JPH01205174A - Image forming device - Google Patents

Abstract

PURPOSE:To excellently mesh gears by normally and reversely rotating a pulse motor for a specified time at a speed lower than at the time of driving a load in case of switching to the selected load. CONSTITUTION:The pulse motor 26 has a such a constitution that it drives a quite different load with the operation of a driving switching solenoid 27. Namely, one load is a unit constituting an exposure lamp 4, a 1st mirror 5, a 2nd mirror 6 and a 3rd mirror 7 and another load is a unit constituting a zoom lens 8, then these loads which need not be synchronously driven are driven by means of a common driving source. At the time of switching the load, the pulse motor 26 is normally and reversely rotated at the speed lower than the load driving speed of the pulse motor 26. Thus, the load can be surely and smoothly switched.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus in which a plurality of loads are independently driven by one motor.

[Conventional technology]

BACKGROUND ART Conventionally, it has been known to drive a plurality of loads, such as a scanner and a lens, by a pulse motor.

[Problems to be Solved by the Invention] However, in the conventional example described above, since the load switching device for switching a plurality of loads is simply driven, the gears do not mesh well (or may not operate).

[Means for solving problems]

According to the present invention, the meshing of the gears is improved by rotating the pulse motor in forward and reverse directions at a speed slower than the load driving speed of the pulse motor when changing the load.

(hereafter: 11) 'J---j Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings, taking as an example a copying apparatus embodying the present invention.

FIG. 1 is a sectional view of the entire copying apparatus in this embodiment. In FIG. 1, the drive system is divided into a main drive system that drives a paper feed section, a conveyance section, a photoreceptor, and a fixing section, and an optical drive system that drives an optical system. An AC synchronous motor 25 is used as the main drive source, and a pulse motor (stepping motor) 26 is used as the optical drive source.

As the paper feeding method, feeding from the cassette 23 or feeding from the manual feed section 24 can be selected. When feeding paper from a cassette, the status is managed by a switch that detects the presence or absence of the cassette 23, a switch group 31 that detects the size of the cassette, and a switch 37 that detects the presence or absence of paper in the cassette. If detected, it is displayed on the display unit, which will be described later. In the case of manual paper feeding, the state of the manual feed guide 24 is managed by a switch 32 that detects the state, and when an abnormality is detected, it is displayed on a display section to be described later.

The photoreceptor 12 rotates clockwise. - The potential charged on the photoreceptor 12 by the charger 13 is exposed to the developing unit 12 at an exposure position, which will be explained in detail later.
The image is developed in step 5 and transferred to a transfer sheet fed from a paper feeder in a transfer unit section 14. Photoreceptor 12 after transfer
The remaining toner is removed by the cleaning unit 38, the residual potential is removed by the pre-exposure lamp 16, and image formation is performed again. This process is repeated.

The transfer paper on which the image has been transferred rides on the conveyor belt of the conveyor unit 2o and is sent to the fixing unit 21. The fixing unit 21 is composed of a heat roller 35' having a temperature sensing element (thermistor) 35 disposed on its surface, and a roller having an elastic surface that is in pressure contact with this roller. The heat roller 35' uses a halogen lamp as a heat source, and this halogen lamp is built in in the axial direction of the roller. This halogen lamp is controlled by a thermistor so that the surface temperature of the heat roller 35' becomes a predetermined temperature.

The paper that has passed through the fixing unit 21 is discharged from the fixing unit 21 by a paper discharge roller 22 and stored on a paper discharge tray 39.

Further, the paper discharge sensor 34 is a sensor that detects whether or not the transfer paper has passed through the fixing unit 21 normally.

The drive source of the optical drive system is the pulse motor 26 as described above. This drive source will be explained in detail later in FIG.
The pulse motor 26 is configured to drive a completely different load by operating a drive switching solenoid 27. One load is an exposure lamp 4, a first mirror 5, a second mirror 6,
This is a unit that constitutes the third mirror 7, and the other load is a unit that constitutes the zoom lens 8. These loads that do not require synchronous driving can be driven by a common driving source.

