JPH1128834A - Print head and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To implement fine image forming with a sufficient recording energy even in a high speed image-forming by setting substantially in parallel a plurality of rows of recording element arrays having a plurality of recording elements arranged in an array, and driving each recording array alternatively every one line. SOLUTION: The distance (d) in the direction Y intersecting the row direction X of luminous element rows 1a, 1b formed on the chip 1 of a photoprint head is formed to be, e.g. 0.5 times the image resolution pitch P on the image carrier in the direction Y intersecting the luminous element rows 1a, 1b. Besides, the luminous elements for forming the luminous element rows 1a, 1b includes a luminous diode or the like. Each of the recording element arrays is driven alternatively every one line. As such, while permitting the degree of freedom to be given the chips of the luminous element rows and, moreover, a sufficient exposure rate, i.e., a recording energy can be given thereto, thus executing high speed image forming operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print head used as a light source of an exposure system, and an image forming apparatus for forming a monochrome image and a color image, such as a printer, a facsimile, and a copying machine.

[0002]

2. Description of the Related Art Conventionally, many image forming apparatuses such as a printer, a facsimile, a digital copying machine, and the like use an electrophotographic type. That is, a latent image is formed on an image carrier in accordance with an image signal output from an external computer or an image reading device.

As an exposure system for this purpose, there is an exposure system that uses an optical print head including a light source in which light emitting elements such as light emitting diodes are arrayed. The optical print head is small in size as compared with the one using a laser, and it is possible to easily configure a quiet image forming apparatus.

A light emitting element in such an optical print head is composed of a light emitting diode or the like, and these elements emit diffused light from a certain point or a certain surface, and are scattered on an image carrier. In order to form a latent image on the surface, it is necessary to form the diffused light emitted from the light emitting element on each minute spot. For this reason, many optical print heads are provided with an imaging element array represented by a rod lens array.

[0005]

However, most of the imaging element arrays only collect a part of the light diffused from the light emitting element, and the amount of light to be exposed is the total amount of light emitted by the light emitting element. Considerably smaller.

On the other hand, the image forming apparatus has been required to operate at a higher speed in recent years. When the image forming speed increases, the exposure time of the light from the light emitting element becomes shorter. In some cases, a good latent image cannot be obtained.

An object of the present invention is to provide a print head and an image forming apparatus capable of forming a good image with sufficient recording energy and reducing the load even in high-speed image formation. To provide.

It is another object of the present invention to provide a print head and an image forming apparatus capable of forming an image at various resolution pitches.

It is a further object of the present invention to provide a print head and an image forming apparatus capable of reducing costs by expanding an allowable range of assembly errors of the apparatus.

[0010]

According to the present invention, there is provided a print head having a plurality of printing element arrays in which a plurality of printing elements are arranged in an array in a substantially parallel manner. By driving alternately,
Configure the print head.

Further, according to the present invention, in a print head having two or more printing element arrays in which a plurality of printing elements are arranged in an array, the printing element arrays are alternately driven by one line. This constitutes a print head.

Further, the present invention is an image forming apparatus for forming an image on an image carrier by using a print head having a plurality of printing element arrays in which a plurality of printing elements are arranged in an array in a substantially parallel manner. The image forming apparatus is constituted by alternately driving each of the recording element arrays by one line.

Further, the present invention is an image forming apparatus for forming an image on an image carrier by a print head having a printing element array in which a plurality of printing elements are arranged in an array in two rows substantially in parallel. The image forming apparatus is constituted by alternately driving each of the recording element arrays by one line.

Further, according to the present invention, in a print head provided with a plurality of printing element arrays in which a plurality of printing elements are arranged in an array, the driving means for driving each of the printing element arrays; And a control unit for controlling the drive timing of the drive unit so that each of the element arrays is driven alternately by one line, thereby forming a print head.

Further, according to the present invention, there is provided a print head having a printing element array in which a plurality of printing elements are arranged in an array in two rows substantially in parallel, and a driving means for driving each of the printing element arrays; Control means for controlling the drive timing of the drive means such that each of the element arrays is driven alternately by one line.
Configure the print head.

According to another aspect of the present invention, there is provided an image forming apparatus for forming an image on an image carrier using a print head having a plurality of printing element arrays in which a plurality of printing elements are arranged in an array. A driving unit for driving each of the recording element arrays, and a control unit for controlling a driving timing of the driving unit such that each of the recording element arrays is driven alternately by one line.
An image forming apparatus is configured.

