JP2921908B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus which reads image information of an original and sequentially thermally transfers a plurality of color materials to form the original. The present invention relates to a heat-sensitive multicolor image forming apparatus for copying image information.

(Prior Art) In general, a multicolor image forming apparatus includes an image reading unit that reads image information of a document, an image that converts image information read by the image reading unit into an electric signal, and performs predetermined image quality improvement and encoding. A processing unit; and an image forming unit that outputs the read image information to the transfer material.

The image reading unit transmits a document table on which the document or the object to be read is placed, an illumination device for illuminating the document table, and reflected light from the document illuminated by the illumination device, that is, information about the document or the object to be read. The optical device includes an optical device and a photoelectric conversion device that receives reflected light transmitted by the optical device and converts the reflected light into an electric signal.

Further, the image processing unit processes and encodes information of the document or the object to be read which has been read by the reading unit, that is, converted into an electric signal, according to a predetermined method, and outputs it as a print signal to the image forming unit. The image processing circuit includes a plurality of electric circuits and a control device such as a main control circuit for driving the image processing circuit and controlling the operation of the entire image forming apparatus.

On the other hand, based on a print signal supplied from the image processing unit, the image forming unit sequentially prints a plurality of color materials on the transfer material, and supplies the transfer material to the printing device. In addition, a feeding / discharging device for discharging the transfer material printed by the printing device after printing is provided.

In the above-described multicolor image forming apparatus, image information of a document or an object to be read is stored in an image forming optical device including a color separation mechanism, that is, in a three-dimensional image forming apparatus.
The light is transmitted to a photoelectric conversion device, that is, an image reading sensor via optical members such as a color separation filter, an imaging lens, and a plurality of folding mirrors, and is converted into an electric signal, that is, an image signal by the image reading sensor. The image signal is processed by the image processing unit to improve the image quality such as intensity correction, contour correction or color correction for each color component, to replace each color component with a complementary color, and to convert the color signal into a color signal including density information. ,as well as,
Image processing is performed according to a predetermined method such as conversion into a binary signal including gradation information, and is output to a printing device as a print signal. The corresponding print head is driven by this print signal, and the ink ribbon supplied between the print head and the transfer material is fed to a predetermined position in advance and the color is transferred to the transfer material which is waiting at the print start position. The material is transferred. The transfer of the color material to the transfer material is repeated in accordance with the number of the color signals (a plurality of color materials are provided because the image forming apparatus is a multicolor image forming apparatus), and the color material is overlaid on the transfer material. A multi-color (color) image is reproduced.

(Problems to be Solved by the Invention) In the above-described image forming apparatus, that is, the thermal transfer type multi-color image forming apparatus, several times the printable transfer material (the multi-color image forming apparatus normally separates white light into (A print signal is formed for each component, and printing is repeated for each color component). This means that, for example, when the breaker trips during the copying operation, that is, when the power of the apparatus is shut off for some reason, or when the transfer material is jammed inside the apparatus during a normal copying operation, it is left inside the apparatus. Unless the transfer material is removed, the contact pressure between the transfer material and the color material during printing may not be uniform, deteriorating the image quality of the printed image, and wasting expensive color material. There is. Further, if printing is repeated without noticing that the transfer material remains inside the apparatus, the expensive print head may be damaged.

[Constitution of the Invention] (Means for Solving the Problems) The present invention has been made based on the above-mentioned problems, and is an image forming means for forming an image by supplying a color material on a sheet based on an image signal. Supply means for supplying a sheet on which an image is formed by the image forming means, and winding the sheet supplied by the supply means at a position where the image forming means performs an image forming operation Holding means for holding, disposed near the holding means,
Detecting means for detecting the presence / absence of paper; and detecting the presence / absence of paper remaining in the holding means during the movement of the holding means for at least one cycle before starting the image forming operation by the image forming means. And control means for controlling not to start an image forming operation by the image forming means when there is a remaining sheet, thereby providing an image forming apparatus.

