JP2019109339A - Image formation apparatus - Google Patents

Abstract

To make the first print out time early by making the timing of the image formation start early in accordance with the drawing range of the image.SOLUTION: An image formation apparatus 1 includes: an image formation unit 5 which forms an image of printing data on a sheet S using a heat roller 71; and a control unit 20. The control unit 20 executes: RIP processing of converting the image data made of an object described in a page description language to the printing data; range decision processing of deciding, on the basis of the object, a drawing range PR where the image is formed on a sheet S; region decision processing of deciding, from the drawing range PR, a region in a width direction where the heat roller 71 needs to reach a fixation possible temperature Tf when the image formation unit 5 forms the image on the sheet S; and image formation processing of causing the image formation unit 5 to start image formation on the sheet S at the timing at which the region in the width direction of the heat roller 71 decided by the region decision processing reaches the fixation possible temperature Tf.SELECTED DRAWING: Figure 11

Description

  The present invention relates to an image forming apparatus for fixing an image formed on a sheet by an image forming unit by a fixing member.

  In general, an image forming apparatus having a fixing member waits for the temperature of the fixing member to rise before forming an image on a sheet. In Patent Document 1, when the pixel density of the portion of the unfixed image corresponding to the side edge of the heating roller of the fixing member is high, the temperature of the side edge of the heating roller is sufficiently raised. There is disclosed a technique for starting the above-mentioned fixing after waiting until

JP, 2006-01120, A

  However, even in the image forming apparatus according to the related art, depending on the image drawing range of the portion of the fixing member corresponding to the side end of the heating roller, the fixing is performed until the temperature of the side end sufficiently rises. Sometimes you do not have to wait for the start.

  An object of the present invention is to provide an image forming apparatus capable of shortening the first printout time by advancing the timing of image formation start according to the image drawing range.

  In order to achieve the above object, the present invention comprises an image forming unit having a fixing member and forming an image of print data on a sheet using the fixing member, and a control unit, the control unit comprising: RIP processing for converting image data consisting of an object described in a page description language into the print data, analyzing the image data, and forming a drawing range in which the image forming unit on the sheet forms an image In the range determination processing determined based on an object, and when the image forming unit forms an image on the sheet, the area in the width direction of the fixing member where the fixing member needs to reach the fixable temperature is the drawing The image forming section at the timing when the area in the width direction of the fixing member determined by the area determining process determined from the range and the area determining process reaches the fixable temperature An image forming processing for starting the image formation on the paper by, characterized in that the run.

  Image formation can be started in the image forming unit at a timing before the entire fixing member reaches the fixable temperature. Thus, the image formation start is started according to the image drawing range, as compared with the conventional method in which the image is at least at a portion corresponding to the side end portion of the fixing member until the side end is uniformly heated. In some cases, the first printout time (hereinafter referred to as "FPOT" as appropriate) can be made faster.

  According to the present invention, the first printout time can be made faster by advancing the timing of image formation start according to the drawing range of the image.

FIG. 1 is a conceptual diagram showing the entire configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 6 is a perspective view showing a detailed configuration of a heating roller and a pressing roller provided in the fixing unit. FIG. 2 is a functional block diagram showing a control system of the image forming apparatus. It is an explanatory view of RIP processing. It is a conceptual diagram showing the temperature rising behavior when a heating roller is heated by a heater and temperature rising. It is a graph which expresses the behavior shown in Drawing 5 (b)-(d) still more concretely. FIG. 10 is a diagram showing a virtual region assumed at time t1 at which the center side portion of the heating roller is heated to the fixable temperature Tf. FIG. 6 is an explanatory diagram for explaining a drawing range determined in object units and a drawing range of the entire page in comparison with each other. It is an explanatory view explaining a case where image formation is started at elapsed time t = t1. FIG. 6 is an explanatory view for explaining a case where image formation is started at elapsed time t = t1 + Δt3. FIG. 7 is an explanatory view for explaining a case where image formation is started at an elapsed time t = t1 + Δt2. FIG. 10 is an explanatory diagram for explaining a case where an image rotation process is performed to determine an overlap between a drawing range and a virtual range. It is a flowchart showing the control procedure performed by CPU of a control part. It is a flow chart showing a detailed procedure of RIP processing (Step S100). It is a flowchart showing the detailed procedure of range determination processing (step S200). It is a flowchart showing the detailed procedure of an area | region determination process (step S300). It is a flowchart showing the detailed procedure of an area | region determination process (step S300).

<Overall Configuration of Image Forming Apparatus>
An overall configuration of an image forming apparatus 1 according to an embodiment of the present invention is shown in FIG. In the following description, the front, rear, left, right, upper and lower directions are determined based on the state where the image forming apparatus 1 is installed so as to be usable as shown in FIG. In FIG. 1, the image forming apparatus 1 includes a housing 2, a supply unit 3, a motor 4, an image forming unit 5 as an example of an image forming unit, and a discharge unit 8.

  The supply unit 3 holds and conveys the sheet S as an example of a sheet to the image forming unit 5. The image forming unit 5 is disposed downstream of the supply unit 3 in the conveyance direction of the sheet S, and forms an image of print data on the sheet S conveyed from the supply unit 3. The details of the print data will be described later. The discharge unit 8 is disposed downstream of the image forming unit 5 in the conveyance direction of the sheet S. The discharge unit 8 discharges the sheet S having an image formed thereon and discharged from the image forming unit 5 to the outside of the image forming apparatus 1.

<Supply unit>
The supply unit 3 includes a sheet cassette 30 detachably mounted to the lower part of the housing 2, a sheet feeding mechanism 32, and a conveyance roller 33 a and a registration roller 34 driven by the motor 4.

  The sheet feeding mechanism 32 includes a pickup roller 32a, a separation roller 32b, and a separation pad 32c. In the image forming apparatus 1, a conveyance path L <b> 1 from the sheet feeding mechanism 32 to the discharge unit 8 via the image forming unit 5 is formed. The sheet feeding mechanism 32 separates the sheets S held in the sheet cassette 30 one by one and takes them out, and is conveyed toward the conveyance roller 33a along the conveyance path L1.

  The conveyance roller 33 a is a roller for applying a conveyance force to the sheet S, and is disposed downstream of the sheet feeding mechanism 32 in the conveyance direction of the sheet S. The sheet S conveyed from the paper feed mechanism 32 toward the conveyance roller 33a is nipped by the conveyance roller 33a and the paper dust removing roller 33b, and conveyed toward the registration roller 34 along the conveyance path L1. .