According to another aspect of the present invention, there is provided an image forming apparatus for forming an image on an image carrier by using a print head having a recording element array in which a plurality of recording elements are arranged in an array in two rows substantially in parallel. A driving unit for driving each of the recording element arrays, and a control unit for controlling a driving timing of the driving unit such that each of the recording element arrays is driven alternately by one line. An image forming apparatus is configured.

Here, each of the recording element arrays can be driven with a predetermined time difference.

The predetermined time difference can be varied.

The predetermined time difference can be changed according to the resolution of an image to be printed.

The predetermined time difference can be changed according to the interval between the arrayed printing element arrays.

The recording element may be a light emitting element.

The function of scanning the printing element array can be provided inside a chip on which the printing element array is arranged.

[0024]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Outline) First, an outline of the present invention will be described.

According to the present invention, in a print head provided with a plurality of printing element arrays in which a plurality of printing elements are arranged in an array, the printing element arrays are alternately driven one line at a time. Features.

Further, the present invention is an image forming apparatus for forming an image on an image carrier by a print head having a plurality of printing element arrays in which a plurality of printing elements are arranged in an array in a substantially parallel manner. Each of the recording element arrays is driven alternately by one line.

(Specific Example) Hereinafter, a specific example will be described.

First, a first embodiment will be described with reference to FIGS.

An outline of the overall structure of the present apparatus will be described with reference to FIGS. In this example, as the recording element,
This is an example in which a light emitting element is used.

FIG. 6 shows a schematic configuration of the light emitting element arrays 1 a and 1 b in the optical print head 30 and an arrangement relationship between the image forming means 3 and the image carrier 2. FIG. 7 shows the optical print head 3.
0 is a detailed sectional view of the image carrier 2 exposed by the optical print head 30. FIG. 8 shows an example of an image forming apparatus on which the optical print head 30 is mounted.

In FIG. 6, the optical print head 3 shown in FIG.
The distance d in the direction Y orthogonal to the column direction X of the light emitting element arrays 1a and 1b formed on the chip 1
This is an example in which the image resolution pitch is 0.5 times the image resolution pitch P on the image carrier 2 in the direction Y orthogonal to b (d = 0.5P). In addition, as the light emitting elements constituting the light emitting element rows 1a and 1b, light emitting diodes or the like can be used.

As shown in FIG. 6, the light emitting element arrays 1a and 1b
Is parallel to the rotation axis of the columnar image carrier 2, and a large number of rod lenses are provided between the chip 1 and the image carrier 2 in two rows in parallel with the light emitting element rows 1a and 1b. There is a rod lens array 3 arranged side by side. Then, the light emitting element rows 1a, 1
The luminous flux diverging from b is accurately positioned at a position where it forms an image as a minute spot on the surface of the image carrier 2.

As shown in FIG. 7, in the optical print head 30, a chip 1, a driver chip 5 for driving each light emitting element, a limiting resistor (not shown) and the like are mounted on an electric board 4. And this electric board 4
Is fixed to the member 7 which also has a heat radiation effect by means such as bonding or screwing. Further, the rod lens array 3 is fixed to a cover 6 having a function of preventing light leaking from the light emitting element arrays 1a and 1b, and is further provided at a position where an image is formed as a minute spot on the surface of the image carrier 2. Accurately positioned.

As shown in FIG. 8, the optical print head 30 is incorporated in an image forming apparatus as an exposure device.

Here, an example will be described in which the image forming apparatus is applied to a copying machine that reads a document and forms an image.

Referring to FIG. 8, a document placed on a document table 24 is read by a reading system 11 comprising a CCD image sensor or the like and converted into image data. On the other hand, when the recording material 80 is fed from the feeding rollers 13 and 14 in the main body or from the outside of the main body via the feeding roller 15 and reaches the position of the registration rollers 16a and 16b, a sensor (not shown) detects the recording material 80. The position of the leading end of the recording material 80 is detected and temporarily stopped.
6a and 16b.

On the other hand, the charging is performed in advance by the charger 17 and the image carrier 2 rotated in the direction of the arrow in the figure is exposed from the optical print head 30 in accordance with the image data to form an electrostatic latent image. Is done. In accordance with this electrostatic latent image, a developing material (not shown) is applied onto the image carrier 2 from the developing device 18.

