JP2814575B2 - Power control device in copier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a copying machine having a scanning exposure lamp for irradiating a document surface with light by performing a relative reciprocating motion with the document according to a set copying magnification. The present invention relates to a power control device for controlling an exposure lamp at a predetermined appropriate amount of light during forward movement and decreasing the amount of light of the exposure lamp during backward movement.

[Prior Art] Conventionally, the present inventors have proposed an electrophotographic copying machine having a scanning system structure as shown in FIG. (See JP-A-57-86852). this is,
This is a type in which the original is scanned while the original to be fixed is fixed, and a mirror 13, 14, 15, a lens system 16, a mirror 17, 18, and 18, together with an exposure lamp 12 below a platen 11 on which the original is placed. 19 are arranged in sequence, the exposure lamp 12 and the mirror
13, 14, 15, 17, 18, and 19 are configured to reciprocate below the platen 11. And this exposure lamp
In the course of the reciprocating motion such as 12, the reflected light from the original placed on the platen 11 is guided to the surface of the photosensitive belt 20 on which the image forming process is to be executed via the mirror and the lens system.

Note that a charger, a developing device, various static eliminators, a cleaning device, and the like are arranged around the photosensitive belt 20 to execute an image forming process (not shown).

In recent medium- and high-speed copying machines, the reciprocating movement of the scanning system including the exposure lamp 12 as described above is performed by a servo motor,
The reciprocating speed profile is, for example, as shown by the solid line in FIG. 6 (g). That is, after the forward scanning is started (time t0, t1), the original is scanned while the exposure lamp 12 is maintained at the constant scanning speed Vgm1 (t2).
→ t3) When the scanning of the original is completed (t3), the servomotor is braked and the motor returns.
Move to In this return movement, in order to return the scanning system to the initial position as soon as possible, a speed higher than the above scanning speed Vg
The scanning system is maintained at Vb, and the brake is applied again at the predetermined position (t4) to stop (t5). Then, in the case of continuous copying, the process shifts to the next document scanning at a predetermined timing after stopping (→ t7), and the drive control with the same speed profile as described above is repeated.

Focusing on the drive control of the scanning system as described above,
In particular, at the time of the backward movement, the speed of the scanning system increases and the total power of the machine in the copying machine is, for example, the fifth
As shown in the figure, after the start of the return (return), it gradually rises from a steady state (input line current IL), and reaches a peak (input line current IH) immediately before the return is completed and the scanning system stops. Will be reached.

From such power consumption characteristics, conventionally, it has been proposed that the light amount of the exposure lamp 12 at the time of the backward movement is reduced from an appropriate light amount to reduce the peak value of the power consumption at the time of the backward movement.

Specifically, for example, as shown in FIG. 6, the light amount of the exposure lamp 12 is reduced (for example, a tube current of 0.6 A) from the start of the return (return) (t3), and after the return is completed ( After a predetermined time T from t5), the light amount is returned to an appropriate amount (for example, a tube current of 1.2 A). In this way, it is possible to reduce the peak value of the entire power consumption at the time of the backward movement by the decrease in the light amount of the exposure lamp 12.

In general, in this type of copying machine, the scanning range and the scanning speed are different depending on the set copying magnification, but the scanning time is substantially shorter because the correlation between the scanning range and the scaling speed has an inverse relationship. It will be constant. Accordingly, since the copy end timing is constant at each set copy magnification, the return timing (time T) can be determined without considering the set copy magnification.

However, for example, when the scanning time or the like differs according to the set copy magnification in order to realize more efficient scanning or the like, the light amount return timing of the exposure lamp is determined in consideration of the set copy magnification. Become. As an example of this,
In a copying machine proposed by the inventors of the present application (the structure of which is shown in FIG. 4), the following light amount return timing control is performed.

First, the speed control (normal speed) of the scanning system as a premise is performed as follows according to the copy magnification m (%).

