JPS63211969A - Image forming device - Google Patents

Abstract

PURPOSE:To eliminate a mirror which is to be inserted into an optical path and to improve the image quality of a forming image by providing an image read means with an image forming means which is arranged in the optical path of a reflected light from an original, and a photodetecting means which can change the length of the optical path with respect to the image forming means and shifting its own photodetecting means at the time of variable power- reading picture information. CONSTITUTION:The image read means 15 image-forms a light beam from an image-forming lens 206 on the photodetecting surface of a CCD line sensor 17 by using the photodetecting 18 consisting of the combination of a first correction mirror 16 and the CCD line sensor 17. With first carriage 20, an operation part consisting of a light source lamp 201 and a first mirror 202, and with a second carriage 21, second and third mirrors 204 and 205 respectively shift to the direction of an arrow as illustrated. The image-forming lens 206 and the means 18 independently shift to the direction of the arrow as illustrated by a driving system. Consequently, a distance between the images can be varied at the time of image reading accompanied by variable power, whereby the deterioration of the quantity of light and deviation can be prevented.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to an image forming apparatus, and more specifically, an image forming apparatus equipped with a variable magnification mechanism for reading double-page information attached to a manuscript. Regarding.

(Prior Art) An overview of a conventional image forming apparatus equipped with a variable magnification mechanism, such as a zoom type copying machine, will be explained with reference to FIG.

The image forming apparatus shown in the figure irradiates light from a light source lamp 201 onto the document surface of a document 220 placed on a document table 202, and uses the light reflected from the document surface in a first. Second. Third mirror 203, 204° 205, imaging lens 206, fourth .
Fifth. The light is guided to the photosensitive drum 210 through an optical system consisting of sixth mirrors 207, 208, and 209 and is imaged thereon.

In the case of this conventional device, the photosensitive drum 21 is
Distance to the light receiving surface formed on the circumferential surface of 0.

That is, the distance between the image information reading surface and the imaging surface (object-image distance) is determined in advance.

For this reason, when reading a document with variable magnification, for example, the 5th. The sixth mirrors 207 and 208 are moved in the direction of the arrow shown in the figure to correct the optical path length during zooming.

That is, in the case of the conventional device described above, the photoreceptor drum 21
Since it is impossible to change the position of 0 according to the magnification ratio due to the constraints of the device, the increase in optical path length due to the magnification change is compensated for by the second lens inserted between the original @ 220 and the imaging lens 206. A fourth mirror inserted between the third mirror 204° 205 or the imaging lens 206 and the photoreceptor drum 210. fifth mirror 2
This is done by position correction such as 07.208.

Furthermore, since the so-called image forming apparatus directly projects the document width onto the circumferential surface of the photoreceptor drum 210, the above-mentioned optical system must be a same-magnification optical system. The term "equal magnification optical system" means an optical system in which the original width and the image width are equal to 1 when the magnification is 100%. In the case of such a same-magnification optical system, it is necessary to make the original surface and the optical path from the imaging lens to the peripheral surface of the photoreceptor drum 210 equal, so as described above, many mirrors are inserted into the optical path to change the optical path. is folded.

However, in the case of the conventional device described above, as the number of mirrors increases, the amount of light decreases due to reflection and the optical axis shifts.
There is a problem in that the quality of the formed image deteriorates.

(Problems to be Solved by the Invention) In the conventional device described above, the distance between the object and image is predetermined, so when changing the magnification, it is necessary to insert a large number of mirrors into the optical path due to the dimensional limitations of the device. As a result, there is a problem in that the quality of the formed image deteriorates.

Therefore, the present invention provides an image forming apparatus that can change the distance between objects when changing the magnification, thereby eliminating the need for mirrors inserted in the optical path or reducing the number of mirrors, thereby improving the quality of formed images. The purpose is to provide the following.

[Structure of the Invention] (Means for Solving the Problems) The present invention optically scans a document placed on a document table, and uses image information read by this scanning to form an image on an image forming medium. In an image forming apparatus equipped with an image reading means adapted to be used in a process, the image reading means includes an imaging means disposed in an optical path of reflected light from a document, and a light receiving means whose optical path length for the imaging means can be changed. The light receiving means itself is moved when reading image information at variable magnification.

(for production) The operation of the image forming apparatus having the above configuration will be explained below.

