JPH0897948A - Image forming device - Google Patents

Abstract

PURPOSE: To allow the device to effectively cope with mis-loading when recording is made to an unrecorded side of recording paper whose one side is already recorded by providing a recording paper recording state detection section and stopping image forming by an image forming section when the recording state detection section detects it that a side of the recording paper is already recorded. CONSTITUTION: This device is provided with a paper feed tray 1 on which recording paper sheets P are stacked, a recording state detection section 2 detecting whether or not a recording object side of the recording paper P is a blank side or a recorded side, and an image forming control section 3 able to stop image formation wen the recording state detection section 2 detects it that the recording paper is already recorded, and also with an electrophotographic system image forming section 4, and a paper feed section 5 carrying the recording paper P to the image forming section 4. Then the recording state detection section 2 detects whether or not a recording object side of the recording paper P on which an image is going to be recorded is a blank side and the recording or non-recording is selected based on the result of detection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming an image on a recording sheet such as a copying machine, a facsimile machine, a printer, etc., and particularly, an image useful for recording on the back side of the recording sheet already recorded on one side. Forming apparatus

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a facsimile machine or a printer, which forms an image on a recording sheet, it is necessary to reuse the back side of a recording sheet which has been recorded on one side as the recording sheet in order to save resources. It has increased. In such a case, when loading recording paper with one-sided recording into a paper feed tray, etc., the reverse side may be reversed and recording may be done by overlapping the recorded side, or when performing double-sided copying. A situation often occurs in which double-sided copying is executed without knowing that one side has already been recorded. This situation occurs not only in copying machines, but also in facsimile machines and printers.
An image forming apparatus such as a printer does not provide an effective solution to such a recording paper loading error.

[0003]

As described above, the prior art does not provide an effective solution to the recording paper loading error when recording is performed by using the back surface of the recorded recording paper.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems of the prior art as described above, and when recording is performed on the unrecorded side of a recording sheet having one side recorded, the recording sheet is fed with the recording sheet. An object of the present invention is to provide an image forming apparatus capable of effectively responding to a mistake in loading when loading the sheet.

[0005]

As a first means, in an image forming apparatus for forming an image on a recording sheet, a recording state detecting section for detecting whether the recording target surface of the recording sheet to be recorded is blank or recorded. The image forming apparatus is configured to stop the image formation when the recording state detecting unit detects that the recording is completed. As a second means, in an image forming apparatus capable of forming an image on the screen of a recording sheet, a recording state detecting unit for detecting whether each recording surface of the recording sheet to be recorded is blank or recorded, and recording on both sides. In this case, the recording state detection unit is configured to include an image formation control unit that records only on one side when it detects that only one side has been recorded.

As a third means, in an image forming apparatus capable of forming an image by reversing the recording surface of the recording paper, a recording state detecting section for detecting whether the recording target surface of the recording paper to be recorded is blank paper or already recorded. And a paper feed unit that reverses the recording surface of the recording paper when the recording state detection unit detects that the recording has been completed, and an image formation control unit that forms an image on the reversed recording surface. did. As a fourth means, in the above description, a recording state detection mode setting means for invalidating the detection result of the recording state detection section is provided.

As a fifth means, in the above description, an unnecessary surface mark forming means for recording an unnecessary surface mark on an unnecessary recorded surface is provided. As a sixth means, in the above, the recording state detection unit is configured to detect an unnecessary surface mark recorded at a predetermined position on the recorded surface. As a seventh means, in a facsimile server capable of facsimile communication with an image processing apparatus equipped with facsimile communication means,
An unnecessary surface mark detection unit that detects an unnecessary surface mark from the image information received from the image processing device, and an unnecessary surface mark that notifies the sender of the received image information when the unnecessary surface mark detection unit detects the unnecessary surface mark The configuration includes a reception notification means.

