JP4250371B2 - Image forming apparatus - Google Patents

Description

【０１２１】
表１には、紙種の一例と、それぞれの坪量、表面性、定着性が示されている。
【０１２２】
この表１からわかるように、坪量が約８０ｇ／ｍ²以上では定着性が満足されておらず、更に表面性が悪い紙でも定着性が悪いと判断できる。尚、この表１中の表面性とは、規準をＸｘ４０２４の坪量７５ｇ／ｍ²とし、この紙種よりも表面性の悪い紙種を「×」とし、表面性の良い紙を「○」とした。又、定着性とは、濃度低下率が１５％以上の場合を「×」とし、濃度低下率が１５％以下の場合を「○」とした。
【０１２３】
次に、上記アナウンスの具体的な仕方について説明する。
【０１２４】
ユーザによってドラフトモードが選択された場合では、ユーザの情報表示装置（例えばモニタ）に図６（ａ）に示すような紙種設定ウィンドウなる画面を表示して、画像形成可能若しくは不可能な記録材の情報を表示してアナウンスする。又、図６（ｂ）に示すように画像形成装置のためのプリンタ設定情報ウィンドウの中に表示したり、図６（ｃ）に示すようにその設定情報ウィンドウの紙種設定部に画像形成可能な記録材の種類のみを表示したりしてアナウンスする。これらのアナウンスによって、ユーザは記録材を選択、若しくは記録材を再セットしなおし画像形成開始動作に移行することとなる。
【０１２５】
尚、このアナウンスの他の方法として、画像形成可能若しくは画像形成不可能な記録材の種類を音声としてユーザにアナウンスする方法もある。
【０１２６】
一方、ユーザによってドラフトモードは選択されなくても、給紙カセット等にセットされている記録材の種類を自動で判別することで、ユーザの手を煩わせることなくドラフトモードに移行してＦＰＯＴの短縮化を図ることができる。又、セットされている記録材の種類が画像形成不可能なものである場合には、ユーザの情報表示装置（例えばモニタ）に紙種設定ウィンドウなる画面を表示して、セットされている紙種の変更を促すための情報を表示したり、画像形成装置のためのプリンタ設定情報ウィンドウの中に同様な変更を促す情報を表示したり、その設定情報ウィンドウの紙種設定部にセットされている記録材の種類を表示し、画像形成可能な紙種情報を一覧で表示したりしてアナウンスする。これらのアナウンスによって、ユーザは記録材を変更し画像形成開始動作に移行することとなる。
【０１２７】
尚、画像形成可能或いは画像形成不可能な記録材の情報を報知する方法としては、上述のような画面等での表示の他に、音声によっても可能であり、又、これらの報知方法を組み合わせることも可能である。
【０１２８】
よって、本実施形態によれば、画像形成可能或いは画像形成不可能な記録材の種類等の情報が給紙タイミング前に報知されることによって、定着に最適な記録材が選択されて給紙されることが可能となるので、上述の第二の実施形態の効果に加え、更なる定着性の向上が図られて高画質な画像を得ることができる。又、記録材の情報が自動判別されることによって、自動的にデフォルトモード又はドラフトモードの選択をすることが可能となり、ユーザビリティの向上を図ることができる。
【０１２９】
【発明の効果】
以上説明したように、本出願にかかる発明によれば、デフォルトモードとドラフトモードとを有する画像形成装置において、ドラフトモードにおける露光手段の動作開始から露光手段が第２の状態になるまでの時間が、通常モードにおける露光手段の動作開始から露光手段が第１の状態になるまでの時間よりも短い時間であって、かつ、ドラフトモードにおける第２の電圧制御動作に要する時間が通常モードにおける第１の電圧制御動作に要する時間よりも短い時間とされるので、形成される画像の画質の確保しつつ、画像形成開始の指令から画像形成完了までの時間であるファーストプリントアウトタイムを必要に応じて短縮できる。
【図面の簡単な説明】
【図１】本発明の第一の実施形態にかかる画像形成装置の概略構成を示す断面図である。
【図２】図１の画像形成装置に備えられた定着装置の概略構成を示す断面図である。
【図３】本発明の第一の実施形態におけるデフォルトモード時の画像形成装置の各部動作を説明するためのタイミングチャートである。
【図４】本発明の第一の実施形態におけるドラフトモード時の画像形成装置の各部動作を説明するためのタイミングチャートである。
【図５】本発明の第一の実施形態における露光手段に備えられたポリゴンミラーの回転数と時間との関係を示した図である。
【図６】本発明の第三の実施形態における画像形成可能な或いは画像形成不可能な記録材の報知方法の一例を示す図である。
【符号の説明】
１ 感光ドラム（潜像担持体）
２ 帯電ローラ（帯電部材）
３ 露光装置（露光手段）
４ 現像装置（現像手段）
４ａ 現像ローラ（現像剤担持体）
５ 転写ローラ（転写部材）
１１ 定着装置（定着手段）
１５ 給紙ローラ（給紙手段）
１０３ 加熱体
Ｐ 記録材[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus that records an image on a recording material by a series of image forming processes.
[0002]
[Prior art]
Conventionally, for example, a photosensitive drum as a latent image carrier capable of carrying a latent image, a charging roller as charging means for charging the surface of the photosensitive drum to a predetermined potential, and the charging roller according to image information. By exposing the charged photosensitive drum to an exposure process, an exposure device as an exposure unit that forms a latent image on the photosensitive drum, and the latent image formed by the exposure device are visualized as a toner image as a developer image. A developing device as developing means; a transfer roller as transfer means for transferring the toner image from the photosensitive drum to a recording material as an unfixed image; and a fixing device as fixing means for fixing the unfixed image onto the recording material. An image forming apparatus is known.
