JP3202712B2 - Apparatus and method for detecting and correcting edge of photosensitive belt - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for detecting and correcting an edge of a photosensitive belt for detecting and correcting a belt edge without being affected by movement of the photosensitive belt in the main scanning direction.

[0002]

2. Description of the Related Art A photosensitive belt forms an electrostatic latent image and forms a toner image corresponding to the electrostatic latent image. A belt edge of such a photosensitive belt may be used as a reference of an image writing position in the main scanning direction.

In this case, if the belt edge has irregularities,
The writing position of the image is shifted by the amount of the unevenness.

[0004] In order to solve this problem, conventionally, the deviation of the writing start position of an image is corrected by an edge detection correction device shown in FIG.

The edge detection and correction device shown in FIG. 5 includes a belt edge detection signal width counter circuit 1, a count value comparison circuit 2,
An up / down counter 3 and a belt edge pulse generation circuit 4 are provided.

Belt edge detection signal width counter circuit 1
Counts the effective width of the belt edge detection signal using a reference clock. The count value comparison circuit 2 compares the count value before correction with the count value after correction and outputs a comparison result signal.

The up / down counter 3 outputs a corrected count value obtained by correcting the held count value based on the comparison result signal. Belt edge pulse generation circuit 4
Outputs a pulse having a width corresponding to the corrected count value as a corrected belt edge signal.

[0008]

In the above-described conventional edge detection and correction device, the photosensitive belt 1 shown in FIG.
In the case of traveling a, if it is possible to make a correction following the movement speed in the main scanning direction with respect to the unevenness 1c of the belt edge 1b, the deviation of the writing position of the image is corrected.

However, when the moving speed of the photosensitive belt 1a increases, it becomes impossible to follow the movement in the main scanning direction with the unevenness 1c of the belt edge 1b. In this case, as shown in FIG. 7, there is a problem in that the unevenness 1c of the belt edge 1b causes an effect of the unevenness 1c on the image (image shift).

The present invention has been made in view of such circumstances, and even if the moving speed of the photosensitive belt is increased,
An object of the present invention is to provide an apparatus for detecting and correcting an edge of a photosensitive belt and an edge detecting and correcting method for the same, which can eliminate the influence of unevenness of a belt edge.

[0011]

According to a first aspect of the present invention, there is provided a photosensitive belt edge detection / correction device for detecting and correcting a belt edge based on a belt edge detection signal of a photosensitive belt detected by a photosensitive belt edge sensor. A belt edge detection and correction device, which counts the effective width of the belt edge detection signal with a reference clock and outputs a pre-correction count value, belt edge detection signal width counter means, a pre-correction count value, a post-correction count value, And compare the results
Count value comparing means for outputting as a comparison result signal, and the effective width of the belt edge detection signal is counted by a reference clock, and if the count value has changed by more than a certain set count value for a certain period of time, the belt corresponding to the change amount A belt movement correction control circuit that outputs a movement count value and a belt movement polarity signal; and, based on the belt movement polarity signal, adding or subtracting a belt movement count value to or from the held count value to obtain a corrected count value. and up-down counter that outputs a pulse width corresponding to the corrected count value, and a belt edge pulse generating means for outputting a corrected belt edge signal, the up-down counter
Holds a count value according to the comparison result signal,
Or count up or down by a certain value
Was carried out, characterized that you output as the corrected count value. The count value comparing means determines one of the following: a count value before correction = a count value after correction> a count value before correction> a count value after correction <a count value before correction <a count value after correction, and outputs the determination result as a comparison result signal. You can make it. The method for detecting and correcting an edge of a photosensitive belt according to claim 3 is a method for detecting and correcting a belt edge based on a belt edge detection signal of a photosensitive belt detected by a photosensitive belt edge sensor. A first step of counting the effective width of the belt edge detection signal with a reference clock and outputting a pre-correction count value, and comparing the pre-correction count value with the post-correction count value and outputting the result as a comparison result signal < a second step of counting the effective width of the belt edge detection signal with a reference clock, and if the count value has changed by a certain count value or more within a predetermined time, a belt movement count corresponding to the change. A belt movement count signal based on the belt movement polarity signal and a third step of outputting the belt movement polarity signal. The fourth of addition or by subtraction, and outputs the corrected count value
And a fifth step of outputting a pulse having a width corresponding to the corrected count value as a corrected belt edge signal . In the fourth step, a counter based on the comparison result signal is used.
Count value or count up by a certain value.
Or count down, and the corrected count value and
It includes the step of and outputting to said Rukoto. Also,
In the second step, one of the following is determined: count value before correction = count value after correction count value before correction> count value after correction count value before correction <count value after correction, and outputs the determination result as a comparison result signal. Steps may be included. The present invention
In the photosensitive belt edge detection and correction device and the edge detection and correction method according to the above, the effective width of the belt edge detection signal is counted by a reference clock to output a pre-correction count value, and the pre-correction count value and the post-correction count value If the count value has changed by more than a set count value during a certain period of time, the belt movement count value is added to the held count value based on the belt movement polarity signal corresponding to the change. Alternatively, after subtracting and outputting the corrected count value, a pulse having a width corresponding to the corrected count value is output as a corrected belt edge signal.

