchart for explaining a first example of a printing operation of the recording apparatus.

FIG. 8 is a flowchart for explaining a normal double-sided printing process in FIG. 7;

FIG. 9 is a flowchart for explaining the one-sided printing process in FIG. 7;

FIG. 10 is a flowchart for explaining a second example of the printing operation of the recording apparatus.

FIG. 11 is a flowchart for explaining the one-sided printing process in FIG. 10;

FIG. 12 is an explanatory diagram illustrating a different example of a printed mark used in the second example.

FIG. 13 is a main part explanatory view for explaining a first example of a mechanism part of another embodiment of the ink jet recording apparatus according to the present invention.

FIG. 14 is an essential part explanatory view for explaining a second example of the mechanism section of the embodiment.

FIG. 15 is an explanatory view of a main part for explaining a third example of the mechanism section of the embodiment.

FIG. 16 is an explanatory view of a main part for explaining a fourth example of the mechanism section of the embodiment.

FIG. 17 is a flowchart for explaining a two-sided printing process in the printing operation according to the embodiment;

FIG. 18 is a flowchart for explaining one-sided printing processing in the printing operation according to the embodiment;

FIG. 19 is an explanatory diagram illustrating an example of a back black density and a back white density of a sheet.

20 is a flowchart for explaining a paper type determination and a print completion detection process using the density detection unit in FIG. 4;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Device main body, 2 ... Printing mechanism part, 3 ... Paper, 4 ... Paper feed cassette, 6 ... Discharge tray, 13 ... Carriage, 14 ... Head, 21 ... Conveying roller, 23 ... Conveying belt, 42 ... Discharge Rollers, 46: First branching pawl, 47: Switchback roller, 49: Second branching pawl, 60, 106: Printed detection sensor.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) B65H 7/14 G03G 15/00 106 2H027 G03G 15/00 106 21/00 376 2H028 21/00 376 H04N 1 / 00 108M 3F048 H04N 1/00 108 B41J 3/00 S 5C062 F-term (reference) 2C055 EE00 EE02 2C059 AA05 AA18 AA22 AA26 AA67 2C062 RA06 2C087 AA13 AC07 BB10 CA02 CB02 DE07 DC07 DC12 AC07 FB07 FD10 2H028 BA09 BB02 BB08 3F048 AA03 AA04 AA05 AB01 BA08 BB02 CC02 DA04 DC14 EA12 5C062 AA05 AB08 AB32 AC04 AC09 AC11 AC71 BA00

Claims (7)

[Claims] 1. An image recording apparatus capable of printing on both sides of a sheet, comprising: means for detecting whether or not the side of the sheet is a printed side. 2. The image recording apparatus according to claim 1, wherein printing is performed on a non-printed surface according to a detection result of whether or not the surface of the paper is a printed surface. 3. The image recording apparatus according to claim 2, wherein a printed mark is printed on a printed surface in accordance with a detection result of whether or not the surface of the sheet is a printed surface. Image recording device. 4. The image recording apparatus according to claim 2, wherein during printing on one side of the sheet, it is detected whether or not the other side has been printed, and when the other side has been printed, printing is performed on the other side. An image recording apparatus that discharges paper without printing on the other side and prints on the other side when the other side is not already printed. 5. The image recording apparatus according to claim 2, wherein during printing on one side of the sheet, it is detected whether or not the other side has been printed, and when the other side has been printed, a printed mark is printed on the other side. An image recording apparatus which prints and discharges paper, and prints on the other side when the other side has not been printed. 6. The image recording apparatus according to claim 1, wherein the means for detecting whether or not the surface of the sheet is a printed surface includes a black reflector, a white reflector, and a light reflector. An image recording apparatus, comprising: a density detecting unit including a light emitting unit that emits light and a light receiving unit that receives reflected light. 7. The image recording apparatus according to claim 6, further comprising means for detecting the type of the sheet based on a detection result of the density detecting means.