JPH09141929A - Recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep a recording element away from a driving part and to realize thermal isolation by loading the recording element and the driving part for driving it respectively on the different base plates and connecting two base plates by wiring. SOLUTION: A recording head has a light emitting element array chip 101 consisting of a plurality of light emitting elements arranged in a row shape. Recording is performed by controlling the light emitting elements in accordance with a recording signal to be recorded. In this case, the light emitting element array chip 101 and a driving IC 104 for driving the light emitting element are loaded on the different base plates 102, 106. The base plate 106 loaded with the driving IC 104 is connected to the base plate 102 loaded with the light emitting element array chip 101 by flexible cables 103.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording head used as a print head for printers, copying machines, facsimiles and the like.

[0002]

2. Description of the Related Art FIG. 8 is a side view showing the appearance of a conventional recording head. In FIG. 8, 200 is a substrate,
A light emitting element array chip 201 and a driving IC chip 202 for driving it are mounted. The light emitting element array chip 201 and the drive IC chip 202 are connected by wire bonding. Further, a heat dissipation plate 203 is attached to the substrate 200, and is configured to dissipate heat generated by the light emitting element array chip 201 and the drive IC chip 202. As the substrate 200 used, a ceramic substrate or a glass resin having a small coefficient of thermal expansion is used in order to suppress the influence of expansion and contraction due to thermal expansion to a minimum.

FIG. 9A is a plan view of the substrate 200 of FIG. 8 seen from above. A plurality of light emitting element array chips 201 and a plurality of driving IC chips 202 are arranged in rows on the substrate 200. A connector 204 for connecting the recording head to the outside is provided at the corner of the substrate 200. FIG. 9B shows an enlarged view of a portion surrounded by a circle in FIG. 9A. The light emitting element array chip 201 is composed of a large number of light emitting portions 205 arranged in rows, and wiring pads 206 are provided corresponding to the respective light emitting portions 205. Further, the drive IC chip 202 is also provided with wiring pads 206 corresponding to the respective light emitting parts 205,
Wire bonding 2 between both wiring pads 206
By connecting at 07, the light emitting element array chip 201 and the driving IC chip 202 are connected. The drive IC chip 202 includes a drive circuit corresponding to each light emitting unit 205, and recording is performed by controlling each light emitting unit 205.

Further, as a conventional recording head, as proposed in Japanese Patent Application Laid-Open No. 7-186442, a surface emitting type light emitting element array and a drive unit are provided in order to narrow the distance between the recording head and the photosensitive drum. It is also known that they are divided and mounted on the same substrate, and the light emitting element array and the driving unit are connected by wire bonding to emit the light emission output of the surface emitting type light emitting element array in a direction parallel to the substrate surface. .

[0005]

In the conventional recording head, when the recording density of the recording head is increased, the density of the light emitting portion is increased as shown in FIG. 9 (b). Therefore, the light emitting element array chip and the driving IC chip should be separated from each other. The method of connecting by direct wire bonding is adopted. However, in the case where the light emitting element array chip and the driving IC chip are connected by wire bonding in this way, the distance between the light emitting element array chip and the driving IC chip is short, and heat generated in the driving IC chip is easily transferred to the light emitting element array chip. Therefore, there is a problem that the amount of light emitted from the light emitting element array chip is adversely affected.

Generally, it is said that the light amount of the light emitting element of AlGaAs decreases by about 0.6% to 1.0% when the temperature rises by 1 ° C. Therefore, the light amount change of the light emitting element array chip is a negligible light amount change. There wasn't. Further, when the temperature of the light emitting element array chip rises in this way, the substrate on which it is mounted is also heated, so a substrate of a material with a small coefficient of thermal expansion must be used, and there is a problem of high cost. It was Further, when attempting to achieve high density recording of 400 DPI or more, when the light emitting element array chips and the driving IC chips are made to correspond one to one as shown in FIG. Difficult to implement.

In such a case, it is conceivable to dispose the driving IC chips on both sides of the light emitting element array chip and alternately bond the light emitting portions of the light emitting element array chip and the driving IC chips on both sides. However, there is a problem that not only bonding is very difficult, but also the driving IC chip which generates heat cannot be kept away from the driving IC chip, and the higher the density, the greater the influence of heat of the light emitting element.