[0008]

In the first means, the recording state detecting section for detecting whether the recording target surface of the recording sheet to be recorded is blank or already recorded, and when the recording state detecting section detects that the recording state has been recorded, Since the image formation by the image forming unit is stopped, even if one side of a blank recording sheet is mistakenly loaded in the paper feed tray, it is not recorded on the recorded recording surface. According to the second means, the recording state detecting section for detecting whether each recording surface of the recording sheet to be recorded is blank or recorded, and when recording on both sides, the recording state detecting section has recorded only one side. Since it is configured with an image forming control unit that records only on the blank side when it detects that there is a blank side even if you load a single-sided blank recording sheet into the paper feed tray and instruct double-sided copying. It is copied only on the blank and never recorded on the recorded surface.

According to the third means, a recording state detecting section for detecting whether the recording target surface of the recording sheet to be recorded is blank or recorded, and recording is performed when the recording state detecting section detects that recording has been completed. The configuration is equipped with a paper feed unit that reverses the recording surface of the paper, and an image formation control unit that forms an image on the reversed recording surface. When loaded, the front and back sides of the recording paper are automatically reversed and recording is performed on the blank surface. In the fourth means, the recording state detection mode setting means for invalidating the detection result of the recording state detection portion is provided in the above description. If you can, you can record on top of the recording paper that has already been recorded.

In the fifth means, since the unnecessary surface mark forming means for recording the unnecessary surface mark on the unnecessary recorded surface is provided in the above, even if recording is performed on the recording paper having one surface recorded, You can see unnecessary areas at a glance. In the sixth means,
In the above, since the recording state detection unit is configured to detect the unnecessary surface mark recorded at the predetermined position of the recorded surface, the recording state detection unit can be realized at low cost, and the recording tray from the paper feed tray to the registration roller can be realized. The distance can be shortened. Seventh
Means for detecting an unnecessary surface mark from the image information received from the image processing apparatus, and when the unnecessary surface mark detecting section detects the unnecessary surface mark, the sender of the received image information is notified of that fact. Since the unnecessary surface mark reception notifying means is provided, it is possible to avoid not knowing that the unnecessary surface is erroneously transmitted even if the unnecessary surface mark detection unit is not provided in the image processing apparatus.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings, using an example in which the image forming apparatus is a copying machine. FIG. 1 is a block diagram showing the arrangement of an image forming apparatus (copier) showing an embodiment of the present invention. In the figure, reference numeral 1 is a recording paper P.
A paper feed tray in which is loaded, 2 is a recording state detection unit that detects whether the recording target surface of the recording paper P is blank or recorded, and 3 is an image formed when the recording state detection unit 2 detects that recording is completed. The image forming control unit 4 is capable of stopping the image forming process, the image forming unit 4 is, for example, an electrophotographic system, the sheet feeding unit 5 conveys the recording paper to the image forming unit 4, and the document S is a document.

An image forming apparatus (copier) having such a configuration
When copying is performed using, the recording paper is loaded in the paper feed tray 1, the document S is set in the image reading unit (not shown), and the image reading is started. When a digital copying machine is used, the read image information is digitized and sequentially transferred from the first pixel data of the first line to the image formation control unit 3, and the pulse width of the laser beam is changed by each pixel data. The latent image forming section 17 (optical writing section) shown in FIG. 2 of the image forming section 4 controls the latent image formation on the photosensitive drum 16. This photosensitive drum 16 is rotating,
The latent image moves to the developing unit 18, is developed with toner from the developing unit, and moves to the transfer unit 19. On the other hand, the recording paper is
When the transfer is started, the leading edge of the recording sheet arrives at the transfer section 19 in synchronization with the recording side, and the sheet is conveyed by the sheet feeding section 5. A feature of the present embodiment is that, when performing image formation as described above, the recording state detection unit 2 detects whether the recording target surface of the recording paper on which an image is to be recorded is a blank paper, and the detection result is Based on this, recording or non-recording is selected.

FIG. 2 is a diagram showing the structure of the main part of this embodiment. In the figure, 11 is an imaging device that constitutes the recording state detection unit 2, 12 is a separation roller that separates and sends out the recording paper P in the paper feed tray 1 one by one, and 13 is sent out from the paper feed tray 1. Conveying rollers for conveying the recording sheet along the guide 15, and 14 are registration rollers for temporarily stopping the recording sheet and then conveying it again to the transfer section 19 in synchronization with the recording side. Constitutes the paper feed unit 5. Further, the photosensitive drum 16 rotating in the direction of the arrow, the latent image forming unit 17 that forms a latent image on the photosensitive drum 16, and the developing unit 18 that develops by attaching toner to the latent image on the photosensitive drum 16. ,
The transfer unit 19 that transfers the developed toner image onto the recording paper constitutes the image forming unit 4.

