JP2001117416A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a user to perform print operation with designated pixel density only by performing print starting operation once in an image forming device, which changes the pixel density of an electrostatic latent image by switching the surface linear velocity of a photoreceptor, for forming the electrostatic latent image on the surface of the photoreceptor, making that electrostatic latent image visible as toner image, transferring that toner image on a recording sheet, passing that recording sheet between a fixing roller and a heating roller and fixing the toner image on the recording sheet with the operation of heat and pressure at such a time. SOLUTION: When the temperature of a fixing roller 16 reaches a target temperature corresponding to the designated pixel density after a print start signal is inputted, print operation is started by rotating a photoreceptor 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming an electrostatic latent image on a surface of an image bearing member, visualizing the electrostatic latent image as a toner image, and converting the toner image directly or via an intermediate transfer member. An image forming apparatus for transferring a toner image on a surface of a recording sheet and fixing the toner image on the surface of the recording sheet to the surface of the recording sheet by the action of at least heat of a fixing member. The present invention relates to an image forming apparatus capable of changing a pixel density of an electrostatic latent image.

[0002]

2. Description of the Related Art An image forming apparatus of the above type configured as a copier, a printer, a facsimile, or a multifunction machine having at least two of these functions has been well known. In this image forming apparatus, it is possible to change the linear velocity on the surface of the image carrier to change the pixel density of the electrostatic latent image and obtain images with different resolutions. That is, by lowering the linear velocity on the surface of the image carrier, the pixel density of the electrostatic latent image can be increased, and a high-resolution image can be formed. Conversely, by increasing the linear velocity on the surface of the image carrier, the electrostatic latent image can be formed. , And a low-resolution image can be formed. In the former mode, the resolution of the image can be increased and a high-quality image can be formed, but the image forming speed, that is, the print speed decreases. Conversely, in the latter mode, the resolution of the image is reduced, but the print speed is increased. The user can obtain a predetermined recorded image by specifying a mode desired by the user.

When a high-resolution toner image is formed on the surface of an image carrier by forming an electrostatic latent image having a high pixel density on the surface of the image carrier, and transferred to the recording sheet surface, a low-resolution toner image is formed. Since the conveyance speed of the recording sheet is lower than when a toner image is formed, it is necessary to lower the fixing temperature of the fixing member for fixing the toner image accordingly.
If a high-resolution toner image is fixed at the same temperature as the fixing temperature for fixing a low-resolution toner image, an excessive amount of heat is applied to the toner image, causing a problem such as wrinkling of a recording sheet. May occur. Conversely, when fixing a low-resolution toner image, if the toner image is fixed at a fixing temperature at which a high-resolution toner image is fixed, the amount of heat given to the toner image is insufficient, and fixing failure occurs. I do.

Therefore, there has been proposed an image forming apparatus in which the fixing temperature of the fixing member is switched in accordance with the pixel density of the electrostatic latent image, and the toner image is fixed at a fixing temperature suitable for each pixel density ( For example, see JP-A-9-146417. At that time, before the temperature of the fixing member reaches a temperature suitable for the pixel density specified by the user, the image forming operation,
That is, if the printing operation is started, the wrinkles of the recording sheet and the insufficient fixing of the toner image described above are unavoidable.

Therefore, the operation for starting the printing operation itself is prohibited until the temperature of the fixing member reaches a temperature suitable for the pixel density designated by the user, and even if the user performs the printing start operation, the printing operation is not performed. There has been proposed an image forming apparatus configured not to accept a start signal.
According to such an image forming apparatus, since the printing operation is performed after the temperature of the fixing member reaches a temperature suitable for the designated pixel density, it is possible to prevent wrinkles on the recording sheet and insufficient fixing of the toner image. Is possible.

However, according to the above configuration, the user needs to confirm the display indicating that the fixing member has reached the predetermined temperature and then perform the print start operation.
The display of the image forming apparatus or other electronic devices must be constantly monitored. Also, if the user erroneously performs a print start operation before the fixing member reaches the predetermined temperature, the print start signal is not received by the image forming apparatus itself. The user must perform the same operation again, which may cause the user to feel confused.

Further, in this type of image forming apparatus which has been conventionally proposed, it takes a long time for the temperature of the fixing member to reach a fixing temperature suitable for a designated pixel density. The disadvantage of long user waits before starting was unavoidable.

[0008]

SUMMARY OF THE INVENTION It is a first object of the present invention to provide an image forming apparatus which can switch the pixel density and does not give a user an embarrassment.

A second object of the present invention is to provide an image forming apparatus capable of switching the pixel density and shortening a user's waiting time before starting a printing operation as compared with the related art. is there.

[0010]

According to the present invention, in order to achieve the first object, an electrostatic latent image is formed on the surface of an image carrier,
Visualize the electrostatic latent image as a toner image, transfer the toner image directly or via an intermediate transfer body to the recording sheet surface,
An image forming apparatus for fixing the toner image on the recording sheet surface to the recording sheet surface by at least the action of heat of a fixing member, wherein the linear velocity of the image carrier surface is switched to reduce the pixel density of the electrostatic latent image. In the image forming apparatus capable of changing, when it is detected that the temperature of the fixing member has reached the target temperature corresponding to the designated pixel density after the input of the print start signal, the image forming apparatus corresponds to the designated pixel density. The present invention proposes an image forming apparatus that starts a printing operation.

According to another aspect of the present invention, there is provided an image carrier, a driving unit for driving the image carrier so that the surface of the image carrier moves, and a driven image carrier. A latent image forming means for forming an electrostatic latent image on the surface of the developing device, a developing device for visualizing the electrostatic latent image as a toner image, and a toner image transferred to the recording sheet surface by at least the action of heat. A fixing member heated to fix the recording sheet surface,
Temperature detection means for detecting the temperature of the fixing member; and linear velocity control means for controlling the driving means so that the image carrier is driven at a surface linear velocity corresponding to the designated pixel density of the electrostatic latent image. A target temperature setting means for setting a target temperature of the fixing member corresponding to the specified pixel density; and a print start signal so that the fixing member fixes the toner image at a fixing temperature corresponding to the specified pixel density. Print control means for starting printing operation control corresponding to the specified pixel density when it is detected that the temperature of the fixing member has reached the target temperature corresponding to the specified pixel density after the input of An image forming apparatus is proposed (claim 2).

