JPH10309822A - Optical print head and image forming equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a good latent image without shortening the exposure time for light from a light-emitting element even in high-speed processing for image formation, by making an optical print head furnished with two rows of light- emitting elements emit light in accordance with prescribed driving conditions. SOLUTION: The interval d of light-emitting element rows 1a, 1b in the direction Y perpendicular to the row direction X is expressed by d=P×N (P is an image resolution pitch, N is an odd number such as 1, 3, 5...). As for the sequence of exposure, the first exposure line is recorded on an image carrier 2 by the light-emitting element row 1a, 1b. The two light-emitting elements rows 1a, 1b are driven so that the exposure line may be formed when the image carrier 2 rotates and an exposure line by the first light-emitting element row 1a which performs nth (n= 1, 2, 3...), arrives at a position distanced to the upstream side by one image resolution pitch P from an exposure line by the second light-emitting element row 1b which performed exposure n-((N-1)/2) th.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical print head used as a light source of an exposure system, and an image forming apparatus such as a printer, a facsimile, and a copying machine for forming a monochrome image and a color image.

[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. In the apparatus, as an exposure system for forming a latent image corresponding to an image signal output from an external computer or an image reading system on an image carrier, a light source including a light source in which light emitting elements such as light emitting diodes are arrayed is used. Some printheads are used. The optical print head is small and can easily constitute a quiet image forming apparatus.

A light emitting element in such an optical print head is constituted by a light emitting diode or the like, and these elements emit diffused light from a certain point or a certain surface, and thus the light emitting element is disposed 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.

[0004]

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, so that a good latent image cannot be obtained. There are cases.

An object of the present invention is to provide an optical print head and an image printing apparatus capable of forming a good latent image without shortening the exposure time and forming an image without unevenness even in high-speed image processing. An object of the present invention is to provide a forming apparatus.

[0007]

According to the present invention, there is provided a light emitting element array comprising a plurality of light emitting elements arranged substantially in parallel with each other in two rows, and the light emitting element row is exposed to an image carrier using the light emitting element rows. When an image resolution pitch in a direction perpendicular to the arrangement direction of the light emitting element rows is P, an arrangement interval d in a direction perpendicular to the arrangement direction of the light emitting element rows is

[0008]

## EQU00002 ## A light emitting portion formed so that d = P.times.N (N = 1, 3, 5...: N is an odd number), and a light flux from a light emitting element array of the light emitting portion is formed on the image carrier. Imaging means for forming an image on
The exposure line of the first light-emitting element row for performing the n-th (n = 1, 2, 3,...) Exposure of the light-emitting section is n-
The image resolution pitch P from the exposure line of the second ((N-1) / 2) -th light-emitting element row that has been exposed
Driving means for driving the two light-emitting element rows so as to form the n-th exposure line when the light-emitting element reaches a position at a distance upstream by one pitch. Construct the head.

Here, when N is an odd number of 3 or more, the first to (N-1) / 2-th exposures are performed using only the second light-emitting element row and starting from the last exposure line. (N-
It is possible to provide a control means for controlling so that only the first light emitting element row is used for the first and second exposures.

[0010] The imaging means may be constituted by an imaging element array comprising a plurality of imaging elements arranged substantially in parallel with the light emitting element array and corresponding to each light emitting element. Further, each of the imaging elements can be constituted by a rod lens.

Each of the light emitting elements can use a light emitting diode.

Each of the light-emitting element rows is constituted by arranging a plurality of light-emitting thyristors capable of electrically controlling a threshold voltage or a threshold current. Connected with electrical elements
Self-scanning can be performed by a two-phase transfer clock.

According to the present invention, there is provided an electrophotographic image forming apparatus which forms a light beam emitted from a light source by an image forming means and exposes the formed light beam on an image carrier to visualize the image. An image forming apparatus, wherein the optical print head described above is provided as the light source, and the optical print head is arranged such that the arrangement direction of the light emitting element rows is a direction orthogonal to the rotation direction of the image carrier. The device can be configured.

[0014]

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

A first embodiment will be described with reference to FIGS.

First, an outline of the entire configuration of the present apparatus is shown in FIGS.
This will be described with reference to FIG. FIG. 7 shows the optical print head 3.
0, the schematic shape of the light emitting element arrays 1a and 1b,
2 and an arrangement relationship with the image carrier 2. FIG. 8 is a cross-sectional view of the optical print head 30 and the image carrier 2 to which the optical print head 30 exposes. FIG. 9 shows the optical print head 3.
1 shows an example of an image forming apparatus in which the image forming apparatus 0 is mounted.