When this device reads image information attached to a document at variable magnification, the optical path length between the image forming means and the light receiving means in the image reading means can be changed. It is possible to eliminate or reduce the number of lenses to be inserted between the lenses, and it is possible to suppress a decrease in light amount and positional shift due to lens insertion, and improve the quality of the formed image.

(Example) Examples of the present invention will be described in detail below.

First, the principle of the image reading means of the present invention will be explained with reference to FIGS. 1 to 3.

Incidentally, in addition to the image reading means 15 shown in FIG. 1, 60 has the same function as that shown in FIG. 17.

This image reading means 15 uses a light receiving means 18 consisting of a combination of a first correction mirror 16 and a CCD line sensor 17 after the imaging lens 206, and a light receiving means 18 on the light receiving surface of the CCD line sensor 17 as an imaging means. The light from the imaging lens 206 is formed into an image, and this is transferred to the CCD line sensor 17.
This converts the signal into an electrical signal.

The operation section consisting of the light source lamp 201 and the first mirror 202 is controlled by the first gear 20 and the second mirror 20. The third mirror 204° 205 is the second
Each of the carriages 21 is configured to move in the direction of the arrow shown in FIG.

In addition, the imaging lens 206. The light receiving means 18 are also configured to move individually in the directions of arrows shown in the same figure by respective drive systems to be described later. In addition, in Figure 1, 201
A is a glue flap for the light source lamp 201.

When the image reading unit 15 having the above configuration changes the magnification and reads the image information attached to the original document 220, the light receiving unit 18 itself is moved to deal with changes in the optical path length for the imaging lens 206 due to the magnification change. Can be done.

In addition, the first type as shown in FIG. Second correction mirror 16
．． It is also possible to use a light receiving means 18 configured by a combination of a mirror unit 23 using 16A and a CCD line sensor 17. In this case, the optical path length can be changed by moving only the mirror unit 23 or by moving the mirror unit 23 and CC.
This is done by moving both the D line sensors 17.

Roughly speaking, as shown in FIG. 3, a CCD is used as the light receiving means 18.
Only the line sensor 17 may be used and the CCD line sensor 17 may be moved.

As described above, the light receiving means 1 having the CCD line sensor 17
8, the document reading width of this CCD line sensor 17, that is, the width of the light receiving surface, does not necessarily have to be equal to the width of the document 220.

For example, after reducing the width of an A3-size document to A4 width, reading it, and converting it into an electrical signal, the image width is electrically doubled in a signal processing unit 100 (described later), and the width of the A3-size document is used as an image forming medium. It is also possible to form an image on copy paper. That is, in this case, the optical system of the image reading means 2 does not need to be a same-magnification optical system, but can be, for example, a 1/2 reduction optical system, and the overall configuration can be miniaturized.

The 1/2 reduction optical system means an optical system that uses 1/2 of the document width as the read image width when the magnification ratio is 100%.

It is also possible to roughly add correction mirrors to the light receiving means 18 shown in FIG. has no meaning.

Furthermore, when using a small photoelectric conversion element such as the CCD line sensor 17, changing the optical path length when changing magnification can be handled by either fixing the light receiving surface or moving the light receiving surface, but depending on the number of mirrors, the light receiving surface moving method may be necessary. In some cases, it may not be possible to cope with changes in the optical path length, and therefore, a light receiving surface moving method, such as the light receiving means 18 shown in FIGS. 1 to 3 described above, is more advantageous in determining the optical system.

Next, a specific example of an image forming apparatus equipped with the image reading means 2 based on the above principle will be described with reference to FIGS. 4 to 16.

FIG. 4 shows a thermal transfer color copying machine as an example of an image forming apparatus, in which an image reading means 15 is provided on the upper surface of the main body 1 of the apparatus. The image reading means 15 is provided with a document cover 3 that can be freely opened and closed, and a document table 202 made of transparent glass on which a document 220 is placed is provided below the document cover 3. This image reading means 15 has a scanner section consisting of an exposure optical system mounted on a document table 20.
By reciprocating along the lower surface of 2, the document table 202
It optically scans the original @22o set at , and converts this optical information photoelectrically.

The information converted by the image reading means 15 is supplied to the image forming means 5 provided on the right side of the apparatus main body 1, and in this image forming means 5, the paper P as an image forming medium is determined according to the converted information. An image is formed.

Here, the image reading means 5 will be briefly described in detail with reference to FIG. 5 as well.