According to the present invention, in order to achieve the second object, an electrostatic latent image is formed on the surface of an image carrier, the electrostatic latent image is visualized as a toner image, and the toner image is formed. An image forming apparatus for transferring a toner image on a recording sheet surface directly or via an intermediate transfer member and fixing the toner image on the recording sheet surface to the recording sheet surface by at least the action of heat of a fixing member, wherein the image carrier In an image forming apparatus capable of changing a pixel speed of an electrostatic latent image by switching a linear velocity on a surface, the fixing member is configured such that the fixing member waits at a target temperature corresponding to a preset initial pixel density. While controlling the temperature of the member, when the designated pixel density matches the default pixel density, when it is detected that the temperature of the fixing member has reached the target temperature corresponding to the default pixel density, the initial value is determined. Set pixel When the specified pixel density is different from the default pixel density, it is detected that the temperature of the fixing member has reached the target temperature corresponding to the specified pixel density. The present invention proposes an image forming apparatus which starts a printing operation corresponding to the designated pixel density.

Further, according to the present invention, in order to achieve the second object, an image carrier, driving means for driving the image carrier so that the surface of the image carrier moves, and an image carrier driven A latent image forming means for forming an electrostatic latent image on the surface of the developing device, a developing device for visualizing the electrostatic latent image as a toner image, and a toner image transferred to the recording sheet surface by at least the action of heat. A fixing member heated to fix the recording sheet surface,
Temperature detection means for detecting the temperature of the fixing member; and linear velocity control means for controlling the driving means so that the image carrier is driven at a surface linear velocity corresponding to the designated pixel density of the electrostatic latent image. Storage means for storing a preset initial pixel density, and target temperature setting means for setting a target temperature such that the fixing member waits at a target temperature corresponding to the initial pixel density. A pixel density determining means for determining whether or not the pixel density is equal to the default pixel density; and a fixing member corresponding to the specified pixel density when the specified pixel density is different from the default pixel density. A target temperature setting unit that sets a target temperature of the image forming apparatus, and when the designated pixel density matches the initial setting pixel density, the fixing member fixes the toner image at a fixing temperature corresponding to the initial setting pixel density. As described above, when it is detected that the temperature of the fixing member has reached the target temperature corresponding to the default pixel density, print operation control corresponding to the default pixel density is started, and the designated pixel density is determined. When the temperature is different from the default pixel density, the temperature of the fixing member is set to the target temperature corresponding to the specified pixel density so that the fixing member fixes the toner image at a fixing temperature corresponding to the specified pixel density. The present invention proposes an image forming apparatus comprising: a print control unit that starts a print operation control corresponding to the designated pixel density when it is detected that the image density has become equal to (4).

Further, in the image forming apparatus according to the third or fourth aspect, it is possible to set a first initial pixel density and a second initial pixel density higher than the first initial pixel density. The target temperature corresponding to the first default pixel density may be higher than the target temperature of the second default pixel density.

Further, according to the present invention, in order to achieve the second object, an electrostatic latent image is formed on the surface of the image carrier, the electrostatic latent image is visualized as a toner image, and the toner image is formed. An image forming apparatus for transferring a toner image on a recording sheet surface directly or via an intermediate transfer member and fixing the toner image on the recording sheet surface to the recording sheet surface by at least the action of heat of a fixing member, wherein the image carrier In an image forming apparatus that can change the pixel density of the electrostatic latent image by switching the linear velocity of the surface, when it is detected that the temperature of the fixing member has reached the target temperature corresponding to the specified pixel density, A printing operation corresponding to the pixel density is started, and after the printing operation is completed, the target temperature of the fixing member is controlled such that the fixing member waits at a target temperature corresponding to the pixel density of the printing operation. It proposes an image forming apparatus, characterized in that (claim 6).

According to another aspect of the present invention, there is provided an image carrier, driving means for driving the image carrier so that the surface of the image carrier moves, and a driven image carrier to achieve the second object. A latent image forming means for forming an electrostatic latent image on the surface of the developing device, a developing device for visualizing the electrostatic latent image as a toner image, and a toner image transferred to the recording sheet surface by at least the action of heat. A fixing member heated to fix the recording sheet surface,
Temperature detection means for detecting the temperature of the fixing member; and linear velocity control means for controlling the driving means so that the image carrier is driven at a surface linear velocity corresponding to the designated pixel density of the electrostatic latent image. And when the fixing member detects that the temperature of the fixing member has reached the target temperature corresponding to the specified pixel density, so that the fixing member fixes the toner image at the fixing temperature corresponding to the specified pixel density. Print control means for starting a print operation control corresponding to the pixel density, and setting the target temperature such that the fixing member waits at a target temperature corresponding to the pixel density at the time of the print operation after the end of the print operation. An image forming apparatus including a target temperature setting unit that performs the operation is proposed.

Further, in the image forming apparatus according to claim 4, the print control means, after inputting a print start signal, adjusts a temperature of the fixing member to a target temperature corresponding to a designated pixel density. It is advantageous to configure so as to start the print operation control corresponding to the pixel density when the change is detected (claim 8).

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a vertical sectional view showing an example of an image forming apparatus. The image forming apparatus shown here is configured as a laser printer and connected to an electronic device (not shown) such as a host computer or a word processor. I have. Inside the image forming apparatus main body 1, a drum-shaped photoconductor 2 as an example of an image carrier rotatably supported by the image forming apparatus main body 1 is housed. When an image forming operation, that is, a printing operation is performed, the photoconductor 2 is driven to rotate counterclockwise in FIG. The rotation of a drive motor (main motor) (see FIG. 2) not shown in FIG.
, Whereby the photosensitive member 2 is driven so that its surface moves. The driver, the driving motor, and the transmission shown in FIG. 2 constitute an example of a driving unit that drives the photoconductor 2. Further, instead of the drum-shaped photoconductor, a belt-shaped photoconductor driven by being wound around a plurality of rollers can be used.

As described above, when the photoconductor 2 rotates, the surface of the photoconductor 2 is uniformly charged to a predetermined polarity by the charging roller 3 as an example of a charging device. A voltage having a predetermined polarity is applied to the charging roller 3, and the charging roller 3 contacts the surface of the photoconductor while rotating, thereby charging the surface of the photoconductor.