  The registration roller 34 is disposed downstream of the transport roller 33 a in the transport direction of the sheet S. The registration roller 34 corrects the posture of the sheet S. Thereafter, the registration roller 34 conveys the sheet S toward the transfer position at a predetermined timing.

  A pre-registration sensor 11 is disposed upstream of the registration roller 34 in the sheet conveyance direction, and a post-registration sensor 12 is disposed downstream of the registration roller 34 in the conveyance direction of the sheet S. The pre-registration sensor 11 and the post-registration sensor 12 detect the presence or absence of the sheet S at the position.

  The registration roller 34 starts to rotate after a predetermined time has elapsed since the leading edge of the sheet S conveyed along the conveyance path L1 in the conveyance direction has reached the position of the pre-registration sensor 11. The registration roller 34 stops its rotation after a predetermined time has elapsed since the trailing edge of the sheet S in the transport direction has reached the position of the post-registration sensor 12.

  The conveyance roller 33a and the registration roller 34 correspond to an example of a conveyance unit.

<Image formation unit>
The image forming unit 5 includes a process cartridge 50, an exposure unit 60, and a fixing unit 70.

  The process cartridge 50 includes a developer storage chamber 51, a supply roller 52, a development roller 53, a photosensitive drum 54, a transfer roller 55, and the like, and the sheet S conveyed from the supply unit 3 Transfer the image to the surface.

  The developer storage chamber 51 contains toner as a developer. The toner stored in the developer storage chamber 51 is sent to the supply roller 52 while being stirred by a stirring member (not shown). The supply roller 52 further supplies the toner sent from the developer storage chamber 51 to the development roller 53.

  The developing roller 53 carries toner supplied from the supply roller 52 and positively charged by a sliding contact member (not shown). Further, a positive developing bias is applied to the developing roller 53 by a bias applying unit (not shown).

  The photosensitive drum 54 is exposed to light by the exposure unit 60 after its surface is uniformly positively charged by a charger (not shown). The exposed portion of the photosensitive drum 54 has a potential lower than that of the other portions, and an electrostatic latent image based on the image data is formed on the photosensitive drum 54. Then, the positively charged toner is supplied from the developing roller 53 to the surface of the photosensitive drum 54 on which the electrostatic latent image is formed, whereby the electrostatic latent image is visualized to form a developer image. Become.

  A negative transfer bias is applied to the transfer roller 55 by a bias application unit (not shown). With the transfer bias applied to the surface of the transfer roller 55, the sheet S is held at the transfer position between the transfer roller 55 and the photosensitive drum 54 on which the developer image is formed, so that the sheet S It is transported. Thus, the developer image formed on the surface of the photosensitive drum 54 is transferred to the surface of the sheet S.

  The exposure unit 60 includes a laser diode, a polygon mirror, a lens, a reflecting mirror, and the like. The exposure unit 60 irradiates a laser beam toward the photosensitive drum 54 based on the image data input to the image forming apparatus 1 to expose the surface of the photosensitive drum 54.

  The fixing unit 70 includes a heating roller 71 and a pressing roller 72 as an example of a fixing member. The heating roller 71 is rotationally driven by the power from the motor 4. At this time, as shown in FIG. 2, the heating roller 71 includes a heater 71 a, and is heated by supplying power to the heater 71 a. The pressure roller 72 is disposed to face the heating roller 71. In FIG. 1, when the sheet S on which the developer image has been transferred is transported to the fixing unit 70 along the transport path L1, the sheet S is nipped between the heating roller 71 and the pressing roller 72 and transported. Thus, the developer image transferred from the photosensitive drum 54 to the sheet S is fixed to the sheet S.

  A pair of conveyance rollers 37 is disposed downstream of the fixing unit 70 in the conveyance direction of the sheet S. The sheet S conveyed from the fixing unit 70 toward the conveyance roller 37 is nipped by the conveyance roller 37 rotationally driven by the power from the motor 4 and conveyed toward the discharge roller 81 along the conveyance path L1. Ru.

  On the upstream side of the conveyance direction of the sheet S with respect to the conveyance roller 37, a discharge sensor 13 formed of, for example, a photo sensor is disposed. The discharge sensor 13 detects the presence or absence of the sheet S at the position. The discharge sensor 13 can be used to detect that the sheet S has passed the conveyance roller 37.

<Ejection unit>
The discharge unit 8 includes a discharge roller 81, a discharge roller 82, a discharge port 83, and a discharge tray 84.

  The discharge roller 81 is rotationally driven by the power from the motor 4, and conveys the sheet S discharged from the image forming unit 5 toward the discharge tray 84.

  The operation of rotation and stop of the motor 4 is controlled by the control unit 20 provided in the image forming apparatus 1. The control unit 20 controls the rotation operation of the motor 4 based on, for example, signals output from the pre-registration sensor 11, the post-registration sensor 12, the discharge sensor 13, and the discharge sensor 13.

  A block diagram showing a control system of the image forming apparatus 1 including the control unit 20 is shown in FIG. As shown in FIG. 3, the control unit 20 includes a CPU 100, and the control unit 20 includes a ROM 110, a RAM 120, an image forming unit 5, a heating drive circuit 171, and a rotation drive circuit 104. It is connected. The ROM 110 stores various control programs necessary for the image forming apparatus 1 to operate, including control programs for executing the respective flowcharts shown in FIGS. 13 to 17 described later. The CPU 100 controls each part according to the program read from the ROM 110, and executes each flowchart shown in FIGS. 13 to 17 described later. The RAM 120 includes an image data storage area 130, an intermediate data storage area 140, and a print data storage area 150. The details of the storage areas 130, 140, and 150 will be described later.

  Further, the CPU 100 instructs the heating of the heating roller 71 by outputting a heating instruction signal to the heating drive circuit 171 for heating the heater 71 a provided on the heating roller 71 through the control unit 20. The control unit 20 also receives a detection signal of a thermistor 71 b provided on the heating roller 71 and detecting the temperature of the heating roller 71. The CPU 100 can detect the temperature of the heating roller 71. The thermistor 71b is provided so as to be able to detect the temperature at the central portion in the axial direction of the heating roller 71b, as indicated by the arrow A in FIG. 2 described above. Furthermore, the CPU 100 controls the rotation of the motor 4 by outputting a drive control signal to the rotation drive circuit 104 that rotationally drives the motor 4 via the control unit 20.