The image reading means 5 includes a first carriage 2o configured to be movable along the document table 202, and a second carriage 21 configured to be movable along the document table 202 similarly to the first carriage 21. , an imaging lens 206, a first correction mirror 16 that corrects the optical path length when magnifying and reading image information attached to a document, and a CCD line sensor 1.
7, the first and second carriages 20, 21, and an imaging lens 206 as shown in FIG.
, a drive system for changing the position of the light receiving means 18.

The first carriage 20 includes a light source lamp 201 as a linear light source, a flipper 201A that focuses light from the light source lamp onto the document surface, and a second carriage that receives reflected light from the document surface. 21 first mirror 203
Equipped with:

The second carriage 21 changes the optical path of the light from the first mirror 203 and sends it to the imaging lens 206. It includes third mirrors 204 and 205.

Also, 1st. The second carriage 20.21 is connected to the drive pulley 25.21 as shown in FIG. Idle pulley 26, 27
, 28 and two timing belts adjusted to these square pulleys, and a drive system comprising a scanning motor 30 (stepping motor) that transmits rotational force to the drive pulley 25, as shown in FIG. It is designed to be driven in the direction of the arrow shown in . Further, in this case, the second carriage 21 is driven in the same direction as the first carriage 20 and at 1/2 the speed.

The imaging lens 206 is of a fixed distance type, and
During zooming, this imaging lens 206 is moved in the optical axis direction.

The light receiving means 18 is capable of varying its position with respect to the imaging lens 206 in response to a change in optical path length caused by a preselected magnification ratio. The light receiving means 18 is
By capturing the reflected light from the original 1220 through the above-mentioned optical system and photoelectrically converting it, the image information attached to the original 220 is converted into cyan, green, yellow (or red, green, etc.).

The signal is separated and output as a color signal (blue).

Signal processing after the light receiving means 18 will be described later. still,
The imaging lens 206 and the light receiving means 18 are driven in the optical axis direction by a spiral shaft 31 driven by a stepping motor (not shown) and a bracket 32 screwed onto the spiral shaft 31, as shown in FIG. This is performed by moving the imaging lens 206 and the light receiving means 18 connected to the bracket 32 in the optical axis direction using a drive system consisting of the following.

As shown in FIG. 4, the image forming means 5 includes a thermal print head 142 that approaches and separates from the outer circumferential surface of a platen drum 140 with a fulcrum 141 as the center of rotation, and a head surface of the thermal print head 142 and the platen drum 14.
The ink ribbon 143 is interposed between the paper P that is wrapped around the outer periphery of the paper P and is transported, the supply roller 144 that supplies and winds up the ink ribbon 143, the take-up roller 145, and the ink ribbon 143. It includes guide rollers 146 and 147 that guide the platen drum 140 so as to come into sliding contact with the outer peripheral surface thereof.

Incidentally, the ink ribbon 143 is prepared in a plurality of colors or in a single color depending on color copying or monochrome copying. Further, the outer peripheral portion of the platen drum 140 is formed of an elastic material such as rubber, and the outer peripheral length is set to be slightly larger than the length in the longitudinal direction of the maximum paper size (for example, A3).

Further, in the apparatus main body 1, a paper feed side conveyance path 15 provided between the paper feed cassette 13 and the platen drum 140 is provided.
0 and a paper discharge side conveyance path 151 that performs the discharge operation of the paper P discharged from the platen drum 140.

The paper feeding side conveyance path 150 is for forming a moving path for the paper P between the paper feeding cassette 13 and the platen drum 140, and along the way there is a registration roller 152 that force-feeds the copying paper while aligning it. It is equipped with

Further, the paper discharge side conveyance path 151 includes the platen drum 14
0 and the paper ejection tray 12, and is provided with a paper ejection roller 153 in the middle and at the end thereof.

Three pressure rollers 161, 162, 163 are arranged around the outer periphery of the platen drum 1'40.
The sheet P is placed in sliding contact with the platen drum 140 and has one end held by a gripper 165 provided on the platen drum 140 .

Here, modified examples of the image forming apparatus are shown in FIGS. 6 to 10.
This will be explained with reference to the figures.

FIG. 6 shows the external appearance of this image forming apparatus, and FIG. 7 shows the operation panel 6.