On the other hand, a laser writing unit 4 which is an example of an image exposure apparatus is arranged in the image forming apparatus main body 1. The laser writing unit 4 outputs a laser beam L modulated in accordance with image data. Is emitted, and the laser beam L exposes the surface of the photoconductor charged as described above in the axial direction (main scanning direction) of the photoconductor 2,
As a result, an electrostatic latent image corresponding to the image data is formed on the surface of the photoconductor. The surface portion of the photoreceptor irradiated with the laser beam in the form of a spot constitutes one pixel of the electrostatic latent image, and a predetermined electrostatic latent image is formed by such a pixel.
The absolute value of the potential of the surface of the photoreceptor to which the laser beam is applied decreases, and the reduced portion forms an electrostatic latent image, and the surface of the photoreceptor to which the laser beam is not applied becomes a background portion. The pixel density of such an electrostatic latent image is switched as described later.

As described above, the charging device including the charging roller 3 and the laser writing unit 4 are provided with a latent image forming means for forming an electrostatic latent image of a charge pattern including pixels on the surface of the driven photosensitive member 2. The electrostatic latent image is stored in a developing device 5 disposed in the main body of the image forming apparatus.
Thus, a visible image is formed as a toner image. The developing device 5 shown here has a developing case 18 containing a powdery developer D, and a developing roller 6 for carrying and transporting the developer, and the toner of the carried developer is exposed to light. The electrostatic latent image formed on the body 2 is electrostatically transferred, and the electrostatic latent image is visualized. The developing device 5 visualizes the electrostatic latent image as a toner image by reversal development.

On the other hand, a paper feeder 7 is disposed below the main body 1 of the image forming apparatus, and a recording sheet P stored in the paper feed cassette 8 is moved from the paper feed cassette 8 by rotation of a paper feed roller 9. It is sent out one by one. The fed recording sheet P is, as shown by arrow A, a pair of registration rollers 10.
Transfer roller 1, which is an example of a transfer device, at a timing matching with a toner image formed on the surface of photoconductor 2
The recording sheet P is fed toward a transfer section between the photoconductor 1 and the photoconductor 2, and when the recording sheet P passes therethrough, the toner image on the photoconductor is transferred to the surface of the recording sheet P. At this time, the transfer roller 11
Rotates while contacting the photoconductor 2 via the recording sheet P, and a voltage having a polarity opposite to the charging polarity of the toner on the photoconductor surface is applied to the transfer roller 11, thereby recording the toner image on the photoconductor surface. It is electrostatically transferred to the surface of the sheet P. As the recording sheet P, paper, resin sheet, resin film, cloth, or the like is used.

The untransferred toner adhering to the surface of the photoreceptor without being transferred to the recording sheet P is removed from the surface of the photoreceptor by the cleaning member 13 of the cleaning device 12, and the surface is cleaned.

The recording sheet P is separated from the photoreceptor 2 by the operation of a separating device including the static elimination needle 15. The recording sheet P that has passed through the transfer unit in this manner is continuously conveyed upward, and the fixing roller 16 of the fixing device 14 and the pressure roller 17
At this time, the unfixed toner image carried on the recording sheet surface is fixed on the recording sheet by the action of heat and pressure. The recording sheet is then discharged onto a discharge tray 20 constituted by an outer cover of the image forming apparatus main body 1 with the surface of the fixed toner image facing downward by a pair of discharge rollers 19 driven to rotate. You. In the illustrated example, the above-described photoconductor 2, charging roller 3, developing device 5, and cleaning device 12 are configured as an integrated process unit U. This process unit U is detachably mounted inside the image forming apparatus main body 1. It is loaded.

The fixing roller 16 and the pressure roller 17 of the fixing device 14 are pressed against each other in pairs, and are driven to rotate by the above-described drive motors in the directions indicated by arrows in FIG. A heater 21 for heating the fixing roller 16 is provided inside the fixing roller 16.
Is in contact with the thermistor 22. The temperature detecting means having the thermistor 22 detects the surface temperature of the fixing roller 16 and, based on the detection signal, detects the temperature of the heater 21.
The power supply to the fixing roller 16 and the cutoff thereof are controlled, so that the surface temperature of the fixing roller 16 is controlled to a fixing temperature suitable for fixing the toner image during the printing operation.

The recording sheet P on which the toner image has been transferred from the surface of the photosensitive member as described above passes while being conveyed between the fixing roller 16 and the pressing roller 17 which rotate as described above.
At this time, the toner image is fixed on the recording sheet surface by the action of the pressure and heat received from the rollers 16 and 17. The fixing roller 16 is an example of a fixing member that is heated to fix the toner image transferred onto the recording sheet surface to at least the action of heat on the recording sheet surface.

FIG. 2 is a block diagram of a control system of the above-described image forming apparatus. The control of the entire apparatus is performed by the main control unit 23 shown in FIG. This main control unit 23
Includes a controller 24 for issuing an instruction for image formation, the above-described thermistor 22 (FIG. 1), various sensors such as a sensor for detecting whether or not the recording sheet P is set in the sheet feeding device 7, and laser writing. Unit 4 and fixing device 1
4 and a high-voltage power supply 25 are connected to each other. In addition to the photoconductor 2 and the fixing roller 16, the above-described drive motor 26 that rotationally drives the paper feed roller 9 and the like via a transmission device is a driver. 27.

The controller 24 develops print data from a host computer or a word processor connected to the image forming apparatus into image data, and the image data is input to the main control unit 23. Further, the main control unit 23 controls a laser device, for example, a semiconductor laser of the laser writing unit 4 based on the image data, and emits a laser beam light-modulated corresponding to the image data from the laser device. . Further, the temperature detection signal from the thermistor 22 is taken into the main control unit 23, and the main control unit 23 transmits the fixing roller 16 during the printing operation.
The power supply to the heater 21 and the cutoff thereof are controlled so that the temperature of the fixing roller 16 becomes the fixing temperature and the temperature of the fixing roller 16 at the time of standby of the image forming apparatus becomes the temperature at the time of standby described later.

