JPS59195637A - Image forming device - Google Patents

Abstract

PURPOSE:To control the inversion of a reciprocating means for scanning a document at the time of multi-stage variable power in a short time by controlling the speed of a movable member in accordance with a pulse for detecting the speed of the movable member for image formation, and when the abnormality of the pulse from a pulse generating means is detected, outputting an error signal. CONSTITUTION:A DC amplifier 34 is actuated by a high level optical system scanning forward signal FAW, a transistor (TR) 35-1 is turned on and a TR35-2 is also turned on. Consequently, current flows through the TR35-1 and the TR35-2 and a motor M2 rotates forwardly to scan a document. An encoder 36 generates pulses E1 having the same frequency as clock pulses CLK driving the motor M2 during the rotation of the motor M2. When the motor M2 reduces its speed, a PLL compares E2 with the CLK and outputs V repeated by the high level H pulse. Therefore, a filter 33 is slightly charged by the pulse and the input voltage of the DC amplifier 34 is risen so that current supply to the motor M2 is increased so as to increase the speed of the motor and when the output of the encoder 36 coincides with the CLK, the output V is stopped.

Description

[Detailed description of the invention] The present invention relates to an apparatus for forming an original image.

Conventionally, in copiers that can only make copies at the same size, in order to determine the scan length for scanning a document, a moving optical system is used to determine the reversal position according to the size of the transfer paper within the optical system device to be scanned. A position detector is provided. For example, if a copying machine is equipped with a detector for the reversal position of the optical system depending on the transfer paper size B5, A4, B4, and A3,
When a cassette is set, the optical system is configured to be reversed when it reaches the detector for the A4 reversal position.

Additionally, in general, copying machines that can make copies at variable magnifications can only make copies at predetermined magnification rates, such as reducing A3 size to B4 size, or A3 size to A4 size. Therefore, the scan length of the optical system could be determined relatively easily. For example, when the magnification is reduced from A3 size to B4 size, the scan length of the optical system is controlled by the detector for the A3 size inversion position.

Furthermore, in a copying machine capable of variable magnification in multiple stages, the variable magnification ratio can be set freely, making it extremely complicated to determine the scan length of the optical system. As a simple control method, there is a method of performing maximum scanning regardless of the magnification ratio or transfer paper size, but it is not practical because the copying speed is slow.

In addition, in a copying machine capable of stepless magnification, the optical system,
Since the speed of the reciprocating means such as the document table is changed steplessly, it becomes difficult to synchronize the speed with the overall speed of the copying machine.

Furthermore, it is possible to use a separate high-speed motor to return the scanner after scanning, but this increases the cost.

Furthermore, when multi-step magnification became possible, it was sometimes difficult to know what magnification the copy was made at.

In addition, if an abnormality occurs in the drive system speed control of the scanning system, the machine may start to move backwards before the scan is completed, or the start of the backward movement may be delayed regardless of the completion of the scan, reducing the reliability of the machine. Ta.

The present invention eliminates the above-mentioned drawbacks, and enables the reversal control of the reciprocating means for document scanning during multi-step magnification change to be performed appropriately and in a minimum amount of time. The invention resides in a copying apparatus that can perform relative motion between a scanning system and a printing system with high precision using a simple method, and also enables high-speed backward movement of the scanning system at low cost. The present invention improves the reliability of speed control of a scanning system, etc.

These and other objects will be apparent from the following examples.

FIG. 1 is a sectional view of an example of a copying machine to which the present invention can be applied. A paper roller 7 is a fixing roller, which performs a well-known electrophotographic process to form a transfer image on the transfer paper P. 8 is a light source 77' for the original 9; 10 to 13 are mirrors; 14 is a lens;
'~11' are the mirror positions at the end of the maximum scan, 13'
, 14' is the mirror lens position % when changing the magnification. M is the main motor that drives the drum 1 and each roller 6.7, and M2 is the scanning motor that reciprocates 8, 10, and 11 as a scanning system (scanner). M3 is a position motor that determines the positions of the mirror 13 and lens 14, and each motor is composed of a DC servo.