<RIP process>
In the present embodiment, the image data to be processed by the image forming apparatus 1 is described in a page description language (abbreviated as PDL (Page Description Language)) such as PDF, TIFF, or XPS described in page units. For this reason, in the image forming apparatus 1, a known RIP (abbreviation of Raster Image Processor) process is performed on the image data. The RIP process will be described with reference to FIG.

  That is, as shown in FIG. 4, the image data X is composed of a plurality of object data such as a text object, a shape information object, and a bitmap object. At this time, each object is described in PDL as described above. In the image forming apparatus 1 of the present embodiment, the image data X is first stored in the image data storage area 130 of the RAM 120. Then, the CPU 100 of the image forming apparatus 1 analyzes the image data X described in the PDL, so that the corresponding plural pieces of object data are intermediated based on the information such as the drawing location and drawing position of each object data. The data Y is sequentially developed and stored in the intermediate data storage area 140 as the data Y. If the free space of the intermediate data storage area 140 is reduced to a certain extent while the above expansion and storage are sequentially performed, compression processing is performed on the stored intermediate data. By this compression process, an empty area is created in the intermediate data storage area 140, and the expansion and storage of the intermediate data thereafter are continued.

  Thereafter, the CPU 100 writes the intermediate data stored in the intermediate data storage area 140 into the print data storage area 150 in consideration of the overlapping portions of the drawing positions of the objects, etc., and the CMYK print data Z, ie, raster data Generate The generation of this raster data is so-called rendering. RIP processing refers to a series of processing including analysis of image data X of PDL, development into intermediate data Y, conversion into print data Z, and the like.

<Overview of the method of the embodiment>
Usually, in an image forming apparatus such as the image forming apparatus 1 described above, image formation on the sheet S, ie, the development described above, is waited for at the time when the entire heating roller 71 is heated to a predetermined fixable temperature Tf. It has started to fix the agent image. However, depending on the drawing range of the image on the sheet S, fixing may be started earlier than the above timing. In the present embodiment, the fixing is started earlier than the timing according to the temperature rising behavior of the heating roller 71, thereby making the first printout time (hereinafter referred to as “FPOT” appropriately) faster. Hereinafter, the details of the method will be described in order.

<The temperature rising behavior of the heating roller>
FIGS. 5A to 5D are conceptual diagrams showing the temperature rising behavior when the heating roller 71 is heated by the heater 71a to raise its temperature. As shown in FIG. 2 above, when the heater 71a is provided along the axial direction at the radial center of the heating roller 71, the heating roller 71 extends in the axial direction from the side of the axial center which is an example of the reference portion. The temperature is gradually raised toward both ends. FIG. 5A shows the temperature rising behavior in each divided portion when the heating roller 71 is virtually divided into five portions (hereinafter appropriately referred to as “divided portions”) in the axial direction. For example, FIG. 5A shows a state immediately after the start of heating by the heater 71a, and the five divided portions n3, n2, n1, n2 and n3 have not yet been heated.

  From this state, as described above, the axial center first rises in temperature. In FIG. 5 (b), among the five divided parts n3, n2, n1, n2 and n3, the divided part n1 closest to the axial center part is the fixable temperature Tf as hatched in the figure. It shows a state where the temperature has been raised. In FIG. 5 (c), after the state of FIG. 5 (b), the divided portions n2 and n2 adjacent to both ends in the axial direction of the divided portion n1 are also fixable temperatures Tf by continuing heating by the heater 71b. It shows a state where the temperature has been raised. In FIG. 5 (d), after the state of FIG. 5 (c), the divided portions n3 and n3 adjacent to both ends in the axial direction of the divided portions n2 and n2 are also fixed by continuing heating by the heater 71b. A state in which the temperature has been raised to the possible temperature Tf is shown.

  FIGS. 6 (a) to 6 (c) are graphs showing the behavior shown in FIGS. 5 (b) to 5 (d) more specifically, and are for the five divided parts n3, n2, n1, n2 and n3. The temperature distribution is shown. FIG. 6 (a) corresponds to FIG. 5 (b), and the time t1 (the time required for the divided portion n1 to reach the fixable temperature Tf) is an elapsed time t from the heating start timing by the heater 71a. 2 represents a state when the required time is an example). At this time, the divided portion n1 on the central portion side, which is the highest temperature, has reached the fixable temperature Tf, and the other divided portions n2 and n3 have not reached the fixable temperature Tf. Specifically, the divided portions n2 and n2 adjacent to both axial end sides of the divided portion n1 have a temperature lower than that of the divided portion n1. The divided portions n3 and n3 adjacent to both ends in the axial direction of the divided portions n2 and n2 have a temperature lower than that of the divided portion n2.

  FIG. 6 (b) corresponds to FIG. 5 (c), and shows the state when time difference Δt2 further elapses from the state of FIG. 6 (a) and the elapsed time t becomes t1 + Δt2. ing. At this time, the divided portions n2 and n2 respectively adjacent to both axial end sides of the divided portion n1 on the central portion side have risen in temperature than in the state of FIG. 6A and reach the fixable temperature Tf . The divided portions n3 and n3 adjacent to both end sides in the axial direction of the divided portions n2 and n2 are also heated to the fixable temperature Tf although the temperature is higher than in the state of FIG. Not reached.

  FIG. 6 (c) corresponds to FIG. 5 (d), and a time difference Δt3 as another example of the temperature rise deviation time further elapses from the state of FIG. 6 (b), and the elapsed time t is t1 +. It shows the state when it becomes Δt3. The time difference Δt3 is a value larger than the time difference Δt2. At this time, the divided portions n3 and n3 respectively adjacent to both axial end sides of the divided portion n2 on the central portion side are higher in temperature than in the state of FIG. 6B and reach the fixable temperature Tf . As a result, all the five divided parts n3, n2, n1, n2 and n3 reach the fixable temperature Tf. The time difference Δt2 and the time difference Δt3 are examples of the temperature rise deviation time. The time t1 + Δt2 and the time t1 + Δt3 are examples of the first required time.