Exposure lamp 12 and mirror 13 speed V1m (scanning speed Vg)
Is: V1m = Vp · K / (m · K−1) Vp: moving speed of the photosensitive belt 20 K: PIS constant (predetermined constant) The speed V2 of the mirrors 14 and 15 is V2m = V1m / 2 of the mirror 19 The speed V4m is controlled as follows: V4m = V1m / K The speed V3m of the mirrors 17 and 18 is controlled such that V3m = V4m / 2. The relationship of m · V1m = Vp + V4m is established (otherwise, a correct projected image cannot be obtained). Thus, in particular, the mirrors 17 and 18 are set to the
When the exposure position is moved on the photosensitive belt 20 by controlling the speed of the mirror 19 to 3 m and the speed of the mirror 19 to V4 m, the inter-image area on the photosensitive belt 20 can be made smaller when performing continuous copying. As a result, the copy speed can be improved without increasing the process speed.

The PIS (Precession Imaging System) constant K
To explain, this PIS constant K is theoretically m · K
If −1> 0, that is, if K> 1 / m, it can take any value.
For example, if 0.64 (64%) ≦ m ≦ 2 (200%), an arbitrary value can be obtained if K> 1.5625, but actually, for example, when Vp = 309 mm / sec and K = 1.6, m = 0.64 (64%), V1m = 309 × 1.6 / (0.64 · 1.6-1) = 20600 mm / sec, resulting in an impractical scanning speed.
In the case of K = 10, m = 1.0 (00%), and V1m = 309 × 10 / (1 · 10−1) = 343.3 mm / sec, and the merit as PIS control is lost.

Depending on the applied magnification range, this
The PIS constant K is selected within the range of 2.5 ≦ K ≦ 4.

When the speed control of the scanning system is performed in accordance with the set copy magnification m as described above, the lower the magnification, the higher the scanning speed, and the degree is larger than the increase in the scanning range. As a result, when the set copy magnification is low, for example, as shown by the broken line in FIG. 6, the scanning time (t1
→ t3 ') is shortened, and accordingly, the return (return) end timing (t4') is advanced. When the return movement end timing changes in accordance with the set copy magnification m in this manner, the time T from the return movement end timing to the light amount return timing of the exposure lamp 12 is the time when the return movement end timing is the latest, that is, Assuming that the set copy magnification m becomes the maximum, the determination is made at the maximum possible timing at which the light amount can be returned to the appropriate amount by the start of the next scan (t7).

If the return timing of the exposure lamp 12 is determined at the above-described predetermined time T from the end of the forward scanning, even if the set copy magnification m changes variously and the forward scanning end timing changes variously, the following timing is surely ensured. By the start of scanning, the light amount of the exposure lamp 12 is maintained at an appropriate light amount.

[Problems to be Solved by the Invention] By the way, it cannot be said that the conventional power control device that controls the light amount return timing of the exposure lamp as described above has sufficiently reduced the peak power.

 It is based on the following reasons.

In the case of the above example, the machine total power changes with characteristics as shown in FIG. That is, the power consumption increases from the end of the return movement (return) to the start of the next forward scan. From this, if the light amount return time of the exposure lamp is delayed and the light amount reduction time is lengthened, experimentally, for example,
As shown in FIG. 7, the amount of reduction in the peak power of the machine total increases. However, when the set copy magnification is low, the light quantity reduction time can be set long (T2 in FIG. 7) and the amount of power reduction can be set to ΔP2. It cannot be set beyond the return timing based on the light amount reduction time (T1 in FIG. 7) that is possible in the case of the magnification (reduction amount ΔP1).
Therefore, when the light amount return timing is determined assuming the condition of the high copy magnification as described above, the power reduction of the originally possible amount is not performed particularly at the low magnification, and the peak power is not efficiently reduced.