8.1o and 11 move forward in the direction of the arrow at a speed ratio of 1:0.5 to expose and scan the original and form an image on the drum 1. 15 is a microswitch that detects the size of the sheet cassette 16, and 17 is a microswitch that indicates the home position (star i/start position HP) of the scanning optical system.

FIG. 2 shows the operation unit, 20 is a numeric keypad for inputting the copy number and magnification as binary data, 21 is a function key for inputting the data on the numeric keypad 20 as the copy number and displaying it on the display 23, 22 is the numeric keypad 20 a key for inputting the data as a magnification and displaying it on the display 24;
25 is a key for inputting a copy start command. For example, if you turn on key 22 and enter 50 on the numeric keypad, it will be 5.
0% reduction [7, Display 050 on display 24, 1
If you enter 50, it means 150 inches, which means 50 inches expansion.
150 is displayed on the display 24. In both cases, the manuscript is vertical,
Horizontal direction.

At the same time, copies are made at different magnifications.

FIG. 3 is an example of a control circuit diagram, where 30 is a microcomputer, 031 is a clock indicated by CLP in the time chart of FIG. Pulse generator, 32 is a well-known PLLIC, 33 is a low-pass filter, 34id
35 is a circuit for switching the direction of rotation of the motor M, 36 is a well-known encoder and nida that detects the speed of the motor, and a photo sensor that senses the hole in the perforated disk that rotates coaxially with the motor M. Become. 37 is a branching device for determining the speed of the DC motor M, and the output E of the encoder 36
, is frequency-divided and input to the PLL as E. PLL
compares the phases of E and clock CLP, and outputs V as shown in FIG. 5 according to the difference. As a result, the speed of M is kept constant. The division ratio m of the frequency divider cv is determined by the code output from the microcomputer 3°. Further, the microcomputer switches the forward and reverse operation by switching the optical system scanning forward signal FAW and the backward movement signal BAW to the rotation switching circuit 35 to switch the output L and the DC motor M between forward and reverse directions. 38 is a DC amplifier that drives the lens position motor M3 and is controlled by the output PM from the computer. 39 is an encoder similar to 36 for determining the lens position. 31a, 32a, 33a134a, 36a related to main motor M1
, 37a are 31, 32, and 33 related to the scanning motor M2, respectively.
．． 34. Similar to 36.37, the clock pulse Wfv generates elf, P L L I C1 low pass filter, DC amplifier, encoder, and frequency divider.

This allows the velocity of Ml to be maintained constant. Further, the microcomputer outputs code data with a frequency division ratio m and a rotational drive signal ARI^I. 40 to 42 are buffer amplifiers,
43 is an inverter amplifier.

In this example, c is the basic pulse f of the scanning motor M2. The basic pulse f of the main motor M and the main motor M have different frequencies. As a result, even if the pulleys, gear heads, and rotors of the motors that transmit power from each motor to each drive section do not have to be exactly the same as those of the scanning system and those of the drum system, it is possible to maintain good image quality at the same magnification. If the fundamental pulses have the same frequency, it is impossible to obtain a strictly correct 1:1 image unless the pulley diameter, number of head stages, rotor rotation speed, and torque are all the same, and it is extremely difficult to make them match. It takes. In other words, it has been found that it is a good idea to design the pulse sources 31, 31 and 31 with different wave numbers so that the velocities of each group become the same as a result.

The operation keys in Figure 2 are in the well-known matrix system -74:
The home switch 17 and size switch 15 are also input.