[0012]

Embodiments of the present invention will be described below.

FIG. 1 is a perspective view showing a belt edge detection system for a photosensitive belt according to an embodiment of the present invention, and FIG. 2 is a perspective view showing a photosensitive belt edge detection / correction device according to the present invention. FIG. 3 is a timing chart for explaining the operation of the photosensitive belt edge detection and correction device of FIG. 1, and FIG.
FIG. 3 is a diagram for explaining the operation of the photosensitive belt edge detection and correction device of FIG. 1.

The belt edge detection system for a photosensitive belt shown in FIG. 1 includes a photosensitive belt 5, a laser unit 6, and a photosensitive belt edge sensor 6a.

The photosensitive belt 5 forms an electrostatic latent image and also forms a toner image corresponding to the electrostatic latent image. The laser unit 6 forms an electrostatic latent image on the photosensitive belt 5. The photosensitive belt edge sensor 6a detects an edge of the photosensitive belt 5.

The detection signal detected by the photosensitive belt edge sensor 6a is corrected by an edge detection correction device shown in FIG.

That is, the edge detection and correction device shown in FIG. 2 includes a belt edge detection signal width counter circuit 7, a count value comparison circuit 8, an up / down counter 9, a belt edge pulse generation circuit 10, and a belt movement correction control circuit 11. ing.

Belt edge detection signal width counter circuit 7
Counts the effective width of the belt edge detection signal with a reference clock and outputs a pre-correction count value. The count value comparison circuit 8 compares the pre-correction count value with a post-correction count value described later.

In this case, one of the following is determined: count value before correction = count value after correction count value before correction> count value after correction count value before correction <count value after correction.

The judgment result is output as a comparison result signal. The up / down counter 9 adds or subtracts a later-described belt movement count value to or from the held count value based on a later-described belt movement polarity signal. in this case,
The count value is held by the comparison result signal, or the count value is incremented or decremented by a certain value, and is output as a corrected count value.

The belt edge pulse generating circuit 10 outputs a pulse having a width corresponding to the corrected count value as a corrected belt edge signal. The belt movement correction control circuit 11
The effective width of the belt edge detection signal is counted by the reference clock, and if the count value has changed by a predetermined count value or more within a certain time, a belt movement count value and a belt movement polarity signal corresponding to the change are output.

The edge detection and correction device having such a configuration is
The following operation is performed. First, the effective width of the belt edge detection signal based on the reference clock is counted by the belt edge detection signal width counter circuit 7, and is output as a pre-correction count value.

Next, the count value comparison circuit 8 compares the count value before correction with the count value after correction, and outputs the result as a comparison result signal.

Here, as described above, the comparison result signal is a signal representing three values: count value before correction = count value after correction count value before correction> count value after correction count value before correction <count value after correction. is there.

At this time, the belt movement correction control circuit 11 counts the effective width of the belt edge detection signal using a reference clock. In this case, if the count value has changed by a certain set value or more within a certain time, a belt movement count value corresponding to the change and a belt movement polarity signal indicating the belt movement direction are output.

Here, the belt movement polarity signal is a signal representing two values of whether the count value of the belt movement in the up / down counter 9 is plus (+) or minus (-).

Next, the up / down counter 9
The held count value is counted up or down.

That is, according to the value of the comparison result signal, a predetermined count value among the held count values is
An operation is performed to perform plus (+), minus (−), or neither plus (+) nor minus (−). In addition, an operation of adding (+) or minus (−) the belt movement count value by the belt movement polarity signal is performed, and the count value is output as a corrected count value.

Next, the belt edge pulse generation circuit 10
Thus, at the timing when the next belt edge detection signal is output, a corrected belt edge signal having a width corresponding to the corrected count value is output.

Next, details of the operation of the edge detection and correction device having such a configuration will be described with reference to FIG.