[0003]
In such an image forming apparatus, a paper feed roller as a paper feed unit feeds a recording material toward a transfer position at a paper feed timing after a command of an image formation start signal. An image forming operation is performed so that the toner image is transferred from the photosensitive drum to the recording material by the transfer roller. Also, from the command of the image formation start signal to the start of the image forming operation, a photosensitive drum, a charging roller, an exposure device, a developing device, a transfer roller, a fixing device, etc. It is a preparation period in which a predetermined preparation operation is performed. For this reason, the image forming operation is performed after the preparatory operation is completed and the state of the image forming apparatus becomes a predetermined operable state.
[0004]
By the way, as a fixing device of such an image forming apparatus, a contact heating method such as a heat roller method and a film heating method is widely used. In a fixing device employing such a contact heating method, a heating element having a halogen lamp or a heating resistor is heated by supplying power, and the toner image on the recording material is heated via a roller or a film. For example, as a film heating type fixing device, a method of heating a recording material through a thin film by heating a heating element in which a resistance heating element pattern is provided on a ceramic substrate is disclosed in JP-A-63-313182. Has been proposed.
[0005]
In such a fixing device, for example, when the electric power input to the fixing device is small, or when the weighing of the recording material is large or the surface property of the recording material is poor, the ambient temperature of the image forming apparatus is extremely low. In such a case, the heating rate of the heating body of the fixing device may decrease, causing a heating delay or a decrease in temperature control temperature at the time of fixing, resulting in a decrease in fixability. For this reason, conventionally, in such cases, the above-mentioned delay is caused by delaying the sheet feeding timing in order to compensate for the heating delay of the heating body of the fixing device or to set the temperature control temperature at the time of fixing high. Control for extending the heating time of the heating body in the preparation period is set. Thereby, even in the above case, a good image can be stably obtained.
[0006]
[Problems to be solved by the invention]
However, in the conventional image forming apparatus as described above, the sheet feeding timing is set so that the image forming operation is started after the state of the image forming apparatus reaches a predetermined operable state. Since the toner image is not transferred from the photosensitive drum to the recording material until after the paper timing, a first printout time (hereinafter abbreviated as FPOT), which is the time from the command of the image formation start signal to the completion of the image formation, is delayed. Will be invited.
[0007]
In addition, as described above, when the power input to the fixing device is small, when the recording material is weighed or the surface quality of the recording material is poor, or when the ambient temperature of the image forming apparatus is extremely low, etc. In an image forming apparatus that employs a control that delays the paper feed timing, the FPOT is further delayed.
[0008]
Even when the user wants to give priority to shortening the FPOT over the image formation with an unnecessarily high image quality, it is difficult to obtain high customer satisfaction if the FPOT delay is caused as described above.
[0009]
Therefore, the present invention provides an image forming apparatus capable of shortening the first out print time, which is the time from the start of image formation to the completion of image formation, as necessary, while ensuring the image quality of the formed image. With the goal.
[0010]
[Means for Solving the Problems]
According to the present application, the object is to provide a latent image carrier capable of carrying a latent image, charging means for charging the surface of the latent image carrier to a predetermined potential, and charging by the charging means according to image information. Exposure means for forming a latent image on the latent image carrier by exposing the latent image carrier to a later exposure; and developing means for visualizing the latent image formed by the exposure means as a developer image; Transfer means for transferring the developer image visualized on the latent image carrier to a recording material; and fixing means for fixing the developer image transferred to the recording material by the transfer means to the recording material. An image forming apparatus comprising: a sheet feeding unit that feeds a recording material; and a control unit that starts an operation of the exposure unit in response to an image formation start signal, after the operation of the exposure unit is started The operating state of the exposure means is the first state Based on the determined timing, a first voltage control operation for determining a voltage for transferring the developer image onto the recording material by the transfer unit is started, and the charging unit, the exposure unit, and the development unit are started. A default mode in which an image forming operation is performed using the image forming unit, the transfer unit, and the fixing unit, and a second mode in which the state of the exposure unit is different from the first state after the operation of the exposure unit is started. The second voltage control operation different from the first voltage control operation for determining the voltage when the developer image is transferred onto the recording material by the transfer unit is started on the basis of the timing when the state is reached. Control means for setting the draft mode for performing the image forming operation using the charging means, the exposure means, the developing means, the transfer means, and the fixing means to be switchable, The time from the start of operation of the exposure means to the second state is shorter than the time from the start of operation of the exposure means to the first state, and the second voltage When the time required for the control operation is shorter than the time required for the first voltage control operation, and the control means is configured to end the first voltage control operation when the default mode is set. After the timing of the exposure, the feeding means is based on the timing at which the exposure means enters the first state so that the recording material reaches the transfer position where the developer image is transferred to the recording material. When the recording mode is controlled to be fed by the paper unit and the draft mode is set, the transfer unit performs the recording after the timing at which the second voltage control operation ends. The recording material is fed by the paper feeding means based on the timing when the exposure means is in the second state so that the recording material reaches the transfer position where the developer image is transferred to the recording material. This is achieved by the invention of controlling as described above.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0022]
(First embodiment)
First, a first embodiment of the present invention will be described.
[0023]
FIG. 1 is a cross-sectional view illustrating a schematic configuration of the image forming apparatus according to the present exemplary embodiment.
[0024]
In such an image forming apparatus, as shown in FIG. 1, a charging roller 2 as a charging means, an exposure apparatus 3 as an exposure means, in order along the rotation direction around the photosensitive drum 1 as a latent image carrier, A developing device 4 as developing means, a transfer roller 5 as transferring means, a cleaning device 6 and the like are arranged.
[0025]
In addition, a paper feed cassette 7 containing a sheet-like recording material P such as paper is disposed at the lower part of the main body of the image forming apparatus. In this order from the upstream side along the transport path of the recording material P from the paper cassette 7, the paper feed roller 15, the transport roller 8, the top sensor 9, the transfer roller 5, the transport guide 10, and the fixing unit are fixed. An apparatus 11, a transport roller 12, a paper discharge roller 13, a paper discharge tray 14, and the like are arranged.
[0026]
Next, the operation of the image forming apparatus having the above configuration will be described.