First, with reference to FIG. 5, maintenance control of the speeds of the main motor and the scanning motor will be explained using the scanning motor M2 as an example. Signal FAW
When the voltage is at a high level, the DC amplifier 34 operates, turning on the transistor 35-1 and turning on the transistor 35-2. 35-1. A current flows through motor M, , 35-2, and motor M rotates in the forward direction to perform scanning. encoder 3
6 is a pulse E+ having the same frequency as the clock pulse CLK that drives motor M2 while motor M is rotating.
If the frequency division ratio m is 1, E and F2 are equal, and therefore the phase of E and CLK are compared to indirectly determine the speed difference of motor M2. E, and CLK have the same phase as clock C.
When the speed corresponds to LK, the port (terminal) that outputs V is in the invertamp HI state and does not affect the input to the DC amplifier 34. Therefore, the current supplied to M is changed, and the motor speed is also constant. ○Motor M2
When F2 becomes slow, F2 becomes as shown in FIG. 5(a). PLL
compares F2 and CLK and outputs the signal ``■'' in which the pulse of the signal H is returned. Therefore, the filter 33 is charged slightly by the pulse. As a result, DC amplifier 3
The input voltage of motor M2 increases, thus increasing the current to motor M2, increasing the speed of motor M2. When the output of the encoder 36 matches CLK as shown in (c), the output V in (a) is stopped as described above. Conversely, as the speed increases, PL
L outputs a low level output V as shown in FIG. 5(b). Therefore, the photoelectric charge of the low-pass filter is slightly discharged. Therefore, the input voltage of the DC amplifier decreases, thereby decreasing the current to motor M2 so that the speed of motor M2 decreases.

The operation continues until the encoder output is equal to the phase of CLK. In this way, when the motor speed becomes different from the CLK speed, control is performed to restore the speed and maintain it.

Incidentally, the speed of the motor M may be increased by 1/2.2 or the like depending on the magnification. In that case, the frequency division ratio m1 is set to 2.
1/2 (assuming the main motor M is constant). Thereby, the motor M can be rotated at a desired speed, and in this state, the above-mentioned return and maintenance control is performed. That is, frequency division ratio data m from the microcomputer.

The pulse train E from the encoder 36 is divided according to the frequency division ratio set by the clock CLP and converted into a pulse train E2 having the same frequency as the clock CLP. Therefore, the input voltage of the DC amplifier 34 is determined by the output of the PLL so that the pulse train from the encoder 36 is maintained at a frequency that is 1/2% twice the frequency of the clocks CI, P.

A similar control method is used for the main motor M1.

In any case, the output frequency of the clock generator 31.31a can also be switched by the division ratios ml and m2.

Next, the forward and reverse rotation of the motor M2 will be explained. Forward signal FA
When W becomes low level, transistor 35-1.35-
2 is in the off state, forward rotation stops. Reverse signal BAW
When becomes the no-low level, the transistors 35-3, 35-
4 is turned on, and motor M2 rotates in reverse. Thereby, the scanning optical system performs a backward movement process. During reverse rotation, 24V is applied to the motor circuit so that the speed is faster than that during normal rotation. Therefore, it is possible to return the bales at high speed for the backward movement independently of the speed detection circuit.

Next, scanning control during stepless magnification will be explained with reference to FIG. 4. When the device's power switch is turned on, the microcontroller executes a key entry routine. First, determine whether the 1 normal key N between the magnification keys is turned on (1)
. In the case of normal key N, the user inputs data using the numeric keypad 20, stores the data in the count area of the RAM as data for the number of copies, and displays the number on the display 23 (2). Next, the division ratio data m1 is output as 1 of 100 (equal magnification) (3
), 100 is displayed on the display 24 at the same time. Next, read the status of the cassette switch 15 and set the cassette size to A4.
It is determined whether or not (4).

When A4, the scanning timer area t of RAM.

Ta2 is stored in (5). Ta2 corresponds to the time required to scan A4 minutes of the document by motor M2. A that is not A4
3, store Ta3 in timer area t1 (6)
.

Next, the input of the copy key is judged (7), and when the copy key is turned on, the main motor M1 is turned on to rotate the drum and other parts (8).
). FAW after t to start the forward movement of the optical system with a slight delay.
Output (9). Since ml is 1, the motor M2 rotates and scans at an equal can speed corresponding to the clock pulse as described above. Then 1. corresponding to the scanning stroke. Determine whether the time has elapsed (10), and when it has elapsed, cut the FAW and BA.
Output W and switch from forward to reverse (1η. After that,
The vehicle moves backward until the optical system activates the home position switch 17 (HP), and stops when HP is detected.

In the case of the magnification key M (1 (3), the data read by the numeric keypad is stored in the magnification area in the RAM as magnification data MD (II+). This data MDd\ and the division ratio m, for example, when inputting 50-chi data. is converted into twice the pitch and output (149 s At the same time, the A sound rate is displayed numerically on the display 24.

