JPS63206772A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent defective image formation by stopping the image formation on fresh paper when the detected voltage of a source voltage drops to a reference value or below and restarting the image formation for the remaining number of copies when the detected value returned to the reference value. CONSTITUTION:The copying machine during the execution of multiple copying under the control of a microcomputer 55 in a control circuit 5 completes the image formation on the paper under the image formation and prohibits the copying on the fresh paper when the detected value in a source voltage detecting circuit 7 drops to the prescribed level or below. The copying with the remaining number of copies in the multiple copying is restarted on condition that there are originals when the source voltage returned to the prescribed level.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to production devices such as copying machines and printers, and in particular, to problems caused by paper jams, toner fixation failure, image defects, etc. when the power supply voltage drops. This is to prevent defective image formation.

[Conventional technology]

Conventionally, proposals have been made to reduce the effects on the copying operation of electrophotographic copying machines caused by a drop in power supply voltage.

FIG. 6 is a graph showing the temperature of the toner constant wear heater when performing multi-copy (copying a large number of sheets) when the power supply voltage drops.

As shown in the figure, when multi-copying (copying multiple sheets) is started (T-ta), if the power supply voltage is low, the temperature of the heat roller falls below the lower limit temperature that does not cause defective fixing, etc. Poor fixing, low temperature offset, etc. occur. This is because it is not possible to supply the heater with a current value sufficient to compensate for the temperature drop in the toner fixing heater caused by heat being taken away by the copy paper.

For this reason, when the power supply voltage drops, the number of copies per unit time is limited in order to reduce the amount of heat absorbed by the paper to be copied, in an attempt to prevent toner fixation failure (Japanese Patent Laid-Open No. 60-2002).
-121480).

On the other hand, in consideration of the fact that when the power supply voltage drops, the amount of light from the exposure device that exposes and scans the document decreases, power is cut off to the fixing heater, which consumes a large amount of power, to reduce the drop in power supply voltage to some extent. This is intended to suppress the reduction in the amount of light from the exposure apparatus (Japanese Patent Application Laid-open No. 135878/1983).

[Problem to be solved by the invention] However, when the power supply voltage drops, the number of copies per unit time is
Even if this is the case, for example, the torque of the main motor that drives the photoreceptor drum etc. is reduced, which may result in image defects or paper jams due to poor rotation of the photoreceptor drum. Further, even if the number of copies per unit time is limited, toner fixation failure may occur. On the other hand, cutting off the power supply to the fixing heater in order to maintain the level of the voltage supplied to the optical device is useful only during a very short FR period.

If the energization is interrupted for a long time, the temperature of the fixing heater will drop, resulting in poor toner adhesion, low-temperature offset, and the like.

Therefore, when the power supply voltage drops below a predetermined level, especially when performing multiple copies (multicopy), it is impossible to make normal copies for the desired number of copies by taking measures for each individual device that makes up the copying machine. Completing an action is a process.

The present invention has been devised in view of the above-mentioned circumstances, and provides an image forming device that can prevent defective image formation when the @ pressure decreases in static electricity removal for forming images on a plurality of paper surfaces. This is what we provide.

[Means for Solving the Problems] An image forming apparatus according to the present invention includes: an image forming unit that forms an image on a paper surface based on image information obtained by scanning a document on a document table; a document detecting means for detecting the presence or absence of a document; a voltage detecting means for detecting the level of the power supply voltage supplied to the image forming means; an entrance angle means for instructing to form images on a plurality of paper surfaces; When the voltage detection value becomes less than the reference value while the image forming means is forming images on multiple paper surfaces, image formation on the new paper surface is stopped and the voltage detection value is equal to or higher than a predetermined value. When this occurs, the image forming apparatus is characterized by comprising a control means for instructing the image forming means to resume image formation on the remaining paper surface on the condition that there is a document on the document table.

Here, as the image forming means, for example, a means can be used which forms an electrostatic latent image on a photoreceptor, develops it with toner, transfers it onto paper, and heats and fixes it to form an image. Examples of image forming means include copying machines based on analog or digital image information, or laser printers.

The document detection means detects the presence or absence of a document to be scanned in order to obtain image information. The presence or absence of a document may also be detected from this movement. For example, the light transmittance that changes as the document is placed on the document table may be directly detected by the first sensor. or,
If a switch that detects the opening and closing of the document table or a device that automatically feeds documents is installed in the image forming 9i1F,
The presence or absence of a document can also be detected based on the document feed signal from the device. In addition, [creating images on multiple paper surfaces] includes creating images on multiple sheets of paper, creating images on the front and back sides of the same paper, and creating images on the same side of the same paper. . Note that when an image is formed on a paper surface on which an image has already been formed, that paper surface is referred to as a new paper surface.