In FIG. 7, 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
3 times the image resolution pitch P in the direction Y orthogonal to b (d = 3
P). 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. 7, 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. 8, in the optical print head 30, a chip 1, a driver chip 5 for driving each light emitting element, a not-shown limiting resistor, 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. 9, the optical print head 30 is incorporated in an image forming apparatus as an exposure device.

Here, the operation will be described by taking a copying machine as an example of the image forming apparatus.

A document placed on the document table 24 is read by the reading system 11 and converted into image data. On the other hand, the recording material 80 is fed to the feeding rollers 13 and 14 in the main body.
Alternatively, the recording material 80 is fed from the outside of the main body via the feeding roller 15, and when the position of the registration rollers 16a and 16b is reached, the leading end position of the recording material 80 is detected by a sensor (not shown). 16b. On the other hand, in accordance with the image data from the optical print head 30, charging is performed by the charger 17 in advance, and the image carrier 2 is rotated in the direction of the arrow in FIG.
To form an electrostatic latent image. 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 up to the position on the transfer device 19, and
The developer 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 80
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. 1 to 6 show exposure patterns formed by driving the optical print head 30. FIG.

In FIGS. 1 to 6, each figure 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. Lines with a large number of circles (○) on the exposure line indicate that exposure has been performed at that time in each figure, and black circles (●) on each line indicate that each line has an image bearing. Indicates that there is data recorded on the body 2 or data already recorded. Note that P indicates an image resolution pitch in a direction Y orthogonal to the column direction X of the light emitting element rows 1a and 1b, and the exposure line near the upstream side of the screen is closer to the first light emitting element row 1a side. Indicates that.

In FIG. 1A, first exposure lines a and b are recorded on the image carrier 2 by the light emitting element arrays 1a and 1b. Thus, the distance between the exposure lines a and b recorded by the light emitting element rows 1a and 1b is three times the resolution pitch P, which is the distance d between the light emitting element rows 1a and 1b.

Then, in FIG. 1B, the image carrier 2
Is rotated and moved, so that the next light emitting element row 1
The position to be recorded on the side a (upstream side) corresponds to the image resolution pitch P from the already recorded exposure line b.
The light-emitting element arrays 1a and 1b emit light at the moment when the light-emitting element arrays 1a and 1b reach a position spaced apart from the light-emitting element array 1a by the pitch, thereby completing the exposure of the second exposure lines a and b.

In FIG. 2, when the third exposure lines a and b are formed, similarly to the formation of the second exposure line, the position where the next light emitting element array 1a is to be recorded is the same as that of the previously recorded exposure line. From line b to resolution pitch (1
Exposure is performed when the light-emitting element array 1a reaches a position spaced apart by a distance of (pitch).

Thereafter, similarly, as shown in FIGS.
When the recording position of the next light emitting element row 1a reaches the light emitting element row 1a by one pitch from the position of the exposure line b recorded at the (n-1) th (n = 2, 3,...) The image is sequentially formed by forming the exposure lines of the above.

When the final exposure lines are a and b, image formation is completed in the state of FIG. 6, but the exposure line a and the final exposure line b are not used for image formation. The reason for this is that there is an interval of twice the image resolution pitch P between the exposure lines a and a and between the exposure lines b and b. This is to prevent a part from being created. For this reason, the image data is also formed so as to start from the exposure line a and end at the end of the image at the exposure line b.

The light emitting element may be a light emitting diode, in which a large number of light emitting thyristors capable of electrically controlling a threshold voltage or a threshold current are arranged. The self-scanning may be performed by a two-phase transfer clock by connecting with an electric element having one direction. The thyristor structure will be described later.

The use of the optical print head 30 as described above allows the chips 1 of the light emitting element arrays 1a and 1b to be designed with a high degree of freedom, but without reducing the amount of light.
High-speed image formation can be performed, and an image without unevenness in resolution can be obtained.

Further, the distance d between the light emitting element rows 1a and 1b in the direction Y orthogonal to the column direction X is set to be three times the image resolution pitch P in the orthogonal direction Y.
The element row interval can be increased, and the degree of freedom in design can be increased.

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

FIG. 16 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. Figure 10
FIG. 15 shows an exposure pattern.

The configuration of the optical print head 30 of this embodiment is basically the same as that of the optical print head 30 of the first embodiment. 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
This is an example in which the image resolution pitch P is five times the image resolution pitch P in the direction Y orthogonal to 101b (d = 5P).