FIG. 4 is an operation flow chart of this embodiment. The operation flow will be described below with reference to FIGS. First,
When the recording paper to be recorded is sent out by the separation roller 12, the density of the target surface to be recorded is sequentially read by the imaging device 11 from the front end,
By the time the leading edge reaches the registration roller 14, the trailing edge of the recording paper passes above the imaging device 11, and in the meantime,
The densities of all the areas on the recording surface are read.

The density signal thus read by the image pickup device 11 is compared with the reference voltage by the level comparator 21 as shown in the block diagram of FIG. When detected from the portion, the state is latched by the latch 22 (S1). It should be noted that 21 and 22 together with the image pickup device 11 constitute the recording state detecting section 2. Further, since the image pickup device 11 is used only for detecting whether or not there is a portion that is not'white ', even if the resolution is lower than that of the image pickup device used for the document reading unit (not shown). It is enough.

The paper feed unit 5 is equipped with a paper feed control unit 23 (see FIG. 3). When the leading edge of the recording paper reaches the registration roller 14, the paper feed control unit 23 acquires the state of the latch 22. If a density other than "white" is detected, it is determined that the recording target surface has been recorded (S2), and a signal for stopping the image formation is given to the image formation control unit 3. As a result, the image formation control unit 3 stops the latent image formation by the laser light,
The paper feeding unit 5 discharges the recording paper stopped at the position of the registration roller 14 through the transfer unit and the fixing unit without being transferred (S4). On the other hand, when the recording target surface is a blank sheet (S2), the recording sheet stopped at the position of the registration roller 14 is re-conveyed in synchronization with the image forming control section 3, and the image forming control section 3 Then, the image formation by the image forming section 4 is started, and the transfer output and the sheet discharge and the subsequent copy output processing are performed (S3).

FIG. 5 is a block diagram showing the arrangement of an image forming apparatus (copier) showing another embodiment of the present invention. In the figure,
Reference numeral 2a denotes a recording state detection unit for detecting whether each side of the recording paper P is blank or recorded. 3a denotes image formation for recording only on the blank side (unrecorded side) when it is detected that only one side has been recorded. A control unit 6 is a copy mode setting unit for setting double-sided or single-sided copying.

According to this embodiment, even if the operator sets a double-sided original and sets double-sided copying, the recording paper set in the paper feed tray 1 has the recording state detecting section 2a.
When it is detected that only one side is blank, the images read from both sides of the document are recorded on the respective blank sides of the two recording sheets (the recording sheet and the recording sheet immediately thereafter). Therefore, as shown in the configuration diagram of the main part of FIG. 6, one image pickup device 11a is provided on each of the upper and lower sides (or left and right sides) of the recording sheet conveyance path so that the recording states of both sides of the recording sheet can be detected simultaneously. .

FIG. 7 is an operation flow chart of this embodiment. The operation flow of this embodiment will be described below with reference to FIGS. When the operator operates a key switch or the like provided on an operation unit (not shown) to set the copy mode setting unit 6 to the double-sided copy mode or the single-sided copy mode in response to the operator's instruction, By the pair of imaging devices 11a, both sides of the recording paper are blank or only the transfer surface (the surface facing the photosensitive drum) is blank by the time the recording paper is fed out and the leading edge of the recording paper reaches the registration roller 14. It is detected whether only the opposite side of the transfer is blank or both sides are not blank (S1
1). If only one side is blank in step 12, the process proceeds to step 13, and the image forming control unit 3a determines that the setting content of the copy mode setting unit 6 is the double-sided copy mode (S13, Ye
s), automatically reset to single-sided copy mode (S14),
If the blank surface is not the transfer surface (S15), the recording paper is reversed to make the blank surface the transfer surface side (S16). In addition,
During this period, the image formation is not started.

In the recording paper reversal, the recording paper which has passed through the transfer section 19 shown in FIG. 6 in a non-transferred state is advanced by the conveying roller 13 in the direction of arrow a and further by the discharge roller 26 in the direction of arrow b to perform recording. This is realized by reversing the paper discharge roller 26 just before the trailing edge of the paper comes off the paper discharge roller 26 and advancing the recording paper in the direction of arrow c. The path c communicates with the paper feed tray 1, and the recording paper is stacked on the uppermost recording paper P on the paper feed tray 1 with its front and back reversed. That is, after this, the recording paper that has been turned upside down on the paper feed tray is again sent out by the separation roller 12 and reaches the registration roller 14. A switching claw (not shown) may be provided to switch the transport direction to c, but if the path b is inclined as shown in the figure,
Conversely, when doing so, it becomes easier to automatically enter the route c.

In this way, when the transfer surface becomes a blank surface and the standby state is reached at the position of the registration roller, the image forming control section 3a starts the first one-sided image formation and re-conveys the recording sheet from the registration roller section. The accompanying copy output processing is performed (S17). After that, the recording paper is ejected in the direction of arrow b via the paper ejection roller 26. In the above, if the blank surface faces the transfer surface from the beginning (when S15 is Yes),
The copy output process is immediately executed (S17).

If both sides of the recording paper are blank in step 12, the process proceeds to step 18, and in the double-sided copy mode (S18Yes), the copy output process is immediately executed on one side (S19), and then the recording paper is reversed. After that (S16), the copy output process is executed on the other surface (S17). In the case of the single-sided copy mode (S18 No), the copy output process is immediately performed on one side (S17) and the sheet is discharged. Incidentally, by any chance, the recording paper on which both sides have been recorded is set in the paper feed tray and conveyed to the position of the registration roller (S12), and then passes through the transfer portion and the fixing portion and is discharged as it is. If the operator has instructed the double-sided copy mode and a blank recording sheet is detected on only one side, instead of automatically setting the single-sided copy mode, a display device (not shown) is displayed. It is also possible to display that effect and interrupt the copy process.

Further, in the above description, the embodiment having the function corresponding to the double-sided copying mode and the recording sheet reversing function at the same time has been described, but it goes without saying that these two functions can be individually implemented (equipped). FIG. 8 is a configuration block diagram of an embodiment having only the function of reversing the front and back of recording paper, and FIG. 9 shows the operation flow thereof. That is, in the present embodiment, when the recording state detection unit 2 detects that the front and back of the recording paper are reversed (S21, S22), the front and back are reversed as described above (S23), and the copy output process is performed. (S24). In this embodiment, only one imaging device 11 needs to be provided as shown in FIG.

FIG. 10 is a constitutional block diagram showing still another embodiment of the present invention. In the present embodiment, as shown in the figure, the recording state detection mode setting means 7 for invalidating the detection result of the recording state detection unit 2 is provided, so that the image forming control unit can be performed even though the recording target surface has been recorded. The operations of 3 and the paper feeding unit 5 are executed as usual. Therefore, in the present embodiment, it is possible to superimpose an image of a new original document on the recorded image (form a composite image, etc.).

FIG. 11 shows a case where the present embodiment is applied to the above-mentioned embodiment which was interrupted when the recording surface was already recorded. The operation flow will be described below with reference to FIGS. 10 and 11. When invalidating the detection result of the recording state detection unit 2, the operator sets the detection result invalidation via the detection mode setting means 7 prior to the copying operation. When the recording paper is delivered from the paper feed tray 1, the recording state of the recording target surface is detected as described above also in this embodiment (S31). If this result is blank (S3
2) The copy output device is operated as described above (S34).
However, if the recording target surface has already been recorded (S32), the subsequent processing differs depending on whether the detection result invalidation is set in the detection mode setting means 7. That is, if the detection result is invalid (Yes in S33), the copy output process is performed as it is even though the recording target surface has been recorded (S34). If invalid is not set (S33 No), Message is output (S35) and image formation (copy output)
Interrupt.

FIG. 12 is a constitutional block diagram showing still another embodiment of the present invention. As shown in the figure, in this embodiment, the unnecessary surface mark forming means 8 for recording the unnecessary surface mark M indicating the unnecessary surface on the unnecessary recorded surface is provided. The paper feeding unit 5a of this embodiment is configured to enable double-sided copying as shown in FIG. It is desirable that the image pickup device also has a one-pair configuration as shown in FIG. The operation flow will be described below with reference to FIGS. 6, 12, and 13.

The recording paper is sent out from the paper feed tray 1 shown in FIG. 6, and the recording condition on the both sides of the recording paper is detected by the recording condition detecting section 2a (S41). As a result, when it is detected that only one surface is a blank sheet (S42), the unnecessary surface mark forming means 8 which has received the notification to that effect shows the unnecessary surface mark on the recorded surface, for example, as shown in FIG. The image data of the X mark having the size over the entire paper surface is generated. The unnecessary surface mark forming means 8 has the same format as the case where the image data of this X mark is transferred to the image forming control unit 3 by the image data obtained by the original reading unit (not shown) reading the original surface. Then, it is passed to the image forming control section 3 (the operator sets the recording paper so that the recorded surface becomes the transfer surface, that is, the surface facing the photosensitive drum) (S43). That is, the latent image forming unit (optical writing unit) that constitutes the image forming unit irradiates image data for the X mark on the photoconductor to form an electrostatic latent image, and development, transfer, and fixing are performed.

In this way, the unnecessary surface mark is recorded on the recorded surface, but the recording paper is reversed upside down by the reversing mechanism shown in FIG.
Is transported to the position. Then, the image read from the document is recorded on a blank surface (S44). In the above,
If both sides of the recording paper are blank (S42), copy output processing (image formation by image data read from the original) is immediately performed (S44). It is also possible for the operator to set the blank surface to the transfer surface side. in this case,
First, copy output processing is performed, and after the recording paper is turned upside down, unnecessary surface mark addition processing is performed.

In the above, instead of adding the unnecessary surface mark over the entire surface of the recording paper, it is also possible to add the unnecessary surface mark at the upper corner of the recorded surface as shown in FIG. 14 by changing the generated image data. Becomes The unnecessary surface mark added with a cross or the like over the entire surface is effective for the operator to distinguish which of the images recorded on both surfaces is a valid image with a single eye. The unnecessary surface mark as shown is effective for the following recording state detection.

In another embodiment of the present invention, the recording state detecting section 2 described above is configured to detect an unnecessary surface mark recorded at a predetermined position on the recorded surface. Figure 15
An explanatory view of the present embodiment is shown in (a), and a circuit configuration is shown in (b).
In FIG. 15A, 11b is a reflection type optical sensor including a light emitting element and a light receiving element, which is arranged at a position corresponding to the passage of the unnecessary surface mark M recorded at a predetermined position on the recording paper P. Then, the light emitting element is caused to emit light at a predetermined timing after the recording paper P starts to be fed from the paper feed tray 1.
The level comparator 21b showing the output of the light receiving element as shown in FIG.
Is received at one end and the output is held by the latch 22b. With this configuration, the recording state detection unit 2 of FIG.
b can be realized at a low cost, and since it is not necessary to detect the state of the entire surface of the recording paper, the distance between the paper feed tray 1 and the registration roller 14 can be shortened.

FIG. 16 is a block diagram showing the configuration of another embodiment of the present invention. In the figure, reference numeral 40 is an image processing apparatus such as a facsimile apparatus having a facsimile communication means, and 30 is a facsimile server capable of performing facsimile communication with the image processing apparatus 40. The facsimile server 30 detects the unnecessary surface mark from the image information received from the image processing device. The unnecessary surface mark detection unit 31, and when the unnecessary surface mark detection unit 31 detects the unnecessary surface mark, notifies the sender of the received image information to that effect. An unnecessary surface mark reception notifying means 32 is provided. Although only one image processing device 40 is shown in the figure, a plurality of image processing devices can actually communicate with the facsimile server.

FIG. 17 is an operation flow chart of this embodiment. The operation flow will be described below with reference to FIGS. 16 and 17. First, the facsimile server 30 receives image information from the image processing device 40 (S51). The facsimile server 30 decodes (decompresses) the received image information and stores it in a memory (not shown).
Expand to the top. At this time, the image information at a predetermined position of the document (received image information) is developed in a predetermined area on the memory. Therefore, after the unfolding, the unnecessary surface mark detection unit 31 checks the presence or absence of the unnecessary surface mark by analyzing whether the image information of the predetermined area is black or white (S52). When the unnecessary surface mark is detected (S53), the unnecessary surface mark reception notifying means 32 transmits an unnecessary surface mark reception notification to the sender of the received image information (S55). Although this notification text is composed of text, the facsimile server 30 prepares a notification text developed in the image information in advance in the storage device by the built-in character generator. Image processing device
When the unnecessary surface mark reception notification is received, the 40 outputs it on the recording paper as shown in FIG. The facsimile server 30 discards the received image information. If the image information received above does not include the unnecessary surface mark, normal service processing is performed (S54).

In the present embodiment, when a document having an unnecessary surface is erroneously transmitted in this way, the facsimile server is notified of that fact, and therefore an unnecessary surface mark detecting means is provided in each image processing apparatus or facsimile apparatus. Even without,
You'll never go unnoticed. As described above, not only the apparatus having the copying function but also the recording paper having one side recorded is used in the printer and the facsimile apparatus, and the present invention can be similarly applied to these image processing apparatuses. Is.

[0034]

As described above, according to the present invention,
A configuration is provided in which a recording state detection unit that detects whether the recording target surface of the recording sheet to be recorded is blank or has been recorded, and the image formation is stopped when the recording state detection unit detects that the recording state has been recorded As a result, even if one side of the blank recording paper is mistakenly loaded into the paper feed tray, it will not be recorded on the recorded recording surface, so that extra work such as re-copying does not occur.

Further, the recording state detecting section for detecting whether each recording surface of the recording sheet to be recorded is blank or recorded, and the recording state detecting section for recording on both sides, only one side is recorded. In the configuration including the image forming control unit that records only on the blank side when it detects such a situation, even if a blank recording sheet on only one side is loaded in the paper feed tray and double-sided copying is instructed, only the blank side is copied. Therefore, it is not necessary to re-copy.

Further, a recording state detecting section for detecting whether the recording target surface of the recording sheet to be recorded is blank or recorded, and the recording surface of the recording sheet when the recording state detecting section detects that the recording state is completed. With a configuration that includes a paper feed unit that reverses the paper and an image formation control unit that forms an image on the reversed recording surface, if you accidentally load a blank recording paper on only one side into the paper feed tray, the Since the front and back sides of the recording paper are reversed and recording is performed on the blank surface, desired copying can be performed without reloading the paper in the paper feed tray.

In addition, in the above, in the configuration provided with the recording state detection mode setting means for invalidating the detection result of the recording state detection unit, by invalidating the detection result of the recording state detection unit, if there is a desire, Can record another image by superimposing it on the image surface of the recording paper which has been recorded. Further, in the above configuration, in the configuration provided with the unnecessary surface mark forming means for recording the unnecessary surface mark on the unnecessary recorded surface, the unnecessary surface can be seen at a glance even if recording is performed on the recording paper having one surface recorded.

Further, in the configuration in which the recording state detecting unit detects the unnecessary surface mark recorded at the predetermined position of the recorded surface,
Since the recording state detection unit can be realized at low cost and the distance from the paper feed tray to the registration rollers can be shortened, it is possible to prevent the cost and size of the image forming apparatus from increasing. Furthermore, an unnecessary surface mark detection unit that detects an unnecessary surface mark from the image information received from the image processing apparatus, and when the unnecessary surface mark detection unit detects the unnecessary surface mark, notifies the sender of the received image information to that effect. With the configuration including the unnecessary surface mark reception notifying means, it is not necessary to notice that the unnecessary surface is erroneously transmitted even if the unnecessary surface mark detection unit is not provided in the image processing apparatus, so that the image is retransmitted at an early stage. You can

[Brief description of drawings]

FIG. 1 is a configuration block diagram of an image forming apparatus showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a main part of an image forming apparatus showing an embodiment of the present invention.