<Virtual area>
As described above with reference to FIGS. 5 and 6, the axial center portion of the heating roller 71 reaches the fixable temperature Tf relatively early after the start of heating of the heater 71a, and the axial end portions are fixed It is slow to reach the possible temperature Tf. That is, the timing of reaching the fixable temperature Tf differs depending on the axial position of the heating roller 71. Therefore, for example, in the case where the drawing range of the image to be formed on the sheet S is a portion corresponding to the axial central portion side of the heating roller 71, compared to the case corresponding to the axial both end portions side. In some cases, the image formation start timing can be advanced.

  In view of the above, elapsed time t = t1 which is a region extending on the sheet S in a direction orthogonal to the axial direction of the heating roller 71 and in the direction orthogonal to the axial direction of the heating roller 71 and for the divided portion n1 to reach the fixable temperature Tf. A virtual area, which is an area that does not reach the fixable temperature Tf, is virtually set. FIG. 7 is a diagram showing the virtual area VR assumed at the elapsed time t = t1, that is, at the timings shown in FIGS. 5 (b) and 6 (a). In this example, as shown in the drawing, the sheet S has five regions N3, N2, N1, N2, N3 corresponding to the five divided portions n3, n2, n1, n2, n3 of the heating roller 71, respectively. Virtually set.

  As described in FIG. 6A, at the timing of t = t1, the divided portion n1 of the heating roller 71 has reached the fixable temperature Tf, and the region N1 of the corresponding sheet S has also reached the fixable temperature Tf. , Outside the virtual area VR.

  On the other hand, as described with reference to FIGS. 6B and 5C, the divided portions n2 and n2 of the heating roller 71 do not reach the fixable temperature Tf at the timing of t = t1, and t = t1 + Δt2. The fixable temperature Tf is reached at the timing of. Therefore, assuming that the conveyance speed of the sheet S is V, in the area N2 of the sheet S, the area corresponding to the distance L2 equal to the conveyance speed V × time difference Δt2 does not reach the fixable temperature Tf. It can be assumed to be located at The distance L2 corresponds to an example of the representative length, and the time difference Δt2 corresponds to an example of the time obtained by dividing the representative length by the transport speed.

  Further, as described in FIGS. 6C and 5D, the divided portion n3 of the heating roller 71 does not reach the fixable temperature Tf at the timing of t = t1, and the timing of t = t1 + Δt3. Reaches the fixable temperature Tf. Therefore, in the area N3 of the sheet S, it can be assumed that the area corresponding to the distance L3 equal to the transport speed V × the time difference Δt3 is located in the virtual area VR which does not reach the fixable temperature Tf.

  From the above, the virtual line VL assumed as a set of points reaching the fixable temperature Tf on the sheet S at the timing of the elapsed time t = t1 is as follows. That is, on the left side in the drawing which is one side in the width direction of the sheet S, the virtual line VL is a point at the distance L2 in the area N2 from the end P of the area N1 at the downstream end in the conveyance direction which is the upper side The end point Q of the region N3 is reached through a point P3 which is the distance L3 between P2 and the region N3. As a result, the virtual area VR is a triangle PQR whose apex is the end P, the end Q, and a corner R which is an end on the left side of the sheet S in the conveyance direction downstream side. It becomes an internal area of

  Similarly, on the right side in the drawing, which is the other side in the width direction of the sheet S, the virtual line VL is from the end U of the area N1 at the downstream end in the conveyance direction, the upper side in the drawing The end point V of the area N3 is reached through the point U2 and the point U3 which is the distance L3 of the area N3. As a result, the virtual area VR is a triangle UVW whose apex is the end U, the end V, and a corner W which is an end on the right side of the sheet S in the conveyance direction downstream side. It becomes an internal area of

<Drawing range>
As described above, in the present embodiment, depending on the positional relationship between the two virtual areas VR and VR and the drawing range of the image formed on the sheet S, that is, the overlapping state of the virtual area VR and the drawing range. The image formation start timing is determined. At this time, in the present embodiment, the drawing range of the image is considered for each page of the sheet S. That is, for example, as conceptually shown in FIG. 8, with regard to a plurality of object data expanded as intermediate data in the intermediate data storage area 140, a drawing range including all of them is considered. In the example of FIG. 8, as indicated by the broken lines in the figure, the drawing range TR of the text object, the drawing range SR of the shape information object, and the drawing range BR of the bitmap object are determined on a sheet S basis in the sheet S Ru. Then, the minimum drawing range including the drawing ranges TR, SR, and BR is determined as the drawing range PR of the whole page for drawing the image on this page, as indicated by the one-dot chain line.

<Determination of image formation start timing>
Examples of various image formation start timings determined in accordance with the positional relationship between the drawing range PR determined as described above and the virtual area VR will be described with reference to FIGS.

<When Starting Image Formation at Time t1>
In the example of the drawing range PR shown in FIG. 9, the drawing range PR including the two objects OB1 and OB2 determined as described above is positioned relatively on the lower side of the sheet S, that is, on the upstream side in the transport direction. doing. As a result, since the virtual region VR and the drawing range PR do not overlap in the sheet S at the above-mentioned time t1, the conveyance of the sheet S is started at this time t1 at which only the divided portion n1 becomes the fixable temperature Tf. Image formation is started. In this case, even if the image formation is started at this time t1, at the timing when the image formation is performed in the subsequent drawing range PR, all the drawing range PR reaches the fixable temperature Tf.

<When Starting Image Formation at Time t1 + Δt3>
In the example of the drawing range PR shown in FIG. 10, the drawing range PR including the two objects OB1 and OB2 determined as described above is positioned relatively on the upper side of the sheet S, that is, on the downstream side in the transport direction. ing. As a result, in the sheet S, the virtual area VR at the above-described time t1 and the drawing range PR overlap. In this example, in detail, the virtual area VR and the drawing range PR overlap in the areas N2 and N3. In this case, unlike the above, the conveyance of the sheet S is started after waiting until the timing of time t1 + Δt3 at which all the heating rollers 71 reach the fixable temperature Tf after the time difference Δt3 elapses from the time t1. Image formation is started. By starting image formation at this time t1 + Δt3, at the timing when image formation is performed in the subsequent drawing range PR, all the drawing range PR reaches the fixable temperature Tf.