Also, the present invention provides a converting means for reading information on an object to be read, converting the information into an electric signal, and further converting it into a print signal; a printing means driven by supplying a print signal from the converting means; Supply means for supplying a transfer material to be printed by the means, disposed between the transfer material supplied from the supply means and the printing means, and supplying a color material to the transfer material by driving the printing means A color material supply unit and the transfer material are wound, and the color material supply unit and the printing unit are pressed against each other, and the color material is transferred to the transfer material, and a transfer material holding unit is disposed near the holding unit, Detecting means for detecting the presence or absence of the transfer material; and detecting the remaining transfer on the transfer material holding means during at least one period of movement of the transfer material holding means prior to the printing operation by the printing means. Lumber Presence is detected, and if there is residual transfer material, there is provided an image forming apparatus characterized by comprising a control means so as not to start the printing operation by the printing means.

(Operation) According to the image forming apparatus of the present invention, the transfer material detector is provided in the vicinity of the member for holding the transfer material in the printing unit, and the presence or absence of the transfer material on the holding member is checked at the same time as the power supply of the apparatus is turned on. Is detected. Further, at the time of initialization by turning on the power, the presence or absence of the transfer material on the holding member due to at least one idle rotation of the holding member is detected. In this case, if the transfer material remains on the holding member, the power of devices other than the display device is cut off. Therefore, even when the transfer material remains on the holding member, the transfer material is reliably detected when the power is turned on, and waste of the color material or damage to the print head can be prevented.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a cross-sectional view of the color image forming apparatus according to the embodiment of the present invention, in which a driving mechanism of a color image forming apparatus capable of forming an image of a plurality of colors is omitted.

The image forming apparatus 2 includes a leg portion (base rubber, a lock bolt, a spacer bolt, or the like) 8 that supports the image forming device 2, an image forming portion 6 having units or devices described below, and a fulcrum 7 of the image forming portion 6. The image scanning unit 4 is provided so as to be rotatable around the center of rotation and houses units or devices described below.

The image scanning unit 4 is formed of, for example, a transparent glass plate, and has a document table 10 on which a document D is placed, disposed near the document table 10, or integrated with a part of the document table 10. , A document holder 12 for bringing the document D into close contact with the document table 10, an interface device for enabling connection with a device such as a computer, and decoding information or signals supplied from peripheral devices. An interface panel having a control mechanism such as a signal conversion device for driving the image forming apparatus, and enabling the image forming apparatus 2 to be used individually or simultaneously as an external printer device or an image reading device.
An operation panel 14 (the second panel 16) is provided so that information necessary for operating the image forming apparatus 2 is input by an operator.
(The figure is a sectional view and cannot be seen.)

The image scanning unit 4 includes a lamp 2 for illuminating the document D inside the document table 10 (that is, below the document table in FIG. 2).
2. A main reflector 24 and a sub-reflector 26 for condensing the illumination light generated from the lamp 22 on the original D, and a part L of the reflected light from the original D toward a second carriage 30 described later. A first carriage 28 is provided which has a first mirror 28 to be moved and is arranged to be movable in parallel with the document table 10 by a pulse motor (not shown) via a toothed belt (not shown).

The image scanning unit 4 further includes second and third mirrors 32 and 34 disposed at right angles to each other and reflecting reflected light L from the document reflected by the first carriage toward a reading unit described later. With respect to the first carriage via a toothed belt (not shown) for driving the first carriage.
A second carriage 30 is provided which is moved at a half speed.

Further, the image scanning unit 4 imparts convergence to the image information of the original D to the reflected light L from the second carriage, that is, the image information of the document D, and forms an image of the image information at a desired magnification by moving itself. An imaging device 42 movably disposed via a drive mechanism (not shown), a color separation filter 43 for separating reflected light L into three primary colors, and a reflection light L disposed at a right angle to the light receiving surface of a conversion device 48. Fourth and fifth mirrors 44 and 46 movable along the optical axis by a drive mechanism (not shown) in order to correct the change in the focal length due to the movement of the imaging device 42 while turning back again. The first mentioned above
To the reflected light L from the original D guided by the fifth mirror
And a reading unit 40 having a converter 48 for converting the reflected light L into an image signal S.

In addition, the image scanning unit 8 includes an image processing unit 50 that converts the image signal S converted by the conversion device 48 into a print signal X according to a predetermined method, and the print signal X is transferred to the transfer material P. A print control unit for performing accurate printing is included together with the image processing unit 50, and a main body control unit 60 that controls the entire image forming apparatus 2 is provided.

On the other hand, the image forming unit 6 includes a print head for outputting the information of the document or the object D read by the image scanning unit 4 and converted into the print signal X by a predetermined method to the transfer material P.
A cartridge 79 containing an ink ribbon 78 for supplying a predetermined color material to the transfer material P by driving the print head 76 and rollers 79F and 79R around which the ink ribbon is wound; A gripper 74 for holding the transfer material P, a pressing roller 71 for holding down the transfer material P, and a print head release mechanism 92 are arranged on its own, and the transfer material P whose surface is formed of an elastic member such as rubber is used. A printing unit 70 having a printing drum 72 held on the circumference is provided.

Further, the image forming section 6 includes transfer materials P of various sizes.
83, a paper feed roller 81 for pulling out the transfer material, that is, the paper P, one by one from the cassette 83, and a transport roller 82 for feeding the paper P toward the printing drum 72.
And a pair of guide plates 84 forming a feeding path, the cassette
A part of the sheet 83, that is, the lid 89, is integrated with the sheet P, and is of a size different from the sheet P stored in the cassette 83 (one side of the sheet discharged to the sheet discharge tray is printed thereon). Paper P, which may be the same size or simply the same size)
, A discharge guide 86 for discharging the paper P separated from the printing drum 72 after printing, and a paper supply / discharge unit 80 having a paper output tray 88 for stocking the paper P. Have.

The image forming unit 6 further includes a power supply unit 9 for driving each device or unit housed in the image scanning unit 4 and each device provided in the image forming unit 6 itself, and a driving device and a driving force (not shown). It has a transmission mechanism.

FIG. 1 shows details of a print drum incorporated in the image forming apparatus shown in FIG.

The printing drum 72 is disposed on the circumference of the drum 72 and outside the image-receiving areas at both ends of the paper P, and the gripper 74 holding the leading end of the paper P. There is provided a pressing roller 71 for removing floating or wrinkles of the sheet P during the accompanying winding operation.

The printing drum 72 is on the circumference of the drum 72 and is several mm from the surface of the drum 72 formed of an elastic body such as rubber.
A paper detector 77 that is arranged closer to the center of the drum than the width of the smallest printable paper at a height of about several tens mm, and detects the presence or absence of paper P; and drum
A gripper position detector 75 is disposed on the cylindrical surface side of the drum 72 and detects the rotation of the gripper 74 disposed at a predetermined position of the drum 72, that is, the position of the gripper 74 accompanying the rotation of the drum 72.

Further, the printing drum 72 is composed of, for example, a roller formed of a resin or the like and a support member formed of a metal or the like. A print head release device 92 is provided outside the area. This print head release device 92
As shown in FIGS. 3A to 4 described below,
A plurality of grippers are arranged outside the image area of the transfer material P and are formed slightly higher (larger) than the projecting portion t from the drum 72 of the gripper 74 (indicated by u in FIGS. 3A to 4). The print head 76 is prevented from being damaged by the collision of 74.

One transfer material, ie, sheet P, fed from the feeding / discharging section 80
Is wound around the circumference of the drum 72 while lifting and wrinkles are removed by the pressing roller 71 with its leading end held by the gripper 74. The gripper 74, that is, the leading end of the paper P, is detected by the gripper position detector 75, and the drum 72 is made to stand by at a predetermined printing start position.

FIGS. 3A and 3B show details of a printing unit incorporated in the image forming apparatus shown in FIG. FIG.
FIG. 3 is a partially enlarged view showing details of a print drum and a print head incorporated in the image forming apparatus shown in FIG. 2. 3B
FIG. 3 is a schematic diagram showing a state during a rotation operation of the print drum and print head shown in FIG. 3A.

The printing drum 72 is ejected from the surface of the drum 72 slightly more than the ejection t at the rear end of the gripper 74 due to the rotation of the gripper 74 and the gripper 74 caused by the rotation of the gripper 74 (u
The print head release device prevents the print head 76 from being damaged by the protrusion of the gripper 74 from the drum 72.
92 are equipped.

On the other hand, the print head 76 includes an eccentric cam 73 that presses the head 76 itself with a predetermined pressure against an elastic body, that is, rubber, formed on the surface of the drum 72. An ink ribbon 78 supplied from a cartridge 79 which is a separate unit (shown schematically in FIG. 2) is inserted between the print head 76 and the print drum 72.

The print head 76 is supplied with a print signal X to be described later, moves the drum 72, that is, the paper P, to a predetermined print start position, and when the print operation is enabled, the eccentric cam 73 rotates to rotate the print drum 72. Pressed to. At this time, the ink ribbon positioned between the print drums 72 is
78 is brought into close contact with the sheet P and is moved by the rotation of the drum 72 at the same peripheral speed as the surface of the drum 72, that is, the sheet P. This ink ribbon 78 moved in synchronization with the rotation of the drum 72
Is taken up by a take-up roller 79F (cartridge).

The drum 72 around which the paper P is wound rotates in a predetermined direction at the start of a printing operation described later (in this embodiment, counterclockwise, ie, counterclockwise as shown in FIG. 2).
A print head release mechanism 92 is provided in front of the slipper 74 in the rotation direction.
Is arranged, after the rear end of the paper P passes through the print head 76, the print head 76 is released from the pressure contact with the drum 72 by the print head release mechanism 92 (ie,
In FIG. 3B, it is pushed down). After the gripper 74 has passed, the print head 76 moves the drum 72, that is, the paper P, to a predetermined printing start position, and when the next printing operation becomes possible, the print drum 76 is rotated again by the rotation of the eccentric cam 73. Pressed to 72.

FIG. 4 is a schematic diagram showing another embodiment of the print drum and print head, that is, the print head release mechanism shown in FIG. 3B.

The printing drum 72 includes a gripper 74 and the gripper 74.
A print head release mechanism 93 formed by a protrusion (projection) of rubber surrounding the surface is provided in the front in the rotation direction of the print head. The print head release mechanism 93 does not require any special processing on the drum 72 main body (it is only necessary to change the shape of the rubber wrapped around the drum 72 main body), so that the print head release mechanism can be provided with a simpler structure. .

In FIG. 5, the information of the manuscript or the object to be read is read,
FIG. 2 is a block diagram of a control unit in the image forming apparatus that controls each process and unit that converts the print signal into a print signal and prints on a transfer material.

The control unit 60 includes an image processing unit 50 to be described later, a main control device or CPU 61 having individual control blocks for controlling each process and unit described below, and an input / output unit that exchanges signals with each process and unit. It has an output (I / O) port or input / output line. In FIG. 5,
For example, for each device or unit indicated by a double frame such as the lamp 22, the name of the control unit should be originally displayed. However, since each control unit is formed integrally with the CPU 61, it is convenient. Device or unit connected to each control unit.

FIG. 6 shows an operation at the time of initialization (initial setting) in the image forming apparatus in which the print drum shown in FIGS. 1 to 4 is incorporated.

When the power is turned on in the initialization by turning on the main switch (not shown) of the image forming apparatus 2, that is, the printing drum 72, the printing drum 72 detects whether or not the paper P is wound around the drum 72 by the paper detector 77 (STP1). ). here,
When the paper P is detected, a JAM display is performed (STP4), and all outputs other than the display system, that is, the output to the operation panel 14 are turned off (STP4).
TP5). On the other hand, if the paper P is not detected in STP1,
The printing drum 72 idles in a predetermined direction (STP2). Here, the idle rotation is performed for at least one circumference of the outer circumference of the drum, and the presence or absence of the winding of the paper P by the paper detector 77 is detected again (STP3). If the winding of the sheet P is not detected by this idling, the gripper 74 is detected by the gripper detector 75.
That is, the position of the sheet P is detected (STP6). Thereafter, based on the position of the gripper 74, the paper P is moved to the print start position (STP7), and waits until a print start signal described later is supplied (STP8).

7A and 7B show details of an ink ribbon used in the printing unit of the image forming apparatus of the present invention and a cartridge containing the ribbon. FIG.
FIG. 7B is a plan view showing an ink ribbon having inks corresponding to four color components, and FIG. 7B is a schematic diagram showing a cueing method of an ink ribbon formed of four colors.

The ink ribbon 78 is a complementary color 78Y = yellow corresponding to each of the three primary colors of light obtained by decomposing white light used for forming a plurality of colors (colors) described later, that is, red r, green g, and blue b. , 78M = magenta, 78C = cyan, and 78B = black to replenish the ink density corresponding to the black bk removed by under color removal described below.

Each of the color components 78Y, 78M, 78C, and 78B is a maximum paper size that the image forming apparatus 2 can print, for example, A3
Alternatively, since the entire surface of A4 paper is printed in close contact, the width H of the ink ribbon is H = 297 mm or more when printing on A3 paper, and when printing on A4 paper,
H = 210 mm or more. When printing on A3 paper, the length 1 per color for each color component is 1 = 42
When printing on A4 paper with a length of 0 mm or more, l = 297 mm or more. In this case, an ink ribbon that can print on A3 paper may be used, and printing may be performed on horizontally placed A4 paper.

The ink ribbon 78 has ink information 78a, 78b, 78c, 78d, 78e corresponding to each color component at one end in the longitudinal direction. The ink information 78a to 78e is a code string based on a combination of a bar code or a punched hole. For example, in this embodiment, one color is used for four colors of 78Y, 78M, 78C, and 78B.
78b indicating the first color of the ink ribbon formed in the unit; 78a, 78 indicating the color of each color component, ie, Y, M, C, B
c, 78d and 78e are arranged at predetermined positions.

According to FIG. 7B, the ink information 78a to 78e are stored in a cartridge 79, and are read out via an ink information reading unit 79Y of the cartridge, that is, a detection light generation unit 79G and a detection light reception unit 79D. This ink information 78a, 78b, 78c, 78d, 78
“e” is used for positioning or color designation at the time of printing.

Next, an outline of the operation of the image forming apparatus incorporating the embodiment of the present invention will be described.

In the image forming apparatus 2, when a main switch (not shown), that is, a power supply is turned on, a paper jam detecting operation shown in FIG.

The document D placed on the platen or the glass 10 is a document holder.
The glass 12 adheres to the glass 10. This original D is
When a copy start signal is input from the operation panel 14 via the operation panel control unit 1, the linear region is illuminated by the illumination lamp 22, the main reflector 24, and the sub reflector 26. The illumination lamp 22 is turned on by the lamp control unit of the CPU 61 only when reading a document, that is, only on the outward path of the first carriage 20.

A part L of the reflected light from the document D passes through the slit area generated by the main reflector 24 and the sub-reflector 26, and the first L
The light is guided to the mirror 28 and is reflected toward the second mirror 32 of the second carriage 30. The reflected light L guided to the second mirror 32
Is bent to the third mirror 34, reflected again, and directed to the reading unit 40. The reflected light L is converted into convergent light by an image forming device or lens 42, is turned back again through fourth and fifth mirrors 44 and 46, and is converted into a photoelectric conversion device or CCD disposed at a predetermined position. An image is formed on the reading surface of the line sensor 48. That is, the reflected light L guided from the linear area of the document D is converted into an electric signal by the CCD sensor 48. Here, the first carriage 20 and the second carriage
30 is moved at a predetermined speed in a direction perpendicular to the main scanning direction, that is, in the sub-scanning direction, by a pulse motor (not shown) driven at a predetermined speed by a pulse motor control unit of the CPU 61. The information of the area is successively guided to the CCD line reading sensor 48, and the information of the entire area of the document D is read (converted into an electric signal).

In the image forming apparatus 2, the lens 42 is movably arranged by a lens motor drive unit of the CPU 61 and a drive motor (not shown) so as to provide a desired magnification. That is, since the distance from the document D to the lens 42 is changed, the distance from the lens 42 to the CCD sensor 48 is changed, and the reflected light L, that is, the information from the document D is enlarged or reduced to a desired magnification. , The magnification guided to the CCD line sensor 48 is varied. At this time, since the shift between the light receiving surface of the CCD line sensor 48 and the focal position due to the change in the focal length due to the movement of the lens 42 must be corrected, the fourth and fifth mirrors 44 and 46 The lens is moved to a predetermined position corresponding to the position in conjunction with the movement of the lens.

In parallel with the series of operations up to this point, one sheet of transfer material, ie, sheet P, is fed from the paper cassette 83 inserted into the feeding / ejection unit 80 or the stack bypass 90 disposed on the lid 89 of the cassette 83 to the printing unit 70. Is sent to Paper P is a paper feed roller
83, a gripper guided to the printing drum 72 via the conveying roller 84 and the feeding path 85 and maintaining a stopped state at a predetermined position.
The tip is held in the gap s of 74. Here, paper P
Is lifted or shifted by a pressing roller 75, and is wound around the surface of the printing drum 72 with the rotation of the printing drum 72 given a predetermined rotation by the main motor control unit of the CPU 61. This paper P is used as a gripper position detector 75.
When the position of the gripper 74 is detected by this, the gripper 74 is moved by a predetermined distance, and the leading end thereof is aligned with the print start position where the print head, that is, the thermal head 76 is opposed to the print head.

On the other hand, the reflected light L formed on the CCD line sensor 48 is
The line sensor 48 separates each color component into red light Lr, green light Lg, and blue light Lb (or yellow Y, magenta M, and cyan C, which are complementary colors of Lr, Lg, and Lb). Line sensor 48 corresponding to each component
r, 48g, 48b, respectively, the electric signal (here,
For convenience, the output signal from the sensor 48r corresponding to the red light Lr is Sr, and the output signal from the sensor 48g corresponding to the green light Lg is S.
g, the output signal from the sensor 48b corresponding to the blue light Lb is Sb).

The reflected light L is converted into an electric signal, that is, an image signal Sr, S
g and Sb are output to an image processing unit 50 formed integrally with the control unit 60, and are converted into print signals Xr, Xg and Xb based on a predetermined method described later.

Here, the image signals Sr, Sg, Sb output to the image processing unit 50
The process of converting the data into print signals Xr, Xg, and Xb will be described.
The image signal S output from the CCD line sensor 48 (actually, for each color component, for example, the line sensor 48
g, 48b, and the image signal S is separated into three signals, Sr, Sg, and Sb. Here, each signal is represented as a representative for convenience.) A / D converter 51, which converts the signal into a digital signal (signal T for identification) and stores reference data relating to the intensity of the reflected light L;
It is output to a resolution conversion circuit 52 that matches the resolution of the CCD line sensor 48 and the thermal head 76. Based on the data output from the memory 59, an image signal U input to the resolving power conversion circuit 52 and matched in resolving power (referred to as a signal U for identification) is an image based on individual characteristics of the CCD sensor 48. The signal S is guided to a correction circuit 52 for correcting a change in the intensity of the signal S, and is subjected to intensity correction (shooting correction). That is, the image signal T whose resolution has been matched is the reference light Lw reflected from the white plate 19.
Is compared with the reference data relating to the intensity of the reflected light L, and the correcting circuit 53 performs the pseudo-correction based on the intensity correction signal Q output from the memory 59. This image signal (signal V for identification) V which has been subjected to the pseudo-correction
Performs a predetermined operation on the image signal V and separates the luminance signal I, the first and second luminance signals through a luminance / chrominance separation circuit 54 that separates the luminance signal I, the first color difference signal C1 and the second color difference signal C2. The signals are separated into two color difference signals C1 and C2, and are guided to an image quality improvement circuit 55 for improving the image quality such as edge enhancement or character identification, and the image quality is improved. The image signals I, C1, and C2 whose image quality has been improved (the signals are denoted by I11, C11, and C12 for identification), that is, the luminance signal I1
1. The first and second color difference signals C11 and C12 are input to a color signal conversion circuit 56 which converts the respective signals into the density of the color of the ink used at the time of printing. A color signal that is converted and contains its density information
It is converted to I21, C21, and C22 (each identified as I21, C21, and C22 for identification). In the color signal conversion circuit 56, together with the color conversion for each color, the ratio (ink density) of the three colors, that is, red r, green g, and blue b, which overlaps with each other to become black bk, is reduced by reducing the amount of ink by that amount. An operation called color removal is performed. That is, when a black bk is formed by overlapping three colors of red, green g, and blue b inks, bleeding or color blur is likely to occur. A method is employed in which the black bk is removed in advance (the ink density relating to the black bk is supplied as it is as a black signal from an ink ribbon at the time of printing, which will be described later). The luminance signal I21 and the first and second color-difference signals C21 and C22 that have been subjected to the color conversion in this manner are output to an area gradation conversion circuit, ie, a binarization circuit 57 that defines the gradation at the time of printing. 2 including key information
The signal is converted into a value signal W and supplied to a thermal head temperature control circuit, that is, a temperature control circuit 62. The binary signal W input to the temperature control circuit 62 is converted into a print signal X used for driving the thermal head 76, and is supplied to the thermal head 76 together with a print start signal from the CPU 61.