Here, in the image forming apparatus of this embodiment,
By switching the rotation speed of the photoconductor 2, that is, the linear velocity of the surface (speed of the peripheral surface of the photoconductor), the density of pixels formed on the surface can be changed, and the resolution of the toner image can be changed. Is configured. In the illustrated example, the pixel density of the electrostatic latent image, that is, the resolution of the toner image is 600 dpi and 1 pixel, where the number of pixels per inch is represented by dpi.
In the case of the former 600 dpi, the surface linear velocity of the photoreceptor 2 is 92 mm.
/ Sec, and in the case of the latter 1200 dpi, the surface linear velocity of the photosensitive member 2 is set to 46 mm / sec. The photoconductor 2 and the fixing roller 16 are driven by the same drive motor 26,
In accordance with the switching of the surface linear speed of the photoconductor, the fixing roller 16 and the pressure roller 17 are driven to rotate at the same surface linear speed as the switched surface linear speed of the photoconductor.

The user can freely select any pixel density. That is, when the user specifies a desired pixel density by operating the host computer or the word processor, the designation signal is input to the main control unit 23 via the controller 24. Main control unit 23
Corresponds to the photosensitive member 2 and the fixing roller 16 according to the designation signal.
The drive motor 26 is controlled so that the pressure roller 17 and the pressure roller 17 are driven at the above-described surface linear velocity. As described above, the main controller 23 controls the surface linear velocity corresponding to the pixel density of the electrostatic latent image specified by the user, that is, 92 mm / sec or 46 m.
drive motor 26 so that the photosensitive member 2 is driven at m / sec.
And linear speed control means for controlling the drive means including the above.

The image forming apparatus has an image reading unit for reading a document image, emits a laser beam from a laser optical system in accordance with the read image data, and forms an electrostatic latent image on the surface of a photoreceptor. In the case where the copier is configured to execute a print operation of converting the toner image into a toner image, transferring the toner image to a recording sheet, and fixing the toner image by a fixing device, the copier By pressing a pixel density selection key provided on the operation unit, a pixel density is designated, and as described above, the photoconductor is driven at a corresponding surface linear velocity. The image forming apparatus illustrated in FIG. 1 is configured to directly transfer the toner image on the photoconductor 2 onto the recording sheet P, but temporarily transfers the toner image on the surface of the image carrier to an intermediate transfer member. Alternatively, the toner image may be primarily transferred onto the recording sheet, and then the toner image may be secondarily transferred onto the recording sheet surface.

As described above, the image forming apparatus of the present embodiment forms an electrostatic latent image on the surface of a photosensitive member, which is an example of an image carrier,
The electrostatic latent image is visualized as a toner image, and the toner image is transferred to a recording sheet surface directly or via an intermediate transfer member.
The fixing member comprising the fixing member 6 is configured to fix on the surface of the recording sheet at least by the action of heat, and is capable of changing the linear velocity of the surface of the image carrier to change the pixel density of the electrostatic latent image. Have been. More specifically, the image forming apparatus includes a photoconductor as an example of an image carrier, a driving unit that drives the image carrier so that the surface of the image carrier moves, and an image carrier that is driven. A latent image forming means for forming an electrostatic latent image on the surface of the sheet, a developing device for visualizing the electrostatic latent image as a toner image, and recording the toner image transferred on the recording sheet surface by at least the action of heat A fixing member which is heated to fix the sheet surface, a temperature detecting means for detecting a temperature of the fixing member, and the image carrier is driven at a surface linear velocity corresponding to a designated pixel density of the electrostatic latent image. like,
Linear velocity control means for controlling the driving means. These configurations are described in first to third embodiments which will be described in detail later.
This is common to the image forming apparatus of the specific example.

By the way, as described above, 120
When a high pixel density of 0 dpi is specified, it is necessary to fix the toner image at a lower fixing temperature than when a low pixel density of 600 dpi is specified. For this reason, in the image forming apparatus of this example, the fixing temperature of the fixing roller 16 when the printing operation is performed at a pixel density of 600 dpi is 190 ° C., and the fixing temperature of the fixing roller 16 when the printing density is 1200 dpi is 160 ° C. It is assumed that the temperature of the fixing roller 16 is controlled such that the temperature becomes ° C.

Here, in this type of image forming apparatus according to the conventional proposal, the temperature of the fixing roller is suitable for the designated pixel density so that the toner image is fixed at each fixing temperature as described above. Even if an operation for starting a printing operation is performed until the fixing temperature is reached, the printing start signal is not received by the main control unit. For this reason, the user has to wait until the fixing roller reaches the fixing temperature before performing the print start operation, which inevitably causes the user to feel a great deal of embarrassment and inconvenience. In order to eliminate such a problem, a first specific example of the image forming apparatus of the present embodiment is configured as described below with reference to FIG. Note that Y in FIG.
Is yes (YES), N is no (NO), and S
Indicates steps, which are the same in FIGS. 4 and 5.

In the conventional image forming apparatus, when the power is turned on and the apparatus is in a standby state, the fixing roller is heated, and when a print start command is issued, the print operation can be started in a short time as possible. However, also in the image forming apparatus of the first specific example, the standby temperature of the fixing roller 16 at the time of standby of the image forming apparatus is set to 175 ° C., and the surface temperature of the fixing roller 16 is set to this temperature. It is controlled (S1 in FIG. 3).

Here, when a print start command, that is, a print start signal is input to the main control unit 23 via the controller 24 shown in FIG. 2 by a print start operation on the host computer or the word processor side,
The main controller 23 accepts the print start request as it is (S2 in FIG. 3). When the image forming apparatus is a copying machine, a print start signal is generated by operating a print start key and is input to the main control unit. In this case, the print start request is also accepted.

Then, the main control unit 23 determines whether the pixel density of the electrostatic latent image designated by the user is 600 dpi or 1200 dpi (S3 in FIG. 3). The corresponding target temperature of the fixing roller 16 is set (S4 in FIG. 3). This target temperature is set to a fixing roller 16 suitable for a pixel density of 600 dpi.
The fixing temperature may be the same as the fixing temperature, but in the example shown in FIG. 3, the target temperature is set to 175 ° C., which is lower than this.