This device uses the pulse motor 26 of the optical drive unit to control the position of the zoom lens 8 and the speed of the lamp systems 4 to 7 to select a multi-stage magnification. A function to automatically select the density using the optical sensor 40 for detection, a function to automatically select the copying magnification by connecting with an external device (not shown) (having communication means), and a function to automatically select the copy magnification when an abnormality such as a paper jam occurs. A memory backup function that stores various statuses of the 1, such as the number of remaining sheets, 1 magnification value, abnormality information, etc., a page quick copy function by controlling the position of the exposure lamp 4 by the pulse motor 26, and a replacement of the developing unit 15. By doing so, it is possible to form a plurality of color images, and by providing a switch 36 that detects replacement of the developing unit 15, it has a function of switching control depending on this state. Next, the operation of this device will be explained.

A power cord (not shown) of the device is connected to a predetermined power source. FIG. 2 shows the operation panel of this device, which is placed on the top surface of FIG. When the I side of the power switch 51 is pressed, power is supplied to the device. At the same time, the power indicator lamp 52
will be lit and displayed.

In the initial state after the power is turned on, the thermistor 35 of the fixing unit 21 detects that the heat roller 35' has not reached a predetermined temperature and controls the lighting of a fixing heater (not shown) as a heat source. When the power is turned on, the display on the operation panel is set as standard mode as shown below. The sheet number display 59 displays 1, the magnification display 67 displays the same magnification, and the automatic density adjustment display 76 A lights up.

Further, the display section of the start key 56 is displayed in red when the temperature inside the fixing unit has not reached the fixing temperature, and when it reaches the fixing temperature, the display changes to green and copying operation is enabled. Show what happened. Normally, all other indicators are off.

Note that the fixable temperature of the fixing unit 21 varies depending on the type of the developing unit 15, and the set temperature is changed by determining the type of the developing unit 15 using a switch 36 provided on the developing unit 15. Further, when the temperature needs to be lowered from a high state, a means for forcibly cooling it using the in-machine cooling fan 28 is provided, thereby achieving a temperature that can be fixed quickly.

Next, the operation of the optical drive system after power is turned on will be explained.

The exposure lamp systems 4 to 7 scan and move the original on the original glass 3 from the left end in FIG.
．． Second mirror 6, third mirror 71 zoom lens 8. Fourth
Mirror 9. The original is exposed to the photoreceptor 12 via the fifth mirror 10° and the sixth mirror 11. In other words, set the starting point of movement to the left end.

This position is called the home position (H, P). HoP
An H, P sensor 29 is provided to detect.

If the H1P sensor does not detect the position of the exposure lamp 4 when the power is turned on, the one-chip microcomputer control unit shown in FIG. 3 controls the rotation of the pulse motor 26 to move the exposure lamp unit to the H and P sides. (A known technique is used to control the forward and reverse rotation of the pulse motor.) The start of the rotation control described above is explained with reference to Fig. 5.
First, when the drive switching solenoid 27 is in the OFF state (there is no force b'), the switching gear (2) moves in the direction A by the spring pressure. As a result, the output of the pulse motor 26 is connected to the lamp drive gear (2) via the switching gear (2), and the exposure lamp units 4 to 7 are driven. During this gear connection, the rotation speed of the pulse motor 26 is controlled to be sufficiently lowered when the switching gear (2) and the lamp driving gear (2) are engaged.

When the exposure units 4 to 7 are located at H and P,
The pulse motor 26 drives the zoom lens unit 8. In other words, the zoom lens position before the power is turned on is unknown.

As mentioned above, when the power is turned on, the same magnification value is selected as the standard mode. For this reason, an operation is performed to temporarily return to the reference position and set it to a predetermined position from that point.

The reference position above is the zoom lens home position (Z,
(referred to as HP). A Z and HP sensor 30 is provided to detect this position. The operation will be explained with reference to FIG.

Turn on the drive switching solenoid 27. This causes the plunger of the solenoid to move in direction b.

Therefore, the force b' causes the switching gear (2) to move in the direction B against the spring force. Due to this movement, the switching gear (2) and the lamp drive gear (3) are disengaged from each other. By further moving in the direction B, the switching gear (2) will fit into the lens drive gear (2). The rotation control when the gears are fitted is the same as described above.