Such a situation is not particularly limited to the copying machine in which the scanning system drive control is performed as described above. The scanning system drive control is performed according to the set copy magnification, and the scanning system drive starts or stops. And the like are common in copying machines in which the respective timings are shifted according to the set copying magnification.

Also, as described above, the exposure position on the photosensitive material moves,
In addition, in the case of the type that performs high-speed control of the scanning system especially at low magnification, because the exposure amount per unit area on the photosensitive material is fixed, the lower the magnification, the more the appropriate amount of the exposure lamp increases. doing. Specifically, for example, as shown by the solid line in FIG. 8 (assuming PIS constant K = 3.5), the exposure amount I changes according to the set copy magnification, but in order to compensate for this, the exposure lamp The light amount is controlled in reverse. For this reason, in the case of the above-described example, it is not preferable from the viewpoint of power reduction that the light amount return timing must be earlier than the originally possible timing at a low magnification.

Incidentally, even in a general copying machine, the exposure amount on the photosensitive material changes due to a change in the optical system due to zooming, for example, as shown by a broken line in FIG. The same can be said if the light amount control of the lamp is performed.

Therefore, an object of the present invention is to realize efficient power reduction at the time of returning the exposure lamp regardless of the set copy magnification.

[Means for Solving the Problems] The present invention relates to a copying machine provided with an exposure lamp 2 which performs relative reciprocating movement with respect to a document 1 according to a set copy magnification to irradiate light to one surface of the document. It is assumed that the power control device controls the exposure lamp 2 at a predetermined appropriate light amount during the forward movement (G) and decreases the light amount of the exposure lamp 2 during the backward movement (B). The technical means for solving the above-mentioned problem is as shown in FIG.
A light amount return timing control means 3 is provided for controlling the return timing of the exposure lamp 2 to the appropriate light amount, which has been reduced in the light amount at the time of the backward movement (B), according to the set copying magnification.

The light amount return time in the light amount return timing control means 3 is controlled to be a constant value above a predetermined set copy magnification, and to increase linearly as the set copy magnification decreases below the predetermined set copy magnification. Is set to

[Operation] When the copy magnification is set and the copying machine is started, the exposure lamp 2 and the original 1 reciprocate relative to each other in a scanning range, a speed profile, and the like according to the set copy magnification. In the process, during the forward movement (G), the exposure lamp 2 is controlled with a predetermined appropriate amount of light, and during the backward movement (B), the exposure lamp 2 is controlled.
Is reduced. Then, the light amount return timing control means 3 returns the reduced light amount of the exposure lamp 2 to an appropriate light amount at a timing corresponding to the set magnification.

Further, according to the present invention, the return time to the appropriate amount of light of the exposure lamp that has decreased in the amount of light at the time of the backward movement is set to a constant value above a predetermined set copy magnification, and is set to a predetermined value below the predetermined set copy magnification. In order to control so as to increase linearly as the magnification decreases, under conditions that are close to the experimentally determined maximum slow time at which the appropriate amount of light is secured by the next forward scan at each set copy magnification, The light amount of the exposure lamp can be returned to the appropriate light amount, and the power can be efficiently reduced almost to the maximum.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 2 is a block diagram showing a basic configuration example of a power control device according to the present invention. The structure of the scanning system including the exposure lamp is assumed to be similar to that shown in FIG.

In FIG. 2, reference numeral 30 denotes a control operation circuit for performing a drive command for the scanning system driving servomotor 22, controlling the light amount of the exposure lamp 12, and the like. It has been implemented as a function. Reference numeral 32 denotes a scanning system driving circuit that drives the servo motor 22 to rotate in a forward / reverse direction corresponding to the reciprocating motion of the scanning system based on a command from the control operation circuit 30. Reference numeral 36 denotes a registration sensor for detecting a reference position for document scanning. A reference position detection signal from the registration sensor 36 is supplied to the control arithmetic circuit 30 and the scanning drive circuit 32. An encoder 24 is attached to the servo motor 22, and a rotation signal from the encoder 24 accompanying the rotation of the servo motor 22 is transmitted to a scanning system driving circuit.
32 is entered. Reference numeral 34 denotes a power supply for the exposure lamp 12. The power supply 34 is turned on / off based on a command from the control arithmetic circuit 30, and its output is controlled.
Numeral 38 is a timing table, in which the relationship between the set copy magnification m and the return timing after the light quantity decreases is predetermined. The specific contents are as follows: Vp = 309 mm / sec (photosensitive belt moving speed) K = 3.5 (PIS constant) C = 940 msec (cycle time) This cycle time C assumes that 63.8 copies are taken in one minute. I have.