Next, when the temperature of the fixing roller 16 detected by the thermistor 22 (FIG. 1) reaches the target temperature (175 ° C.) (S5 in FIG. 3), the printing operation is performed under conditions corresponding to a pixel density of 600 dpi. Is executed (S in FIG. 3).
6). That is, under the control of the main control unit 23, FIG.
Starts rotating at a surface linear velocity of 92 mm / sec, the recording sheet P is fed to the transfer section by the rotation of the paper feed roller 9, and the toner image formed on the photoreceptor surface is transferred to the recording sheet. The toner image is transferred onto P, and the toner image is fixed by the fixing device 14. At this time, a certain period of time is required from when the recording sheet P is sent out from the paper feed cassette 8 to when the recording sheet P reaches between the fixing roller 16 and the pressure roller 17, so that the temperature of the fixing roller 16 Even if the printing operation is started before the temperature reaches 190 ° C. required for fixing the image, when the recording sheet P reaches the fixing device 14, the temperature of the fixing roller 16 becomes the fixing temperature (190 ° C.).
, Whereby the toner image is fixed at a fixing temperature suitable for a pixel density of 600 dpi. The temperature of the fixing roller 16 at the time of fixing the toner image is the fixing temperature (190
° C), but the actual temperature of the fixing roller 16 at the time of fixing the toner image depends on the set fixing temperature (19).
It is well known that the temperature may be slightly lower than (0 ° C.) or slightly higher.

On the other hand, when the designated pixel density is 1200 dpi
, The corresponding target temperature of the fixing roller 16 is set (S7 in FIG. 3). In this example, the target temperature is 160 ° C., which is the same as the fixing temperature suitable for 1200 dpi.
However, the target temperature may be set to a temperature lower than the fixing temperature (160 ° C.) for the same reason as described above.

Next, when the temperature of the fixing roller 16 detected by the thermistor 22 reaches the target temperature (160 ° C.) (S8 in FIG. 3), a printing operation is executed under conditions corresponding to a pixel density of 1200 dpi (S8). S9 in FIG. 3). That is, when the control of the main control unit 23 is started, the photoconductor 2 is driven at a surface linear velocity of 46 mm / sec to start the above-described printing operation, and the toner image transferred to the recording sheet P has a surface temperature of 160. The fixing is performed on the recording sheet by a fixing roller 16 which is controlled to attain a temperature of ° C. and a pressure roller 17 which is paired with the fixing roller 16.

The main controller 23 controls the fixing roller 16 to
After inputting the print start signal, the fixing roller 16 causes the fixing roller 16 to set the target temperature (17) so as to fix the toner image at the fixing temperature corresponding to the designated pixel density.
(5 ° C. or 160 ° C.), the printing operation control under the conditions corresponding to the respective pixel densities is started.

As described above, the image forming apparatus according to the first embodiment detects that the temperature of the fixing member has reached the target temperature corresponding to the designated pixel density after the input of the print start signal. , The print operation corresponding to the designated pixel density is started.

More specifically, in the image forming apparatus of this example, target temperature setting means for setting a target temperature of the fixing member corresponding to the designated pixel density, In order to fix the toner image at the corresponding fixing temperature, when it is detected that the temperature of the fixing member has reached the target temperature corresponding to the specified pixel density after the input of the print start signal, the specified pixel is detected. Print control means for starting print operation control corresponding to the density; in the illustrated example, the main control unit 23 constitutes the target temperature setting means and print control means.

According to the above-described image forming apparatus of the first specific example, even when the user performs a print start operation before the fixing roller 16 reaches a temperature suitable for the pixel density specified by the user, the image forming apparatus is not limited to this. Since the print start signal is received as it is and the print operation is automatically started thereafter, the user can obtain a predetermined recorded image only by performing the print start operation once. In the conventional image forming apparatus, it is necessary to perform the print start operation after the fixing roller has reached the fixing temperature, which may give the user a feeling of embarrassment. Can be eliminated.

By the way, in this type of conventional image forming apparatus, after a user specifies a pixel density, it takes a considerably long time for the fixing roller to reach a fixing temperature suitable for the pixel density. The disadvantage of long waiting time was inevitable.

Here, the user can select and specify a desired pixel density, but the pixel density that is frequently used in each user or in each part using the image forming apparatus is usually determined. Therefore, if a pixel density that is frequently used is set in advance and the fixing roller 16 is maintained at a temperature corresponding to the pixel density when the image forming apparatus is on standby, the user can print at the pixel density. When a print start operation is performed to obtain an image, it is possible to start the print operation after a very short waiting time or with substantially no waiting time. The second specific example shown in FIG. 4 is configured from such a viewpoint, and details thereof are as follows.

First, by operating the host computer or word processor (or by operating an operation key in the case of a copying machine), the user sets a pixel density which is frequently used, and sets the initially set pixel density. 2 is stored in the memory of the main control unit 23 shown in FIG. Then, when the image forming apparatus is on standby, the main control unit 23 determines whether the initial setting pixel density is 600 dpi or 1200 dpi (S1 in FIG. 4), and when this is 600 dpi,
The target temperature of the fixing roller 16 corresponding to the pixel density is set (S2 in FIG. 4). This target temperature is a pixel density of 60
Although the fixing temperature (190 ° C.) suitable for 0 dpi may be used, in the illustrated example, the target temperature is the fixing temperature (190 ° C.).
(° C.).

On the other hand, when the initial pixel density is 1200 dpi, the fixing roller 16 corresponding to the pixel density
Is set (S7 in FIG. 4). In this case, the target temperature may be lower than a fixing temperature (160 ° C.) suitable for a pixel density of 1200 dpi, but in the example of the drawing, the target temperature is set to a temperature (160 ° C.) that matches the fixing temperature.

The image forming apparatus stands by in each of the states described above. That is, when the fixing roller 16 is set to the target temperature (175
C or 160 ° C.) so that the fixing roller 1
6 is controlled. Thus, the main control unit 23
Sets the target temperature so that the fixing roller 16 stands by at a target temperature (175 ° C. or 160 ° C.) corresponding to a preset initial pixel density, and sets the fixing roller 16 to the initial setting pixel density. Target temperature corresponding to the density (1
75 ° C. or 160 ° C.)
It controls the temperature.