[0027]
The photosensitive drum 1 is rotationally driven in the direction of the arrow R1 by a driving means (not shown), and the surface thereof is uniformly charged to a predetermined polarity and a predetermined potential by the charging roller 2. Next, the surface of the photosensitive drum 1 charged by the charging roller 2 is subjected to image exposure based on image information by an exposure device 3 such as a laser optical system, and the charge of the exposed portion is removed to form an electrostatic latent image. It is formed.
[0028]
The electrostatic latent image is developed by the developing device 4. The developing device 4 has a developing roller 4a. By applying a developing bias between the developing roller 4a and the photosensitive drum 1, the toner is attached to the electrostatic latent image on the photosensitive drum 1. Then, the electrostatic latent image is visualized as a toner image.
[0029]
On the other hand, the recording material P is stored in the paper feed cassette 7, fed and transported by the paper feed roller 15 and the transport roller 8, passes through the detection position of the top sensor 9, and passes through the photosensitive drum 1 and the transfer roller 5. Is transferred to the transfer nip between the two. At this time, the leading edge of the recording material P is detected by the top sensor 9 and is synchronized with the toner image on the photosensitive drum 1.
[0030]
The toner image is transferred onto a recording material P such as paper by a transfer roller 5. At this time, application of a transfer bias is started between the photosensitive drum 1 and the transfer roller 5 by a signal from the top sensor 9, whereby the toner image on the photosensitive drum 1 becomes an unfixed toner image on the recording material P. Transcribed.
[0031]
The recording material P carrying the unfixed toner image is transported to the fixing device 11 along the transport guide 10, where the unfixed toner image is heated and pressurized and fixed on the surface of the recording material P. The recording material P after the toner image is fixed is conveyed and discharged onto a discharge tray 14 on the upper surface of the image forming apparatus main body by a transfer roller 12 and a discharge roller 13.
[0032]
On the other hand, after the toner image is transferred to the recording material P by the transfer roller 5, the toner remaining on the surface of the photosensitive drum 1 without being transferred to the recording material P is removed by the cleaning blade 6a of the cleaning device 6 and the next. Prepare for image formation.
[0033]
Thus, in such an image forming apparatus, it is possible to perform image formation one after another by repeating the above-described operation.
[0034]
In the present embodiment, the transfer roller 5 has a conductive rubber or conductive sponge elastic layer (not shown) formed on a core metal (not shown) such as SUS or Fe. This elastic layer is formed by adding a low resistance material such as carbon to rubber having a high resistance to a medium resistance. ⁶ -10 ^Ten The resistance is adjusted to Ω to form an electronic conductor.
[0035]
Further, a constant current control is performed between the photosensitive drum 1 and the transfer roller 5 at a constant current value until image information is written on the photosensitive drum 1 by a laser beam from the exposure device 3 or between sheets. Applied bias. Then, the voltage Vo generated in the transfer roller 5 during this constant current control is detected, and the transfer bias transfer voltage Vt is determined based on this Vo (the control for determining the transfer voltage is the Active Transfer Voltage). Control (hereinafter referred to as ATVC). A transfer bias controlled at a constant voltage by the transfer voltage Vt is applied to the transfer roller 5. The reason why ATVC is performed is that the resistance value in the circumferential direction of the transfer roller varies, and in the contact transfer method, the optimum voltage value to be applied varies depending on the resistance value of the transfer roller. This is to obtain an appropriate transfer property accordingly.
[0036]
Here, the fixing device 11 of the present embodiment will be described with reference to FIG.
[0037]
FIG. 2 is a cross-sectional view illustrating a schematic configuration of the film heating type fixing device 11.
[0038]
In the fixing device 11, as shown in FIG. 2A, an endless and heat-resistant film 102 is externally fitted to a heating body support 101 including a heating body 103 and is rotatably guided. The inner peripheral length of the film 102 is formed to be, for example, about 3 mm larger than the outer peripheral length of the heating body support 101. Therefore, the film 102 is loosely fitted to the heating body support 101 with a sufficient margin. Yes.
[0039]
Further, the film 102 has a heat-resistant PTFE, PFA, FEP monolayer or polyimide having a film thickness of 100 μm or less, preferably 50 μm or less and 20 μm or more in order to reduce the heat capacity and improve the quick start property. A composite layer film in which PTFE, PFA, FEP or the like is coated on the outer peripheral surface of polyamideimide, PEEK, PES, PPS or the like can be used. In the present embodiment, the outer peripheral surface of the polyimide film is coated with PTFE or PFAE.
[0040]
The heating body 103 is coated on the substrate surface made of alumina or the like with an electric resistance material such as Ag or Pd (silver and palladium) with a thickness of about 10 μm and a width of 1 to 3 mm by screen printing or the like. The protective layer 107 is coated with glass, fluorine resin, or the like.
[0041]
The pressure roller 104 is a rotating body that drives the film 102 by forming a nip N by being pressed against the heating body 103 through the film 102. The pressure roller 104 has a cored bar 104a and a heat-resistant rubber 104b having good releasability such as silicon rubber, and is rotated by a driving means (not shown) connected to the axial end of the cored bar 104a. It is designed to be driven.
[0042]
As shown in FIG. 2 (b), the output of the thermistor 105 provided on the heating body 103 is A / D converted and taken into the CPU 110, and the CPU 110 drives the triac 111 based on the information, and the heating body 103 The temperature of the power supplied to is controlled so as to be maintained at a predetermined target temperature control temperature by controlling the phase of the AC voltage, the wave number control, and the like.
[0043]
Next, the operation timing of each unit in the image forming apparatus having the above-described configuration will be described.
[0044]
FIG. 3 is a timing chart showing the operation timing of each unit of the image forming apparatus during normal printing (default mode described later).
[0045]
As shown in FIG. 3, in response to a command of an image formation start signal (hereinafter referred to as a print signal) to the image forming apparatus (time A), after that, heating of the heating body 103 of the fixing device 11 is started and at the same time, the exposure apparatus 3. The rotation of the polygon mirror (not shown) is started.