In view of the above-mentioned conventional problems, the present invention divides the printing element array and the substrate of the driving section for driving the printing element array so that the printing element array and the driving section as a heat source are thermally isolated and driven. It is an object of the present invention to provide a recording head capable of removing the influence of heat generation in a portion.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to have a recording element array composed of a plurality of recording elements arranged in rows, and to control the recording elements according to a recording signal to be recorded. In a recording head for recording, the recording element array and a drive element for driving the recording element are mounted on separate substrates, and a substrate on which the recording element array is mounted,
This is achieved by a recording head characterized in that the substrate on which the drive element is mounted is connected by wiring.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a diagram best representing the features of the present invention. In FIG. 1, 101 is a light emitting element array chip in which a plurality of light emitting elements are formed in a row on the same wafer. The light emitting element array chip 101 is
It has a self-scanning circuit inside, and is configured so that one light emitting element array chip can sequentially emit light by one light emitting signal and three scanning signals. A plurality of light emitting element array chips 101 are mounted in a row on a substrate 102.

Reference numeral 104 denotes a drive IC for driving the light emitting element array chip 101. In this embodiment, one driving IC 104 drives five light emitting element array chips 101. These drive ICs 104
Is a substrate 10 on which the light emitting element array chip 101 is mounted.
It is mounted on a board 106 different from the board 2. In addition to the drive IC 104, a current limiting resistor R for limiting the drive current is mounted on the substrate 106. The current limiting resistance R is 1
One light emitting element array chip 101 is required, and one light emitting element array chip 101 is provided for each light emitting element array chip 101. Further, on the substrate 106, a connector capacitor (not shown) for connecting to the outside
Is provided. The substrate 102 and the substrate 106 are connected by wiring, but here the flexible cable 10
3 are used for connection.

Regarding the self-scanning function of the light emitting element array chip 101, JP-A-1-238962, JP-A-2-208067, JP-A-2-212170, JP-A-3-20457, and JP-A-3-20457. -1949
78, Japanese Patent Application Laid-Open No. 4-5872, Japanese Patent Application Laid-Open No. 4-2
The light emitting element array chip 101 has a self-scanning function, although detailed description is omitted here because it is disclosed in JP-A-3367, JP-A-4-296579, and JP-A-5-84971. As a result, the substrate 102 on which the light emitting element array chip 101 is mounted and the drive I
The number of wires between the boards 106 on which the C104 is mounted is 1
It can be reduced to 1/0. Therefore, an ordinary bundled wire or a flexible cable can be used as the wiring between the two substrates 102 and 106, which keeps the substrate 102 of the light emitting element array chip 101 away from the other substrate 106 such as the driving IC 104. It makes it possible.

FIG. 2 is a diagram showing an example of a case in which the above substrate 102 and substrate 106 are used to form a recording head. In FIG. 2, reference numeral 107 denotes a holding member formed in an L-shaped cross section, the side surface of which is a heat dissipation plate 1 made of aluminum.
08 is attached. On the side of the heat sink 108,
The substrate 106 on which the driving IC 104 and the current limiting resistor R described in FIG. 1 are mounted is attached, and the substrate 102 on which the light emitting element array chip 101 is mounted is attached to the lower part. Therefore, in the example of FIG. 2, the board 102 and the board 106 are arranged on two adjacent surfaces of the heat dissipation plate 108 at an angle of 90 degrees, and the two boards 102 and 106 are placed at the position of the angle of 90 degrees. 103
Connected by At the lower end of the L-shaped holding member 107, a lens fiber array 109 is arranged in a row so as to face the light emitting element array chip 101. Then, the light emitted from each light emitting element of the light emitting element array chip 101 is configured to be applied to the photosensitive drum (not shown) via the lens fiber array 109.

Here, as the flexible cable 103, in the case of a recording head of 600 DIP (length of about 300 mm), the number of lines is about 200, and a flexible cable with a density of 2 lines / mm and a width of about 20 mm is used. It is possible to easily connect the two substrates 102 and 106 by soldering each flexible cable by thermocompression bonding. Further, in FIG. 2, as described above, the substrate 102 is provided on the two surfaces of the aluminum heat sink 108.
Since the current limiting resistor R that generates the most heat is arranged above the substrate 106, the current limiting resistor R on the substrate 106 and the heat of the driving IC 104 are not easily transferred to the substrate 102. Current limiting resistor R
And the driving IC chip 104 as the light emitting element array chip 101.
Can be kept away from the light emitting element array chip 101
Can be significantly reduced as compared with the conventional one. Therefore, in the light emitting element array chip 101,
A thermally stable light emission output can be obtained, and since it is not necessary to use a substrate having a small thermal expansion coefficient as the substrate 102 on which it is mounted, it is possible to reduce the cost.

FIG. 3 is a diagram showing an electrical circuit configuration of the recording head described with reference to FIGS. In this embodiment, one light emitting element array chip 101 is composed of 128 light emitting elements, and one driving IC 104 drives five light emitting element array chips 101. The drive IC 104 is connected in a cascade. Here, when driving the recording head, various signals for driving and controlling the recording head, which are input from a main control circuit (not shown) such as a printer or a copying machine, will be described.
First, print data (8 bits are used here)
Are supplied to the first driving IC 104 connected in cascade. Only the print data is supplied to the first driving IC 104, and the other signals are supplied to the respective driving ICs 104.

ΦS, Φ1, Φ2, and ΦI are timing signals for driving each light emitting element of the light emitting element array chip 101, and SCK, LOADX, RS, and RCK are controls for controlling the recording operation by the light emitting element array chip 101. It is a signal. These signals are supplied to the respective drive ICs 104, and print data is recorded on the photosensitive drum line by line based on these signals, as will be described later in detail. Further, φS, φ1, φ2, and φI are signals created in the drive IC 104 based on the previous φS, φ1, φ2, and φI, respectively, of which φS is five light emission from the drive IC 104 via the resistor R _S. It is supplied to the element array chip 101 and is commonly used by the five light emitting element array chips 101. Further, φI is supplied to the five light emitting element array chips 101 via the respective current limiting resistors R, and φ1,
φ2 is also supplied to each of the five light emitting element array chips 101, and one driving IC 104 drives the five light emitting element array chips 101. In addition,
The operation using each of the above signals will be described later in detail.

FIG. 4 is an equivalent circuit diagram showing the light emitting element array chip 101 in detail. Although only five light emitting elements are shown in FIG. 4, one light emitting element array chip 101 has 128 light emitting elements as described above. In FIG. 4, R _{1 to} R ₅ are resistors of 50 to 100 KΩ, and D _{1 to} D ₆ are diodes. Diode D ₁ ~
D ₅ is connected in series, and the connection point a between the diodes
The other ends of the respective resistors, one end of which is connected to VGA (ground), are connected to (e). SR1 'to SR5' are transfer thyristors, and SR1 to SR5 are light emitting thyristors which are light emitting elements, and the gate terminals of these transfer thyristors and light emitting thyristors are connected to the preceding connection points.

That is, the resistor, the transfer thyristor, and the light emitting thyristor make a pair, and are connected to the gate terminals of the transfer thyristor SR1 'and the light emitting thyristor SR1 from the leading resistor R ₁ through the connection point a. ing. Also,
Transfer thyristor S from the next resistor R ₂ via connection point b
It is connected to R2 'and the gate terminal of the light emitting thyristor SR2. Hereinafter, the configuration is similar.

Next, the operation of the light emitting element array chip 101 will be described with reference to FIG. FIG. 5A shows a start pulse φS. When the level changes from low level to high level, the operation of the light emitting element array chip 101 starts. FIG.
5B shows the drive timing signal φ1, and FIG. 5C shows the drive timing signal φ2. φ1 is an odd-numbered thyristor SR1, SR3 among the transfer thyristors as shown in FIG.
.Phi.2 is supplied to the cathode terminals of SR5 ... And the cathode terminals of even-numbered thyristors SR2 ', SR4'.
Here, when the start pulse φS becomes high level and φ1 changes from high level to low level in this state as shown in FIG. 5B, the leading transfer thyristor SR1 ′ is turned on.

When the transfer thyristor SR1 'is turned on,
Since the gate voltage becomes the anode potential (about 5V),
When the recording signal φI changes from the low level to the high level at the next timing as shown in FIG. 5D, the leading light emitting thyristor SR1 is turned on and emits light for recording during the time T. The light from the light emitting thyristor SR1 is applied to the photosensitive drum (not shown) via the lens fiber array 109 as described with reference to FIG. In this case, the other light emitting thyristors do not emit light because the gate voltage is not 5V.

Next, as shown in FIG. 5D, the recording signal φI
Returns to high level, the first light emitting thyristor SR1
Is turned off, and when .phi.2 changes from high level to low level at the next timing as shown in FIG. 5C, the transfer thyristor SR2 'of the next stage is turned on. That is, the gate voltage (about 5V) is the transfer thyristor SR via a diode D ₁ connected to the gate of the transfer thyristor SR1 '
Since it is connected to the gate of 2 ', the gate voltage of the transfer thyristor SR2' becomes about 3.6V. Therefore, when φ2 goes low in this state, the transfer thyristor SR2 'is turned on.