First, as shown in (e), the count value before correction is set to N1, and as shown in (f), the count value after correction is set to M1. At this time, N1 and M1 are compared by the count value comparison circuit 8 in a section in which the belt edge detection signal shown in (b) is at the Hi level. When the comparison result is, for example, N1 <M1, the comparison result is output as a comparison result signal.

Further, the belt movement correction control circuit 11 controls the belt movement count value S1 shown in FIG.
A signal indicating a plus (+) of the belt movement polarity signal (d) is output. Next, the up-down counter 9
Based on the comparison result signal, the belt movement count value S1, and the belt movement polarity signal (+), M1- △ M + S1
Is calculated, and the corrected count value M2 (= M
1− △ M + S1).

Here, N, M, and S are count values indicating the number of reference clocks in (a). Also, △
M is a certain value indicating the number of reference clocks, and an optimum value is set for each model. ΔM
Is performed in a section where the belt edge detection signal is at the Hi level.
Count value before correction by the count value comparison circuit 8 and correction
Based on the result of the comparison with the post-count value,
Count value performed during the interval when the edge detection signal is at the Hi level
Results of comparison by the comparison circuit 8, count values of belt movement, etc.
From the previous time output by the up / down counter 9 based on
Count for subtracting or adding to the corrected count value of
Value. The up-down counter 9 has the power after the previous correction.
Count for the und value based on the belt movement count value, etc.
And the count value before correction <
If the count value is after correction, subtract ΔM and
If count value> corrected count value, add ΔM
Add. Also, image writing by addition and subtraction of $ M
In general, the deviation of the position is limited to the belt of the photosensitive belt 5 without limit.
It is smaller than the size of the unevenness 5b of the edge 5a.

Next, the belt edge pulse generation circuit 10
As a result, a corrected belt edge signal (g) corresponding to the corrected count value M2 set by the up / down counter 9 is output. This corrected belt edge signal is generated at the timing when the next belt edge detection signal falls to Low.

Here, taking the case where N> M as an example,
N3 and M3 in (e) and (f) apply. When N3 and M3 are compared by the count value comparison circuit 8, the comparison result is N3> M3. At this time, the up / down counter 9 calculates M3 + △ M−S3 based on the belt movement count value S3 and the belt movement polarity signal (−), and calculates the corrected count value M4 (= M3 + △ M−S3). )
Is output.

When the corrected count value M4 is output, the belt edge pulse generation circuit 10 outputs the corrected belt edge signal (g) at the timing when the next belt edge detection signal falls to Low.

Taking the case where N = M as an example, (e),
N5 and M5 in (f) apply. When N5 and M5 are compared by the count value comparing circuit 8, the comparison result is N
5 = M5. At this time, based on the belt movement count value S3 and the belt movement polarity signal (-), the up / down counter 9 calculates M5-S5 without adding ΔM, and the corrected count value M6 (= M5-S5). ) Is output.

When the corrected count value M6 is output, the belt edge pulse generation circuit 10 outputs the corrected belt edge signal (g) at the timing when the next belt edge detection signal falls to Low.

By the above series of operations, as shown in FIG. 4, there is no sudden change in the low-level section of the belt edge detection signal due to the unevenness 5b of the belt edge 5a of the photosensitive belt 5, and △ M × the reference clock Only the displacement occurs.

If the unevenness 5b continues K times in a row, it is shifted by K × ＫM × the reference clock. However, in general, the ΔM × reference clock is infinitely uneven 5b
, The writing position of the image does not shift by the unevenness 5b of the belt edge 5a.

Further, the deviation of the image which cannot follow the movement of the photosensitive belt 5 in the main scanning direction becomes extremely small.

As described above, in this embodiment, the effective width of the belt edge detection signal is counted by the reference clock to output the pre-correction count value, and the pre-correction count value and the post-correction count value are compared. If the count value has changed by a certain set value or more during a certain period of time, based on the belt movement polarity signal corresponding to the change, the belt movement count value is added to or subtracted from the held count value, After outputting the post-correction count value, a pulse having a width corresponding to the post-correction count value is output as a correction belt edge signal. Therefore, even if the moving speed of the photosensitive belt is increased, the unevenness 5b of the belt edge 5a is increased. Can be eliminated.

