JPS63210967A - Image forming device - Google Patents

Abstract

PURPOSE:To avert unnecessary image printing to a platen drum by forming the image on a held image forming medium in accordance with the detected width of the image forming medium. CONSTITUTION:The image forming device is constituted by having a medium holding means 12 for holding the image forming medium, a medium width detecting means 11 for detecting the width of the image forming medium held by this medium holding means 12, and an image forming means 4 for forming the image on the image forming medium held on the medium holding means 12 in accordance with the result of the detection made by the medium width detecting means 11. The image forming medium held by the medium holding means 12 is subjected to an image forming process by the image forming means 4. The width of the image forming medium is detected by the medium width detecting means 11 at this time. The image forming means 4 forms the image corresponding to the detected width of the image forming medium on this image forming medium in accordance with the result of the detection made by the medium width detecting means 11. The printing of the image information to the unnecessary region is thereby averted and the quality of the formed image is improved.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an image forming apparatus, and more specifically, to a thermal transfer type copying apparatus having a function of detecting the width of copy paper, which is an image forming medium. The present invention relates to an image forming apparatus such as a machine.

(Prior Art) Conventionally, in an image forming means that detects the width of a copy paper and sets a print area of image information on the copy paper based on the detection result, the width of the copy paper is detected. A paper guide placed facing the transport path is used.

However, if this vapor guide is set wider than the width of the copy paper that is actually conveyed along the conveyance path, the printing area of the image information will be set wider than the width of the copy paper, and the copy paper will not be printed. Image information may be printed on the surface of the platen drum where no paper is present. When image information is printed on the surface of the platen drum, the image quality of subsequent printing information will deteriorate unless the printed area is removed.

Additionally, if the width of the copy paper is detected in the middle of the conveyance path before the copy paper is wrapped around the platen drum,
An error in width detection occurs due to variations in the conveyance path due to vertical movement of the copy paper, and there is a risk that image information may be printed on the platen drum.

Generally speaking, some image forming apparatuses using a platen drum do not detect copy paper conveyance information, and in this case, the copy paper may be transferred to the platen drum due to a paper jam, etc. There is a problem in that image information is printed on the platen drum even though it is not wound around the platen drum.

(Problems to be Solved by the Invention) As described above, in conventional image forming apparatuses, the width of the image forming medium used in the image forming process is not properly detected, and as a result, unnecessary image forming is performed. There is a problem in that image information is printed in an area of the medium transport means where no image forming medium exists, resulting in deterioration of image quality.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that can avoid printing image information in unnecessary areas and improve the quality of formed images.

[Structure of the Invention] (Means for Solving Problems) The present invention provides a medium holding means for holding an image forming medium, and a medium width for detecting the width of the image forming medium held by the medium holding means. The image forming apparatus includes a detecting means and an image forming means for forming an image on the image forming medium held in the medium holding means based on the detection result of the medium width detecting means.

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

The image forming medium held by the medium holding means is subjected to an image forming process by the image forming means, and at this time, the width of the image forming medium is detected by the medium width detecting means.

The image forming means, based on the detection result of the medium width detection means,
An image corresponding to the detected width of the image forming medium is formed on the image forming medium.

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

FIG. 1 shows a thermal transfer type color copying machine capable of making multicolor copies, which is the image forming apparatus of this embodiment.

This image forming apparatus includes an original platen 2 formed of, for example, a glass plate provided on the upper part of the apparatus main body 1, and an original (not shown) placed on the original platen 2, which is scanned and attached to the original. An image reading means 3 for reading image information, an image forming means 4 disposed below the image reading means 3, a platen drum 6 as an image forming medium conveying means for conveying copy paper P as an image forming medium, and A document cover 5 that is openable and closable on the upper surface of the document table 2, a paper feed side transport path 7 that supplies document paper to the platen drum 6, and copy paper P discharged from the platen drum 6.
A paper discharge side conveyance path 8 performs a discharge operation, a paper feed means 9 feeds the copy paper P into the paper feed side conveyance path 7, and a paper feed means 9 feeds the copy paper P into the paper discharge side conveyance path 8. A paper discharge tray 10 for storing therein, a medium width detecting means 11 arranged at a predetermined position near the outer periphery of the platen drum 6, and a holding means for the image forming medium mounted facing the surface of the platen drum 6. The gripper 12 is configured to include a gripper 12. The platen drum 6 and the gripper 1
2 constitutes a medium holding means.