Next, a print start signal is input to the main control unit 23 in the same manner as in the above-described example (FIG. 4).
(S3, S8), at this time, the main control unit 23 determines whether or not the pixel density specified by the user matches the initial set pixel density (S4, S9 in FIG. 4). At this time, when the designated pixel density matches the default pixel density, the temperature of the fixing roller 16 has reached the target temperature (175 ° C. or 160 ° C.) corresponding to the default pixel density by the thermistor 22. Is detected (S in FIG. 4).
5, a print operation is executed under the conditions corresponding to the pixel density (S6, S11 in FIG. 4). That is, when the designated pixel density is 600 dpi, the photosensitive member 2 is driven at a surface linear velocity of 92 mm / sec, and when the recording sheet P reaches the fixing device 14, the surface temperature becomes the fixing temperature (190 ° C.).
The toner image is fixed by the fixing roller 16 controlled so as to satisfy
When the specified pixel density is 1200 dpi, photoconductor 2
Is driven at a surface linear velocity of 46 mm / sec, and the surface temperature is controlled so as to be a fixing temperature (160 ° C.) suitable for the pixel density. Thus, the toner image is fixed. in this way,
When the designated pixel density matches the default pixel density, the main control unit 23 adjusts the temperature of the fixing roller 16 so that the fixing roller 16 fixes the toner image at a fixing temperature corresponding to the default pixel density. When the thermistor 22 detects that the target temperature corresponding to the initially set pixel density has been reached, the printing operation control is started.

When the specified pixel density is different from the initially set pixel density, the main controller 23 sets the target temperature of the fixing roller 16 corresponding to the specified pixel density.

For example, when it is checked in step S4 of FIG. 4 that the designated pixel density is 1200 dpi, the pixel density is set to the initial pixel density (60 pixels).
0 dpi), the target temperature of the fixing roller 16 is set to 160 ° C. in this case (S12 in FIG. 4). Then, the temperature of the fixing roller 16 becomes the target temperature (160
° C) (S10 in Fig. 4).
The printing operation is executed under the conditions corresponding to the designated pixel density (1200 dpi) (S11 in FIG. 4).

When it is determined in step S9 in FIG. 4 that the designated pixel density is 600 dpi different from the initial setting pixel density of 1200 dpi, the fixing roller 16 corresponding to the designated pixel density (600 dpi) is determined. The target temperature (175 ° C.) is set (S13 in FIG. 4), and when the thermistor 22 detects that the temperature of the fixing roller 16 has reached the target temperature (175 ° C.) (S5 in FIG. 4), The printing operation is executed under the conditions corresponding to the pixel density (600 dpi) (S6 in FIG. 4). As described above, when the designated pixel density is different from the default pixel density, the main control unit 23 controls the thermistor 22 so that the fixing roller 16 fixes the toner image at the fixing temperature corresponding to the designated pixel density. When it is detected that the temperature of the fixing roller 16 has reached the target temperature corresponding to the designated pixel density, the printing operation control is started.

As described above, in the image forming apparatus of the second specific example, the fixing member including the fixing roller 16 is set so that the fixing member stands by at the target temperature corresponding to the preset initial pixel density. While controlling the temperature, when the designated pixel density matches the initial setting pixel density, when it is detected that the temperature of the fixing member has reached the target temperature corresponding to the initial setting pixel density, the initial setting pixel When the printing operation corresponding to the density is started and the designated pixel density is different from the default pixel density, it is detected that the temperature of the fixing member has reached the target temperature corresponding to the designated pixel density. , The print operation corresponding to the designated pixel density is started.

More specifically, in the image forming apparatus according to the second embodiment, the storage means for storing the preset initial pixel density, and the fixing member comprising the fixing roller 16 are provided with the initial pixel density. Target temperature setting means for setting the target temperature so as to stand by at a target temperature corresponding to the target temperature; pixel density determining means for determining whether a specified pixel density matches the initial setting pixel density; When the specified pixel density is different from the default pixel density, target temperature setting means for setting a target temperature of the fixing member corresponding to the specified pixel density, and the specified pixel density matches the default pixel density When, the temperature of the fixing member has reached the target temperature corresponding to the default pixel density so that the fixing member fixes the toner image at the fixing temperature corresponding to the default pixel density. When the detected pixel density is different from the default pixel density, the fixing member starts fixing operation corresponding to the specified pixel density. In order to fix the toner image at the temperature, when it is detected that the temperature of the fixing member has reached the target temperature corresponding to the designated pixel density, the printing operation control corresponding to the designated pixel density is performed. Print control means for starting. In the illustrated example, the storage unit, the two target temperature setting units, the pixel density determination unit, and the print control unit are all configured by the main control unit 23.

According to the above configuration, if a pixel density frequently used by a certain user or a certain part of the company is set in advance as an initial setting pixel density, in many cases, the user can set Since the designated pixel density matches the default pixel density, the printing operation can be started in a very short time or substantially without a waiting time after the printing start operation is performed. That is, 600
The first initial pixel density of dpi and the second initial pixel density of 1200 dpi higher than this can be set, and the target temperature (175) of the fixing roller 16 corresponding to the first initial pixel density can be set. .Degree. C.) is higher than the target temperature (160.degree. C.) of the fixing roller 16 at the second initial pixel density, and the fixing roller 16 waits at the target temperature at the set initial pixel density. When the initial pixel density and the designated pixel density match, the fixing roller 1
The temperature 6 becomes a fixing temperature suitable for the pixel density in a very short time, and the waiting time of the user can be effectively reduced.

On the other hand, when a certain user uses an image forming apparatus and then uses that image forming apparatus, the same pixel density is often specified when both image forming apparatuses are used. Therefore, after a series of printing operations is completed, the same pixel density as that of the previous printing operation is automatically designated during the next printing operation.
If the printer is configured to stand by at a fixing temperature suitable for the pixel density or at a temperature close to this, the printing operation is often performed in a very short time after the printing start operation or with substantially no waiting time. Can be started. The third specific example shown in FIG. 5 is configured from such a viewpoint, and details thereof are as follows.

Here, it is assumed that the temperature of the fixing roller 16 at the time of standby of the image forming apparatus is set to 175 ° C. (S1 in FIG. 5). When the fixing roller 16 reaches the target temperature (1
The fixing roller 16 is controlled by the main controller 23 so as to stand by at 75 ° C.).

Next, when a print start signal is input to the main controller 23 via the controller 24 (S in FIG. 5).
2) At this time, the pixel density specified by the user is 60
It is determined whether it is 0 dpi or 1200 dpi (see FIG. 5).
S3). Here, the designated pixel density is 600 dp
i, the thermistor 22 fixes the fixing roller 1
When it is detected that the temperature of No. 6 has reached the above-mentioned target temperature (175 ° C.) (S4 in FIG. 5), as in the above specific example,
The main controller 23 controls the designated pixel density (600 dp
The printing operation control corresponding to i) is started, and the printing operation is performed under the conditions (S5 in FIG. 5). That is, the photoconductor 2 is driven to rotate at a surface linear velocity of 92 mm / sec, and the fixing roller 16
The fixing temperature (190 ° C.) suitable for 00 dpi is controlled, and the toner image is fixed substantially at this temperature.