The zoom lens 8 has a magnification rate of 200% when the lens position is located near the Z and HP sensor with the Z and HP sensor as the reference position, and a reduction rate of 50% when moved further to the right.
Position control is performed within the range of .

At the start of zoom lens driving, the operation is determined as follows depending on the Z and HP states.

(1) When the position of the zoom lens 8 is detected by the Z and HP sensors.

(1) Move the -1-degree zoom lens 8 to the right and Z.

Move it out of the range where the HP sensor can't detect it and stop.

(1)-2 Move to the left and Z, move a predetermined distance from the point when the HP sensor detects it, and stop.

However, if the Z and HP sensors do not detect the position of the zoom lens, execution starts from operation (1)-2.

The above operation is necessary control to prevent setting position errors due to backlash of gears.

After this, the zoom lens 8 is moved to the right again, and the zoom lens 8 moves from the position where it misses the Z and HP sensor to a predetermined position, that is, a position corresponding to the same magnification in the case of standard mode setting, and then stops. do. After this, drive switching solenoid 2
Turn off 7. As a result, as mentioned above, the switching gear
moves in the direction of engagement with lamp drive gear (2). However, in order to fit smoothly, it is necessary to rotate the switching gear (2) as already mentioned. At this point, the exposure lamp units 4 to 7 are at H, P29. Therefore, the pulse motor 26 rotates the exposure lamp units 4 to 7 in a direction to move them to the right. As a result, when the exposure lamp units 4 to 7 are disengaged from the H and P sensors 29 (this means that the switching gear ■ and the lamp drive gear ■ have finished mating), the rotation is stopped, and the rotation is started again in the opposite direction. H, P sensor 29
After detecting, it stops at a predetermined position.

The initial operation of the optical drive system and the fixing unit 21 explained above
The preparation of the copying operation of this apparatus is completed by reaching the fixable temperature.

Next, the copying operation by feeding paper from the cassette 23 will be explained.

When the copy start key 56 is pressed, transfer paper size data is generated based on the input signal of the switch group 31 that detects the cassette size, sheet number data is set using the number key 54, and magnification selection key 61, 62, 64, 65° 66 is generated. A copying operation is started based on magnification data and other data from various mode selection means.

When the copy start key 56 is accepted, the display changes from green to red, and the numeric key 54 and magnification keys 61 and 62 are pressed.
．． 64. 65. Input of mode switching keys such as 66 is prohibited. The main drive motor 25 starts rotating, and the paper feeding roller 18. Photoreceptor 12. Transport unit 20. The driving force is transmitted to the fixing unit 21 and the like.

Further, at the time when the copy key 56 is received, the temperature at which fixing can be performed in the fixing unit 21 is changed depending on the cassette size data.

A paper feed solenoid (not shown) operates 0.5 seconds after the main drive motor 25 starts rotating, and the paper feed roller 17 rotates accordingly, moving the transfer paper in the cassette 23 in the direction of the paper feed roller 18. send out.

The transfer paper feed amount of the paper feed roller 17 is controlled by cassette size data. In other words, if the transfer paper is larger than a predetermined value, the amount of feed is increased. Transfer paper is fed by paper feed roller 18
When the transfer paper reaches the registration roller 19, the paper feed roller 18 moves the transfer paper to the registration roller 19, and the transfer paper stops there. A manual feed switch 33 installed between the paper feeding roller 18 and the registration roller 19 detects the feeding state of the transfer paper.

At a predetermined timing until the transfer paper is sent along the paper feed path and reaches the registration rollers 19, the exposure lamp units 4 to 7 are allowed to start scanning the document.

At this time, the exposure lamp is at a position where it can be detected by the H1P sensor 29. More specifically, during the initial operation or during the backward movement of the copying operation, the robot stops at a position that is a distance that corresponds to the selection magnification at that time from the position where the H and P sensors are detected.

With the start of document scanning, the pulse motor 26, which is the optical system drive source, increases the pulse rate in the direction in which the exposure units 4 to 7 move forward (rightward) until the drive hull rate is reached according to the selected magnification value. increases gradually (called slow-up control). In other words, the moving speed is gradually accelerated to reach the target speed. Although not particularly shown, the pulse motor drive circuit of this device adopts a constant current control method and has a configuration in which the drive current value can be switched in multiple stages (two stages in the example) (as shown in Fig. 3). (Selected by the PB4 output signal of the optical drive pulse motor control signals).