The paper feeding side conveyance path 7 includes a paper feeding means 9 and a platen drum 6.
This is for forming a moving path for the copy paper P between the rollers 1 and 2, and includes registration rollers 21 that forcefully feed the copy paper P while aligning the copy paper P along the way.

Further, the paper ejection side conveyance path 8 is for forming a moving path for the copy paper P on which image formation is performed between the platen drum 6 and the paper ejection tray 10, and a paper ejection roller is provided in the middle and at the end thereof. It is equipped with 22.

The paper feed means 9 includes a paper feed cassette 2OA that stores copy sheets P in a stacked state, and a manual feed guide 20B for manually feeding the copy sheets P to the paper feed side transport path 7.

Two pressure rollers 2 are provided on the outer periphery of the platen drum 6.
3, 24, and 25 are arranged so as to be in sliding contact with the platen drum 6, and the copy paper P, one end of which is held by the gripper 12, is pressed against the circumferential surface of the platen drum 6.

Among the pressure rollers 23, 24, 25, the pressure roller 25
, the conveyance path 7 on the paper feed side is slightly wider than the medium width detection means 11.
It is located on the side.

Further, the image forming means 4 includes the medium width detecting means 11.
In contrast, it is arranged at an odd position on the discharge side conveyance path 8 side.

Here, the medium width detecting means 4 will be described in detail with reference to FIGS. 2 to 9.

As shown in FIGS. 3 and 4, the medium width detection means 4 detects the paper size of the copy paper P, for example, As, Bs
, Aa, Ba, and A3 paper sizes, five reflective optical sensors S1 to S5 are arranged in a straight line along the platen drum 6. These reflective optical sensors S1 to S5 each consist of a combination of a light-emitting element and a light-receiving element, and when light from the light-emitting element hits the surface of the copy paper and is reflected, the reflected light is detected by the light-receiving element. The signal is converted into an electrical signal indicating the presence of copy paper P.

1) The i-type optical sensors S1 to S5 are used as transmissive optical sensors that block or transmit the optical path between the light-emitting element and the light-receiving element depending on the presence or absence of the copy paper P. This is because it is difficult to arrange it near the drum 6.

By using the reflective optical sensors S1 to S5 as described above, it is possible to detect the width of the copy paper P conveyed on the platen drum 6.

The principle of detecting the width of a copy sheet by the medium width detecting means 4 will be explained below.

As shown in FIG. 5, reflective optical sensors S1 to S5 are linearly arranged at intervals corresponding to the five paper sizes described above. In this case, if the ON state of the 6 optical sensors S1 to S5 is represented by 1 and the OFF state is represented by 0, the logical value table of the 6 optical sensors S1 to S5 corresponding to the 5 types of paper sizes is shown in Table 1. It becomes like this.

(Margin below) Table 1 On...1 Off...2 By using the logical values of these six optical sensors S1 to S5, the width of each size of copy paper P is converted into an electrical signal. can be detected.

Next, the principle of width detection when the copy paper P whose width is to be detected is disposed diagonally with respect to the platen drum 6 for some reason will be explained with reference to FIGS. 6 to 9.

Here, for simplicity, two optical sensors Sz, 8
Only 2 shall be used. As shown in FIG. 6, the optical sensors St and S2 are arranged at a distance of Ix and J12, respectively, from the center of the paper width of the copy paper P, and the optical sensors Sz and S2 are arranged at a distance of 1/2 of the paper width detected by these optical sensors Sz and 32, respectively.
The length of j! Let it be represented by P.

At this time, when both optical sensors Sz and S2 are turned off at the same time, that is, when the copy paper P is arranged parallel to both optical sensors 31 and S2 as shown in FIG.
As shown in Figure (b), the rear edge of the copy paper P
1. The image forming means 4 may be controlled to end printing on the copy paper P after a certain period of time Tc after passing through S2.

On the other hand, as shown in FIG. 8(a), copy paper P is detected by both optical sensors S1. If the slope is downward to the left in the figure with respect to S2, the time T2 from when one sensor S1 turns off until the other sensor S2 turns off, and one end of the copy paper P at this time. When TX is the elapsed time after passing through the line where both optical sensors S1 and S2 are arranged, the following (1
) holds true.

J12-4'1: D2 = i'p + J12: Tx
...(1) Therefore, from the above formula (1), the following (2)
The formula can be derived.

If T1 is a certain period of time until the end of printing on the copy paper P at this time, this T1 can be expressed by the following equation (3).

Roughly speaking, when the copy paper P is tilted downward to the right as shown in FIG. 9, the fixed time T1 until the end of printing at this time is calculated as follows (4) using the same calculation as in the above case.
It can be expressed by the formula.

As described above, by controlling the image forming means 4 so as to change the printing time on the copy paper P on the platen drum 6 when the copy paper P is tilted, unnecessary printing on the platen drum 6 is avoided. becomes possible.

Next, details of the image reading means 3 are shown in FIGS. 10 and 11.
This will be explained with reference to the figures.

The image reading means 3 includes a first carriage 31 configured to be movable along the document table 2;
1, which is configured to be movable along the document table 2.
A carriage 32, an imaging lens 33, a group of optical path length correction mirrors 34 that corrects the optical path length when magnifying and reading image information attached to a document, and a photoelectric conversion unit 35 using COD.
And, as shown in FIG. 11, the first. Second carriage 31, 32, imaging lens 33, optical path length correction mirror group 34
It is constructed with a drive system that changes the position of.

The first carriage 31 includes a light source lamp 30 as a linear light source, a flipper 36 that focuses the light from the light source lamp 30 onto the document surface, and a second carriage that receives reflected light from the document surface. 32, a first mirror 37 is provided.

The second carriage 32 includes second and third mirrors 38 and 39 that change the optical path of the light from the first mirror 37 and send it to the imaging lens 33.

Also, 1st. The second carriage 31.32 has a drive pulley 40.32 as shown in FIG. Idle pulley 41,4
2.43 and a drive iW1 consisting of a timing belt 44 adjusted to each of these pulleys, and the drive pulley 4.
10 is driven in the direction of the arrow shown in FIG. Further, in this case, the second carriage 32 is driven in the same direction as the first carriage 31 and at 1/2 the speed.

With this configuration, the document surface is scanned while keeping the optical path length from the light source lamp 35 to the imaging lens 33 constant.

The imaging lens 33 is of a fixed focal length type, and the imaging lens 33 is moved in the optical axis direction when changing the magnification.

The optical path length correction mirror group 34 adjusts the imaging lens 33 in response to a change in optical path length caused by a preselected magnification ratio.
The position relative to the 4th. It is composed of a combination of fifth mirrors 45 and 46.

Then, the light from the imaging lens 33 is transmitted to the fourth lens. The optical path is bent by the fifth mirror 45, 46, and the photoelectric conversion unit 35
It is designed to be incident on .

The photoelectric conversion unit 35 captures the reflected light from the original through the above-mentioned optical system and photoelectrically converts it, thereby converting the image information attached to the original into cyan and green.

It separates and outputs a yellow (or red, green, or blue) color signal, and is mainly composed of, for example, a COD image sensor. Signal processing after the photoelectric conversion section 35 will be described later.

Incidentally, as shown in FIG. 1, the driving of the aperture lens 33 and the group of optical path length correction mirrors 34 in the optical axis direction is performed by a spiral shaft 51 driven by a stepping motor (not shown) and this spiral shirt 1-. Using a drive system consisting of a bracket 52 embedded in the bracket 51, the bracket 5
An imaging lens 33 and an optical path length correction mirror 8 connected to
This is done by moving f34 in the optical axis direction.

As shown in FIGS. 1 and 2, the image forming apparatus 4 includes a thermal print head 62 that approaches and separates from the outer peripheral surface of the platen drum 6 with a fulcrum 61 as the center of rotation, and a head surface of the thermal print head 62. An ink ribbon 63 interposed between the copy paper P wrapped around the outer periphery of the platen drum 6 and conveyed, and the ink ribbon 6
3, and a guide roller 66.6 that guides the ink ribbon 63 so as to come into sliding contact with the outer peripheral surface of the platen drum 6.
It is equipped with 7.

It should be noted that the ink ribbon 63 is commonly used in a plurality of colors or in a single color depending on color copying or monochrome copying. The outer periphery of the platen drum 6 is formed of an elastic material such as a rubber cap, and the outer periphery is set to be slightly larger than the length in the longitudinal direction of a maximum paper size (for example, A3).

Next, the control system of the entire apparatus of this embodiment will be outlined with reference to FIG.

This control system includes a main control section 81, a first sub-control section 82, and a second sub-control section 83 provided in the signal processing section 100. The main control unit 81 includes an operation panel, a correction circuit 84,
It is connected to the luminance/color difference separation circuit 85, the image quality improvement circuit 86, the color signal conversion circuit 87, the gradation conversion circuit 88, the first sub-control section 82, and the second sub-control section 83, and controls these sections.

The first sub-control unit 82 includes a light source control unit 89 and a motor drive unit 9.
0. It is connected to the photoelectric conversion section 35, A/D converter 91, and resolution conversion section 92, respectively, and controls these.

The light source control section 89 is connected to the illumination lamp and controls the amount of light thereof. A motor drive unit 90 is connected to the motor and drives the motor. The second sub-control unit 83 includes a thermal head temperature control unit 93, the thermal print head 62, the medium width detection unit 112, and the image forming width control unit 8.
0 and the drive system 95, respectively, and control these dollars. Further, the image forming width control means 80 controls the predetermined time Tc based on the width signal of the copy paper P detected by the medium width detection means 11 (3).

A fixed time T1 is calculated using the formula (4), and the image forming width control section 93 uses these values to control the thermal head temperature control section 93 (described later).
1, that is, it is sent as a printing end signal.

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 86 are sent to the color signal conversion circuit 87, where they are converted into Y and M signals.

One of the color signals of C and BK is sent to the gradation conversion circuit 88, and the Y and M signals are sent to the gradation conversion circuit 88.

The selection of C and BK color signals is performed by the main control section 81. That is, as shown in Table 2 below, the main control unit 81
The Y, M, C, and BK color signals sent to the gradation conversion circuit 88 are selected by the combination of the signals 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 having the above configuration will be explained with reference to a flowchart showing the processing procedure of the entire apparatus shown in FIG.

When this apparatus starts copying a document (ST1), the image reading means 3 scans the document and feeds the document from the paper feed cassette 9 to the paper feed side transport path.

First, reading scanning by the image reading means 3 and signal processing of the read image information will be explained.

The light irradiated onto the original from the light source lamp 30 hits the original and is reflected, and is reflected by the first mirror 37, the second mirror 38,
Third mirror 39, imaging lens 33, fourth mirror/1
5.46, the image is formed on the photoelectric conversion unit 35, and the photoelectric conversion unit 35 converts electrical signals, namely red (R) and green (
G) and blue (B), and send these to the A/D converter 91. The A/D converter 91 converts each analog color signal into, for example, an 8-bit digital multivalued signal and sends it to the resolution converter 92.

The resolution conversion unit 92 performs resolution conversion to match the resolution of the photoelectric conversion unit 35 and the resolution of the thermal print head 62, and sends the result to the correction circuit 84. The correction circuit 84 receives the R, G,
Correction processing is performed on each color signal of B to correct variations in the photoelectric conversion section 35, and the results are sent to the luminance and color difference separation circuit 8.
Send to 5.

The luminance and color difference separation circuit 85 performs various calculation processes on the R, G, and B color signals sent from the correction circuit 84, and outputs a luminance signal (I), color signal 1 (C1), and color difference signal 2 (C2).
> signals and send them to the image quality improvement circuit 86. The image quality improvement circuit 86 receives the luminance signal, color difference signal 19, and color difference signal 9? sent from the luminance and color difference separation circuit 85. is analyzed, subjected to image improvement processing such as specifying two characters with edge emphasis, and sent to the color signal conversion circuit 87. The color signal conversion circuit 87 performs color conversion based on the luminance Shintan 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), black (BK) [three primary colors at the time of printing (Y, M, C)
) plus BK] and sends it to the gradation conversion circuit 88. The gradation conversion circuit 88 receives the multivalued color signal (Y, M, C,
8) is subjected to gradation conversion processing using, for example, a dither method, to create a signal 21 for printing, which is sent as is to the thermal head temperature control section 93. The thermal head temperature control section 93 sends a print signal to the thermal print head 62 based on the 2g1i signal.

The thermal print head 62 heats and melts the ink as a colorant on the ink ribbon 63 in response to this print signal, and prints (images are formed) on the paper P that is sent through a conveyance process as described below.

On the other hand, the copy paper P fed from the paper feed means 9 (for example, the paper feed cassette 20A) to the paper feed side transport path 7 (ST2) is aligned by the registration rollers 21 and then placed on the platen drum 6. The gripper 12 fixes its tip to the outer peripheral surface of the platen drum 6 (ST3). The copy paper P fed from the manual feed guide 20B is also fixed to the platen drum 6 in the same manner as described above.

Next, the platen drum 6 starts normal rotation (clockwise rotation in FIG. 1) (5T5), and the copy paper P is wound around the outer peripheral surface of the platen drum 6 itself. The wrapped copy paper P is pressed against the outer circumferential surface of the platen drum 6 by pressure rollers 23, 24, 25, thereby preventing misalignment during overlapping printing.

In parallel with the winding of the copy paper P by the platen drum 6, the above-described image reading means 3 performs the document reading operation (ST5), thereby generating a signal of the read image information as described above. The process is performed and a binary signal is sent to the thermal head temperature control section 93.

In addition, when the leading edge of the copy paper P passes through the pressure roller 25 (5T6), passes through the media width detection means 11, and reaches the printing area roughly set on the outer peripheral surface of the platen drum 6, the media width is detected. The means 11 operates to detect the paper width of the copy paper P (ST7) and to detect the presence or absence of the copy paper P (ST7).
8), paper length detection (ST9) is performed. When the medium width detection means 11 does not detect the presence of the copy paper P, the second W11 control section 83 controls the drive system 95 based on the detection signal of the medium width detection means 11 to
The rotation is stopped (ST19). Also, Konotogi 1st
The fVJ control section 82 controls the motor drive section 90, stops the scanning motor 50, and stops the scanning of the image reading means 3 (ST20>. Then, in this state, a constant display is displayed on the display section (not shown) of this device. is issued (ST21), and thereafter the movement recovery process (ST22>) will be performed.

On the other hand, when the medium width detection stage 11 detects the paper width (ST7) and the presence of the copy paper P (ST8), the width signal from the medium width detection means 11 is sent to the image forming width control means 80. The image forming width control means 80 sends an image forming width control means based on the width detection principle described above to the thermal head heating control section 93 based on the sent width signal. Thereby, the printing width for the copy paper P is set for the thermal head heating control section 93 (ST10).

In this case, if the length of the copy paper P is detected by the medium width detection means 11 (ST9), the print length in the longitudinal direction of the copy paper P can also be set at the same time (ST
10A>.