A guide section 11 for manually feeding paper is provided on the front side of the image forming apparatus, and a guide section 11 is provided on the top surface of the image forming apparatus so as to be able to be opened and closed.
is provided. Roughly speaking, a paper feed cassette 13 for storing paper is provided in the main body 1 of the apparatus located below the image forming means 5 so as to be able to be taken in and out. Note that 8 is a door for attaching and detaching a thermal transfer ink ribbon as a transfer agent, which will be described later, to and from the main body 1 of the apparatus.

FIG. 7 shows the operation panel 6. As shown in FIG.

This operation panel 6 includes a print key 41 for instructing the start of printing (forming both parties), a numeric keypad 42 for specifying the number of prints, a clear/stop key 43 for instructing to cancel the number of prints or stop printing, and a keypad for displaying the number of prints, etc. Number display 44, base color setting section 4 for setting the shade of the base color
5. Color intensity setting section 46 for setting color intensity, color tone setting section 47 for setting color tone, and display device 4 for performing various displays.
8. Original mode key 491 for selecting a mode according to the image quality of the original and a display section 492 for displaying the selected mode
, a density designation key 71 for switching and setting the print density in five levels, and a display section 72 for displaying the set density. The display 48 includes a jam display section 481 that lights up when a paper jam occurs in the apparatus main body 1;
a ribbon display section 482 that displays various states such as no ribbon in the ribbon cassette installed in the ribbon cassette or no water in the cassette; a paper display section 483 that displays the installation state of the paper feed cassette 13 or the presence or absence of paper; Scanner section 2
Scanner display units 48a, 48 that display the operating status of 1
5, a paper size display section 486 that displays the paper size in the attached paper feed cassette 13;

Further, the image forming means 5 has a configuration as shown in FIG. That is, a platen drum 50 is disposed approximately in the center of the image forming means 5, and a thermal head as a recording head (thermal head) is located in front of the platen drum 50 (towards the left in the state of FIG. 8). 51
is arranged so as to be able to approach and separate from the platen drum 50.

Roughly speaking, the thermal head 51 is a ribbon cassette Rc.
A thermal transfer ink ribbon (thermal transfer ribbon) is housed in a space between the thermal head 51 and the platen drum 50.
52 is present. Then, the paper (image forming medium) P is pressed against the platen drum 50 with the thermal transfer ink ribbon 52 interposed therebetween, and in this state, the heat generating elements (not shown) formed in the shape of ink dots of the thermal head 51 generate image information. The ink on the thermal transfer ink ribbon 52 is heated and melted by the heat generated in accordance with the
It is now transcribed into .

Further, a paper feed roller 53 is provided in the apparatus main body 1 diagonally below the platen drum 50, and is adapted to sequentially take out the sheets P stored in the paper feed cassette 13 one by one. The taken out paper P passes through the paper guide path 54 and is guided to a registration roller 55 disposed diagonally above the paper feed roller 53, and the registration roller 55 aligns its leading edge. The sheet is transferred toward the platen drum 50 and is wound around the platen drum 50 by rollers 56 and 57, and is accurately fed.

Further, a manual feed detection switch 69 made of, for example, a photo coupler is provided in the guide section 200 to detect manually fed paper, and is driven in response to the detection of this manual feed detection switch 69 to detect paper fed manually. A pair of rollers 66 for feeding the paper PeW1 is provided. The paper P conveyed by this pair of rollers 66 is guided to the registration rollers 55 via a guide path 68 and a switch 67, which is a detection means, such as a microswitch.
As described above, it is wound around the platen 50 and is fed accurately.

The switch 67 is normally in an on state, and is turned off in response to the passage of paper. Further, the guide section 200 is provided with a manual feed guide (not shown) that is set according to the width of the paper when feeding the paper. The mutual spacing between the manual feed guides is supplied to a seed control section, which will be described later.

On the other hand, the thermal head 51 is connected to the thermal transfer ink ribbon 5.
The paper P is pressed against the platen 50 through the ninth
As shown in Figure (a), the ink 601 on the thermal transfer ink ribbon 52 is heated and melted.
is transferred onto paper P.

Further, the thermal transfer ink ribbon 52 is illustrated in FIG. 9(b), for example.
), yellow (Y) and magenta (M) with approximately the same size as paper P, as shown by range A.

Each cyan (C) ink portion 60a, 60b.

60c side by side, or yellow (Y), magenta (M), cyan (C), and black (as shown in the range opening).
BL) each ink section 60a, 60b.