Generally, the characteristics of a pulse motor are such that the pull-in torque decreases as the pulse rate increases.

For this reason, means for switching the constant current setting value is provided, and the current value is switched as necessary.

In this device, the set current is kept low during a relatively low pulse rate from the start of movement, and the set current value is increased from the point when the speed exceeds a predetermined value, and after reaching the target speed, the set current value is controlled to be increased. As time passes, control is implemented to lower the set current value again. This is mainly aimed at preventing noise, temperature rise, and step-out phenomena of the pulse motor.

Next, a method for forming a margin at the leading edge of the image and a method for aligning the leading edge with the transfer paper will be explained based on FIG.

LED as a means to prevent toner adhesion in non-image areas
Although static eliminating means using light sources such as lamps and fuse lamps are generally used, the present device achieves the same effect by controlling the voltage value of the grid 13' provided in the primary charging unit 13. This is an important method in the current situation where it has become difficult to arrange a plurality of members on a photoreceptor layer due to miniaturization of devices. Since the distance between the exposure point and the grid cannot be placed sufficiently short compared to the distance between the H and P sensor 29 and the document placement position, the exposure lamp 4 is used to form a margin of 2 mm at the leading edge of the document. The grid is switched from the L level to a predetermined voltage after a predetermined time period corresponding to the magnification selection value from the start of movement.

In other words, when the grid voltage is at the L level, no toner image is formed because the photoconductor is not charged with potential, and an image is formed from the timing when the voltage is switched to the above-mentioned predetermined voltage. It forms a margin.

Next, regarding alignment of the leading edge of the image with the transfer paper, the distance C between the exposure point and the transfer section is made shorter than the distance C between the registration roller 19 and the transfer section. For this reason, before the image at the leading edge of the document is actually exposed on the photoreceptor 12, it is necessary to re-feed the transfer paper waiting in the registration roller 19 section and send it toward the transfer section.

In this apparatus, when the exposure lamp 4 starts moving and reaches the target speed, the H and P sensors 29 are still detecting the movement. The exposure lamp 4 reaches the edge of the white board after passing the H, P sensor 29, which is the value obtained by dividing the distance +2 mm by the speed based on the selected magnification. This is the time required to do this, and let this time be X.

In addition, y is the value obtained by subtracting the time required for the image at the exposure point of the photoreceptor 12 to reach the transfer section from the time from the start of paper refeeding by the registration roller 19 until the transfer paper reaches the transfer section. , the time required to feed the transfer paper 2 mm to this y (2 mm + 100 mm/s = 0, 02 sec ・=
Add conveyance speed = 100 mm/s).

The above values are calculated using the following formula.

x − (y + 0.02) = Z (sea) that is, H
, If the registration roller 19 is operated at the timing when the above formula value Z has passed from the time when the paper passes the P sensor 29, and the paper is re-feeded, the margin is reduced to 2 mm according to the selected magnification.
The formed transfer paper image can be changed.

The scanning distance of the exposure units 4 to 7 is moved a predetermined distance according to the cassette size data, magnification data, etc., and when the target position is reached, the pulse rate is gradually decreased (this is called slowdown control). Slow-up control and constant speed control are performed in the direction of the P sensor 29 to move backward. When the H and P sensors 29 are detected, slowdown control is performed to stop the exposure units 4 to 7 at positions corresponding to the selected magnification.

The manual copy operation is started when the manual feed sensor 33 detects the inserted transfer paper.

The main drive motor 25 starts rotating, which causes the paper feeding roller 18 to rotate. As a result, the inserted transfer paper is transferred to the registration roller 19 by the paper feed roller 18.
sent in the direction. Also, after a predetermined period of time from the time when the manual feed sensor 33 detects the transfer paper, the exposure lamp units 4 to
7 is permitted to start scanning the original. The subsequent operations of the exposure lamp system and the leading edge of the transfer paper are the same as in the case of cassette paper feeding, and will therefore be omitted.