Next, determine the cassette size as in step 4 +5)
, calculate the appropriate scanning distance for that size sheet. Immediately, when A4, the A4 sheet length A4t is (1/MD)
Multiply to find A4L (10). When the tabs are 50q6, the distance is doubled. Then, calculate this A4Lt - the time required to move from the speed of N2 at that time vm, and Ta
Store it in Taimayu 1 Noah 1° as 2 M (17).

Vml is stored in the ROM in advance as a table memory in order to be determined from the clock CLP and the frequency division ratio m1.

In this example, since the speed of the main motor M1 is also changed according to the magnification change, the frequency division ratios m and m are assigned from the magnification change data MD.

For example, ml % m2 may be set in step 14 so that 1v12 is the highest speed when the magnification is the same, and the speed is slow when changing the magnification.

If the cassette is A3, find the appropriate scanning length A3L and find the required time (18.19). Next, turn on the N key, turn on the numeric keypad, and select RA as the desired number of copies.
Store number data in the count area of M (20 s
21) Step 7 and subsequent steps are performed to control the variable magnification scan length. Even if stepless magnification is performed in this way, one cycle can be completed in the minimum necessary time. Therefore, the time required for continuous copying can be appropriately and minimized.

Incidentally, instead of finding the time and setting it in the memory in steps 17 and 19, it is also possible to find the number of pulses N, N3 from the encoder 36 corresponding to A4L, A3L, and set them in the memory. Then, in step 10, the input pulses from the encoder 36 to the EP shown in FIG.
When 3) is reached, the stroke at the time of magnification change can be determined by turning off the FAW.

Similarly, when using the same magnification, A4. The stroke can be determined by counting the number of encoder pulses NI and NN corresponding to A3 paper.

In step 14, the position motor M is driven to determine the lens position for zooming, but this is because the microcomputer counts a predetermined number of pulses from the encoder 39 when the lens has moved a predetermined distance and stops the motor. It can be done. still,
By counting a predetermined number of pulses from the encoder 36 from the start of forward movement of the scanner and activating the resistor 26o, accurate registration timing corresponding to the scanner position can be determined.

Next, other examples of scanning control will be explained with reference to FIGS. 6 to 8.

FIG. 6 shows a configuration in which board position detectors 18 to 21 according to the size of the transfer paper are provided inside the optical system device (inside the path of the mirror 10) where the moving optical system is scanned. For example, by providing a detector for the mirror 10 for the optimum inversion position of the optical system when copying at the same size according to each size of transfer paper size B5, A4, B4, and A3, it is possible to It is constructed so as not to slow down the copying speed, and when changing magnification, the reversal position of the optical system is selected depending on the magnification ratio and transfer paper size. 1 Table 1 shows the distance from the optical system home position to the reversal position.

Table 1 (Optical system scan length) B5 25mm A4 297van B4 364mm A3 420+n+1+ As an example, a case where the transfer paper size is set to B5 will be described. When the magnification ratio is 1.0 (same magnification), the optical system is inverted by detecting the inversion position sensor 18 of B5. The magnification ratio is 1) small 0.86
If the size is too large, use the A4 reversing position sensor 19 (A4
BP), the optical system is inverted. Also, the magnification ratio is 0.
If it is smaller than 86 and larger than 0.70, the optical system is reversed by the B4 reversal position sensor 20 (B4BP), and the
．． If it is smaller than 70 and larger than 0.61, the optical system is configured to be reversed by the A3 reversal position sensor 21.

As mentioned above, by determining the predetermined reversal position according to the cassette size and magnification ratio, the scan length of the optical system can be increased without increasing the number of reversal sensors or slowing down the copying speed. It is something that can be controlled.

FIG. 7 shows the control example shown in FIG. 6 added to FIG. 3, in which each of the detection sensors (microswitches) described above is connected to the input port.

Figure 8 is the control flow diagram, and the inversion step 1 in Figure 4
This can be achieved by replacing 0 with this.

