US-12625044-B2 - Methods and apparatus to perform load measurements on flexible substrates

US12625044B2US 12625044 B2US12625044 B2US 12625044B2US-12625044-B2

Abstract

An example flexible substrate testing system includes: a first substrate support structure configured to hold stationary a first portion of a flexible substrate under test; a second substrate support structure configured to hold a second portion of the flexible substrate; an actuator configured to move the second substrate support structure to fold the flexible substrate and to unfold the flexible substrate; and a load cell configured to measure a load on the flexible substrate.

Inventors

Philippe Levesque
Alexander T. Carbone
Christopher Joyce

Assignees

ILLINOIS TOOL WORKS INC.

Dates

Publication Date: 20260512
Application Date: 20240130

Claims (20)

1 . A flexible substrate testing system, comprising: a first substrate support structure configured to hold stationary a first portion of a flexible substrate under test; a second substrate support structure configured to hold a second portion of the flexible substrate; an actuator configured to move the second substrate support structure to fold the flexible substrate and to unfold the flexible substrate; a load cell configured to measure a load on the flexible substrate; and a flexure configured to hold the first substrate support structure and to limit motion for the first substrate support structure to a direction in which the load cell is configured to measure the load.
2 . The flexible substrate testing system as defined in claim 1 , further comprising a first guide configured to guide a motion of the second substrate support structure to fold the flexible substrate and to unfold the flexible substrate.
3 . The flexible substrate testing system as defined in claim 2 , wherein the first guide is configured to guide the motion of the second substrate support structure in accordance with a first predetermined bend radius of the flexible substrate.
4 . The flexible substrate testing system as defined in claim 1 , further comprising: a first guide configured to guide a motion of the second substrate support structure to fold the flexible substrate and to unfold the flexible substrate, wherein the first guide is configured to guide the motion of the second substrate support structure in accordance with a first predetermined bend radius of the flexible substrate and wherein the first guide is interchangeable with a second guide configured to guide the motion of the second substrate support structure in accordance with a second predetermined bend radius of the flexible substrate.
5 . The flexible substrate testing system as defined in claim 4 , wherein the first guide comprises a first guide plate having a groove configured to guide a cam follower attached to the second substrate support structure.
6 . The flexible substrate testing system as defined in claim 1 , further comprising: a first guide configured to guide a motion of the second substrate support structure to fold the flexible substrate and to unfold the flexible substrate wherein the first guide comprises a first guide plate having a groove configured to guide a cam follower attached to the second substrate support structure and the first guide plate comprises an actuator groove configured to guide an actuator pin coupled to the second substrate support structure and positioned within the actuator groove, wherein the actuator is configured to move the second substrate support structure by moving the actuator pin.
7 . The flexible substrate testing system as defined in claim 6 , wherein the first guide is configured to guide the motion of the second substrate support structure without incurring additional stress on the flexible substrate due to the motion or weight of the second substrate support structure.
8 . The flexible substrate testing system as defined in claim 6 , further comprising a second guide plate coupled to the second substrate support structure and on an opposite side of the second substrate support structure from the first guide, the second guide plate configured to guide the motion of the second substrate support structure to fold the flexible substrate and to unfold the flexible substrate.
9 . The flexible substrate testing system as defined in claim 1 , further comprising a load limiter configured to limit displacement of the first substrate support structure toward the load cell.
10 . The flexible substrate testing system as defined in claim 1 , further comprising control circuitry configured to determine the load on the flexible substrate based on load information from the load cell.
11 . The flexible substrate testing system as defined in claim 10 , wherein the control circuitry is configured to determine the load on the flexible substrate based on a dynamic load measured by the load cell during the folding or unfolding of the flexible substrate.
12 . The flexible substrate testing system as defined in claim 10 , wherein the control circuitry is configured to determine the load on the flexible substrate based on a static load measured by the load cell at a completion of the folding or unfolding of the flexible substrate.
13 . The flexible substrate testing system as defined in claim 1 , further comprising control circuitry configured to control the actuator to move the second substrate support structure in a first direction to fold the flexible substrate or in a second direction to unfold the flexible substrate.
14 . The flexible substrate testing system as defined in claim 1 , wherein the flexure, the first substrate support structure, and the second substrate support structure are coupled to same base plate.
15 . The flexible substrate testing system as defined in claim 1 , wherein the load cell is configured to measure the load on the first portion of the flexible substrate.
16 . The flexible substrate testing system as defined in claim 1 , wherein the load cell is configured to measure at least a portion of the load on the second portion of the flexible substrate.
17 . The flexible substrate testing system as defined in claim 16 , further comprising control circuitry configured to compensate a load measurement from the load cell for a weight of the second substrate support structure and an inertial load of the second substrate support structure during folding or unfolding, and to determine at least a portion of the load on the flexible substrate based on load information from the load cell and the compensation.
18 . The flexible substrate testing system as defined in claim 16 , further comprising a second load cell configured to measure a portion of the load on the first portion of the flexible substrate.
19 . A method to measure loads on a flexible substrate, the method comprising: holding stationary, via a substrate support structure, a first portion of a flexible substrate under test; moving, via an actuator, a second portion of the flexible substrate to fold the flexible substrate or to unfold the flexible substrate; limiting motion, via a flexure, for the first portion of the substrate support structure in a direction parallel to the first portion of the substrate support structure; and measuring a load on the flexible substrate resulting from the moving.
20 . A flexible substrate testing system, comprising: a first plate comprising a first surface configured to hold stationary a first side of a flexible substrate under test; a flexure configured to hold the first plate and to limit motion of the first plate in directions parallel to the first surface of the first plate; a second plate comprising a second surface configured to hold a second side of the flexible substrate; a first guide plate configured to guide a motion of the second surface to fold the flexible substrate and to unfold the flexible substrate; an actuator configured to move the second plate in accordance with the first guide plate to fold the flexible substrate and to unfold the flexible substrate; and a load cell configured to measure loads on the first plate while the actuator moves the second plate.