Then, the image carrier 2 to which the developing material has been applied is rotated to the position above the transfer device 19, and
0 also reaches the transfer device 19, and the developing material is transferred onto the recording material 80 by the transfer device 19. Thereby, the recording material 8
In the case of No. 0, the developer reaches the fixing devices 22a and 22b through the transport path 21, the transferred developer is fixed on the recording material 80, and is discharged to the tray 23 to complete the image formation.

Next, the sequence of exposing the light emitting element arrays 1a and 1b of the optical print head 30 will be described with reference to FIGS.

FIGS. 1 to 3 show exposure patterns formed by driving the optical print head 30. FIG.

FIG. 4 shows the light emission timing of the two light emitting element rows 1a and 1b.
a and 1b are 1 in synchronization with the pulses φsa and φsb, respectively.
Start recording for the line.

In FIGS. 1 to 3, each of the drawings is a time-dependent description from FIG. 1 to FIG. ,,,
.. Indicate the exposure order of each exposure line, and the suffixes a and b indicate which of the light emitting element arrays 1a and 1b has been exposed. In addition, the exposure line of the light emitting element array 1a is indicated by a solid line, and the exposure line of the light emitting element array 1b is indicated by a broken line. A line with a large number of circles (○) on the exposure line indicates that the exposure was performed at that time in each drawing, and a black solid circle (）) on each line indicates that the image is carried on each line. Indicates that there is data recorded on the body 2 or data already recorded. P indicates an image resolution pitch on the image carrier 2 in a direction Y orthogonal to the column direction X of the light emitting element arrays 1a and 1b, and v indicates a peripheral speed of the image carrier 2.

FIG. 4 shows an input pulse for determining the light emission timing of the light emitting element rows 1a and 1b from the upstream side (the first light emitting element row 1a side). Here, one line is expressed as a single pulse, but each light emitting element row 1a, 1
In the case of performing transfer within b, a plurality of pulses may be used. The sign of the pulse may be either positive or negative.

Hereinafter, a specific operation will be described.

In FIG. 4, φsa is positive when T = 0, and n
By transmitting the image data of the line to the light emitting element array 1a, the first exposure line a is first recorded on the image carrier 2 by the light emitting element array 1a in FIG. At this time T = 0, as shown by the two-dot chain line in FIG.
The relative position from the exposure line a to the light emitting element row 1b is
It is at a position 0.5P away from a.

In FIG. 4, at the time T = 0.5 P / v, the image carrier 2 moves at the peripheral speed v, so that the light emitting element array 1b reaches a position P away from the exposure line a. As shown in FIG. 4, φsb is made positive, and the image data of the (n + 1) th line is given to the light emitting element array 1b, so that the light emitting element array 1b emits light, and the line of the exposure line b in FIG. Perform formation.

Before reaching the time of T = 2P / v, φsa becomes 0, and at the time of T = 2P / v, the light emitting element array 1a moves relative to the distance 2P away from the exposure line a. By setting φsa to be positive again and giving the image data of the (n + 2) th line to the light emitting element array 1b,
An exposure line a is formed as shown in FIG.

Hereinafter, as shown in FIG.
a and ΔT = 0.
By alternately applying start pulses of φsa and φsb with a predetermined time difference so as to be 5 P / v, the respective light emitting element rows are driven alternately. At the time of T = 10.5 P / v, FIG. As shown in 3, 6 line pairs (total 12 lines)
Is completed.

Each start pulse is for instructing the start timing of image formation for each line. Actually, image formation for each line is performed after the start pulse is applied to the corresponding light emitting element row. On the other hand, it is sufficient to take the time until the next start pulse is given, that is, in other words, it is possible to take the maximum 2P / v time.

For example, if an image having the same resolution P as that of the above example is realized at the same image forming speed v by a print head having only one printing element array, the time required for P / v Must complete the image formation for one line. Therefore, in this example, by providing two printing element arrays, compared to the case of one example, two printing element arrays are used.
Double recording time, that is, double recording energy can be given, and a good image can be formed at high speed.

FIG. 5 shows an example in which the distance d between the light emitting element rows 1a and 1b is different from the above example.

For example, if the interval d is 2.5P and ΔT =
Even at 2.5 P / v, an image can be formed. However, since the exposure line b is formed next to the exposure line a in position, data formation is different from the above. Further, it is the next line in position from the exposure line a which is the start line. Since the exposure line a has an interval of 2P and the resolution is different from that of other places, the actual exposure on the exposure line a is not performed. The exposure line b, which is the last line, is not used for exposure for the same reason.