<When Starting Image Formation at Time t1 + Δt2>
In the example of the drawing range PR shown in FIG. 11, the drawing range PR including the two objects OB1 and OB2 determined as described above is the upper side of the sheet S shown in FIG. It is located on the lower side of the figure than in the case of. As a result, in the sheet S, the virtual area VR and the drawing range PR overlap in the area N2, but do not overlap in the area N3. In this case, conveyance of the sheet S is started after waiting until the timing of time t1 + Δt2 at which the divided portions n2, n1 and n2 reach the fixable temperature Tf since the time difference Δt2 elapses from the time t1. Is started. By starting image formation at this time t1 + Δt2, at the timing when image formation is performed in the subsequent drawing range PR, all the drawing range PR reaches the fixable temperature Tf.

Image rotation processing
When the overlap between the drawing range PR and the virtual area VR is determined as described above, the sheet S direction and the positive direction of the image may be different. For example, in the example of FIG. 12A, the sheet feeding direction, which is the upper direction in the drawing, and the positive direction of the image, which is the lower direction in the drawing, are different. In this case, the above determination is not performed along the positive direction of the image as shown in FIGS. 9 to 11, but the image is rotated by 180 ° as shown in FIG. The above-mentioned determination of overlapping is performed in a state in which the paper direction is matched.

  Further, for example, in the example of FIG. 12B, the sheet feeding direction which is the upper direction in the drawing and the positive direction of the image which is the right direction in the drawing are different. Also in this case, as shown in FIG. 12B, the determination of the overlapping is performed in a state where the image is rotated by 90 ° and the positive direction of the image matches the sheet feeding direction.

<Image enlargement / reduction printing>
Further, when the image is actually printed by the generated print data, enlargement printing or reduction printing of the image may be performed. In such a case, the determination of the overlap is performed based on the drawing range PR corresponding to the image after such enlargement printing / reduction.

<Half speed mode>
Further, as a mode relating to the transport speed of the sheet S, a normal printing mode in which the transport is performed at the above-described transport speed V (an example of the first speed) and half speed printing in which the transport is performed at the transport speed V / 2 (an example of the second speed) A mode may be provided. Then, in the case where the overlap between the drawing range PR and the virtual area VR is determined as described above, if the half-speed printing mode is specified, the virtual area VR is set to the ratio of the two transport speeds. The virtual area VR is reduced along the transport direction based on That is, the virtual area VR in this case has a size obtained by compressing the triangle PQR and the triangle UVW shown in FIG. 7 in the vertical direction in the drawing to a half height.

<Control procedure>
Control procedures executed by the CPU 100 in order to realize the above-described method will be described with reference to the flowcharts of FIGS.

  In FIG. 13, first, in step S 5, CPU 100 is based on an input result from an appropriate operating terminal or the like connected to image forming apparatus 1 or an operation result on an appropriate operating unit provided in image forming apparatus 1. Make various print settings. The print settings include settings relating to the transport speed based on the input result and the operation result. That is, this setting includes the setting of the above-mentioned normal printing mode or half speed printing mode.

  Thereafter, in step S10, the CPU 100 determines whether a print command including image data has been issued. Specifically, the CPU 100 determines whether the image data input from an appropriate operation terminal or the like connected to the image forming apparatus 1 is acquired and stored in the image data storage area 130 or not. Alternatively, CPU 100 may determine whether the image data corresponding to the operation of the appropriate operation unit provided in image forming apparatus 1 has been acquired. The determination is not satisfied until a print command including the image data is issued (S10: No), and the process waits for a loop. If the print command is issued, the determination is satisfied (S10: Yes), and the process proceeds to step S100.

  In step S100, the CPU 100 executes the above-described RIP process on the image data acquired in step S10 and stored in the image data storage area 130.

  The detailed procedure of step S100 is shown in FIG. In FIG. 14, first, in step S110, the CPU 100 reads one of the image data stored in the image data storage area 130, and analyzes a corresponding print command by a known method.

  Thereafter, in step S120, the CPU 100 determines whether the image data is a drawing object based on the analysis result in step S110. If the object is not a drawing object, the determination is not satisfied (S120: No), and the process proceeds to step S160 described later. If the object is a drawing object, the determination is satisfied (S120: Yes), and the process proceeds to step S130.

  In step S130, the CPU 100 creates object data corresponding to the analysis result in step S110. Thereafter, the process proceeds to step S140.

  In step S140, the CPU 100 expands the object data created in step S130 in the intermediate data storage area 140. Thereafter, the process proceeds to step S150.

  In step S150, the CPU 100 generates the above-described drawing range PR that includes all the object data of the page that has been expanded in the intermediate data storage area 140 at this time. If the drawing range PR has already been generated, the CPU 100 updates the drawing range PR to a new drawing range PR including the object data expanded most recently. Thereafter, the process proceeds to step S160.

  In step S160, the CPU 100 determines whether the next print command, which has not been processed, still remains. If an unprocessed print command remains, the determination is satisfied (S160: Yes), the process returns to step S110, and the same procedure is repeated. If no unprocessed print command remains, the determination is not satisfied (S160: No), and the process proceeds to step S170.

  In step S170, the CPU 100 renders in the print data storage area 150 all object data of the page that has been expanded into the intermediate data storage area 140 in the above steps S110 to S160. Thereafter, the routine ends, and the process proceeds to step S200 of FIG.

  Returning to FIG. 7, in step S200, the CPU 100 performs final drawing range determination processing as an example of range determination processing based on the latest drawing range PR generated in step S150.

  The detailed procedure of step S200 is shown in FIG. In FIG. 15, first, in step S210, the CPU 100 needs the rotation processing of the above-mentioned image based on the analysis result of the print command corresponding to the image data in the above-mentioned step S110. It is determined whether reduction printing is performed. If rotation processing is not necessary and neither enlargement nor reduction printing is performed, the determination is not satisfied (S210: No), and the process proceeds to step S230 described later. If rotation processing is necessary, or if enlargement / reduction printing is performed, the determination is satisfied (S210: Yes), and the process proceeds to step S220 described later.

  In step S220, the CPU 100 performs affine transformation on the latest drawing range PR generated in step S150 by a known method, performs rotation processing or enlargement / reduction processing, and converts the drawing range PR after conversion. Generate Thereafter, the process proceeds to step S230.

  In step S230, the CPU 100 determines the drawing range PR generated at this time as the final drawing range PR. Thereafter, the routine ends, and the process proceeds to step S300 in FIG.

  Returning to FIG. 13, in step S300, the CPU 100 performs area determination processing including determination of the virtual area VR.

  The detailed procedure of step S300 will be described with reference to FIGS. First, in step S305 in FIG. 16, the CPU 100 determines the above-mentioned time-dependent temperature rising behavior of the heating roller 71 according to the predetermined axial dimension of the heating roller 71, the heating capacity of the heater 71b, and the like. Do. Specifically, in this example, each of the divided portions n3, n2, n1, n2, n3 of the heating roller 71 shown in FIGS. 5 (a) to 5 (d) and 6 (a) to 6 (c). Determine the temperature rising behavior over time. Thereafter, the process proceeds to step S310.

  In step S310, the CPU 100 determines whether or not the above-described half speed print mode has been set in the print setting performed in step S5. If the normal printing mode is set instead of the half-speed printing mode, the determination is not satisfied (S310: NO), and the CPU 100 sets the conveyance speed V to the predetermined V in step S315, and proceeds to step S325. Do. If the half speed printing mode is set, the determination is satisfied (S310: YES), the CPU 100 sets the conveyance speed V to a value of 1/2 of the V in step S320, and the process proceeds to step S325.

  In step S325, the CPU 100 initializes the value of the variable N related to the areas N1, N2 and N3 of the sheet S to N = 2. Then, it moves to step S330.

  In step S330, based on the temperature rising behavior of each of the divided portions n3, n2, n1, n2, n3 determined in step S305, the time difference .DELTA.t related to the corresponding regions N3, N2, N2, N3 of the sheet S. Determine (N). For example, since N is initially 2 as described above, the time difference Δt2 related to the divided portion n2 described above with reference to FIG. 6B is determined. The process executed in step S330 corresponds to an example of the time determination process. Thereafter, the process proceeds to step S335.

  In step S335, using the transport speed V determined in step S315 or step S320, the CPU 100 sets the distance L (N) related to the above-mentioned areas N3, N2, N2, N3 to L (N) = V. It is determined by × Δt (N). For example, since initially N = 2 as described above, the distance L2 = V × Δt2 related to the area N2 described above with reference to FIG. 7 is determined. Thereafter, the process proceeds to step S340.

  In step S340, CPU 100 determines whether the value of N has reached the maximum value corresponding to the maximum value of divided portion n used in step S305. In this example, in the heating roller 71, the divided portion n1 on the central side in the axial direction gives the minimum value 1 and n2 and n3 are provided from the divided portion n1 toward both ends in the axial direction, and the maximum value is 3 . Further, in the sheet S, the area N1 corresponding to the divided portion n1 gives the minimum value 1 and the areas N2 and N3 are provided from the area N1 toward the both axial end sides of the heating roller 71, and the maximum value is 3 It is. Therefore, in this example, in step S340, it is determined whether N = 3. For example, the determination is not satisfied because N = 2 at first as described above (S340: NO), and after incrementing the value of N in step S345, the process returns to step S330 and repeats the same procedure.

  In step S330, the CPU 100 determines the time difference Δt3 related to the divided portion n3 described above with reference to FIG. 6C, as described above, because N = 3. Similarly, in the subsequent step S335, since N = 3, the CPU 100 determines the distance L3 = V × Δt3 related to the area N3 described above with reference to FIG. Thereafter, since the determination in step S340 is satisfied, the process moves to step S350.

  In step S350, in the repetition of steps S330 to S345 until N = 2 to N reaches the maximum value as described above, the virtual area VR is calculated based on the L (N) sequentially calculated in step S335. Decide. In this example, since the maximum value of N is 3 and the distances L2 and L3 are obtained as described above, the virtual region VR as shown in FIG. 7 is determined using these distances L2 and L3. Thereafter, the process proceeds to step S410 in FIG.

  In step S410, the CPU 100 determines whether the drawing range PR determined in step S230 overlaps the area N3 among the areas N1 to N3 of the sheet S. For example, if the drawing range PR overlaps the area N3 as shown in FIG. 10A, the determination is satisfied (S410: YES), and the process moves to step S420.

  In step S420, the CPU 100 determines the conveyance start timing of the sheet S as follows. That is, from the sum of the time t1 when the divided portion n1 of the heating roller 71 rises to the fixable temperature Tf and the time difference .DELTA.t3 related to the area N3 of the sheet S, the conveyance time to the heating roller 71 of the sheet S It is the time which reduced tf. The time t1 is determined in the step S305.

  On the other hand, in step S410, if the drawing range PR does not overlap the area N3 as shown in, for example, FIG. 9A or 11A, the determination is not satisfied (S410: NO). Move.

  In step S430, the CPU 100 determines whether the drawing range PR determined in step S230 overlaps the area N2 among the areas N1 to N3 of the sheet S. For example, as shown in FIG. 9A, if the drawing range PR does not overlap the area N2, the determination is not satisfied (S410: NO), and the process moves to step S440. The process executed in step S430 and step S410 corresponds to an example of the determination process.

  In step S440, the CPU 100 sets the conveyance start timing of the sheet S to a time obtained by subtracting the conveyance time tf from the time t1.

  On the other hand, in step S430, if the drawing range PR overlaps the area N2 as shown in FIG. 11A, for example, the determination is satisfied (S430: YES), and the process moves to step S450.

  In step S450, the CPU 100 determines the conveyance start timing of the sheet S as a time obtained by subtracting the conveyance time tf from the sum of the time t1 and the time difference Δt2 related to the area N2 of the sheet S.

  Incidentally, the determination of the overlapping degree of the drawing range PR with the regions N2 and N3 in the above steps S410 and S430 can be expressed by the temperature rising behavior of the heating roller 71 with respect to the drawing range PR at the time of image formation. It is decided what to do. That is, the divided portions n1, n2, n3,... Which are an example of the area in the sheet width direction of the heating roller 71 which needs to be heated to the fixable temperature Tf when forming an image on the sheet S are determined. It corresponds to the

  As described above, when step S420, step S440, or step S450 is completed, this routine is ended, and the process proceeds to step S15 of FIG.

  Returning to FIG. 13, in step S15, the CPU 100 outputs a heating instruction signal to the heating drive circuit 171 to instruct the start of heating, thereby turning on the heater 71a to start the temperature rise.

  Then, in step S20, the CPU 100 starts measurement of the elapsed time t after the start of heating, using a timer (not shown) provided in the control unit 20.

  Thereafter, in step S25, the CPU 100 determines whether or not the elapsed time t when the measurement has been started in step S20 has reached the conveyance start timing determined in step S420, step S440, or step S450. The determination is not satisfied until the transfer start timing (S25: NO), and the loop waits. When the conveyance start timing comes, the determination is satisfied (S25: YES), and the process moves to step S30.