Subsequently, as shown in FIG. 5B, when φ1 changes from low level to high level, the transfer thyristor SR.
Although 1'is turned off, the transfer thyristor SR2 'maintains the on state, and in this state, the recording signal φ is changed as shown in FIG.
When I goes high, the next light emitting thyristor SR2
Is turned on for a time T, and the emitted light is applied to the photosensitive drum. By repeating this operation 64 times, 128 light emitting thyristors are scanned. In practice,
Since a plurality of light emitting element array chips 101 are provided in a row, scanning is performed by the same operation in other light emitting element array chips.

FIG. 6 is a block diagram showing the drive IC 104 in detail, and FIG. 7 is a time chart showing the signals of the respective parts of the drive IC 104. In FIG. 6, reference numeral 120 is a shift register for fetching print data for each line. In the present embodiment, as described above, the print data is 8 bits, and since one driving IC 104 drives five light emitting element array chips 101 each having 128 light emitting elements, one light emitting element array chip is used. 16 shift registers 120 are provided for each 101, and one drive IC 104 as a whole has 80 shift registers 120.
Is provided. The print data is taken into the shift register 120 in synchronization with the shift clock SCK shown in FIG.

Reference numeral 121 is a latch for holding the data set in the shift register 120. Latch 12
1 is provided corresponding to each shift register 120 (latch capacity is 128 × 5 bits), and the data of each shift register 120 is stored in each latch 121 at the low level timing of the latch clock LOADX in FIG. 7B. Latched. Therefore, the data shift operation and the printing operation can be performed in parallel. In this way, the print data for one line is held.

Reference numeral 122 is a counter for counting the read clock RCK, and 123 is a selector for switching the reading of the data of the latch 123 according to the output of the counter 122. Five selectors 123 are provided corresponding to the five light emitting element array chips 101. More specifically, first, the counter 122 is set to the initial value by the read start signal RS of FIG. 7C, and counts the read clock RCK of FIG. 7C. Each selector 12
In 3, the 128-bit latch data is sequentially output according to the output of the counter 122. FIG. 7E shows the output of the selector 123. Then, when the counter 122 counts up to 128, the selector 123 finishes outputting the 128-bit data, and the counter 122
Is set to the initial value again, and the same operation is repeated thereafter. In this way, recording is performed line by line.

The output signal of each selector 123 is ΦI which determines the light emission timing of the light emitting element by the NAND gate 124.
The signal and the NAND are taken and further output through the buffer 125. This output signal is φI described in FIGS. 4 and 5.
The signal is a recording signal for turning on or off the light emitting element. This signal is sent from each selector 123 to 5
For each light emitting element array chip 101, φI-1,
Output as φI-2 ... φI-5. The ΦS signal described in FIG. 3 is output via the buffer 126. This signal φS is used as the start signal of the light emitting element array chip 101 as described above.

The Φ1 signal is output via the buffer 127 and the resistor 128, and is output as the Φ1 signal described with reference to FIGS. φ1 signal is 5 light emitting element array chip 1
01 is supplied as φ1-1, φ1-2, ... φ1-5. The φ2 signal is also output via the buffer 127 and the resistor 128, which also includes the five light emitting element array chips 10.
1 is supplied as φ2-1, φ2-2, ... φ2-5. The ICONT signal is a control signal for adjusting the current values of the φ1 signal and the φ2 signal. As described above, the drive IC 104 generates a signal for driving the light emitting element array chip 101 based on various input signals, and as described with reference to FIGS. 4 and 5, the light emitting element array chip 101.
To control the operation of the individual light emitting elements within. As a result, the light emitting elements arranged in a row emit light or turn off according to the recording signal, and perform recording on the photosensitive drum.

In the above embodiments, the recording head using the light emitting element array chip having the self-scanning function has been described as an example, but the present invention is not limited to this, and the same process as the light emitting element is used for scanning. Shift register made on the same chip, shift register made on silicon and GaAs light emitting element made on it, or vice versa, m elements in n-dimensional matrix form The number of drive wires is (n × m) ^{1 / n}
It is also possible to apply to those reduced to.
The present invention is also effective for a device using an element that controls light transmission and reflection such as liquid crystal.

Further, in the above embodiment, the two substrates are connected by using the flexible cable.
When connecting the substrate 106 and the substrate 106, since the number of wires is small, so-called flat cable bundles and the like may be used in addition to the flexible cable. Moreover, since the connection density of the wiring is low, the connection is not limited to the solder thermocompression bonding, and an ordinary connector can be used.