Description

RELATED APPLICATIONS The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/865,634, filed Jun. 24, 2019, entitled “METHODS AND APPARATUS TO PERFORM LOAD MEASUREMENTS ON FLEXIBLE SUBSTRATES.” The entirety of U.S. Provisional Patent Application Ser. No. 62/865,634 is expressly incorporated herein by reference. BACKGROUND This disclosure relates generally to materials testing, and more particularly, to methods and apparatus to perform load measurements on flexible substrates. Reliability testing for an assembly, or moving components of an assembly, may involve repetitively performing intended and/or unintended movements of the components to verify that the components and/or assembly reliably operates for a defined minimum number of cycles of the movements. For example, reliability testing of a flexible substrate may involve repeatedly flexing the substrate in one or more ways, while testing for continued operation of the device and/or monitoring various modes of failure. SUMMARY Methods and apparatus to perform load measurements on flexible substrates are disclosed, substantially as illustrated by and described in connection with at least one of the figures, as set forth more completely in the claims. BRIEF DESCRIPTION OF THE DRAWINGS These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: FIG. 1A is a block diagram of an example flexible substrate test system to perform mechanical property testing on a flexible substrate, in accordance with aspects of this disclosure. FIG. 1B is a block diagram of another example flexible substrate test system to perform mechanical property testing on the flexible substrate. FIG. 2 is a block diagram of an example implementation of the flexible substrate test system of FIG. 1A. FIG. 3 is a perspective view of an example implementation of the flexible substrate test system of FIG. 1A. FIG. 4 is an elevation view of the example substrate test system of FIG. 1A, including a guide plate. FIG. 5 is a partially exploded view of the translation linkage of FIG. 3. FIG. 6 is a perspective view of the example flexible substrate test system of FIG. 3 in which the second plate has been moved to position to fold the substrate under test. FIG. 7 is a perspective view of another example implementation of the flexible substrate test system of FIG. 1A. FIG. 8 is an elevation view of the example flexible substrate test system of FIG. 7. FIG. 9 is a plan view of the example flexible substrate test system of FIG. 7. FIG. 10 is an elevation view of the example flexible substrate test system of FIG. 7. FIG. 11 is a more detailed view of the example first plate, the flexures, and the load cell of FIG. 7. FIG. 12 is a flowchart representative of an example method to measure loads on a flexible substrate, which may be performed by the example flexible substrate test systems of FIGS. 1A-11. The figures are not necessarily to scale. Wherever appropriate, similar or identical reference numerals are used to refer to similar or identical components. DETAILED DESCRIPTION Conventional flexible substrate testing systems do not measure loads or stresses on the flexible substrates during folding or unfolding. Instead, conventional flexible substrate testing systems may involve testing such as defect analysis and other static testing and analysis. Disclosed example flexible substrate testing systems and methods provide stress testing for flexible substrates, including measurement of dynamic and/or static loads on the flexible substrate during deformation such as folding and/or unfolding. Some disclosed example systems and methods reduce or minimize additional stress induced on the flexible substrate by the flexible substrate testing system itself. For example, some disclosed flexible substrate testing systems include fixturing that provides repetitive folding and unfolding of a flexible substrate, such as a flexible display screen. Disclosed examples configure the fixturing, such as guiding of the moving parts, such that the fixturing does not create additional compression or tension on the flexible substrate as the ends of the substrate are folded together or unfolded. Disclosed example flexible substrate testing systems include: a first substrate support structure configured to hold stationary a first portion of a flexible substrate under test; a second substrate support structure configured to hold a second portion of the flexible substrate; an actuator configured to move the second substrate support structure to fold the flexible substrate and to unfold the flexible substrate; and a load cell configured to measure a load on the flexible substrate. Some example flexible substrate testing systems further include a first guide configured to guide a moti