  In step S30, the CPU 100 outputs a control signal to the rotation drive circuit 104 to control the driving of the motor 4 to start driving the conveyance roller 33a and the registration roller 34, and start conveyance of the sheet S. Let

  Thereafter, in step S35, the CPU 100 controls the image forming unit 5 by a known method to start the above-described image forming process on the sheet S which has been started to be conveyed in the step S30. According to the contents described above, this is at the timing when the divided portions n1, n2, n3,... As an example of the area in the sheet width direction determined as described above rise to the fixable temperature Tf. It corresponds to starting the image formation on the sheet S.

  Further, the processing executed in steps S30 and S35 after step S25 according to the conveyance start timing in step S440 is an example of the first processing at the temperature rise timing to the fixable temperature Tf of the divided portion n1 of the heating roller 71. Is equivalent to

  The processing executed in steps S30 and S35 after step S25 by the conveyance start timing in step S420 corresponds to an example of the second processing at the timing when the entire heating roller 71 is heated to the fixable temperature Tf. ing.

  Further, the process executed in steps S30 and S35 after step S25 according to the conveyance start timing in step S450 corresponds to an example of the third process. That is, when the time difference ΔT2 corresponding to the distance L2 of the area N2 elapses from the elapsed time t = t1 at which the divided portion n1 of the heating roller 71 reaches the fixable temperature Tf, the image Formation has begun.

  In this case, as described above, the sheet S is divided into five areas N3, N2, N1, N2, N3 corresponding to the five divided parts n3, n2, n1, n2, n3 of the heating roller 71. It is an example configuration. Then, in the sheet S, the virtual area VR and the drawing range PR overlap in the second area N2 from the side of the central portion toward the both end sides in the width direction, and the virtual area VR and the drawing in the 2 + 1st area N3 It was a case where it did not overlap with the range PR. In such a case, when the time difference ΔT2 corresponding to the distance L2 in the region N2 elapses from the timing of the elapsed time t = t1 when the divided portion n1 on the central portion side reaches the fixable temperature Tf , Image formation had been started.

However, the present invention is not limited to the above, and the heating roller 71 may be divided into a plurality of appropriate divided portions. Then, the sheet S, opposite to the width direction end sides from the side of the central portion, the positive in the m-th region N _m is an integer and the virtual region VR and drawing range PR overlap, with m + 1 th region N _{m + 1} The areas VR and PR may not overlap. That is, in this case, the above example corresponding to m = 2 is expanded, and from the timing of elapsed time t = t1, a time difference corresponding to the representative length T _m of the virtual area VR not shown in the m th area N _m When ΔT _m has elapsed, image formation is started.

<Effect of the embodiment>
As described above, in the present embodiment, when the image forming unit 5 forms an image on the sheet S, the area in the width direction of the heating roller 71 where the heating roller 71 needs to reach the fixable temperature Tf is , Determined from the drawing range PR. Then, the image formation on the sheet S by the image forming unit 5 is started at the timing when the determined region in the width direction of the heating roller 71 reaches the fixable temperature Tf.

  Thus, it is possible to cause the image forming unit 5 to start image formation at the timing before the entire heating roller 71 which is an example of the fixing member reaches the fixable temperature Tf. Thus, the image formation start is started according to the image drawing range, as compared with the conventional method in which the image is at least at a portion corresponding to the side end portion of the fixing member until the side end is uniformly heated. In some cases, the first printout time (hereinafter referred to as "FPOT" as appropriate) can be made faster.

  Further, in the present embodiment, in particular, the temperature does not reach the fixable temperature Tf based on the behavior from when the divided portion n1 of the heating roller 71 reaches the fixable temperature Tf until the entire heating roller 71 reaches the fixable temperature Tf. A virtual area VR on the sheet S is determined. Then, in the subsequent image forming process, one of a plurality of processes relating to the image forming timing is selectively executed in accordance with the degree of overlap between the virtual area VR and the drawing range PR.

  That is, when the second process is performed, the image forming unit 5 starts image formation until the timing of an elapsed time t = t1 + Δt3 when the entire heating roller 71 reaches the fixable temperature Tf. On the other hand, when the first process is executed, the image forming unit 5 starts image formation at the timing of the elapsed time t = t1 when the divided portion n1 of the heating roller 71 reaches the fixable temperature tf. Thus, the image forming unit 5 can reliably start image formation at the timing before the entire heating roller 71 reaches the fixable temperature Tf.

  Further, particularly in the present embodiment, the conveyance of the sheet S is started at the timing of the elapsed time t = t1 in the first processing and at the timing of the elapsed time t = t1 + Δt3 in the second processing. Thus, when the first process is executed, the conveyance of the sheet S is started at the timing when the divided portion n1 of the heating roller 71 reaches the fixable temperature Tf, so that the FPOT can be reliably made faster. it can.

  Further, in the present embodiment, in particular, the virtual area VR is determined based on the multiplication result of the transport speed V and the time differences Δt 2 and Δt 3 respectively determined for the divided portions n 2 and n 3. As a result, the virtual region VR can be accurately determined according to the behavior of the divided portions n2 and n3 being sequentially heated as the temperature of the heating roller 71 is increased by heating.

  Further, particularly in the present embodiment, when it is determined that the virtual area VR and the drawing range PR do not overlap, at the timing when the divided portion n1 reaches the fixable temperature Tf in the first process. The sheet S is conveyed. That is, when the virtual area VR and the drawing range PR do not overlap, the conveyance of the sheet S when the divided portion n1 reaches the fixable temperature Tf does not affect the drawing. In response to this, in the first process, the sheet S is conveyed at the timing of an elapsed time t = t1 when the divided portion n1 reaches the fixable temperature Tf. This ensures that FPOT can be made faster.

In the present embodiment, in particular, even when the virtual area VR and the drawing range PR overlap, in detail, the m-th area when the sheet S is divided may overlap and the m + 1-th area does not overlap. is there. In this case, if the sheet S is started when the m-th area reaches the fixable temperature Tf as described above, the drawing is not affected. Accordingly, after the time difference Δt _m corresponding to the representative length L _m of the virtual area VR in the m-th area from the timing when the divided part n1 reaches the fixable temperature Tf in the first process, the sheet The transport of S can be started. As a result, FPOT can be reliably made faster compared to at least the above-described conventional method.