60c and 60d are arranged side by side, and after transferring one color at a time, the paper P is returned to the transfer starting position and accurately overlapped one after another.

In addition, each ink portion 60a7' of the thermal transfer ink ribbon 52
On the side edges corresponding to Ll to 60d, there is a barcode B necessary for identifying each ink portion 60a to 60d and controlling the leading edge of each ink portion 60a to 60d to coincide with the leading edge of paper P.
C is provided. This barcode BC is read by a barcode detector (not shown).

If the thermal transfer ink ribbon 52 is provided with a black ink portion 60d, this black ink portion 60d is used when it is desired to produce black clearly.

Even if the ink does not have the black ink portion 60d, substantially black can be produced by overlapping three colors (60a to 60c).

In this way, the paper P is reciprocated by the number of colors by the rotation of the platen drum 50, but the path of the paper P at this time is the first one, which is sequentially arranged along the lower surface of the paper output tray 12. Second
guides 61 and 62.

That is, the transfer operation will be explained with reference to FIGS. It passes through and is wound around the platen drum 50 (see FIG. 10 (a>)).

Next, the platen drum 50 rotates using a pulse motor (not shown) as a driving source to transport the paper P at a predetermined speed, and a thermal head 510 heating element formed in a line tread shape runs along the axial direction of the platen drum 50. (not shown) generates heat according to the image information, and the ink 60 of the thermal transfer ink ribbon 52 is transferred to the paper P.

Further, the leading edge of the paper P that has passed through the platen drum 50 is sent onto a first guide 61 provided along the lower surface of the paper output tray 12 by a gate 64 for a second distribution (
(See FIG. 10(b)).

In this way, the paper P onto which the ink 60 of one color has been transferred is transported backwards by reversing the platen drum 50, and is also transferred to the first guide 61 by the rotational displacement operation of the first distribution gate 63. It is sent onto a second guide 62 provided along the lower surface (see FIG. 10(C)).

As described above, by reciprocating the paper P a plurality of times, a plurality of colors are transferred.

Finally, the paper P to which all the colors of ink 60 have been transferred is
The paper is guided by the second sorting gate 64 to a pair of paper discharge rollers 65 and discharged onto the paper discharge tray 12 (see FIG. 10 (d)).

Next, the overall control system of the image forming apparatus shown in FIG. 4 will be schematically explained.

This control system includes a main control section 110, a 101st control section 111, and a second sub-control section 11 provided in the signal processing section 100.
It has 2. The main control unit 110 includes an operation panel, a correction circuit 124, a luminance/color difference separation circuit 125, and an image quality improvement circuit 1.
26, color signal conversion circuit 127, binarization circuit 128, mode changeover switch 121, operation key part 122, display section 12
3. It is connected to the 1u1 control section 111 and the second sub-control section 112, respectively, and controls these. The first flI control section 111 includes a light source control section 114, a motor drive section 115,
The light receiving means 18. It is connected to the A/D converter 19 and the resolution converter 120, respectively, and controls these. The light source control section 89 is connected to the illumination lamp 116 and controls the amount of light thereof. The motor drive section 115 is connected to the scanning motor 30 and drives it. Second sub-control unit 1
12 is connected to a thermal head temperature control section 132, the thermal head 142, a detection switch 129, and a drive section 130 to control them.

Further, the drive unit 130 is connected to a drive system and drives each element such as a motor and a solenoid.

Here, the color signal conversion circuit 127 will be explained in more detail with reference to FIG. The luminance signal @(I>, color difference signal 1 (C1), and color difference signal 2 (C2)) sent from the image quality improvement circuit 126 are respectively sent to the color signal conversion circuit 12.
Sent to 7, here Y.

Any one of M, C, and B color signals is sent to the binarization circuit 128;

The selection of C and B color signals is performed by the main control section 110. That is, as shown in Table 1 below, the main control unit 11
The Y, M, C, and B color signals sent to the binarization circuit 128 are selected by the combination of the signals 0 and a and b. Note that the above color signals are automatically selected sequentially in the normal color copying mode. (For example, the order of Y-M-+C,→B) Table 1 Next, the operation of the image forming apparatus shown in FIG. 4 will be explained with reference to FIGS. 13 to 16.