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 sequence of exposing the light emitting element arrays 101a and 202b will be described with reference to FIGS. FIG.
In FIG. 0 to FIG. 15, each figure is described from FIG. 10 to FIG. 15 with time. ,... Indicate the exposure order of each exposure line, and the suffixes a and b indicate which of the light emitting element arrays 101a and 101b is the line recorded. In addition, the exposure line of the light emitting element row 101a is indicated by a solid line, and
The line b is indicated by a broken line. Lines with a large number of circles (○) on the exposure line indicate that exposure has been performed at that time in each figure, and black circles (●) on each line indicate that each line has an image bearing. This indicates that there is data to be recorded on the body 102 or data that has already been recorded. P indicates an image resolution pitch in a direction Y orthogonal to the column direction X, and an upstream side in the drawing indicates that the exposure line is closer to the first light emitting element column 1a side.

In FIG. 10, first, the light emitting element arrays 101a and 101a
01b, the first exposure lines a and b
Are simultaneously recorded on the image carrier 102. This allows
The distance between the exposure line a and the exposure line b recorded by the light emitting element rows 101a and 101b is five times the resolution pitch P, which is the distance d between the light emitting element rows 101a and 101b.

Then, in FIG. 11, the image carrier 102
Is rotated and moved, so that the next light emitting element row 1
The light is emitted at the moment when the position to be recorded on the 01a side (upstream side) reaches the position at a distance of twice the image resolution pitch P from the already recorded exposure line b to the light emitting element row 101a side. The element arrays 101a and 101b emit light, thereby completing the exposure of the second exposure lines a and b.

In FIG. 12, when the third exposure lines a and b are formed, the light emitting element row 101 is formed.
Exposure is performed when the position to be recorded a reaches a position spaced apart from the b that was exposed two times before by the resolution pitch (one pitch) toward the light emitting element array 101a side.

Similarly, as shown in FIGS. 13 to 15, the light emitting element array 101a is shifted by one pitch of the (n-2) th (n = 1, 2, 3,...) Exposure line b. When the recording position of the next light emitting element array 101a reaches
An image is sequentially formed by forming the second exposure line.

When the final exposure lines are a and b, the image formation is completed in the state of FIG. 15, but the exposure lines a and a and the exposure lines b and b are not used for image formation. . The reason is that the distance between the exposure lines a and a, between the exposure lines a and a, between the exposure lines b and b, and between the exposure lines b and b are twice the image resolution pitch P. This is because there is an interval between minutes, and this is to prevent a portion having a different resolution from being created at the beginning and the end of the image. For this reason, the image data is also formed so as to start from the exposure line a and end at the rear end of the image at the exposure line b.

Also in this embodiment, the light emitting element may be a light emitting diode, in which a large number of light emitting thyristors capable of electrically controlling a threshold voltage or a threshold current are arranged. Self-scanning may be performed by a two-phase transfer clock by connecting each other with an electric element having unidirectional voltage or current. The thyristor structure will be described later.

By using the optical print head 30 of the present embodiment as described above, the light emitting element arrays 101a, 101
The 01b chip 1 can be used for image formation at high speed without any reduction in light amount and with no unevenness in resolution, while allowing more freedom in design.

Further, in this example, the interval d in the direction Y orthogonal to the column direction X is set to be five times the image resolution pitch P, so that the degree of freedom in design is further improved than in the first embodiment. Can be expanded.

FIG. 17 shows an equivalent circuit configuration of a self-scanning recording element array chip 2102 having a thyristor structure according to the present invention. The self-scanning printing element array chip 2102 is formed by a light-emitting element array of a self-scanning printing element array composed of thyristors. Then, such a linear light emitting element array is arranged on the substrate as two light emitting element arrays, similarly to the above-described chip 1 in FIG. 7 and the chip 101 in FIG.

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 V _Ga via the load resistor 2003. Further, transfer clocks φ1 and φ2 for the transfer operation are applied to the cathode of thyristor 2004.

Now, assuming that thyristor 2004 is 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.