Thermal head 76 corresponding to the print signals Xr, Xg, Xb described above
(In this type of image forming apparatus, generally, the color material forming the ink ribbon is actually four colors as described later, but the printing drum or the paper P is rotated a plurality of times in accordance with the number of each color material. Then, one color material is sequentially transferred by each rotation, so that the head is one set).
C and 78B (In this embodiment, the color separation is performed in three colors of red r, green g, and blue b, but the colors of the ink ribbon used in printing are complementary colors. (Y = yellow, M = magenta, C = cyan + black corresponding to black bk = B = black), and ink corresponding to each color component is wound around the printing drum 72 and melted on the paper P waiting at the printing start position. The information is transcribed and recorded. In this case, actually, printing (fusion transfer) on the paper P is performed in a predetermined order for each color component (for example, in the order of 78Y, 78M, 78C, 78B).
That is, printing is performed using the ink ribbon 78Y in the first rotation of the printing drum 72, and printing is performed using the ink ribbon 78M in the second rotation of the printing drum 72 (the printing start position is aligned). (Partially overlap). Further, the ink ribbon 78C is used for the third rotation of the printing drum 72 (with the printing start position aligned), and printing is performed again, and finally printing is performed for 78B. In this way, the inks that have been melt-transferred from the four-color ink ribbons 78Y, 78M, 78C, and 78B are superimposed at predetermined positions, that is, the predetermined colors are reproduced, and the information of the document D is printed on the paper P. Are reproduced in multiple colors.

Here, the drive control of the print drum 72, the print head 76, and the ink ribbon 78, that is, the alignment when printing each color component will be described. As described above, the paper P is inserted into the gripper 74 of the print drum 72, and the print drum 72 is on standby with the gripper 74, that is, the leading end of the paper P being aligned with the print start position. The ink ribbon 78 has ink information 78a indicating the first color.
And 78b, which is the first color, is moved to a predetermined printing start position and is on standby based on 78b and 78b. In this state in which the print drum 72 and the ink ribbon 78 are aligned at predetermined positions, the print signals Xr, Xg, Xb are sequentially supplied to the thermal head 76 together with a print start signal from the CPU 61.

When the print start signal is supplied, the first color ink 78Y is moved at a predetermined speed with the rotation of the drum 72, and the paper P
Are sequentially transferred. When the transfer of the first color is completed, the print head releasing mechanism 92 or 93 described above, that is, the movement of the drum 72, and the rotation of the eccentric cam 73, or these are simultaneously operated, and the print head 76 is moved to the drum.
Leave from 72. At this time, the print head release mechanism 92
Alternatively, by rotating the eccentric cam 73 slightly earlier with respect to the movement of the 93, it is possible to reduce the impact when the release mechanism 92 or 93 comes into contact with the print head 76, and to rotate the print drum 72. The load fluctuation applied to the drive device can be minimized.

The print drum 72 continues to rotate as it is, and waits until the print start position is adjusted again based on the position detection of the gripper 74 by the gripper detector 75 and the second color print start signal is supplied. The ink ribbon 78 is taken up by a take-up roller 79F (schematically shown in FIG. 4) during the movement (rotation) of the printing drum 72 to the second color printing start position. At the same time, the next ink information 78c is detected by the reading unit 79Y, and the second color 78M is moved to a predetermined printing start position. When the movement of the second color, that is, the cueing of the ink ribbon 78M is completed, the eccentric cam 73 is rotated and the print head 76 is rotated.
Is pressed against the print drum 72 again. At the same time, a print start signal of the second color is supplied from the CPU 61 to the drum drive unit and the print head drive unit, and the second color is transferred in the same manner as the first color described above.