When this device starts copying the original 220, the image reading means 15 reads and scans the original, and the paper is fed from the paper feed cassette 13 to the paper feed side transport path 150.

First, reading scanning by the image reading means 15 and signal processing of the read image information will be explained.

The light irradiated onto the original from the light source lamp 201 hits the original 220 and is reflected, and is reflected by the first mirror 203, the second mirror 204, the third mirror 205, the imaging lens 206,
The light passes through the fourth mirror 45.degree. 46 and enters the light receiving means 18, where it is imaged.

At this time, when reading the document 202 at variable magnification, the above-mentioned scanning motor 30 is started to scan the first and second carriages 20, 21 along the document table 202, and the spiral shaft 31 is driven to 32 is moved along the document table 202, and a 1/2 optical system, for example, based on the operating principle of the image reading means 15 shown in FIG. 1 is set.

In this way, the CCD line sensor 1 of the light receiving means 18
The optical signal containing the image information focused on 7 is converted by this CCD line sensor 17 into a color signal which is an analog signal of cyan (C), green (G), and yellow (Y), and then sent to an A/D converter. Sent to 119. A/D converter 119
converts each of these color signals into digital signals and sends them to the resolution conversion section 120. The resolution conversion unit 120 performs resolution conversion to match the resolution of the light receiving means 18 and the resolution of the thermal head 142, and converts the result to the correction circuit 12.
Send to 4. The correction circuit 124 performs correction processing on each of the R, G, and B color signals sent from the resolution converter 120 in order to correct variations in the photoelectric converter 118, and sends the results to the luminance color difference separation circuit 125. . The luminance/color difference separation circuit 125 uses the R, G, and B signals sent from the correction circuit 124.
Various calculation processes are performed on each color signal of the luminance signal (■
), color signal 1 (C1), and color difference signal 2 (C2), and send them to the image quality improvement circuit 126.

The image quality improvement circuit 126 analyzes the luminance signal 12 color difference signal $2 sent from the luminance color difference separation circuit 125, performs image improvement processing such as edge emphasis and specifying one character, and sends the signal to the color signal conversion circuit 127. send.

The color signal conversion circuit 127 performs color conversion based on the luminance signal 1 color difference signal 11 color difference signal 2 that has been subjected to image quality improvement processing, and converts yellow (Y), magenta (M), cyan (C), and black (B). [Three primary colors (Y, M, C) plus B when printing]
Convert to any one color signal and binarize 'If! 1
Send to 128. The binarization circuit 128 is the color signal conversion circuit 1
The multi-valued color signal (any one of Y, M, C, B) sent from 27 is subjected to gradation conversion processing using, for example, a dither method, and converted into a binary code for printing. is made and sent as is to the thermal head temperature control section 32.

The thermal head temperature control section 132 sends a print signal to the thermal print head 142 based on the binary code.

The thermal print head 142 heats and melts the ink as a colorant on the ink ribbon 143 in response to this print signal, and prints (image formation) on the paper P that is sent through a conveyance process as described below. .

Next, FIG. 13(a) shows the conveyance process of the paper P.

(b), and will be explained with reference to FIGS. 14 to 16.

The paper P taken out from the paper feed cassette 13 is aligned by the registration rollers 152, and then transferred to the platen drum 140.
The gripper 165 disposed at the tip P1
(non-image area) is fixed to the outer peripheral surface of the platen drum 140. Note that the paper P fed from the manual feed guide 13A
The platen drum 14 also operates in the same manner as described above.
Fixed to 0.

Next, the platen drum 140 starts normal rotation (clockwise rotation in FIG. 15).
Wrap paper P around the outer peripheral surface of 0 itself. The wound paper P is pressed against the outer circumferential surface of the platen drum 6 by a pressure roller, thereby preventing positional shift during overlapping printing.

The paper P, whose leading end P1 is fixed by the gripper 165, is wound around the platen drum 140 by clockwise rotation, and then its leading end P1 is attached to the thermal print head 1.
42, this thermal print head 142 is pressed against the platen drum 140 side, and printing is performed through the process described above.

At this time, if the gripper 165 is protruding outside the circumference of the platen drum 140 as shown in FIG.
Thermal print head 1 must be removed after 5 has escaped sufficiently.
42 pressure cannot be applied, the leading edge P1 of the paper P
The width becomes large. Therefore, it is preferable that the gripper 165 enters inside the circumferential surface of the platen drum 140 as shown in FIG.