[0046]
Then, when the heating state of the heating body 103 of the fixing device 11 and the rotation state of the polygon mirror of the exposure device 3 satisfy certain conditions (time B), the recording material P is fed from the paper feed cassette 7 by the paper feed roller 15. Paper.
[0047]
Laser exposure of the exposure device 3 is started at a timing after a predetermined time has elapsed (time D) from when the top sensor 9 detects the leading end of the fed recording material P (time C-1), and the photosensitive drum 1 A latent image is formed on top.
[0048]
The latent image formed on the photosensitive drum 1 moves as the photosensitive drum 1 rotates, and is visualized as a toner image by the developing device 4. Thereafter, when the leading end position of the toner image in the rotation direction of the photosensitive drum 1 reaches the transfer portion (time E-1), application of the transfer bias by the transfer roller 5 is started, and the transfer of the toner image to the recording material P is started. Made.
[0049]
Next, when the recording material P position corresponding to the leading edge position of the toner image reaches the fixing device 11 (time F), the fixing processing by the fixing device 11 is started, and the recording material P which has received the transfer of the toner image is started. The toner image is permanently fixed on the recording material P.
[0050]
Thereafter, the top sensor 9 no longer detects the recording material (time C-2) from the time when the rear end of the recording material P in the transport direction passes the detection position of the top sensor 9 (time C-2).
[0051]
When a plurality of recording materials are continuously printed on the recording material, a predetermined timing is reached after a predetermined time from the time when the trailing end of the preceding recording material passes through the top sensor 9 (time C-2). At (time G), the succeeding recording material following the preceding recording material is fed by the feed roller 15 and the top sensor 9 detects the leading end in the transport direction (time C-3). The same processing is performed. Hereinafter, the time between the time C-2 and the time C-3, or the distance between the preceding recording material and the succeeding recording material is referred to as “paper interval”.
[0052]
In this example, the transfer bias is applied only when the recording material passes through the transfer portion. Then, as soon as the recording material passes through the transfer portion and no longer exists in the transfer portion (time E-2), the transfer bias is set smaller than the voltage value and current value at the time of transfer. This is because when a high bias, such as a transfer bias, is applied to the photosensitive drum 1 when no recording material is present in the transfer portion, a phenomenon similar to exposure occurs on the photosensitive drum 1, and This is because memory may be generated.
[0053]
In this example, the charging bias application start timing (time G) and the development bias application start timing (time H) must be set before ATVC. The charging bias and the developing bias need to be terminated before the top sensor 9 detects the recording material P (before time C-1). Furthermore, the development bias (time H) needs to be applied later than the charging bias (time G). To briefly explain these time relationships, when the developing bias is applied at a timing earlier than the charging bias, a portion that is not charged on the photosensitive drum 1, that is, an exposed state exists on the photosensitive drum 1. Since the portion is developed, the developing bias needs to be applied after the charging bias. In addition, regarding ATVC, it is possible to obtain better detection accuracy if measurement is performed in a state where a charging bias and a developing bias are applied to the photosensitive drum 1. Although a detailed description is omitted here, a mixed bias of an AC component and a DC component is used as the charging bias, and the charging bias mainly means a DC component. Further, a mixed bias of an AC component and a DC component is used for the developing bias, and the developing bias mainly means a DC component.
[0054]
As described above, in the present embodiment, as shown in FIG. 3, the paper feed timing is determined by the time from the command of the print signal until the state of the image forming apparatus becomes a predetermined operable state. After (time B), the toner image is transferred onto the recording material. That is, in this embodiment, the time from the command of the print signal to the transfer of the toner image onto the recording material is the time from the command of the print signal until the fixing device 11 and the exposure device 3 are ready. It is determined by the time from the ready state to the completion of the ATVC operation of the transfer roller 5.
[0055]
Therefore, in the present embodiment, an example in which FPOT is shortened by shortening the time from the command of the print signal until the toner image as an unfixed image is formed on the recording material will be described.
[0056]
In this embodiment, a default mode in which an image forming operation is performed after the state of the image forming apparatus reaches the above-described predetermined operable state by a print signal command, and the state of the image forming apparatus by the print signal command is The draft mode in which the image forming operation is performed before reaching the operable state is set to be switchable. The paper feed roller 15 has a paper feed timing in the draft mode earlier than a paper feed timing in the default mode.
[0057]
First, a default mode similar to the above-described conventional example in this embodiment will be described in detail with reference to FIG.
[0058]
The conditions of the image forming apparatus of the present embodiment are as follows: temperature 23 ° C., humidity 50%, power supply voltage 106 V, power supply frequency 60 Hz, and recording material basis weight 75 g / m. ² (Xx4024 manufactured by Xerox). The specifications of the image forming apparatus of the present embodiment are as follows: the number of image forming sheets per unit time is 14 sheets / minute, the maximum sheet passing size LTR size, the process speed is 105 mm / sec, and the heater total resistance of the heating body 103 of the fixing device 11. The value is 20Ω. Further, regarding the dimensions of the parts, the photosensitive drum 1 is φ30, the charging roller 2 is φ12, the developing roller 4a is φ16, and the transfer roller 5 is φ14.5. A line extending from the rotation center of the photosensitive drum 1 to the rotation center of the transfer roller 5, a rotation center of the charging roller 2 from the rotation center of the photosensitive drum 1, a laser irradiation position on the photosensitive drum 1 by the exposure device 3, and a rotation center of the charging roller 2. The angles formed by the lines extending respectively are 95 °, 160 °, and 185 °.
[0059]
<Default mode>
(1) First, when image information is input to the image forming apparatus in the above-described state in response to a print signal command, the image information is developed. At this time, for example, in a so-called host base in which image information is created by a host device such as a personal computer, the image information is developed by the host device.