Further, in the embodiment, the heat dissipation plate 108 is shown in FIG.
However, the substrate 102 may be attached to the bottom surface of the substrate 102 and the side surface of the substrate 106, for example. By doing this, the substrate 1
Since the protrusion of 06 is eliminated, the size of the recording head can be further reduced. Further, in the embodiment, two substrates 1
Although 02 and 106 are connected by the flexible cable 103, since the substrate 106 on which the driving IC 104 is mounted is not required to have flatness, the driving IC 104 may be mounted on the flexible substrate using a flexible substrate. Therefore, in this case, since the connection on the drive IC 104 side is eliminated, the labor of the work can be saved and the cost required for manufacturing can be reduced.

[0031]

As described above, the present invention has the following effects. (1) By mounting the printing element and the driving unit for driving the printing element on different substrates and connecting the two substrates by wiring, the printing element can be kept away from the driving unit, and thermal isolation can be realized. it can. Therefore, it is possible to eliminate the influence of heat generation of the drive unit of the recording element and obtain stable recording output. (2) Since the substrate of the recording element can be thermally isolated, it is possible to minimize the use of an expensive substrate having a small coefficient of thermal expansion, and the cost can be reduced accordingly. (3) Since the recording element and the substrate of the driving unit are divided into two, each substrate can be attached to two surfaces of the heat dissipation plate, and the area occupied by the recording head can be reduced. Therefore,
The photosensitive drum having a smaller diameter can be used, and the device can be downsized. (4) Since the area of the substrate of the recording element is small, it is possible to reduce the number of steps required to secure the highly accurate flatness required for this substrate, for example, the processing cost for polishing the heat sink to which this is attached. Therefore, the cost can be reduced accordingly. (5) Since the substrates for the recording element and the driving element are divided into two,
Compared to the case where the light emitting element and the drive unit are mounted on one board,
The yield when the substrate is completed is improved, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a plan view showing a configuration example of a main part of a recording head of the present invention.

FIG. 2 is a front view showing the outer appearance of the recording head of the present invention.

FIG. 3 is a block diagram showing an example of an electrical circuit configuration of the recording head of the present invention.

FIG. 4 is a circuit diagram showing an example of a light emitting element array chip used in the recording head of the present invention.

5 is a time chart for explaining the operation of the light emitting element array chip of FIG.

FIG. 6 is a block diagram showing an example of a drive IC used in the recording head of the present invention.

FIG. 7 is a time chart for explaining the operation of the drive IC of FIG.

FIG. 8 is a side view showing the outer appearance of a conventional recording head.

9 is a plan view of the recording head of FIG.

[Explanation of symbols]

101 light emitting element array chip 102 substrate 103 flexible cable 104 driving IC 106 substrate 107 holding member 108 heat sink 109 lens fiber cable 110 connector 120 shift register 121 latch 122 counter 123 selector 124 NAND gate 125 to 126 buffer R current limiting resistance D _{1 to} D ₅ Diodes SR1 'to SR5' Transfer thyristors SR1 to SR5 Light emitting thyristors

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takahiro Watanabe 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Naohisa Nagata 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. Incorporated (72) Inventor Hiroshi Tanioka 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yoshio Komaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hideyuki Tanaami 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Shigemi Kumagai 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Invention Person Shigeo Hatake 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (6)

[Claims] 1. A recording head comprising a recording element array composed of a plurality of recording elements arranged in a line, and performing recording by controlling the recording elements according to a recording signal to be recorded. A recording head, wherein an array and a driving element for driving the recording element are mounted on separate substrates, and the substrate on which the recording element array is mounted and the substrate on which the driving element is mounted are connected by wiring. . 2. The recording head according to claim 1, wherein:
The recording head, wherein the recording element array is internally provided with a self-scanning circuit so as to sequentially select a recording operation of the recording elements. 3. The recording head according to claim 1, wherein:
The recording head, wherein the wiring is a flexible cable. 4. The recording head according to claim 1, wherein:
The recording head, wherein the substrate on which the recording element array is mounted and the substrate on which the driving element is mounted are attached to two adjacent surfaces of a heat dissipation plate. 5. The recording head according to claim 1, wherein:
A recording head, wherein the recording element is a light emitting element that performs recording by emitting / turning off light. 6. The recording head according to claim 1, wherein:
The drive element, means for holding data to be recorded,
A recording head comprising means for sequentially and serially outputting the data of the holding means to the plurality of recording elements.