In the case of two B5 wrestlers, it is first determined whether the magnification data is 1 (81), and it is determined whether the B5 sensor 18 is turned on when the magnification is equal (82). If it is on, proceed to step 11, turn off the FAW, turn on the BAW, and switch to reverse. When the magnification X is 1>X>0.86, for example o, 88, the operation of the A4 sensor 19 is waited (83). 0.86
>X > 0.70 and FJ is, for example, 0.75, it waits for the B4 sensor 2o to operate (84). Similarly, in the case of A4 cassettes, select one with an A4 sensor or larger according to the magnification as shown in the figure. Although not shown, the first enlargement (1, 15
>X>1>, B5 cassette), B for A4 cassette
Select 5 sensors. Second expansion (1゜a o ＞X＞
1.15), select the B5 sensor for small cassettes below B4, and use the third enlargement (1,40>X>1.30) (
In case D, select B5 sensor for small cassettes of A3 or smaller.

Note that there is a method in which a document is read by a photoelectric signal conversion means such as a COD, the read data is processed, and the data is transmitted or printed. When this COD is moved back and forth along the document for scanning.

This can be performed using the aforementioned DC motor M2 and its control circuit. This allows scaling in the sub-scanning direction.For scaling in the main scanning direction, the read data in the COD line direction is frequency-divided according to the scaling. - Caused by ear sweat.

It is also possible to change the magnification of the document vertically (main scanning direction) and horizontally (sub-scanning direction) at different magnification ratios, in which case the scanning speed of the reciprocating member in the sub-scanning direction must be set as described above. do. In other words, by using the above-mentioned MD as the input data for the horizontal direction magnification ratio, the magnification side (IJ, jl) can be obtained.In addition, the present invention can perform the entire conveyance of the sheet original in a type in which the sheet original is exposed and scanned while being transported. By controlling the speed of the rollers, etc., as described above, the variable magnification side flI can be achieved.

Note that this example can be applied not only to a DCC morph as a driving means but also to an apparatus having a pulse encoder.

FIG. 9 is a flowchart for diagnosing the scanner by inputting a writing pulse l- to the port EP in the microcomputer 30 of FIG. 3, and outputting an error signal when an abnormality occurs.

In step 1, timer T1 is set to a time BK corresponding to the maximum pulse interval that is considered abnormal. A timer is an area of memory. BK is a value according to the magnification data MD. If a pulse is input after the scanner starts moving forward, this is determined and the process proceeds to step 4, but if no pulse is input, step 6 is repeated, and when it is determined that the TI time-up is reached, an error signal is output and the forward signal FAW is turned off.

(Step 7) When the pulse is long, the timer T1 is set again in step 4. Check the next pulse interval in the same manner as above. Step 3 passes since timer T2 was reset in step 1, and timer T2 is set in step 5. This is a timer that determines whether the motor speed is too fast, and a time αK corresponding to the minimum pulse interval that is considered abnormal is set. This is magnification data M
The value corresponds to DK. Next, when a pulse is input, it is checked in step 3 whether the time set by timer T2 has elapsed or not, and if it is, it is considered normal, and if it is not, it is considered abnormal, and an error signal is output, and the FAW is turned off. Stop the scanner.

It should be noted that it is also possible to configure so that errors in the case of %TzT2 are displayed separately. As described above, abnormal speed of the scanner can be monitored, and if the speed exceeds the control range, a warning can be issued or the machine can be stopped immediately. This monitoring is performed during the entire time period when the motor M2 rotates. Therefore, abnormalities can be checked even when the motor is rotated in reverse to return the scanner.

The above-mentioned error check can also be performed by inputting the pulse E of the main motor M1 to the microcomputer 30.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a copying machine to which the present invention can be applied, FIG. 2 is a plan view of the operation section of the copying machine shown in FIG. 1, and FIG. 3 is a control circuit diagram.
FIG. 4 is a control flowchart diagram other than the control flow of FIG. 3, in which M2 is a scanning motor and Ml is a main motor.

Claims (1)

[Claims] A process means including a movable member for forming an image, a pulse generating means for detecting the speed of the movable member, a means for controlling the speed of the movable member according to the pulse, and a pulse abnormality from the pulse generating means. an image forming apparatus having means for detecting and outputting an error signal.