Next, the operation of the registration roller 19 is started after the time X' required for the transfer paper to pass the distance between the manual feed sensor 33 and the transfer section after the rear end of the transfer paper passes the manual feed sensor 33. Stop. However, if the manual feed sensor 33 detects the next sheet while counting the time X', the registration rollers will be moved once the time required for the transfer paper to pass the distance between the manual feed sensor 33 and the registration rollers 19 has elapsed. Stop the operation of 19.

Further, the document scanning distance is also controlled by the trailing edge signal of the transfer paper. The control operations described above are controlled by the one-chip microcomputer shown in FIG. Third
Ql in the figure indicates a one-chip microcomputer with built-in ROM and RAM. FIG. 4 shows the basic configuration of this microcomputer program. Note that detailed explanation of FIG. 4 will be omitted.

Next, the case where two loads (optical system and lens) are driven independently will be explained using FIG. 5' again.

The lamp drive gear (2) is an integrated pulley and gear for driving an optical load. 26 is a geared pulse motor for driving the load.

The switching gear (2) is a gear that moves to switch the load. 27 is a solenoid operated to switch the load. ■ is a rod for moving the switching gear ■. The lens driving gear (2) is a gear for driving the lens.

The speed of the optical system is slowest when the magnification is greatest, and that speed is υ. shall be. Let the lens driving speed be υ. When the optical system/lens switching solenoid 27 is turned on, the rod (2) is pulled in the direction b, and the switching gear (2) is pushed down to engage with the lens drive gear. However, since the gears are interlocked, there is a risk that the gear may get caught between the teeth of the gears, as shown in the seventh diagram. Therefore, the motor is rotated to try to engage the gears, but if the motor rotates too fast, the gears will not engage properly. It can also cause strange sounds.

Therefore, the speed υ when driving the load. .

It is driven at speed υ2, which is sufficiently slower than υ.

The eighth figure is a diagram showing a control part for switching the load. The controller 101 is a controller that controls the optical system/lens that is a load, the load switching solenoid 27, and a series of copy sequences.

This is the same as the one-chip microcomputer shown in FIG. 102 is a constant current driver for driving the stepping motor.

Next, the operation will be explained using the flowchart of FIG.

This control is performed by a one-chip microcomputer (Fig. 3).
controller 101).

First, regarding a) when turning on the power, please check whether the optical system is at the home position after turning on the power.
), if it does not go to the home position, it is moved to the home position (131).

In order to move the lens to a predetermined position, the optical system/lens switching solenoid 4 is turned on (122), and a weight is applied until the solenoid is completely turned on (123). Move the lens toward the lens home position (12
4) Move the lens by a distance corresponding to the set magnification from the home position (125).

After moving the lens, wait for a certain period of time (1
26), the optical system/lens switching solenoid is turned off (127). Also, wait for a certain period of time (128
), one end of the optical system is taken out from the home position sensor (129), the optical system is put back into the home position sensor, and the optical system is stopped at a certain position of the home position sensor (130).

Next, the operation when the copy key is turned on will be explained. If the copy start key is pressed (132),
If there is a change in the set magnification, the process explained earlier (122)
to (130), and is controlled to perform a series of copy processing (135).

〔Effect of the invention〕

As explained above, by rotating the load in the forward and reverse directions at a speed slower than the driving speed of the load when switching the load, there is an effect that the load can be switched reliably and smoothly.

[Brief explanation of the drawing]

Fig. 1 shows a copying machine which is an embodiment of the present invention, Fig. 2 shows an operation panel of this machine, and Fig. 3 shows a one-chip microcomputer that performs all control of this machine. Figure 4 is a diagram showing the basic configuration of the one-chip microcomputer program in Figure 3, Figure 5 is an explanatory diagram for switching the load driven by a pulse motor, and Figure 6 is the front end of the image. FIG. 8 is a flowchart showing the control in this embodiment. 4・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
...Exposure lamp 5, . 6,7,8,9,10.1
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・・・Mirror 12・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
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Claims (1)

[Claims] A driving means for independently driving a plurality of loads with one pulse motor, a switching means for selecting and switching the loads, a transmission means for transmitting the driving force between the motor and the load by a gear train, and a predetermined time when switching to the selected load. An image forming apparatus characterized by rotating a pulse motor in forward and reverse directions at a speed slower than the speed when driving a load.