When the above-described printing operation is completed, the main control unit 23 sets the pixel density (600
dpi) corresponding to the target temperature (175
C.) (S1 in FIG. 5), and controls the temperature of the fixing roller 16 so that the fixing roller 16 stands by at the target temperature when the image forming apparatus is on standby. Also in this case, the target temperature may be the same as the fixing temperature (190 ° C.),
In the illustrated example, the target temperature slightly lower than this temperature (1
75 ° C).

On the other hand, if it is determined in step S3 in FIG. 5 that the designated pixel density is 1200 dpi, the target temperature of the fixing roller 16 corresponding to the pixel density is set (S6 in FIG. 5). . In this case as well, in this example, the target temperature is set to the same value as the fixing temperature (160 ° C.) of the fixing roller 16 suitable for the pixel density of 1200 dpi, but the target temperature may be lower than this temperature. .
Next, when the thermistor 22 detects that the temperature of the fixing roller 16 has reached the target temperature (160 ° C.) (S7 in FIG. 5), a printing operation corresponding to 1200 dpi is executed (S8 in FIG. 5). Photoconductor 2 is 46mm / sec
And the fixing roller 16 is driven at approximately 160 ° C.
Is controlled to fix the toner image at the fixing temperature.

When the above-described printing operation is completed, the main controller 23 sets the target temperature (160 ° C.) of the fixing roller 16 corresponding to the pixel density (1200 dpi) during this printing operation (FIG. 5). S9), the temperature of the fixing roller 16 is controlled so that the fixing roller 16 stands by at the target temperature when the image forming apparatus is on standby.

When a print start signal is input again after step S9 in FIG. 5 (S10 in FIG. 5), it is checked whether the designated pixel density at this time is 600 dpi or 1200 dpi (S11 in FIG. 5), and this is 1200 dpi. When the thermistor 22 detects that the fixing roller 16 has reached the target temperature (160 ° C.) set in step S9 (S7 in FIG. 5), the specified pixel density ( 1200 dpi) is executed (S8 in FIG. 5). On the other hand, when it is determined in step S11 that the designated pixel density is 600 dpi, the main control unit 23 determines the target of the fixing roller 16 corresponding to the pixel density (600 dpi) as in step S1. Set the temperature (175 ° C) (S in FIG. 5).
12) When the thermistor 22 detects that the temperature of the fixing roller 16 has reached the target temperature (175 ° C.) (S4 in FIG. 5), the printing operation control corresponding to the pixel density (600 dpi) is started. Then, the printing operation is executed under the conditions (S5 in FIG. 5). Hereinafter, the same operation is repeated.

As described above, in the image forming apparatus of the third specific example, when it is detected that the temperature of the fixing member including the fixing roller 16 has reached the target temperature corresponding to the designated pixel density, A printing operation corresponding to the pixel density is started, and the temperature of the fixing member is controlled so that the fixing member waits at a target temperature corresponding to the pixel density of the printing operation after the printing operation is completed. Have been.

More specifically, in the image forming apparatus of this example, the temperature of the fixing member is adjusted such that the fixing member including the fixing roller 16 fixes the toner image at the fixing temperature corresponding to the designated pixel density. When it is detected that the target temperature corresponding to the specified pixel density has been reached, a print control means for starting a print operation control corresponding to the pixel density, and after the end of the print operation, a pixel at the time of the print operation Target temperature setting means for setting the target temperature so that the fixing member stands by at a target temperature corresponding to the density. Here also, the main control unit 23 controls the print control means and the target temperature setting means. Make up.

According to the above configuration, after the printing operation is completed, the target temperature of the fixing roller 16 corresponding to the pixel density at the time of the printing operation is automatically set.
Waits at that temperature, so during the next print operation, if the same pixel density as in the previous print operation is specified,
The printing operation can be started in a very short time or with substantially no waiting time. That is, the first pixel density (600 dpi) and the second pixel density (1200 dpi) having a higher pixel density can be designated, and the target temperature (1) of the fixing roller 16 corresponding to the first pixel density can be specified.
75 ° C.) is fixed to the fixing roller 16 corresponding to the second pixel density.
Is higher than the target temperature of the fixing roller 16
Waits at the target temperature corresponding to the pixel density at the time of the previous printing operation. Therefore, if the same pixel density as at the time of the previous printing operation is designated at the next printing operation, the fixing roller 16
Is a fixing temperature suitable for the pixel density in a very short time, and the waiting time of the user can be effectively reduced. When a pixel density different from the pixel density at the time of the previous printing operation is specified, the target temperature of the fixing roller 16 corresponding to the specified pixel density is set again, so that the waiting time of the user is slightly longer, The printing operation itself can be performed without any trouble.

Further, the second and the third shown in FIG. 4 and FIG.
In the specific example, as in the first specific example, when the print control unit detects that the temperature of the fixing member has reached the target temperature corresponding to the specified pixel density after the input of the print start signal, The print operation control corresponding to the pixel density is started. For this reason,
The print operation is performed only once by the user performing the print start operation, thereby preventing the user from being confused.

The present invention is not limited to the laser printer shown in FIG. 1, but can be widely applied to other types of printers, copiers, facsimile machines, and multifunction machines having at least two of these functions. .

[0070]

According to the first and second aspects of the present invention, when it is detected that the temperature of the fixing member has reached the target temperature after the input of the print signal, the printing operation is started. Therefore, the printing operation can be executed at the specified pixel density without giving the user a feeling of embarrassment.

According to the third to fifth aspects of the present invention, the initial setting pixel density is set in advance, and the fixing member waits at the target temperature corresponding to the pixel density. When the density matches, the printing operation can be started substantially without a waiting time or within a very short time after the input of the printing start signal.

According to the sixth and seventh aspects of the present invention, the fixing member waits at the target temperature corresponding to the pixel density at the time of the previous printing operation. When the pixel density is specified,
After inputting the print start signal for the next print operation,
The printing operation can be started with substantially no waiting time or in a very short time.