FIG. 3 is a block diagram of a main part of an image forming apparatus showing an embodiment of the present invention.

FIG. 4 is an operation flow chart of the image forming apparatus showing the embodiment of the present invention.

FIG. 5 is a configuration block diagram of an image forming apparatus showing another embodiment of the present invention.

FIG. 6 is an explanatory diagram of a main part of an image forming apparatus showing another embodiment of the present invention.

FIG. 7 is an operation flow chart of the image forming apparatus showing another embodiment of the present invention.

FIG. 8 is a configuration block diagram of an image forming apparatus showing another embodiment of the present invention.

FIG. 9 is an operation flow chart of the image forming apparatus showing another embodiment of the present invention.

FIG. 10 is a configuration block diagram of an image forming apparatus showing another embodiment of the present invention.

FIG. 11 is an operation flow chart of the image forming apparatus showing another embodiment of the present invention.

FIG. 12 is a configuration block diagram of an image forming apparatus showing another embodiment of the present invention.

FIG. 13 is an operation flowchart of the image forming apparatus showing another embodiment of the present invention.

FIG. 14 is an explanatory diagram of a main part of an image forming apparatus showing another embodiment of the present invention.

15A and 15B are explanatory views of the main part of the image forming apparatus showing another embodiment of the present invention.

FIG. 16 is a configuration block diagram of a facsimile server or the like showing another embodiment of the present invention.

FIG. 17 is an operation flowchart of a facsimile server or the like showing another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Paper feed tray, 2 ... Recording state detection unit, 3 ... Image forming control unit, 4 ... Image forming unit, 5 ... Paper feeding unit, 6 ... Copy mode setting unit, 7 ... Recording state detection mode setting unit, 8 ... Unwanted surface mark forming means, 11 ... Imaging device, 12 ... Separation roller, 14
... Registration roller, 19 ... Transfer section, 21 ... Level comparator, 26
... Paper discharge rollers, 30 ... Facsimile server, 31 ... Unwanted surface mark detection unit, 32 ... Unwanted surface mark reception notification means, 40 ... Image processing device.

Claims (7)

[Claims] 1. An image forming apparatus comprising an image forming unit for forming an image on a recording sheet, comprising a recording state detecting section for detecting whether a recording target surface of the recording sheet to be recorded is blank or recorded. An image forming apparatus having a configuration in which the image forming operation by the image forming unit is stopped when the recording state detecting unit detects that the image has been recorded. 2. An image forming apparatus having an image forming unit for forming an image on a recording sheet, and a recording state detecting section for detecting whether each recording surface of the recording sheet to be recorded is blank or recorded. An image forming apparatus, comprising: an image forming control section which, when the recording state detecting section detects that only one side has been recorded, records the image on only a blank side. 3. An image forming apparatus capable of forming an image by reversing the recording surface of a recording sheet, a recording state detecting section for detecting whether a recording target surface of a recording sheet to be recorded is blank or recorded, and the recording. An image characterized by comprising a paper feed unit for inverting the recording surface of the recording paper when the state detection unit detects that the recording has been completed, and an image formation control unit for forming an image on the inverted recording surface. Forming equipment. 4. The image forming apparatus according to claim 1, further comprising a recording state detection mode setting unit that invalidates a detection result of the recording state detection unit. 5. The image forming apparatus according to claim 1, further comprising an unnecessary surface mark forming means for recording an unnecessary surface mark on an unnecessary recorded surface. 6. The image forming apparatus according to claim 1, wherein the recording state detecting unit is configured to detect an unnecessary surface mark recorded at a predetermined position on a recorded surface. 7. An unnecessary surface mark detecting section for detecting an unnecessary surface mark from image information received from the image processing apparatus in a facsimile server capable of facsimile communication with an image processing apparatus having facsimile communication means, and the unnecessary surface mark. A facsimile server comprising: an unnecessary surface mark reception notifying means for notifying the sender of the received image information when the detecting unit detects an unnecessary surface mark.