Further, in the control means, the base half value of the point at which image formation is stopped and the predetermined value at which image formation is restarted may be the same or may be different.

[Embodiment 1] Hereinafter, an embodiment will be described with reference to the attached drawings, taking as an example the case where the production device is a copying machine.

FIG. 1 schematically shows a copying machine according to this embodiment.

A photoreceptor drum 1 that can be rotated counterclockwise by a main motor M1 (AC synchronous motor) is arranged approximately in the center of the copying machine body, and around it are a main eraser lamp 2 and a sub charger 3. , sub eraser lamp 4, main charging charge t? 5, a developing device 6, a transfer charger 7, a copy paper separation charger 8, and a blade type cleaning device 9 are provided. A photoreceptor drum 1 (with a photoreceptor layer provided on its surface), this photoreceptor is connected to the eraser lamp 2.4 and charger 3.5.
It is sensitized and charged by passing through the optical system 10, and is subjected to image exposure from the optical system 10.

The optical system 10 starts from below the original glass 16.
6 and the original gS image of the document placed between the document holder 30 and is configured to be able to scan the original gS image of the document placed between the document presser 30 and the document presser 30. has been done.

The light source and the movable mirror 11 are arranged at (v/m
) (where m: copying magnification), and the movable mirror 12.13 is driven by a DC motor M3 to move leftward at a speed of (v/2 m). As the optical system scans the original image, the photosensitive drum 1 receives image exposure and forms an electrostatic latent image. Further, toner is attached to the electrostatic latent image in the development step 5AH6. Note that when changing the copying magnification, the lens 14 is moved on the optical axis by the stepping motor M4, and the mirror 15 is also moved and oscillated.

The document presser 30 is fixed to the copying machine by a hinge at one end, and the original fi presser detection switch 5W300 is turned on and off in accordance with opening and closing of the document presser 30.

On the other hand, there are paper feed rollers 21 on the left side of the copying machine body.
．． A paper feed section 20.22 with a roller pair 24.25, a timing roller pair 26, and a conveyor belt 27 is installed.
, a fixing device 28, and a pair of discharge rollers 29 constitute a copy paper conveyance path.

Here, the timing roller pair 26 sends out the copy paper conveyed from the paper feed section with its leading edge aligned with the toner image forming area formed on the photoreceptor drum.

The sent copy paper is transferred by the transfer charger 7.
After the toner image is transferred, peeled off from the surface of the photoreceptor drum 1 by the separation charger 8, passed through the conveyor belt 27, and the toner is melted and fixed in the fixing device 2F28.
It is discharged outside the machine by a pair of discharge rollers 29.

(Description of the operation panel) An operation panel 100 as shown in FIG. 2 is installed on the upper front of the copying machine, and the operation panel 100 includes a print start key 102 for starting the copy operation, In addition to numeric keys 110 to 119 for entering the number of sheets, known key switches and the like are provided. Further, the round LEDIO3 is a warning indicator light that lights up when the power supply voltage falls below a predetermined level.

(Description of the control circuit of the copying machine) The copying machine described above has a plurality of C
It is controlled by PIJ, and communication is performed between each CPU as necessary. Of these, the control associated with the drop in power supply voltage, which is a feature of the present invention, is processed by the i-th CPU. Further, the other processes in the CPU are well known and will not be explained unless specifically required.

FIG. 3 is a circuit configuration diagram showing a power supply voltage abnormality detection processing circuit according to this embodiment.

As shown in FIG. 3, the above circuit is a single-phase AC iat! i1
, an AC drive circuit 3 that drives the toner constant wear heater 31 and the main motor M1, a DC control circuit 5 that controls the AC drive circuit 3, and a power supply voltage detection circuit 7.

In the AC drive circuit 3, the SSR (solid state relay) 32 energizes the toner constant spring heater (lamp) 31 built in the fixing device 28.
At the same time, the 5SR 33 controls the energization of the AC synchronous motor M1 that rotationally drives the photoreceptor drum 1.

Further, the DC control circuit 5 stably supplies D05V.
It is composed of a C power supply 50 and a one-chip microcomputer 55 (incorporating a first CPtJ) having a built-in A/D converter that receives DC power from the DC power supply.

Note that the AC power supplied to the DC power supply 50 is
The voltage is lowered by a transformer 4.

The power supply voltage detection circuit 7 divides the voltage converted into low-voltage DC by the transformer 70 and the rectifying element 71 using resistors 73 and 74 to obtain a predetermined level of voltage.

The one-chip microcomputer 55 (hereinafter referred to as one-chip microcomputer 55) performs power supply voltage detection processing, and also controls the fixing heater lamp 31 via the 5SR 32 to maintain the temperature of the toner constant wear heater of the fixing device [28] at a predetermined value. Control it so that it drips. It also controls starting and stopping of the synchronous motor M1 via the 5SR33.

Here is the analog input port A of the one-chip microcontroller 55.
Nφ is connected to the voltage dividing point of the power supply detection circuit 7, and
The analog input boat ANI is connected to a thermistor that detects the temperature of the heat roller (heater for fixing) of the fixing device d. Further, the output port PAφ is connected to the 5SR32 via the driver rC, and the output port PA1 is connected to the 5SR33 via the driver IC. In addition, the output capo-1-P A2 is connected to the I-E via the driver IC.
It is connected to the lighting circuit of D103.

Roughly speaking, the document holder opening/opening detection switch 5W300 is connected to the input boat PBφ.

FIG. 4 is a flowchart outlining the processing of the first CPCI. As shown in FIG. 4, when the power is turned on, the 10th PLJ initializes the internal registers, various timers, etc., initializes them (S3), and starts an internal timer that defines the time for one routine (S5). Next, power supply voltage detection processing is performed (S7), then input processing (S9) and output processing (811) related to the copy operation are performed, and when the timer ends (813), the process returns to S5. It should be noted that the above steps S9 and S11 are well known, so their explanation will be omitted.

FIG. 5 is a flowchart showing details of the power supply voltage detection process (S7). First, analog signal input capo-1
The voltage level input to ~ANφ is A/D converted to detect the power supply voltage level (8101). Note that the power supply voltage level can be detected by known methods such as peak level detection and area (integral value) detection.

Next, the detected value is compared with a predetermined level (S103).

When the detected value is less than a predetermined level, it is determined whether a copying operation is in progress (8105). Here, the term "during a copying operation" refers to the period from when the copying operation is started by inputting the print start key 102, etc. until the copying on the - side of the copying paper is completed. Note that whether or not a copying operation is in progress is not limited to the above case, and can be determined from the viewpoint of whether or not a defective copy is generated, as will be described later. Further, whether or not a copying operation is in progress is determined based on transmissions from other CPUs. 8107-511 if copying is in progress
Perform processing 1. In other words, 7 lag 1 is set to "1" on the condition that multi-copying (copying multiple copies of the same original) is in progress.
(8107.109). Here, 7lag 1 is a flag for determining whether or not to restart the multicoder and - when the power supply voltage returns to a predetermined level or higher.

Also, copy stop processing is performed (8111). Copy stop processing here means that the copy paper currently being copied remains in the copier, requiring the effort to remove the paper, or
This is executed to prevent paper jams from occurring when copy protection is canceled. Furthermore, it is possible to prevent defective copies from occurring due to interruption of a copying operation currently in progress. That is, in this embodiment, for a copy sheet in the middle of copying, the copy operation is completed and the copy sheet is discharged outside the machine. Also, [When the 1 pressure level is less than a predetermined level, the warning indicator light LED 103 is turned on (S118).
. In addition to lighting the LED 103, other CPUs or
A copy stop request may be sent to the connected external device via communication.

On the other hand, if copying is not in progress (S105), processing is performed to place the copying machine in copy prohibition (standby state) so that copying is not performed on a new copying surface (8113). Here, copy prohibition refers to a state in which a new copying operation is not started. For example, when copying is prohibited, input from the print start key 102 is not accepted by the CPU.

Next, by inputting the document presser detection switch 5W300, it is determined whether the document presser 30 is opened or closed (5115), and when it is determined that the document presser 30 is opened by inputting the document presser 300.
: Set flag 1 to "PAO" (S115.8117).

this is,! ! If the document holder 30 is opened before the lightning voltage returns to a predetermined level or higher, it is assumed that the document on the document table has been removed. This is to prevent copying from being restarted.

In step 5103, when it is determined that the detected value exceeds a predetermined level, copying is prohibited (
8113) (S119) and L E I
) Turn off 103. Further, when flag 1 is 1° (S123), copying is started for the number of uncopied sheets among n failed sheets in advance when multi-copy El is determined (S125), and flag 1 is set to 0'' (S125). 8127),.