Under the scanning drive conditions of V1m to V4m at 60000 (ms) /63.8≒940 (ms), the relationship between the set copy magnification m and the time T from the fall of the scan end signal to the return of the light amount is, for example, It is determined as shown by the solid line in FIG. That is, when (lowest magnification) 64% ≦ m <72%, T = 845−11 m (msec) When 72% ≦ m ≦ 155% (highest magnification), T = 62 (msec).

The relationship between the established copy magnification m and the time T until the light quantity returns is that the maximum late timing at which the appropriate light quantity is secured by the next forward scan at each set copy magnification m is, for example, the third.
It is determined within the range below the result obtained experimentally as shown by the characteristic Q ₀ (two-dot chain line) in the figure.

Next, the operation will be specifically described according to the timing chart of FIG.

When an operator sets a document on the platen 11 and performs a start operation after setting a desired copy magnification m, for example, m = 100%, the start signal is controlled and calculated together with information on the set copy magnification m (= 100%). The signal is input to the circuit 30 (time t0).
Then, the control arithmetic circuit 30 raises the scanning start signal and sends the information of the copy magnification m to the scanning system driving circuit 32.
At the same time as raising the ON signal of the exposure lamp 12 (t1), a light amount control signal corresponding to the set magnification is sent to the power supply 34 for the exposure lamp 12. The scanning drive circuit 32 drives the scanning servomotor 22 at a speed corresponding to the set copy magnification m (the speed of the exposure lamp 12 is V1m) based on an output signal and the like from the control operation circuit 30, and the power source 34 Power is supplied to the exposure lamp 12 in accordance with the set copy magnification m (for example, a tube current of 1.2 A). Thus, the forward scanning by the optical system is started in a state where the exposure lamp 12 is lit at appropriate brightness, and the original is scanned from the ON signal output timing (t2) from the registration sensor 36. The scanning drive circuit 32 counts the rotation pulse signal from the encoder 24 based on the ON signal from the registration sensor 36, and sets the scanning end signal when the counted value reaches a value corresponding to the scanning range determined by the set copy magnification. Raise (t3). At this point, the scanning of the original is substantially completed, the scanning drive circuit 32 performs the brake control and the inversion control on the scanning servomotor 22, and the optical system shifts to the backward scanning. Upon receiving the scanning end signal, the control operation circuit 30 lowers the scanning start signal and sends a light amount reduction control signal to the power supply 34. Then, the return is performed in a state where the supply tube current to the exposure lamp 12 is reduced (for example, 0.6 A). In the process, when the scanning system drive circuit 32 receives the ON signal from the registration sensor 36 again (t4), Predetermined brake control is performed on the servo motor 22, and thereafter, the scanning end signal falls, and the apparatus enters a state of waiting for the input of the next scanning start signal. Control operation circuit 30
Outputs the light amount reduction control signal as described above, reads the time T (= 62 msec: m = 100%) corresponding to the set copy magnification m from the timing table 38, and reads out the scanning system drive circuit 32
After the time T (62 msec) from the falling timing (t5) of the scanning end signal from the controller, a light amount control signal for giving an appropriate light amount is sent to the power supply 34 (t6) to prepare for the next document scanning. The exposure lamp 12 is supplied with power from a power supply 34 (m
= 100% and a tube current of 1.2 A), and the appropriate light amount corresponding to the set copying magnification is reached by the time (t7) when the registration sensor 36 outputs in the next document exposure cycle.