In this way, the four color materials are sequentially transferred to the paper P, and the information of the document or the object D is printed. With the rotation of the eccentric cam 73, the print head 76 is separated from the print drum 72 (the pressure contact between the print drum 72 and the print head 76 is released) on the paper P on which the transfer of the four color materials has been completed. The print tray 72 is separated from the print drum 72 by the reverse rotation of
Discharged to 88.

(Effects) As described above, according to the present invention, even when the transfer material remains on the holding member for holding the transfer material, the transfer material is reliably detected when the power is turned on, and the color material is detected. Waste or damage to the print head can be prevented. Therefore, when forming a multicolor image, the consumption of the coloring material and the usage of the transfer material are minimized, and the printing cost is reduced. Further, since the copying operation is not repeated in a state where the transfer material remains in the printing unit, a stable image with little image quality deterioration is output. Furthermore, since damage to the print head can be prevented,
Equipment maintenance costs can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a printing unit incorporated in the image forming apparatus shown in FIG. 2, and FIG. 2 is an image forming apparatus capable of forming an image in a plurality of colors using one embodiment of the present invention. FIG. 3A is a cross-sectional view of a state in which a driving mechanism of the apparatus is omitted, FIG. 3A is a partially enlarged view showing details of a print drum and a print head incorporated in the image forming apparatus shown in FIG. 2, and FIG. FIG. 3A is a schematic diagram showing the state of the print drum and the print head during the rotation operation shown in FIG. 3A; FIG. 4 is another embodiment of the print drum and the print head, ie, the print head release mechanism shown in FIGS. 3A and 3B; FIG. 5 is a schematic diagram showing an example. FIG. 5 is a schematic diagram of a control unit in this image forming apparatus which reads information on a document or a reading object, converts the information into a print signal, and prints the image on a transfer material, and controls each process and unit. FIG. 6 is a block diagram showing 7A is a flowchart showing an operation at the time of initialization (initial setting) in the image forming apparatus in which the print drum shown in FIG. 7 is incorporated. FIG. 7A is a plan view showing an ink ribbon having ink corresponding to each color component. FIG. 7B is a schematic diagram showing a method of cueing the ink ribbon. 71 ... Pressing roller, 72 ... Print drum, 74 ... Gripper, 75 ... Gripper position detector, 76 ... Print head, 77
…… Transfer material detector, 92 …… Print head release mechanism, P ……
Transfer material

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B41J 13 / 22,13 / 00 B41J 17/36

Claims (2)

(57) [Claims] An image forming apparatus having an image forming unit for forming an image by supplying a color material onto a sheet based on an image signal, wherein the supplying unit supplies the sheet on which an image is formed by the image forming unit. Holding means for winding and holding the sheet supplied by the supply means at a position where the image forming means performs an image forming operation; and detecting means arranged near the holding means for detecting the presence or absence of the sheet. Prior to the start of the image forming operation by the image forming unit, during the movement of the holding unit for at least one cycle, the detection unit detects the presence or absence of a sheet remaining in the holding unit, and when there is a remaining sheet, Control means for controlling not to start an image forming operation by the image forming means. 2. A conversion means for reading information on an object to be read, converting the information into an electric signal, and further converting the information into a print signal; a print means supplied with a print signal from the conversion means and driven; A supply unit for supplying a transfer material to be printed by the printer, a supply unit disposed between the transfer material supplied from the supply unit and the printing unit, and a color material supplied to the transfer material by driving the printing unit A color material supply unit, the transfer material is wound, and the color material supply unit and the printing unit are pressed against each other; the color material is transferred to the transfer material; a transfer material holding unit; Detecting means for detecting the presence or absence of the transfer material; and detecting the remaining transfer on the transfer material holding means during the movement of the transfer material holding means for at least one cycle prior to the printing operation by the printing means. Lumber Presence is detected, and if there is residual transfer material, the image forming apparatus characterized by comprising a control means for so as not to start the printing operation by the printing means.