[0060]
(2) Thereafter, rotation of a motor (not shown) in the image forming apparatus is started, and rotation of each component such as the transfer roller 5, the fixing film 102, the transport rollers 8 and 12 is started.
[0061]
(3) Heating by the heating body 103 shown in FIG. 2 and rotation of a polygon mirror (not shown) of the exposure apparatus 3 are started at substantially the same timing as the start of rotation of the motor.
[0062]
(4) The heating element 103 is in a ready state (in this embodiment, the fixing device has reached a target temperature control temperature of 200 ° C. from normal temperature), and the polygon mirror has reached a ready state (99% of the target rotation speed). The first criterion is the time when the state is reached. In the default mode, the above condition requires “6.00 sec” in steps (1) to (4).
[0063]
(5) Simultaneously with the first criterion, application of the AC component and DC component of the charging bias to the photosensitive drum 1 is started.
[0064]
(6) The DC component of the developing bias is applied 0.56 sec after the first criterion. As described above, this is because, when a developing bias is applied to the surface portion of the photosensitive drum 1 that is not charged, the toner is developed. Accordingly, a developing bias is applied to the surface of the photosensitive drum 1 after charging.
[0065]
(7) ATVC of the transfer roller 5 is started after 0.81 sec from the first criterion. As described above, it is possible to perform transfer bias control with high accuracy by performing ATVC by applying a bias for ATVC while the photosensitive drum 1 is at a predetermined charging potential and developing potential.
[0066]
(8) The end of ATVC in (7) above is 2.83 seconds after the first criterion. This is to secure time for performing ATVC for four rotations of the transfer roller 5 in order to increase the accuracy of ATVC.
[0067]
(9) Feeding of the recording material P is started after 1.80 sec from the first criterion. This is because the steps from (1) to (8) are completed before reaching the transfer portion of the recording material in consideration of the time from when the recording material P is fed until it is transported to reach the transfer portion. The paper feed timing is later than these steps. In the present embodiment, the sheet feeding timing is set so that the leading end of the recording material P in the transport direction reaches the top sensor 9 at the timing when the ATVC ends.
[0068]
(10) The recording material P reaches the top sensor 9 after 2.83 sec from the first standard (the timing at this time is the second standard).
[0069]
(11) Application of the AC component of the developing bias is started 0.03 sec after the second criterion. In the present embodiment, a jumping development method is employed, and the development of a latent image on the photosensitive drum 1 is possible only by applying this AC component. Further, based on the timing of starting the application of the AC component, the timing of the leading edge of the latent image on the photosensitive drum 1 and the leading edge of the recording material in the conveyance direction are synchronized, and the exposure process on the photosensitive drum 1 is started. The
[0070]
(12) The application of the transfer bias is started 0.42 sec after the second criterion. The transfer bias application timing is the timing at which the front end of the toner image on the photosensitive drum 1 is synchronized with the front end of the recording material P in the transport direction, as described above.
[0071]
As described above, by applying the charging, developing, and transfer biases at appropriate timings by the steps (1) to (12), an image is formed at an appropriate position on the recording material. It becomes possible.
[0072]
In this default mode, the time required from the instruction of the print signal until the leading edge of the recording material P in the conveyance direction arrives at the transfer site is
(A) 6.00 seconds from the command of the print signal until the polygon mirror of the exposure device 3 and the heating element 103 of the fixing device 11 are in a ready state.
(B) 2.83 sec from when the ready state is reached until the leading edge of the recording material P in the conveyance direction reaches the top sensor 9;
(C) 0.42 sec from the time when the leading end of the recording material P in the conveying direction reaches the top sensor 9 to the time when the recording material P reaches the transfer site and the transfer bias starts to be applied.
That is, (a) + (b) + (c) = 9.25 sec.
[0073]
The time required for the recording material P to be discharged from the transfer portion by the paper discharge roller 13 after the recording material P is conveyed in the conveyance direction at the front end in the conveyance direction. d) is 5.00 sec (LTR size length: 279 mm).
[0074]
Therefore, the time required from the start of the rotation of the motor in response to a print signal command to the start of the image forming process until the recording material is discharged, that is, FPOT is 9.25 sec + (d) = 14.25 sec. Become.
[0075]
Next, the draft mode in the present embodiment will be described in detail with reference to FIG. The conditions of the image forming apparatus are the same as those in the draft mode described above.
[0076]
FIG. 4 is a timing chart showing the operation timing of each part of the image forming apparatus in the draft mode.
[0077]
<Draft mode>
(1) First, when image information is input to the image forming apparatus in the above-described state in response to a print signal command, the image information is developed.
[0078]
(2) Thereafter, rotation of a motor (not shown) in the image forming apparatus is started, and rotation of each component such as the transfer roller 5, the fixing film 102, the transport rollers 8 and 12 is started.
[0079]
(3) Heating by the heating body 103 and rotation of the polygon mirror of the exposure apparatus 3 are started at substantially the same timing as the start of rotation of the motor.
[0080]
(4) The heating element 103 is in a ready state (in this embodiment, the fixing device has reached a target temperature control temperature of 200 ° C. from normal temperature), and the polygon mirror has reached a ready state (90% of the target rotational speed). The first criterion is the time when the state is reached. In the draft mode, the above condition requires “5.50 sec” in steps (1) to (4).
[0081]
(5) Simultaneously with the first criterion, application of the AC component and DC component of the charging bias to the photosensitive drum 1 is started.
[0082]
(6) Application of the DC component of the developing bias is started 0.56 seconds after the first criterion.
[0083]
(7) ATVC of the transfer roller 5 is started after 0.81 sec from the first criterion.
[0084]
(8) The end of ATVC in (7) above is 1.30 sec after the first criterion. This is to secure time for performing ATVC for one rotation of the transfer roller 5 in order to maintain the accuracy of ATVC.
[0085]
(9) Feeding of the recording material P is started 0.27 sec after the first criterion.
[0086]
(10) The recording material P reaches the top sensor 9 after 1.30 seconds from the first criterion (the timing at this time is the second criterion).