[0043]

As described above, according to the apparatus and method for detecting and correcting an edge of a photosensitive belt according to the present invention, an effective width of a belt edge detection signal is counted by a reference clock to output a pre-correction count value. In addition to comparing the pre-correction count value with the post-correction count value, if the count value has changed by a certain set value or more within a certain period of time, the count value is held based on the belt movement polarity signal corresponding to the change. Since the corrected count value is output by adding or subtracting the belt movement count value to or from the count value, a pulse having a width corresponding to the corrected count value is output as a corrected belt edge signal. Even if the moving speed of the belt is increased, the influence of the unevenness of the belt edge can be eliminated.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a belt edge detection system for a photosensitive belt according to an embodiment of the photosensitive belt edge detection and correction device of the present invention.

FIG. 2 is a block diagram illustrating an embodiment of a photosensitive belt edge detection and correction device according to the present invention.

FIG. 3 is a timing chart for explaining the operation of the photosensitive belt edge detection and correction device of FIG. 1;

FIG. 4 is a diagram for explaining the operation of the edge detection and correction device of the photosensitive belt of FIG. 1;

FIG. 5 is a block diagram illustrating an example of a conventional edge detection and correction device.

FIG. 6 is a diagram for explaining the operation of the edge detection correction device of FIG. 5;

FIG. 7 is a diagram for explaining the operation of the edge detection correction device of FIG. 5;

[Explanation of symbols]

 Reference Signs List 5 photosensitive belt 5a belt edge 5b unevenness 6 laser unit 6a photosensitive belt edge sensor 7 belt edge detection signal width counter circuit 8 count value comparison circuit 9 up / down counter 10 belt edge pulse generation circuit 11 belt movement correction control circuit

Continuation of the front page (56) References JP-A-4-9975 (JP, A) JP-A-4-181276 (JP, A) JP-A-9-90816 (JP, A) JP-A-4-16968 (JP) JP-A-4-251874 (JP, A) JP-A-4-275574 (JP, A) JP-A-4-301661 (JP, A) JP-A-4-303859 (JP, A) 6-83127 (JP, A) JP-A-4-362658 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 21/00 370-540 G03G 21/14 G03G 15/00 303 G03G 15/04-15/04 120 G03G 21/00 350 B41J 3/00

Claims (4)

(57) [Claims] 1. An apparatus for detecting and correcting a belt edge based on a belt edge detection signal of a photosensitive belt detected by a photosensitive belt edge sensor, wherein the effective width of the belt edge detection signal is determined. counting the reference clock, it compares the belt edge detection signal width counter means for outputting the pre-correction count value, the pre-correction count value and the corrected count value formation
Count value comparing means for outputting the result as a comparison result signal, and counting the effective width of the belt edge detection signal with a reference clock. A belt movement correction control circuit that outputs a corresponding belt movement count value and a belt movement polarity signal, and, based on the belt movement polarity signal, add or subtract the belt movement count value to a held count value, wherein the up-down counter that outputs a corrected count value, the width of the pulses corresponding to the corrected count value, and a belt edge pulse generating means for outputting a corrected belt edge signal, the up-down counter, said comparator Depending on the result signal
Keep count value or count a certain value
Up or count down and count after the correction
Edge detection and correction apparatus of the photosensitive belt, characterized that you output as a value. 2. The count value comparison means determines one of the following: the count value before correction = the count value after correction> the count value before correction> the count value after correction> the count value before correction <the count value after correction, and compares the determination results. 2. The apparatus according to claim 1, wherein the apparatus outputs the result as a result signal. 3. A photo-sensitive belt edge sensor detects
Based on the belt edge detection signal of the photosensitive belt
Edge detection correction of photosensitive belt that performs edge detection correction
A method of counting the effective width of the belt edge detection signal with a reference clock.
And outputting a count value before correction and comparing the count value before correction with the count value after correction.
Outputting the result as a comparison result signal, and using the reference clock to determine the effective width of the belt edge detection signal.
Set count value that counts for a certain period of time
If it has changed, the belt movement corresponding to the change
A third signal for outputting a moving count value and a belt moving polarity signal.
And a counter held based on the belt movement polarity signal.
The belt movement count value is added to or subtracted from the
Calculating the corrected count value and outputting the corrected count value
And a pulse having a width corresponding to the corrected count value,
And a fifth step of outputting as Toejji signal, wherein the fourth step, counting by the comparison result signal
Keep the value, or count up or
Performs a countdown, and as the post-correction count value
Output of the photosensitive belt is characterized by including the step of outputting
Edge detection correction method. 4. In the second step, one of the following is determined: count value before correction = count value after correction count value before correction> count value after correction count value before correction <count value after correction. 4. The method according to claim 3 , further comprising the step of outputting a comparison result signal.