  Further, in the present embodiment, in particular, when the half-speed printing mode is designated, the virtual area VR is reduced along the transport direction based on the ratio to the transport speed V of the normal print mode. As a result, even if the normal print mode is specified or the half-speed print mode is specified, the virtual area VR can be set with high accuracy.

  Further, particularly in the present embodiment, when the sheet feeding direction to the image forming unit 5 and the normal direction of the image related to the image data are different, the image data is rotated to align the image position with respect to the sheet feeding direction. In this state, it is determined whether the virtual area VR overlaps the drawing range PR. Thereby, even when the sheet feeding direction to the image forming unit 5 is different from the normal direction of the image related to the image data, the overlap determination between the virtual area VR and the drawing range PR is accurately performed.

  In addition, in the above, the arrow shown in FIG. 3 shows an example of the flow of a signal, and does not limit the flow direction of a signal.

  Further, the flowcharts shown in FIG. 13 to FIG. 17 do not limit the present invention to the procedure shown in the above flow, but the addition / deletion of the procedure or the change of the order within the scope not departing from the spirit and technical idea of the invention. You may

  Further, other than those described above, the methods according to the above-described embodiment and each modification may be combined as appropriate for use.

  In addition, although not illustrated one by one, the present invention is to be implemented with various modifications without departing from the scope of the invention.

1 Image Forming Apparatus 5 Image Forming Unit (Image Forming Unit)
20 Controller 33a Conveying Roller (Conveying Unit)
34 Registration roller (conveying unit)
71 Heating roller (fixing member)
L2 distance (representative length)
PR drawing range P
S sheet (paper)
t1 time (second required time)
Tf Fixable temperature tt2 Time difference (temperature rise deviation time, time obtained by dividing the representative length by the transport speed)
Δt3 time difference (temperature rise deviation time)

Claims (9)

An image forming unit having a fixing member and forming an image of print data on a sheet using the fixing member;
A control unit,
Equipped with
The control unit
RIP processing for converting image data consisting of objects described in a page description language into the print data;
A range determination process of analyzing the image data and determining a drawing range on the sheet on which the image forming unit forms an image based on the object;
An area determining process of determining an area in the width direction of the fixing member, which needs to reach the fixable temperature when the image forming unit forms an image on the sheet, from the drawing range;
An image forming process for starting the image formation on the sheet by the image forming unit at the timing when the area in the width direction of the fixing member determined by the area determining process reaches the fixable temperature;
An image forming apparatus characterized by performing. In the image forming apparatus according to claim 1,
Further, in the area determination process,
The time elapsed from when the predetermined reference portion of the fixing member reaches the fixable temperature to when the region in the width direction reaches the fixable temperature and the entire fixing member reaches the fixable temperature Based on the behavior, a virtual area is determined, which represents an area which does not reach the fixable temperature, which spreads in the width direction of the fixing member and the orthogonal direction orthogonal to the width direction on the sheet;
In the image forming process,
A first process for starting the image formation by the image forming unit at a timing when the reference portion of the fixing member reaches the fixable temperature according to the overlapping degree of the virtual area and the drawing range; One of a plurality of processes including a second process of starting the image formation by the image forming unit when the entire fixing member reaches the fixable temperature is selectively executed.
An image forming apparatus characterized by In the image forming apparatus according to claim 2,
The image forming unit further includes a conveyance unit configured to convey the sheet to the image forming unit,
In the first process,
Causing the sheet to be transported to the transport unit at a timing when the reference portion reaches the fixable temperature;
In the second process,
Causing the sheet to be transported to the transport unit at a timing when the entire fixing member reaches the fixable temperature;
An image forming apparatus characterized by The image forming apparatus according to claim 3,
The area determination process is
The reference from the heating start timing of the fixing member from the first required time from the heating start timing of the fixing member to the timing when each of the divided parts obtained by dividing the fixing member in the width direction reaches the fixable temperature A time determination process of determining a temperature increase deviation time according to each of the plurality of divided portions, subtracting a second required time until the site reaches the fixable temperature;
Including
The virtual area is determined based on a multiplication result of the temperature rise deviation time according to each of the plurality of divided portions determined by the time determination processing and the transport speed of the sheet by the transport unit.
An image forming apparatus characterized by In the image forming apparatus according to claim 3 or 4,
The area determination process
It includes a determination process of determining whether the virtual area and the drawing range overlap.
When it is determined in the determination process that the virtual area and the drawing range do not overlap, in the first process, the sheet relative to the conveyance unit at the timing when the reference portion reaches the fixable temperature. Let the
When it is determined in the determination process that the virtual area and the drawing range overlap, in the second process, the conveyance unit performs the conveyance at a timing when the entire fixing member reaches the fixable temperature. Transport the paper,
An image forming apparatus characterized by In the image forming apparatus according to claim 4,
In the image forming process,
When the sheet is divided into a plurality of areas corresponding to the plurality of divided portions of the fixing member, the virtual area and the drawing are drawn in the m-th area from the side of the reference portion toward the both ends in the sheet width direction When the range overlaps and the virtual area and the drawing area do not overlap in the (m + 1) -th area, the virtual area is representative of the m-th area from the timing when the reference part reaches the fixable temperature. A third process is performed to transport the sheet to the transport unit when a time corresponding to the length has elapsed.
An image forming apparatus characterized by In the image forming apparatus according to claim 6,
In the third process,
When a time obtained by dividing the representative length in the m-th area by the conveyance speed of the sheet by the conveyance unit has elapsed from the timing when the reference portion reaches the fixable temperature, the conveyance unit Transport the paper;
An image forming apparatus characterized by The image forming apparatus according to any one of claims 3 to 7,
In the area determination process,
Among the modes related to the transport speed of the sheet by the transport unit, the half-speed printing among the normal printing mode for transporting at a first speed and the half-speed printing mode for transporting at a second speed slower than the first speed When a mode is specified, the virtual area is reduced along the transport direction based on the ratio between the second speed and the first speed.
An image forming apparatus characterized by In the image forming apparatus according to claim 5,
In the determination process,
When the sheet feeding direction to the image forming unit and the normal direction of the image related to the image data are different, the image data is rotated and the image position with respect to the sheet feeding direction is aligned with the sheet feeding direction. Determine whether a virtual area overlaps the drawing range;
An image forming apparatus characterized by

Images