In the above embodiment, when the power supply voltage supplied to the copying machine decreases, the copying machine that is performing multi-copying completes image formation for the paper that is currently being created, and starts copying for new paper. It is placed in a prohibited state (standby state). For this reason, image defects on new paper may occur due to insufficient torque of the AC synchronous motor for driving the photoreceptor drum due to the electric voltage, a decrease in the light intensity of the exposure means, a decrease in the current supplied to the constant toner wear heater, etc. 1-ner's 2nd place poor,
Defective copies such as paper jams will not be made in advance. Furthermore, when the power supply voltage returns to a predetermined level, the copy prohibition is canceled and copying of the remaining number of multi-copy sheets is resumed. Therefore, according to the copying machine according to the above embodiment, once multi-copying is set, it is possible to carry out copying of the desired number of copies despite a drop in the power supply voltage.

Further, in the above embodiment, the detection of the power supply voltage level and the comparison with a predetermined level are performed by software using a microcomputer, but they may be configured by a hardware circuit.

In this embodiment, the amount of power supply voltage drop Δv1 that causes a defective copy and the amount of power supply voltage drop Δ■2 that causes a non-maskable auto-reset on the microcomputer.
If we compare ΔV1<ΔV2. Therefore, the above processing becomes possible.

(Reference to Other Embodiments) In the above embodiment, the copy prohibition is executed by processing to prevent the start of a new copying operation, and also performs the copying stop processing to prevent copying paper from being copied during a close-up operation.
The copying operation is understood as a series of operations from scanning the original to discharging the copied paper to the outside of the machine. However, copy prohibition and copy stop processing are
J: This is done in such a way that no defective copies occur. Therefore,
It is possible to define the content of the copying operation from this point of view, and it is possible to define the "copying operation" as the toner 1iTj (i) being transferred and heat-fixed onto the paper surface.

For this reason, for example, the timing roller pair 26 determines that copying is not in progress prior to the time when the copy paper is carried out to the photosensitive drum 1 side, and that copying is in progress thereafter. It's okay. In this case, for example,
It is determined whether or not copying is in progress based on the time point at which a known timing clutch-on signal is output.

In the embodiment described above, by setting a plurality of copy numbers using the numeric keys 110 to 119, multiple copies of the same original are commanded, and images are formed on a plurality of paper surfaces.

However, when creating images on multiple paper surfaces, in addition to the above cases,
Even when a plurality of Qi plates are self-fed by a known auto document feeder that automatically feeds the original side of the original onto the document table, and copies are made based on the fed original. executed.

Further, when a known paper refeeding unit for re-forming an image on a sheet of paper on which an image has been formed on one side is used, double-sided copying and composite copying can also be performed, and the present invention can be applied to each case.

[Effects of the Invention] As described above, according to the present invention, when the power supply voltage drops below a reference value during image formation on a plurality of paper surfaces, image formation on a new paper surface is stopped.

Therefore, defective image formation due to a decrease in power supply voltage is prevented in advance. Furthermore, when the power supply voltage returns to a predetermined value or higher, image formation on the remaining paper surfaces is resumed on the condition that there is a document on the document table. Therefore, for example, if a document is removed from the document table while the power supply voltage is dropping,
Since image creation is not restarted, copy mistakes can be prevented. In addition, if there is a document on the document table, image formation on the remaining paper surface is automatically restarted, so it is possible to complete the image formation on the originally intended paper surface while preventing defective image formation. can.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view schematically showing the present embodiment before copying. FIG. 2 is a front view of the operation panel of the copying machine according to this embodiment. FIG. 3 is a circuit configuration diagram showing a power supply voltage abnormality detection processing circuit of the copying machine according to the present embodiment. FIG. 4 is a flowchart outlining the processing of the 10th P IJ. FIG. 5 is a flowchart showing details of the power supply voltage detection process (S7). FIG. 6 is a graph showing the qualitative temperature of the fixing device when performing multi-copying when the power supply voltage drops. 28... Fixing device 55... One-chip microcomputer special r [Applicant: Minolta Camera Co., Ltd.? 1 Agent Patent attorney Hirotoshi Okawa Patent attorney Akio Maruyama Figure 3 Figure 4 Figure 6 Figure 7 Jl, fkogo-pAtff

Claims (2)

[Claims] (1) An image forming device that forms an image on a paper surface based on image information obtained by scanning the document on the document table; a document detecting device that detects the presence or absence of the document on the document table; and the image forming device. a voltage detection means for detecting the level of a power supply voltage supplied to the image forming means; an input means for instructing to form images on a plurality of paper surfaces; When the detected voltage value falls below the reference value, image formation on the new paper surface is stopped, and when the voltage detection value exceeds a predetermined value, image formation on the remaining paper surface is stopped. An image forming apparatus comprising: control means for instructing the image forming means to restart on condition that there is a document on top of the image forming apparatus. (2) When the power supply voltage detection value becomes less than the reference value while the image forming means is forming images on a plurality of paper surfaces, the image forming means An image forming apparatus according to claim 1 which directs the following.