According to the eighth aspect of the present invention, the printing operation can be executed at the designated pixel density without giving the user a feeling of embarrassment.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional view showing an example of an image forming apparatus.

FIG. 2 is a block diagram illustrating an example of a control system of the image forming apparatus illustrated in FIG.

FIG. 3 is a flowchart of a first specific example.

FIG. 4 is a flowchart of a second specific example.

FIG. 5 is a flowchart of a third specific example.

[Explanation of symbols]

 5 Developing device P Recording sheet

Claims (8)

[Claims] An electrostatic latent image is formed on a surface of an image carrier, the electrostatic latent image is visualized as a toner image, and the toner image is transferred to a recording sheet surface directly or via an intermediate transfer member. An image forming apparatus for fixing a toner image on the surface of the recording sheet to the surface of the recording sheet by at least the action of heat of a fixing member; In the image forming apparatus capable of changing the temperature, when it is detected that the temperature of the fixing member has reached the target temperature corresponding to the designated pixel density after the input of the print start signal, the designated pixel density is decreased. An image forming apparatus for starting a corresponding print operation. 2. An image carrier, driving means for driving the image carrier so that the surface of the image carrier moves, and latent image forming means for forming an electrostatic latent image on the surface of the driven image carrier. A developing device that visualizes the electrostatic latent image as a toner image, and a fixing member that is heated to fix the toner image transferred to the recording sheet surface to the recording sheet surface by at least the action of heat, Temperature detection means for detecting the temperature of the fixing member; and linear velocity control means for controlling the driving means so that the image carrier is driven at a surface linear velocity corresponding to the designated pixel density of the electrostatic latent image. A target temperature setting means for setting a target temperature of the fixing member corresponding to the specified pixel density; and a print start signal so that the fixing member fixes the toner image at a fixing temperature corresponding to the specified pixel density. After entering the An image forming apparatus comprising: a print control unit that starts a print operation control corresponding to a designated pixel density when it is detected that the target temperature corresponding to the element density has been reached. 3. An electrostatic latent image is formed on the surface of an image carrier, the electrostatic latent image is visualized as a toner image, and the toner image is transferred to a recording sheet surface directly or via an intermediate transfer member. An image forming apparatus for fixing a toner image on the surface of the recording sheet to the surface of the recording sheet by at least the action of heat of a fixing member; In the image forming apparatus, the fixing member controls the temperature of the fixing member such that the fixing member waits at a target temperature corresponding to a preset initial pixel density. When it is detected that the temperature of the fixing member has reached the target temperature corresponding to the initially set pixel density, the printing operation corresponding to the initially set pixel density is started,
When the designated pixel density is different from the default pixel density, when it is detected that the temperature of the fixing member has reached the target temperature corresponding to the designated pixel density, the temperature corresponding to the designated pixel density is detected. An image forming apparatus for starting a printing operation. 4. An image carrier, driving means for driving the image carrier so that the surface of the image carrier moves, and latent image forming means for forming an electrostatic latent image on the surface of the driven image carrier. A developing device that visualizes the electrostatic latent image as a toner image, and a fixing member that is heated to fix the toner image transferred to the recording sheet surface to the recording sheet surface by at least the action of heat, Temperature detection means for detecting the temperature of the fixing member; and linear velocity control means for controlling the driving means so that the image carrier is driven at a surface linear velocity corresponding to the designated pixel density of the electrostatic latent image. Storage means for storing a preset initial pixel density, and target temperature setting means for setting a target temperature such that the fixing member waits at a target temperature corresponding to the initial pixel density. Pixel density matches the default pixel density Pixel density determining means for determining whether or not the target pixel density is different from the initial setting pixel density, and target temperature setting means for setting a target temperature of the fixing member corresponding to the specified pixel density. When the designated pixel density matches the default pixel density, the temperature of the fixing member is set to the initial setting so that the fixing member fixes the toner image at a fixing temperature corresponding to the default pixel density. When it is detected that the target temperature corresponding to the pixel density has been reached, printing operation control corresponding to the initial set pixel density is started, and when the designated pixel density is different from the initial set pixel density, fixing is performed. It is verified that the temperature of the fixing member has reached the target temperature corresponding to the specified pixel density so that the member fixes the toner image at the fixing temperature corresponding to the specified pixel density. When the image forming apparatus and a print control means for starting the printing operation control corresponding to the designated pixel density. 5. A first initial pixel density and a second initial pixel density higher than this pixel density can be set, and a target temperature corresponding to the first initial pixel density is:
The image forming apparatus according to claim 3, wherein the temperature is higher than a target temperature of the second initial pixel density. 6. An electrostatic latent image is formed on a surface of an image carrier, the electrostatic latent image is visualized as a toner image, and the toner image is transferred to a recording sheet surface directly or via an intermediate transfer member. An image forming apparatus for fixing a toner image on the surface of the recording sheet to the surface of the recording sheet by at least the action of heat of a fixing member; When it is detected that the temperature of the fixing member has reached the target temperature corresponding to the designated pixel density, the printing operation corresponding to the pixel density is started, and An image forming apparatus, comprising: controlling a temperature of a fixing member so that the fixing member waits at a target temperature corresponding to a pixel density of the printing operation after a printing operation is completed. 7. An image carrier, driving means for driving the image carrier so that the surface of the image carrier moves, and latent image forming means for forming an electrostatic latent image on the surface of the driven image carrier. A developing device that visualizes the electrostatic latent image as a toner image, and a fixing member that is heated to fix the toner image transferred to the recording sheet surface to the recording sheet surface by at least the action of heat, Temperature detection means for detecting the temperature of the fixing member; and linear velocity control means for controlling the driving means so that the image carrier is driven at a surface linear velocity corresponding to the designated pixel density of the electrostatic latent image. And when the fixing member detects that the temperature of the fixing member has reached the target temperature corresponding to the specified pixel density, so that the fixing member fixes the toner image at the fixing temperature corresponding to the specified pixel density. A process to start print operation control corresponding to the pixel density An image forming apparatus comprising: a lint control unit; and a target temperature setting unit that sets the target temperature such that the fixing member waits at a target temperature corresponding to a pixel density during the printing operation after the printing operation. . 8. The print control unit, when it is detected that the temperature of the fixing member has reached a target temperature corresponding to a designated pixel density after inputting a print start signal.
The image forming apparatus according to claim 4, wherein printing operation control corresponding to the pixel density is started.