[0087]
(11) Application of the AC component of the developing bias is started 0.03 sec after the second criterion.
[0088]
(12) The application of the transfer bias is started 0.42 sec after the second criterion.
[0089]
As described above, the application of the respective biases for charging, developing, and transfer is started at an appropriate timing through the above steps (1) to (12), so that an image is formed at an appropriate position on the recording material P. It becomes possible to form.
[0090]
In the draft mode of this embodiment, the time required from the instruction of the print signal until the leading edge of the recording material P in the conveyance direction arrives at the transfer portion is
(A) 5.50 seconds from the command of the print signal until the polygon mirror of the exposure device 3 and the heating element 103 of the fixing device 11 become ready;
(B) 1.30 sec from when the ready state is reached until the leading edge of the recording material P in the conveyance direction reaches the top sensor 9;
(C) 0.42 sec from the time when the leading end of the recording material P in the conveying direction reaches the top sensor 9 to the time when the recording material P reaches the transfer site and the transfer bias starts to be applied.
That is, (a) + (b) + (c) = 7.22 sec.
[0091]
Therefore, the FPOT in the draft mode of this embodiment is 7.22 sec + (d) = 12.22 sec.
[0092]
Here, when comparing the default mode and the draft mode, the draft mode in step (4) and step (8) is 0.5 sec shorter in step (4) and 1.53 sec in step (8). .
[0093]
In step (4), the default mode is not ready until it reaches 99%, but in the draft mode, 90% can be set as the first standard. 3 shows the relationship between the rotational speed of the polygon mirror and time as shown in FIG. 5. In the default mode, the rotational speed of the polygon mirror after the startup is far exceeding the specified rotational speed and overshoots. For this reason, it took time to converge to the specified rotational speed. In the default mode, the energization current to the coil for rotating the polygon mirror also remained constant at the time of start-up, so it continued to be energized until it exceeded 99% of the specified rotation speed. there were. Therefore, when the draft mode in the present embodiment is selected, the first criterion is set to 90%, and the amount of current supplied to the coil is reduced at that time to prevent overshoot, and further up to the specified rotational speed. The focusing time can be shortened.
[0094]
On the other hand, in step (8), when performing ATVC in the default mode, the resistance value of the transfer roller was measured for four rounds in the circumferential direction, and the bias application voltage was determined by the average value. With regard to this voltage, even when the image forming apparatus is operated in any environment, the toner holding power is reduced due to “piercing”, which is an image problem caused by a drum memory caused by a strong transfer bias, or due to a weak transfer bias. In order to prevent the occurrence of the “explosion” phenomenon, which is the scattering of toner due to the decrease and separation from the recording material, the control is performed so that the bias at the center value of the transfer bias that does not cause these phenomena is applied. It was made. However, in the draft mode of this embodiment, since ATVC is performed only for one rotation of the transfer roller, an optimum transfer bias cannot be applied, but the “punch-through” image, which is not a relatively problematic image problem, is slightly relieved. A transfer bias having a voltage in the direction is applied. In the present embodiment, control is performed to determine the transfer bias application voltage based on a value higher than the average value of one rotation of the measured resistance value in the circumferential direction of the transfer roller. As a result, a relatively optimal transfer bias can be applied.
[0095]
As described above, in this embodiment, the FPOT in the default mode is 14.25 sec, the FPOT in the draft mode is 12.22 sec, and the FPOT is 2.03 sec shorter in the draft mode than in the default mode. .
[0096]
As described above, in the present embodiment, the conditions for enabling the image forming operation by changing the polygon mirror rotation speed control and the ATVC control are set to be before the predetermined operable state in the default mode, and from the default mode. By setting the paper feeding timing as early as possible, the FPOT can be shortened. In addition, by setting the paper feed timing earlier than that in the default mode, the application start timing of each bias for charging, developing, and transfer can be made earlier than in the default mode. By making this faster than in the default mode, it is possible to normally form a toner image and ensure image quality.
[0097]
(Second embodiment)
Next, a second embodiment of the present invention will be described. In addition, the description is abbreviate | omitted regarding the structure similar to the above-mentioned 1st embodiment.
[0098]
As described in the first embodiment, the FPOT can be shortened. However, if the time for the recording material to reach the transfer portion from the rotation of the motor is shortened, the time for the recording material to reach the fixing device. Will also get shorter. In the first embodiment described above, the recording material enters the fixing device earlier than the 2.03 sec default mode. For this reason, if fixing is performed in the draft mode without changing the control of the fixing device in the default mode, the fixing device may not be warmed and fixing failure may occur.
[0099]
Therefore, in this embodiment, when the draft mode is selected, the above-described problem is solved by changing each control relating to fixing as described later.
[0100]
In default mode,
Target temperature control temperature 200 ℃
Startup power 90% of input power
Offset power 60% of input power
Fixability at this time 10% (target fixability 15% or less, FoxRiverBond 90g / m ² ). Here, the fixability means an image density reduction rate due to fixing.
[0101]
However, in the above-described first embodiment, when the draft mode (when nothing is changed regarding fixing) is selected,
Target temperature control temperature 200 ℃
Startup power 90% of input power
Offset power 60% of input power
Fixability at this time 17 to 20% (target fixability 15% or less, FoxRiverBond 90 g / m ² )
Therefore, the fixability is slightly worse than in the default mode.
[0102]
Therefore, as one of the methods to improve the fixability in the draft mode,
Target temperature control temperature 210 ℃
Startup power 90% of input power
Offset power 60% of input power
Fixability at this time 14% (target fixability 15% or less, FoxRiverBond 90g / m ² ) And increasing the target temperature control temperature, it is possible to ensure the fixing property of the first recording material.
[0103]
However, since this still has a small margin for the target fixability, in the draft mode of this embodiment, in order to further improve the fixability,
Target temperature control temperature 210 ℃
Startup power 100% of input power
Offset power 60% of input power
Fixability at this time 10 to 12% (target fixability 15% or less, FoxRiverBond 90 g / m ² )
It is said.