As described above, a light emitting diode can be used as the light emitting element, and a self-scanning recording element chip can be used. Note that a self-scanning recording element chip is one in which a number of light-emitting thyristors capable of electrically controlling a threshold voltage or a threshold current are arranged, and neighboring light-emitting thyristors have a unidirectional voltage or current. By connecting with electrical elements,
Self-scanning is performed by a two-phase transfer clock.

The thyristor structure will be described later.

As described above, an image having a resolution pitch P smaller than d can be formed by two printing element arrays arranged at an interval of d = 2.5P. As compared with the case where d = 0.5P, the degree of freedom of the print head can be given.

By using the optical print head 30 as described above, a sufficient exposure amount, that is, recording energy can be given to the chips 1 of the light emitting element arrays 1a and 1b while allowing a degree of freedom in design. Image formation can be performed.

Next, a second embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

FIG. 13 shows a schematic configuration of the light emitting element arrays 101 a and 101 b in the optical print head 30 and the image forming means 10.
3 and the arrangement relationship with the image carrier 102 are shown. 9 to 11 show exposure patterns. FIG. 12 shows the light emission timing of the two light emitting element arrays 1a and 1b.

The configuration of the optical print head 30 of this example is basically the same as the optical print head 30 of the first embodiment described above. As shown in FIG.
The distance d in the direction Y orthogonal to the column direction X of the light emitting element rows 101a and 101b formed on
In this example, the pitch is 1.5 times the image resolution pitch P (d = 1.5P) on the image carrier 102 in the direction Y orthogonal to 101b.

The structure of the optical print head 30 including a specific electric board and the like and the example of the image forming apparatus in which the optical print head 30 performs exposure are the same as those in the first embodiment. The description here is omitted.

Here, the exposure order of the light emitting element arrays 101a and 101b will be described with reference to FIGS.

In FIGS. 9 to 11, each figure is for explaining the steps from FIG. 9 to FIG. 11 with time. ,
,, ... indicate the exposure order of each exposure line,
The subscripts of a and b are light emitting element rows 101a and 101, respectively.
b indicates which line was recorded. In addition, the exposure line of the light emitting element row 101a is indicated by a solid line, and the line of the light emitting element row 101b is indicated by a broken line. A line having a large number of circles (）) on the exposure line indicates that the exposure was performed at that time in each drawing, and a black solid circle (●) on each line indicates the image carrier 102 in each line. Indicates that there is data to be recorded or data that has already been recorded. P indicates the image resolution pitch in the direction Y orthogonal to the column direction X of the light emitting element rows 101a and 101b, and v indicates the peripheral speed of the image carrier.

FIG. 12 shows a light emitting element array 1 from the upstream side.
Input pulses for determining the light emission timing of 01a and 101b are shown. Here, one line is expressed as a single pulse, but a plurality of pulses may be used in a case where transfer is performed in each of the light emitting element arrays 1a and 1b. The sign of the pulse may be either positive or negative.

Hereinafter, a specific operation will be described.

When φsa in FIG. 12 becomes positive at time T = 0, the first exposure line a is first recorded on the image carrier 102 by the light emitting element array 101a in FIG. 9A. At this time T = 0, as shown by a two-dot chain line in FIG. 9, the distance from the exposure line a to the light emitting element row 101b is 1.5P away.

In FIG. 12, at time T = 1.5 P / v, the image carrier 102 moves at the peripheral speed v, so that the light emitting element row 101 b side is 3 P from the exposure line a.
9A, and as shown in FIG.
By making sb positive and giving the image data of the (n + 1) th line to the light emitting element row 101b, the light emitting element row 101b
To form a line of the exposure line b.

Before the time T = 2P / v, φ
sa is 0, and at the time of T = 2P / v, the light emitting element row 101a is relatively located at a distance of 2P away from the exposure line a. By providing image data to the light emitting element row 101a, an exposure line a is formed as shown in FIG.

Subsequently, as shown in FIG. 12, φsa and φsb are alternately given so that the difference between the light emission timings of the light emitting element row 101a and the light emitting element row 101b becomes ΔT = 1.5 P / v. Are formed, and at the time of T = 9.5 P / v, as shown in FIG. 11, an image with 5 line pairs (total 10 lines) is completed.

However, the exposure line a which is the starting line
Since the line and the exposure line a, which is the next line in position, have an interval of 2P and the resolution is different from that of other places, actual exposure is not performed on the exposure line a. The exposure line b, which is the last line, is not used for exposure for the same reason.