Furthermore, as shown in FIG. 16, the gripper 165 extends in the longitudinal direction (axial direction) of the platen drum 140, so that alignment can be performed using the contact surface of the paper P on the gripper 165. In this case, the registration roller 152 can also be omitted.

At the stage when printing of the first color is completed by the above-described printing operation, the platen drum 140 has completed approximately one revolution.

At this stage, the printing operation of the thermal print head 142 is temporarily canceled. Then, the ink ribbon is wound up and the second color is cued up. Then, the platen drum 140 starts rotating clockwise again, and when the leading end P1 passes through the printing area, the thermal print head 1
42 is pressurized and the next color is superimposed and printed. In this way, in the case of full-color copying, printing operations are performed four times for yellow, magenta, cyan, and black, or three times for yellow, magenta, and cyan. It goes without saying that in the case of monochromatic copying using only black or the like, one printing operation is performed.

When discharging the print flow faP, the platen drum 140 rotates clockwise until the rear end of the paper P reaches the paper guide provided in the paper discharging side conveyance path 151.
Then it rotates backwards.

As a result, the paper P is moved through the paper guide and the paper ejection roller 15.
3 and then conveyed to the paper discharge tray 12.

At this time, the gripper 165 releases the paper P.

The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the invention.

For example, in the embodiment shown in FIG. 4, the optical system shown in FIG. 1 is used, but the optical system shown in FIG. 2 or 3 can also be used.

[Effects of the Invention] According to the present invention described above, it is possible to change the distance between objects and images during image reading with variable magnification, thereby preventing optical deterioration and positional deviation, and improving the image quality of formed images. It is possible to provide an image forming apparatus that can perform various functions.

[Brief explanation of the drawing]

FIG. 1 is a principle explanatory diagram showing an optical system of an image reading means in an embodiment of the present invention, FIG. 2 is a principle explanatory diagram showing another example of the same optical system, and FIG. 3 is a general outline of the same optical system. 4 is a schematic cross-sectional view showing an embodiment of the image forming apparatus of the present invention, FIG. 5 is a cutaway perspective view showing the drive system of the same device, and FIG. 6 is an example device. 7 is a plan view showing the operation panel of the device shown in FIG. 6, FIG. 8 is a schematic sectional view showing an outline of the image forming means of the device shown in FIG. 6, and FIG. 9(a) is an explanatory diagram showing the positional relationship of the thermal head, ink ribbon, and paper in the apparatus shown in FIG. 6, and FIG. 9(b) is an abbreviated plan view showing the ink ribbon inserted into the apparatus shown in FIG. 6. , FIG. 10 (a>, (b)
, (c) and (d> are explanatory diagrams showing the transfer operation of the apparatus shown in FIG. 6, respectively. FIG. 11 is a block diagram showing the overall control system of the apparatus shown in FIG. 4, and FIG. 12 is a diagram showing the overall control system of the apparatus shown in FIG. 4. Explanatory diagram showing the operation of the color signal conversion circuit shown in FIG. 11, FIG. 13(a)
, (b) are respectively schematic cross-sectional views showing the conveyance state of the paper in the apparatus shown in FIG. The figure is a perspective view showing the positional relationship between the paper and the gripper, and FIG. 17 is a schematic explanatory view showing the optical system of the conventional apparatus. 1... Apparatus body, 5... Image forming means, 15...
Image reading means, 16.16A... Correction mirror, 17... CCD line sensor, 18... Light receiving means,
1'18 Figure 3 Figure 5 Funeral Figure 8 Figure 11 Figure 12 (b) Figure 13 Figure 14 Figure 17

Claims (3)

[Claims] (1) In an image forming apparatus equipped with an image reading means that optically scans a document placed on a document table and provides image information read by this scanning to an image forming process on an image forming medium. , the image reading means includes an imaging means disposed in the optical path of the reflected light from the document, and a light receiving means whose optical path length with respect to the imaging means can be changed, and when reading the image information at variable magnification, the light receiving means An image forming apparatus characterized in that the image forming apparatus itself is movable. (2) The image forming apparatus according to claim 1, wherein the light receiving means is constituted by a CCD line sensor. (3) The light receiving means includes a CCD line sensor and this CCD line sensor.
2. The image forming apparatus according to claim 1, further comprising a mirror disposed in an optical path between a CD line sensor and said image forming means.