[0104]
As a result, in the present embodiment, the target temperature adjustment temperature is raised, and it is possible to quickly reach the target temperature adjustment temperature by increasing the input power when starting up to the target temperature adjustment temperature, and the fixing device is warmed up. Is possible.
[0105]
Here, the reason why the power at the time of startup in the default mode is 90% is to prevent overshoot of the temperature after reaching the target temperature control temperature. In this example, the reason that the startup power can be made 100% is that although the above overshoot may occur and some hot offset may occur at the tip, This is because an optimum value can be obtained. As another method, the same effect can be obtained by increasing the offset power.
[0106]
Next, the fixability of the first recording material can be ensured by the above method, but the fixability of the second recording material conveyed continuously is not as high as that of the first because the FPOT is short. There may be some poor fixability. In the default mode, this is a target temperature control temperature between sheets (hereinafter referred to as a target temperature between sheets) as a countermeasure for increasing the temperature of the non-sheet passing portion when a narrow recording material is passed through the fixing device. This occurs because the fixing device is not warmed up until the second recording material arrives.
[0107]
In default mode,
Target temperature control temperature between paper 190 ° C
Fixability of second sheet at this time 15% (target fixability 15% or less, FoxRiverBond 90 g / m ² )
It is said.
[0108]
In the first embodiment described above, when the draft mode (when nothing is changed with respect to the sheet interval) is selected,
Target temperature control temperature 190 ℃
Fixability of second sheet at this time 17-20% (target fixability 15% or less, FoxRiverBond 90 g / m ² )
Therefore, in this state, the fixability of the second and subsequent recording materials is slightly deteriorated.
[0109]
Therefore, in the present embodiment, as a method for improving the fixability of the second and subsequent sheets in the draft mode,
Target temperature control between papers 195 ℃
Fixability at this time 15% (target fixability 15% or less, FoxRiverBond 90 g / m ² ).
[0110]
As a result, in this embodiment, it is possible to secure the fixability of the second and subsequent recording materials by raising the target temperature adjustment temperature between sheets.
[0111]
In the present embodiment, no particular measures are taken against the temperature increase of the non-sheet passing portion, and there is no problem. The reason for this is that the target temperature adjustment temperature between the sheets in this embodiment is higher than that in the default mode, between the first and second sheets of continuous paper, between the second and third sheets, Performed only between the third and fourth sheets, and between each sheet between the fourth and fifth sheets. The target temperature control temperature between the fifth and subsequent sheets is the same as the default mode. Because it makes it. If the target temperature control temperature is increased only between the first and fifth sheets of paper, the temperature rise of the non-sheet passing part is slightly worsened and the margin for abnormal temperature rise is reduced. No change is seen (except for FPOT).
[0112]
Therefore, according to the present embodiment, when the draft mode is selected, these values are set in the default mode for the control of the fixing device target temperature control temperature, the paper-to-paper target temperature control temperature, the startup power, the offset power, and the like. By changing the value from the above value as described above, it is possible to shorten the FPOT as in the first embodiment described above, and to secure the fixing property.
[0113]
In this embodiment, the example in which the target temperature control temperature in the draft mode is set higher than that in the default mode has been described. However, the draft is limited by limiting the type of the recording material to a thin one or a surface having a good surface property. The target temperature control temperature in the mode can be set lower than in the default mode. By setting to such a low target temperature control temperature, the rise time to the target temperature control temperature is shortened, and FPOT can be shortened.
[0114]
(Third embodiment)
Next, a third embodiment of the present invention will be described. In addition, the description is abbreviate | omitted regarding the structure similar to the above-mentioned 1st embodiment or 2nd embodiment.
[0115]
In the present embodiment, an example will be described in which the types of recording materials that can form an image in the draft mode are limited and the recording material types can be automatically determined.
[0116]
According to the second embodiment described above, it is possible to secure the fixability while shortening the FPOT, but depending on the type of the recording material, a fixing failure may occur.
[0117]
Therefore, in the present embodiment, in order to form a normal image and improve the fixability, the type of recording material that can be formed or cannot be imaged is announced, so that it is used in the second embodiment described above. Fixing control for the draft mode can be secured without separately providing fixing control other than the fixing control for the default mode.
[0118]
The content of the announcement is such that, when an image-forming recording material is announced, it has good fixability, for example, “basis weight 80 g / m ² Please set the following ". On the other hand, when announcing a recording material incapable of image formation, for example, “basis weight 80 g / m ² Do not set the above "or make an announcement such as" Do not set Bond paper or recycled paper "because the fixing performance is affected even if the surface quality of the recording material is poor.
[0119]
As a background to selecting these paper types, fixing properties were confirmed for various paper types using an image forming apparatus similar to that of the first embodiment described above. The results are shown in Table 1.
[0120]
[Table 1]

[0121]
Table 1 shows an example of paper types and their basis weights, surface properties, and fixing properties.
[0122]
As can be seen from Table 1, the basis weight is about 80 g / m. ² As described above, it is possible to determine that the fixing property is not satisfied, and even a paper having a poor surface property has a poor fixing property. In addition, the surface property in Table 1 is based on a basis weight of 75 g / m of Xx4024. ² The paper type having a surface property worse than that of this paper type was “X”, and the paper type having a good surface property was “◯”. In addition, the fixing property is “x” when the density reduction rate is 15% or more, and “◯” when the density reduction rate is 15% or less.
[0123]
Next, a specific method of the announcement will be described.
[0124]
When the user selects the draft mode, a screen that is a paper type setting window as shown in FIG. 6A is displayed on the user's information display device (for example, a monitor) so that an image can be formed or cannot be recorded. Display and announce information. Further, it can be displayed in the printer setting information window for the image forming apparatus as shown in FIG. 6B, or an image can be formed in the paper type setting section of the setting information window as shown in FIG. 6C. Only the type of recording material is displayed. By these announcements, the user selects a recording material or resets the recording material and shifts to an image formation start operation.