When the set copy magnification or m is changed from the above m = 100% to m = 64%, the time T for determining the light amount return timing of the exposure lamp 12 is calculated from the timing table 38 as T
= 141 msec (845-11 × 64) is read out, and the power (for example, 2.0 A) for providing an appropriate light amount is supplied to the exposure lamp 12 141 msec after the fall of the scanning end signal in the same manner as described above.

In the light amount control of the exposure lamp 12 as described above, the time T from the fall of the scan end signal that determines the light amount return timing of the exposure lamp 12 is set so as to be longer at a lower copy magnification. Even in the case of m (= 64%), the decrease in the light amount of the exposure lamp 12 can be held until a later timing. Accordingly, the peak power at a low copy magnification is efficiently reduced.

In the above embodiment, the exposure lamp 12
Is controlled, but a mode in which the tube current at the time of decrease is controlled in accordance with the supply tube current for obtaining the appropriate amount of light is also possible. In this case, the tube current at the time of the drop, which changes according to the copy magnification, is also a factor that determines the light amount return timing.

It should be noted that the present invention is not limited to the original fixed-type copying machine, but can be similarly applied to an original moving type copying machine.

[Effects of the Invention] As described above, according to the present invention, since the light amount return timing of the exposure lamp is controlled in accordance with the set copy magnification, the exposure lamp can be moved back regardless of the copy magnification. In this case, more efficient power reduction can be realized. As a result, the power consumption of the copying machine is reduced, and the power consumption of the copying machine is reduced.

Further, according to the present invention, the return time to the appropriate amount of light of the exposure lamp that has decreased in the amount of light at the time of the backward movement is set to a constant value above a predetermined set copy magnification, and is set to a predetermined value below the predetermined set copy magnification. In order to control so as to increase linearly as the magnification decreases, under conditions that are close to the experimentally determined maximum slow time at which the appropriate amount of light is secured by the next forward scan at each set copy magnification, The light amount of the exposure lamp can be returned to the appropriate light amount, and the power can be efficiently reduced almost to the maximum.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of the present invention, FIG. 2 is a diagram showing an example of a basic configuration of a power control device according to the present invention, and FIG. 3 is an example of a relationship between a set copying magnification and a light amount return timing of an exposure lamp. FIG. 4 is a diagram showing an example of the structure of a scanning system in a copying machine. FIG. 5 is a diagram showing an example of the relationship between reciprocating motion of the scanning system and power consumption. FIG. 6 is a diagram showing reciprocating motion of the scanning system. FIG. 7 is a diagram showing the relationship between the light amount reduction time and the peak power reduction amount, and FIG. 8 is a diagram showing the relationship between the copy magnification and the exposure amount on the photosensitive material. [Explanation of Signs] 1 Original 2 12 Exposure lamp 3 Light amount return timing control means 22 Servo motor 24 Encoder 30 Control arithmetic circuit 32 Scanning drive circuit 34 Power supply 36 …… Register sensor 38 …… Timing table

Claims (1)

(57) [Claims] 1. A copying machine having a scanning exposure lamp (2) for irradiating light to the surface of a document (1) by reciprocating relative to the document (1) in accordance with a set copying magnification. A power control device that controls the exposure lamp (2) with a predetermined appropriate light amount during the forward movement (G) and reduces the light amount of the exposure lamp (2) during the backward movement (B); The return time of the exposure lamp (2) to which the light quantity has been reduced to the appropriate light quantity at the time is set to a fixed value when the copy magnification is equal to or more than a predetermined set copy magnification, and when the exposure lamp is less than the predetermined set copy magnification, the return time becomes linear as the set copy magnification decreases. A power control device, comprising: a light amount return timing control means (3) for controlling the light amount to be increased in a manner as described above.