In this way, when the binary value corresponding to the image information and the print width (or both print width and print length) are set in the thermal head temperature control section 93, the thermal print head 62 is controlled by the drive system 95. Based on the control, pressure is applied to the copy paper P side wrapped around the outer periphery of the platen drum 6 (
ST11), the print width of the image information is as described above (
or print width and print length) (ST12). Therefore, during printing, printing on the outer circumferential surface of the platen drum 6 where no copy paper P is present is avoided.

Next, when the printing of the first color by the above-described printing operation is completed, the platen drum 6 is in a state of approximately one revolution, and the thermal print head 62 is temporarily released (S
T13).

Then, the ink ribbon 63 is wound up (ST14),
Cueing for the second color is performed. After that, step 1 mentioned above
Steps 1 to 14 are repeated a predetermined number of times, and multicolor printing is performed on the copy paper P. That is, in the case of full-color copying, printing operations are naturally 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.

In this way, when all the printing operations are completed, the platen drum 6 rotates forward until the rear end of the copy paper P after printing reaches the paper guide of the paper discharge side conveyance path 8 (ST1
6) As a result, the photographic paper P after printing is discharged to the paper discharge tray 10 via the paper guide and the paper discharge roller 22 (ST17).

This completes the series of operations (ST18).

As described above, in the apparatus of this embodiment, the paper width detection is performed near the platen drum, so the detection accuracy is good and it can be performed automatically.

Furthermore, compared to the case where a paper width detection means is provided on the paper feed side conveyance path, the number of parts can be reduced and detection errors can be reduced.

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, reflective optical sensors are not limited to the case where they are arranged in a row of five as described above, but by using a roughly increased number of optical sensors, for example, a connected type, it is possible to control not only the paper width but also the amount of paper deviation to the left and right. It also becomes possible to detect. If the printing area by the thermal print head is controlled based on the paper misalignment m, unnecessary printing on the platen drum can be more effectively prevented.

[Effects of the Invention] According to the present invention described in detail above, it is possible to provide an image forming apparatus that can avoid unnecessary printing on the platen drum as an image forming medium conveying means and can contribute to improving image quality. .

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of an apparatus according to an embodiment of the present invention, FIG. 2 is a schematic side view showing the platen drum and image forming means of the same apparatus, and FIG. 3 is a schematic side view showing the platen drum and medium width detection means of the same apparatus. FIG. 4 is a perspective view, and FIG. 5 is a perspective view showing a medium width detection means of the apparatus. Fig. 6, Fig. 7 (a), (b), Fig. 8 (a). (b), FIGS. 9(a) and (b) are explanatory diagrams showing the paper width detection principle, respectively. FIG. 10 is a block diagram showing the configuration of the image reading means of the embodiment device, and FIG. 11 is an image of the same device. FIG. 12 is a block diagram showing the overall system of the device; FIG. 13 is a block diagram for explaining the operation of the color change circuit of the device; FIG. FIG. 14 is a flowchart showing the operating procedure of the device. 4... Image forming means, 6... Platen drum, 11... Medium width detection means, 12... Gripper as clamping means, Sl to S5.
...Reflective optical sensor. Figure 4 Figure 5 Figure 7 Figure 8 Figure 9 Figure 11

Claims (6)

[Claims] (1) a medium holding means for holding an image forming medium; a medium width detecting means for detecting the width of the image forming medium held in the medium holding means; and a medium width detecting means for detecting the width of the image forming medium held in the medium holding means, and a An image forming apparatus comprising an image forming means for forming an image on the image forming medium held by a holding means. (2) The image forming apparatus according to claim 1, wherein the medium width detecting means is provided opposite to the medium holding means. (3) The image forming apparatus according to claim 2, wherein the medium width detection means includes a reflective optical sensor. (4) The image forming apparatus according to claim 1, wherein the medium holding means includes a holding means for holding a part of the image forming medium. (5) The medium width detecting means is provided at a stroke position after the medium holding means has held the image forming medium between the holding means and before the image forming means starts forming the image. The image forming apparatus described above. (6) The image forming apparatus according to claim 1, wherein the medium width detecting means detects the trailing edge of the image forming medium held by the medium holding means.