[0125]
As another method of this announcement, there is also a method of announcing to the user the type of recording material capable of image formation or image formation not possible.
[0126]
On the other hand, even if the user does not select the draft mode, by automatically determining the type of recording material set in the paper feed cassette or the like, the mode is shifted to the draft mode without the user's trouble, and the FPOT Shortening can be achieved. If the type of the recording material that has been set is an image that cannot be formed, a paper type setting window is displayed on the user's information display device (for example, a monitor), and the paper type that has been set is displayed. Is displayed in the printer type information window for the image forming apparatus, or is displayed in the paper type setting section of the setting information window. The type of recording material is displayed, and the paper type information on which image formation is possible is displayed in a list and announced. With these announcements, the user changes the recording material and shifts to an image formation start operation.
[0127]
In addition to the display on the screen as described above, the method of notifying the information of the recording material capable of forming an image or not capable of image formation is also possible by sound, and these notification methods are combined. It is also possible.
[0128]
Therefore, according to the present embodiment, information such as the type of recording material capable of image formation or non-image formation is notified before the paper feeding timing, so that the optimum recording material for fixing is selected and fed. Therefore, in addition to the effects of the second embodiment described above, the fixing property is further improved and a high-quality image can be obtained. Further, by automatically determining the recording material information, it is possible to automatically select the default mode or the draft mode, and the usability can be improved.
[0129]
【The invention's effect】
As described above, according to the invention of the present application, in the image forming apparatus having the default mode and the draft mode, the time from the start of the operation of the exposure means in the draft mode until the exposure means becomes the second state. The time required for the second voltage control operation in the draft mode is shorter than the time from the start of the operation of the exposure unit in the normal mode until the exposure unit is in the first state, and the first time in the normal mode. Therefore, the first printout time, which is the time from the start of image formation to the completion of image formation, is set as necessary while ensuring the image quality of the image to be formed. Can be shortened.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a schematic configuration of an image forming apparatus according to a first embodiment of the present invention.
2 is a cross-sectional view illustrating a schematic configuration of a fixing device provided in the image forming apparatus of FIG. 1;
FIG. 3 is a timing chart for explaining the operation of each part of the image forming apparatus in the default mode according to the first embodiment of the present invention.
FIG. 4 is a timing chart for explaining the operation of each part of the image forming apparatus in the draft mode according to the first embodiment of the present invention.
FIG. 5 is a diagram showing the relationship between the number of rotations of a polygon mirror provided in the exposure means and time in the first embodiment of the present invention.
FIG. 6 is a diagram illustrating an example of a method for informing a recording material capable of image formation or image formation in a third embodiment of the present invention.
[Explanation of symbols]
1 Photosensitive drum (latent image carrier)
2 Charging roller (charging member)
3 Exposure equipment (exposure means)
4 Developing device (Developing means)
4a Development roller (developer carrier)
5 Transfer roller (transfer member)
11 Fixing device (fixing means)
15 Paper feed roller (paper feed means)
103 Heating body
P Recording material

Claims (4)

A latent image carrier capable of carrying a latent image, a charging unit for charging the surface of the latent image carrier to a predetermined potential, and exposing the latent image carrier after charging by the charging unit according to image information. An exposure unit that forms a latent image on the latent image carrier by processing, a developing unit that visualizes the latent image formed by the exposure unit as a developer image, and the latent image carrier visualized on the latent image carrier An image forming apparatus comprising: a transfer unit that transfers the developer image to a recording material; and a fixing unit that fixes the developer image transferred to the recording material by the transfer unit.
A paper feeding means for feeding the recording material;
A control means for starting the operation of the exposure means in response to an image formation start signal, and after starting the operation of the exposure means, the timing when the operation state of the exposure means becomes the first state as a reference And starting a first voltage control operation for determining a voltage when the developer image is transferred to the recording material by the transfer unit, and the charging unit, the exposure unit, the developing unit, and the transfer unit, A default mode in which an image forming operation is performed using the fixing unit, and a timing at which the state of the exposure unit becomes a second state different from the first state after the operation of the exposure unit is started. As a reference, a second voltage control operation different from the first voltage control operation for determining a voltage for transferring the developer image onto the recording material by the transfer unit is started, and the charging unit in front A control unit for setting capable of switching between draft mode that performs an image forming operation by using said exposure means and the developing means and the transfer means and said fixing means,
The time from the start of operation of the exposure means to the second state is shorter than the time from the start of operation of the exposure means to the first state, and the second voltage A time required for the control operation is shorter than a time required for the first voltage control operation,
When the default mode is set, the control unit is configured to transfer the developer image onto the recording material by the transfer unit after the timing at which the first voltage control operation ends. If the recording material is to reach, by the feeding means based on the timing of the exposing unit becomes the first state controlled to feeding the recording material, the draft mode is set The exposure means includes the first and second exposure means so that the recording material reaches a transfer position at which the developer image is transferred to the recording material by the transfer means after the end timing of the second voltage control operation. 2. An image forming apparatus, wherein the recording material is controlled to be fed by the paper feeding unit based on the timing when the state 2 is reached.   The fixing unit includes a heating body that is heated at a predetermined target temperature control temperature when fixing the developer image on the recording material, and the target temperature in the draft mode is higher than the target temperature in the default mode. The image forming apparatus according to claim 1, wherein the temperature is higher.   The image forming apparatus according to claim 2, further comprising a power value input to the fixing device in the draft mode greater than a power value input to the fixing device in the default mode. Further, when the image forming operation is continuously performed on a plurality of recording materials, the heating body between the recording material and the recording material is heated in each of the default mode and the draft mode. Is set to a temperature lower than the predetermined target temperature, and the target temperature between sheets in the draft mode is higher than the target temperature between sheets in the default mode. The image forming apparatus according to claim 2, wherein the image forming apparatus is an image forming apparatus.

Images