In this embodiment, as in the first embodiment, a light emitting diode can be used as the light emitting element, and a self-scanning recording element chip can be used.

As described above, in the optical print head 30 of the present embodiment, since the distance d between the light emitting element arrays 101a and 101b is made large, the degree of freedom in the structural design in the chip 1 can be further increased. . In addition, good image formation can be performed at high speed and with sufficient recording energy while allowing design freedom.

Further, since the interval d in the direction Y orthogonal to the column direction X of the light emitting element arrays 101a and 101b is set to d = 1.5P, the element array interval can be increased, and the design in the chip 1 can be freely performed. The degree can be further expanded.

Further, in the above configuration, it is possible to perform recording at a plurality of types of resolution pitches with one print head. That is, as is apparent from the above-described example, the time difference ΔT between the drive timings of the respective light emitting element arrays is based on the arrangement interval d of the light emitting element arrays and the resolution pitch P of the image to be recorded. T is a function of P. For more information,

[0075]

ＴT = △ T (P) = | (P−d) / v |

Accordingly, for example, the above equation is calculated according to the resolution pitch P instructed from the operation unit or the like, and the drive timing time difference ΔT (P) of each light emitting element array is variably controlled to obtain an arbitrary resolution. Image recording can be performed with the pitch P.

Next, the circuit configuration in the first example will be described. In this example, in order to realize the light emitting element arrays 1a and 2b, a self-scanning recording element array chip described in detail below was employed.

More specifically, by arranging, for example, 56 self-scanning recording element array chips each having 128 light emitting elements arranged in the axial direction of the image carrier 2, one light emitting element array is arranged. Realize. This light emitting element row is further divided into 2
By arranging the light emitting element rows in this row substantially in parallel with each other at intervals d, ie, the light emitting element row 1
a and 1b were realized. Note that the following circuit configuration is similarly configured in the second example.

Hereinafter, the self-scanning recording element array chip will be described in detail.

FIG. 14 shows an equivalent circuit configuration of a self-scanning recording element array chip 2102 having a thyristor structure. This self-scanning printing element array chip 2102
Are constituted by light emitting element columns of a self-scanning recording element array composed of thyristors. Then, similar to the above-described chip 1 in FIG. 6 and the chip 101 in FIG. 13, such a linear light-emitting element array is arranged on the substrate as two light-emitting element arrays.

Reference numeral 2001 denotes a shift register unit, and 2002 denotes a light emitting unit. 2003 is the load resistance, 2004, 200
5 is a thyristor. Each of these thyristors 2
004, 2005 are connected to the diode 2006
, And to the power supply VGa via the load resistor 2003.

Further, φs is a start pulse for instructing each self-scanning recording element array chip to start recording, and corresponds to φsa and φsb described above. Further, transfer clocks φ1 and φ2 for the transfer operation are applied to the cathode of thyristor 2004.

Assuming that thyristor 2004 is now turned on by transfer clock φ1, the gate potential thereof becomes almost zero volt. This potential is the diode 2
Affects to the right through 006. Only the elements in the right direction are selectively turned on by the next transfer clock φ2, so that data can be transferred in the right direction. By applying a print data clock (DATA) corresponding to the image information at the same time as the above address, the thyristor 2
005 emits light. By repeating such an operation, a predetermined thyristor can emit light in accordance with image data. Thus, a predetermined self-scanning recording element array chip has a scanning function inside the chip.

FIG. 15 is a block diagram for explaining the inside of the print head.

In the print head, self-scanning printing element array chips 2102-1 to 2102-56 are arranged in an array to form the printing element array 1a in the first example, and to form a self-scanning printing element array. Chip 210
3-1 to 2103-56 are arranged in an array, and constitute the printing element array 1b in the first example.

Reference numeral 2101 denotes a control unit of the self-scanning printing element array. From the control unit 2101, the self-scanning printing element array chip 2 forming the printing element row 1 a
With respect to 102-1 to 2102-56, VGa, φsa,
φ1a and φ2a are commonly input, and DATA1a to DAT which serially supply image data to be recorded by the self-scanning recording element array chip to the chip.
A56a is connected.

Similarly, the control unit 2101 sends VGa, φ to the self-scanning printing element array chips 2103-1 to 2103-56 constituting the printing element array 1b.
sb, φ1b and φ2b are commonly input, and DATA1b to DATA1b to D which supply serially image data to be recorded by the self-scanning recording element array chip to the chip.
The ATA 56b is connected.

FIG. 16 is a detailed diagram of the control unit 2101 described above.

Reference numeral 2201 denotes a buffer section corresponding to each self-scanning printing element array chip 2102. 2
Reference numeral 202 denotes an image data storage unit; and 2203, a data distribution unit.

FIG. 17 shows the image data stored in the image data storage section 2202.

A0 to A127 are print data to be printed by the first self-scanning recording element array chip 2102 in the first column. A128 to A255 correspond to 2 in the first row.
This is image data to be printed by the second self-scanning recording element array chip 2102. B0 to B127 indicate print data to be printed by the first self-scanning recording element array chip 2102 in the second column.

Then, such print data is distributed to the buffer units 2201 corresponding to the respective self-scanning recording element array chips 2102 by the data distribution unit 2203, and necessary clocks are added as described above, and the print data clocks are added. At the same time, the data is transferred to each self-scanning printing element array chip 2102. Thus, self-scanning can be performed by the two-phase transfer clocks φ1 and φ2.

The timings at which the start pulse and the image data corresponding to each line are applied are as described above in each example.

In the above example, an example in which an optical print head in which light-emitting elements are arranged in an array as recording elements and an electrostatic latent image is formed on an image carrier has been described. In addition, the present invention can be applied to examples using various recording elements, such as a thermal head in which heating elements are arranged in an array, or an inkjet head.

Further, in the above example, an example has been described in which two printing element arrays are arranged with an interval d and driven with a time difference ΔT, but three or more printing element arrays are used. By arranging them at an arbitrary interval dn and driving each printing element array with an optimal time difference, further high-speed printing is possible.

In the manufacturing stage at the factory, the interval d between the two recording element arrays in each of the assembled individuals is measured, and the time difference ΔT between the drive timings of these recording element arrays is changed according to the interval d. With such a configuration, the allowable range of the assembly error Δdn in the manufacturing stage can be widened. As a result, the rate of occurrence of defects can be suppressed, and the cost can be reduced.

[0097]

As described above, according to the present invention,
An optical print head having a plurality of printing element arrays is used, and is driven alternately under a predetermined driving condition. Therefore, even when image formation is performed at a high speed, sufficient recording energy can be provided, and good An image can be formed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an exposure sequence by driving an optical print head according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an exposure sequence following FIG. 1;

FIG. 3 is an explanatory view showing an exposure order following FIG. 2;

FIG. 4 is a timing chart showing light emission timing of a light emitting element array of the optical print head.

FIG. 5 is a timing chart showing another example of the light emission timing of the light emitting element array of the optical print head.

FIG. 6 is a perspective view showing a schematic configuration of a light emitting element array in an optical print head and an arrangement relationship between an image forming unit and an image carrier.

FIG. 7 is a sectional view of an optical print head and an image carrier.

FIG. 8 is a front view illustrating an example of an image forming apparatus on which an optical print head is mounted.

FIG. 9 is an explanatory diagram showing an exposure sequence by driving an optical print head according to a second embodiment of the present invention.

FIG. 10 is an explanatory diagram showing an exposure order following FIG. 9;

FIG. 11 is an explanatory diagram showing an exposure sequence following FIG. 10;

FIG. 12 is a timing chart showing light emission timing of a light emitting element array of the optical print head.

FIG. 13 is a perspective view showing a schematic configuration of a light emitting element array in an optical print head and an arrangement relationship between an image forming unit and an image carrier.

FIG. 14 is a circuit diagram showing a configuration of a self-scanning recording element array chip having a thyristor structure.

FIG. 15 is a block diagram illustrating a configuration of a control system of the self-scanning printing element array.

FIG. 16 is a block diagram illustrating a configuration of a control unit of the self-scanning printing element array.

FIG. 17 is an explanatory diagram illustrating image data stored in an image data storage unit.

[Explanation of symbols]

 1a, 1b Light-emitting element array 2 Image carrier 3 Imaging means 101a, 101b Light-emitting element array 102 Image carrier 103 Imaging means 2005 Light-emitting thyristor

Claims (32)

[Claims] 1. A print head comprising a plurality of printing element arrays in which a plurality of printing elements are arranged in an array, and wherein a plurality of printing element arrays are arranged substantially in parallel, each of the printing element arrays is driven alternately by one line. Print head. 2. A print head comprising a plurality of printing element arrays in which a plurality of printing elements are arranged in an array in two rows substantially in parallel, wherein each of the printing element arrays is driven alternately by one line. Print head. 3. The print head according to claim 2, wherein each of said recording element arrays is driven with a predetermined time difference. 4. The print head according to claim 3, wherein the predetermined time difference is variable. 5. The method according to claim 4, wherein the predetermined time difference is changed according to a resolution of an image to be printed.
Printhead as described. 6. The print head according to claim 4, wherein the predetermined time difference is changed according to the interval between the arrayed recording element arrays. 7. The print head according to claim 1, wherein said recording element is a light emitting element. 8. A function for scanning the printing element array,
7. The print head according to claim 1, wherein the print head is provided inside a chip on which the recording element array is arranged. 9. An image forming apparatus for forming an image on an image carrier by a print head having a plurality of printing element arrays in which a plurality of printing elements are arranged in an array in a substantially parallel manner. An image forming apparatus, wherein each of the arrays is driven alternately by one line. 10. An image forming apparatus for forming an image on an image carrier by a print head having a recording element array in which a plurality of recording elements are arranged in an array in two rows substantially in parallel. An image forming apparatus, wherein each of the arrays is driven alternately by one line. 11. The image forming apparatus according to claim 10, wherein each of said recording element arrays is driven with a predetermined time difference. 12. The image forming apparatus according to claim 11, wherein the predetermined time difference is variable. 13. The image forming apparatus according to claim 12, wherein the predetermined time difference is changed according to a resolution of an image to be printed. 14. The image forming apparatus according to claim 12, wherein the predetermined time difference is changed according to an interval between the arrayed recording element arrays. 15. The image forming apparatus according to claim 9, wherein said recording element is a light emitting element. 16. The image forming apparatus according to claim 9, wherein a function of scanning the printing element array is provided inside a chip on which the printing element array is arranged. 17. A print head comprising a plurality of printing element arrays in which a plurality of printing elements are arranged in an array, and a driving unit for driving each of the printing element arrays, and each of the printing element arrays. Control means for controlling the drive timing of the drive means such that the drive means is alternately driven one line at a time. 18. A print head having a printing element array in which a plurality of printing elements are arranged in an array in two rows substantially in parallel, a driving unit for driving each of the printing element arrays, and each of the printing element arrays Control means for controlling the drive timing of the drive means such that the drive means is alternately driven one line at a time. 19. The print head according to claim 18, wherein said control means controls said drive timing such that each of said print element arrays is driven with a predetermined time difference. 20. The print head according to claim 19, wherein the predetermined time difference is variable. 21. The print head according to claim 20, wherein said control means changes said predetermined time difference according to the resolution of an image to be printed. 22. A print head according to claim 20, wherein said control means changes said predetermined time difference in accordance with an interval between the arranged printing element arrays. 23. The print head according to claim 17, wherein the recording element is a light emitting element. 24. The print head according to claim 17, wherein a function of scanning the print element array is provided inside a chip on which the print element array is arranged. 25. An image forming apparatus for forming an image on an image carrier by a print head having a plurality of printing element arrays in which a plurality of printing elements are arranged in an array in a substantially parallel manner. Image forming apparatus comprising: driving means for driving each of the arrays; and control means for controlling the driving timing of the driving means such that each of the printing element arrays is driven alternately by one line. apparatus. 26. An image forming apparatus for forming an image on an image carrier by a print head having a recording element array in which a plurality of recording elements are arranged in an array in two rows substantially in parallel. Image forming apparatus comprising: driving means for driving each of the arrays; and control means for controlling the driving timing of the driving means such that each of the printing element arrays is driven alternately by one line. apparatus. 27. The image forming apparatus according to claim 26, wherein the control unit controls the drive timing so that each of the print element arrays is driven with a predetermined time difference. 28. The image forming apparatus according to claim 27, wherein the predetermined time difference is variable. 29. The image forming apparatus according to claim 28, wherein the control unit changes the predetermined time difference according to a resolution of an image to be printed. 30. The image forming apparatus according to claim 28, wherein the control unit changes the predetermined time difference according to an interval between the printing element arrays arranged. 31. An image forming apparatus according to claim 25, wherein said recording element is a light emitting element. 32. The image forming apparatus according to claim 25, wherein the function of scanning the printing element array is provided inside a chip on which the printing element array is arranged.