FIGS. 18 and 19 show a control section of the self-scanning recording element array. Reference numeral 2101 denotes a driver unit and a buffer unit of the self-scanning printing element array. 22
01 denotes each self-scanning recording element array chip 21
02 corresponds to the buffer unit. Reference numeral 2202 denotes an image data storage unit, and 2203 denotes a data distribution unit. FIG.
The image data stored in the image data storage unit 2202 is shown. A1 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 are image data to be printed by the second self-scanning recording element array chip 2102 in the first column. B1 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 transferred to the buffer unit 220 corresponding to each self-scanning printing element array chip 2102 by the data distribution unit 2203.
1 and the necessary clocks are added as described above and transferred to each self-scanning printing element array chip 2102 together with the print data clock. in this way,
Self-scanning can be performed by two-phase transfer clocks φ1 and φ2. In addition, in the present example, regarding the control of performing exposure under predetermined conditions simultaneously using two rows of light emitting elements,
The operation can be performed in the same manner as in the above-described embodiment, and the description thereof is omitted.

[0050]

As described above, according to the present invention,
An optical print head having two light emitting element rows is used to emit light under a predetermined driving condition. Therefore, even if image formation is performed at a high speed, the exposure time of light from the light emitting elements is not shortened, so that it is preferable. A latent image can be formed. In addition, this eliminates the presence of portions having different resolutions in the formed image, so that an image can be formed with high quality without unevenness.

[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 an explanatory view showing an exposure order following FIG. 3;

FIG. 5 is an explanatory diagram showing an exposure sequence following FIG. 4;

FIG. 6 is an explanatory diagram showing an exposure sequence following FIG. 5;

FIG. 7 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. 8 is a sectional view of an optical print head and an image carrier.

FIG. 9 is a front view illustrating an example of an image forming apparatus on which an optical print head is mounted.

FIG. 10 is an explanatory diagram showing an exposure sequence by driving an optical print head according to a second embodiment of the present invention.

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

FIG. 12 is an explanatory view showing an exposure order following FIG. 11;

FIG. 13 is an explanatory view showing an exposure order following FIG. 12;

FIG. 14 is an explanatory diagram showing an exposure sequence following FIG. 13;

FIG. 15 is an explanatory diagram showing an exposure order following FIG. 14;

FIG. 16 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. 17 is a circuit diagram showing a configuration of a self-scanning recording element array chip having a thyristor structure.

FIG. 18 is a block diagram illustrating a configuration of a control system of the self-scanning printing element array.

FIG. 19 is a block diagram illustrating a configuration of a control unit of the self-scanning printing element array.

FIG. 20 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 (7)

[Claims] 1. A light-emitting element array comprising a plurality of light-emitting elements is arranged in two rows substantially in parallel to each other, and the arrangement direction of the light-emitting element rows when an image carrier is exposed using the light-emitting element rows. When the image resolution pitch in the orthogonal direction is P, the array interval d in the direction orthogonal to the array direction of the light emitting element row is: d = P × N (N = 1, 3, 5...) : N is an odd number); an image forming means for forming a light beam from the light emitting element array of the light emitting unit on the image carrier; and n (n = 1) of the light emitting unit. , 2, 3...), The exposure line of the first light-emitting element row to be exposed is n-
The image resolution pitch P from the exposure line of the second ((N-1) / 2) -th light-emitting element row that has been exposed
And driving means for driving the two light-emitting element rows so as to form the n-th exposure line when the light-emitting element reaches a position at a distance upstream by one pitch. Optical print head. 2. When N is an odd number of 3 or more, the first to (N−1) / 2-th exposures are performed using only the second light-emitting element column, and starting from the last exposure line. N-1)
2. The optical print head according to claim 1, further comprising control means for performing control so as to use only the first light emitting element row for exposing up to the second light. 3. The image forming device according to claim 2, wherein the image forming unit is arranged substantially in parallel with the light emitting element array and includes an image forming element array including a plurality of image forming elements corresponding to each light emitting element. Item 3. The optical print head according to item 1 or 2. 4. The optical print head according to claim 3, wherein each of said imaging elements is constituted by a rod lens. 5. The optical print head according to claim 1, wherein each of the light emitting elements is a light emitting diode. 6. Each of the light emitting element rows is constituted by arranging a plurality of light emitting thyristors capable of electrically controlling a threshold voltage or a threshold current, and the light emitting thyristors in the vicinity are arranged in one direction of a voltage or a current. 6. The optical print head according to claim 1, wherein the optical print head is connected by an electric element having a characteristic and performs self-scanning by a two-phase transfer clock. 7. An electrophotographic image forming apparatus for forming an image of a light beam emitted from a light source by an image forming means, and exposing the imaged light beam on an image carrier to visualize the image. The optical print head according to claim 1 is provided as the light source, and the optical print head is arranged such that the arrangement direction of the light emitting element rows is a direction orthogonal to the rotation direction of the image carrier. An image forming apparatus comprising: